|
Cytotoxic activity evaluated against A549 tumor cells
|
Homo sapiens
|
24.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic Activity was evaluated against D54 tumor cells
|
Homo sapiens
|
230.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
In vitro inhibition of Pneumocystis carinii (Pc) dihydrofolate reductase.
|
Escherichia coli
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Inhibition of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductases by 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines: marked improvement in potency relative to trimethoprim and species selectivity relative to piritrexim.
Year : 2002
Volume : 45
Issue : 1
First Page : 233
Last Page : 241
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : A series of previously undescribed 2,4-diamino-5-[2-methoxy-5-alkoxybenzyl]pyrimidines (3a-e) and 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines (3f-k) with up to eight CH2 groups in the alkoxy or omega-carboxyalkyloxy side chain were synthesized and tested for the ability to inhibit partially purified dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat liver in comparison with two standard inhibitors, trimethoprim (1) and piritrexim (2). The latter drug is known to be extremely potent but shows a marked preference for binding to mammalian DHFR, whereas the former is very selective for the parasite enzymes but is a much weaker inhibitor. The underlying strategy for the synthesis of compounds 3a-k was that a hybrid structure embodying some features of both 1 and 2 might possess a more favorable combination of potency and selectivity than either parent drug. The choice of analogues 3f-k was based on the idea that the acidic omega-carboxyl group might interact preferentially with a basic center in the active site of DHFR from any of the parasite species relative to the active site of mammalian DHFR. In addition, the omega-carboxyl group was expected to improve water solubility relative to 1 or 2. In standardized spectrophotometric assays with dihydrofolate as the substrate and NADPH as the cofactor, 2,4-diamino-5-[(2-methoxy-4-carboxybutyloxy)benzyl]pyrimidine (3g) inhibited Pc DHFR with an IC(50) of 0.049 microM and rat DHFR with IC(50) of 3.9 microM. Its potency against Pc DHFR was 140-fold greater than that of 1 and close to that of 2, and its selectivity index, defined as the ratio IC(50)(rat liver)/IC(50)(P. carinii), was 8-fold higher than that of 1 and >10(4)-fold higher than that of 2. Although it was less potent and less selective against Tg than Pc DHFR, it was very potent as well as highly selective against Ma DHFR, with an IC(50) of 0.0058 microM and an IC(50)(rat liver)/IC(50)(M. avium) ratio of >600. Because of this favorable combination of potency and selectivity relative to 1 and 2, compound 3g may be viewed as a promising lead in the search for new antifolates with potential clinical activity against P. carinii and other opportunistic pathogens in patients with AIDS.
|
Inhibition of Pneumocystis carinii dihydrofolate reductase
|
None
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 5-methyl-5-deaza nonclassical antifolates as inhibitors of dihydrofolate reductases and as potential antipneumocystis, antitoxoplasma, and antitumor agents.
Year : 1993
Volume : 36
Issue : 22
First Page : 3437
Last Page : 3443
Authors : Gangjee A, Shi J, Queener SF, Barrows LR, Kisliuk RL.
Abstract : A series of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines 4-9 were synthesized as 5-deaza nonclassical antifolates containing trimethoxy, dichloro-, or trichlorophenyl substitutions and a N-H, N-CH3, or N-CHO at the 10-position. The compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (P. carinii), Toxoplasma gondii (T. gondii), rat liver (RL), and Lactobacillus casei (L. casei); as inhibitors of T. gondii and P. carinii cell growth in culture; and as antitumor agents. The compounds were prepared by modifications of procedures for classical 5-deaza folates. 2,4-Diamino-5-methyl-6-[(3',4',5'-trimethoxy-N- methylanilino)methyl]pyrido[2,3-d]pyrimidine (5a) exhibited high potency as well as selectivity (compared to RL DHFR) for P. carinii and T. gondii DHFR. Compound 5a is one of the most potent and selective nonclassical folate inhibitors of T. gondii DHFR known. The N-10 formyl analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]pyrido-[2,3-d]pyrimidine (6a) had decreased potency, but it maintained high selectivity for T. gondii DHFR. The corresponding chloro-substituted analogues maintained potency or had decreased potency; N-10 substitution did not increase potency or selectivity to the extent observed in the 3',4',5'-trimethoxy series. Partial reduction of the B ring to afford the dihydro analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]-5,8-dihydropyrido[2,3-d]pyrimidine (7), its 5,6,7,8-tetrahydropyrido[2,3-d]pyrimidine analogue 8, and 2,4-diamino-5-methyl-6-[(3',4',5'-trimethoxyanilino)methyl]-5,6,7, 8- tetrahydropyrido[2,3-d]pyrimidine (9) resulted in a significant decrease in potency. In T. gondii cell culture inhibitory studies, 2,4-diamino-5-methyl-6-[(3',4',5'- trimethoxyanilino)methyl]pyrido[2,3-d]pyrimidine (4a), 5a, and 6a were less potent compared to their DHFR inhibitory potencies. Against P. carinii cells in culture, 4a and 5a at 10 micrograms/mL were as effective as the clinically used combination of trimethoprim/sulfamethoxazole (50/250 micrograms/mL). With the exception of the B ring reduced analogues 7-9, all of the compounds were significantly cytotoxic to leukemia CCRF-CEM cells in culture. The chloro-substituted analogues, in general, were more potent against a variety of other tumor cells in culture than the trimethoxy analogues. These results were corroborated by the preclinical tumor screening program at the National Cancer Institute where the most potent compound 2,4-diamino-5-methyl-6-[(3',4'-dichloroanilino)methyl]pyrido[2,3- d]pyrimidine (4b) was found to inhibit the growth of 26 tumor cell lines at an IG50 < 1.00 x 10(-8) M.
|
Inhibition of Pneumocystis carinii (pc) Dihydrofolate reductase
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Novel 2,4-diamino-5-substituted-pyrrolo[2,3-d]pyrimidines as classical and nonclassical antifolate inhibitors of dihydrofolate reductases.
Year : 1995
Volume : 38
Issue : 12
First Page : 2158
Last Page : 2165
Authors : Gangjee A, Mavandadi F, Queener SF, McGuire JJ.
Abstract : Eight novel, nonclassical, antifolate 2,4-diamino-5-(anilinomethyl)pyrrolo[2,3-d]pyrimidines, 1-8, with 3',4',5'-trimethoxyphenyl, 3',4'-dimethoxyphenyl, 2',5'-dimethoxyphenyl, 4'-methoxyphenyl, 2',5'-diethoxyphenyl, 3',4'-dichlorophenyl, 1'naphthyl, and phenyl substituents were synthesized as potential inhibitors of dihydrofolate reductases (DHFRs). The classical analogue N-[4-[N-[(2,4-diaminopyrrolo[2,3-d]pyrimidin- 5-yl)methyl]amino]benzoyl]-L-glutamic acid (9) was also synthesized as an inhibitor of DHFR and an antitumor agent. The classical and nonclassical analogues were obtained via reductive condensations of the key intermediate 2,4-diamino-5-cyanopyrrolo[2,3-d]pyrimidine (12) with the appropriate substituted aniline or (p-aminobenzoyl)-L-glutamate followed by reduction of the intermediate Schiff bases with NaCNBH3. Compounds 1-9 were evaluated in vitro as inhibitors of rat liver (rl), Pneumocystis carinii (pc), and Toxoplasma gondii (tg) DHFRs. The nonclassical analogues were significantly selective against tgDHFR (vs rat liver DHFR), ranging from 7- to 92-fold. The inhibitory activity was lower in pcDHFR and rlDHFR (IC50s > 10(-5) M) than in tgDHFR (IC50s = 10(-6) M). The classical analogue had inhibitory activity similar to that of methotrexate (MTX) against the growth of human leukemia CCRF-CEM, A253, and FaDu squamous cell carcinoma (SCC) of the head and neck cell lines. Further evaluation of 9 against CCRF-CEM and its sublines having defined mechanisms of MTX resistance demonstrated that the analogue utilizes the reduced folate/MTX-transport system and primarily inhibits DHFR and poly-gamma-glutamylation plays a role in its mechanism of action. Compound 9 was found to be 3-fold more efficient than aminopterin as a substrate for human folylpolyglutamate synthetase.
|
Inhibitory activity against Pneumocystis carinii dihydrofolate reductase.
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-8-deazafolate analogues as inhibitors of dihydrofolate reductases from rat liver, Pneumocystis carinii, and Toxoplasma gondii.
Year : 1996
Volume : 39
Issue : 9
First Page : 1836
Last Page : 1845
Authors : Gangjee A, Zhu Y, Queener SF, Francom P, Broom AD.
Abstract : The synthesis and biological activity of 42 6-substituted-2,4-diaminopyrido[3,2-d]pyrimidines (2,4-diamino-8-deazafolate analogues) are reported. The compounds were synthesized in improved yields compared to previous classical analogues using modifications of procedures reported previously by us. Specifically, the S-phenyl-; mono-, di-, and trimethoxyphenyl-; and mono-, di-, and trichlorophenyl-substituted analogues with H or CH3 at the N10 position and methyl and trifluoromethyl phenyl ketone analogues with H, CH3, and CH2C identical to CH at the N10 position were synthesized. The S10 and N10 alpha- and beta-naphthyl analogues along with the N10 CH3 analogues were also synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg); selectivity ratios were determined against rat liver (rl) DHFR as the mammalian reference enzyme. Against pcDHFR the IC50 values ranged from 0.038 x 10-6 M for 2,4-diamino-6-[(N-methyl-2'-naphthylamino)methyl]pyrido[3,2-d]pyrimidine (28) to 5.5 x 10(-6) M for 2,4-diamino-6[(2',4'-dimethoxyanilino)methyl]pyrido[3,2-d]pyrim idi ne (15). N10 methylation in all instances increased potency. None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was 2,4-diamino-6-[(N-methylanilino)methyl]pyrido[3,2-d]pyrimidine (5) (IC50 0.0084 x 10(-6) M) and the least potent was 2,4-diamino-6[(2'-naphthylamino)methyl]-pyrido[3,2-d]pyrimidine (37) (IC50 0.16 x 10-6 M). N10 methylation afforded an increase in potency up to 10-fold. In contrast to pcDHFR, several of the 8-deaza analogues were significantly selective for tgDHFR, most notably 2,4-diamino-6-[(2'-chloro-N-methylanilino)-methyl]pyrido[3,2-d] pyrimidine (13), 2,4-diamino-6-[(3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyr pyrimidine (29), and 2,4-diamino-6-[(2',4',6'-trichloroanilino)methyl]pyrido[3,2-d] pyrimidine (32) which combined high potency at 10-8 M along with selectivities of 8.0, 5.0, and 12.4, respectively. The potency of these three analogues are comparable to the clinically used agent trimetrexate while their selectivities for tgDHFR are 17-43-fold better than trimetrexate.
|
Compound was tested for inhibition activity against pneumocystis carinii (Pneumocystis carinii) Dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-6,7-dihydro-5H-cyclopenta[d]pyrimidine analogues of trimethoprim as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1998
Volume : 41
Issue : 6
First Page : 913
Last Page : 918
Authors : Rosowsky A, Papoulis AT, Queener SF.
Abstract : Three previously unreported (R,S)-2,4-diamino-5-[(3,4,5-trimethoxyphenyl) alkyl]-6,7-dihydro-5H-cyclopenta[d]pyrimidines 15a-c were synthesized as analogues of trimethoprim (TMP) and were tested as inhibitors of Pneumocystis carinii, Toxoplasma gondii, and rat liver dihydrofolate reductase (DHFR). The length of the alkyl bridge between the cyclopenta[d]pyrimidine and trimethoxyphenyl moiety ranged from one in 15a to three carbons in 15c. The products were tested as competitive inhibitors of the reduction of dihydrofolate by Pneumocystis carinii, Toxoplasma gondii, and rat liver DHFR. Compounds 15a-c had IC50 values of > 32, 1.8 and 1.3 microM, respectively, against P. carinii DHFR, as compared to 12 microM for TMP. Against the T. gondii enzyme, 15a-c had IC50 values of 21, 0.14 and 0.14 microM, respectively, as compared to 2.7 microM for TMP. Inhibitors 15b and 15c with two- and three-carbon bridges were significantly more potent than 15a against all three enzymes. Unlike TMP, 15b and 15c were better inhibitors of the rat liver enzyme than of the microbial enzymes. The potency of 15b and 15c against rat liver DHFR was less than has been reported for the corresponding 6,7-dihydro-5H-cyclopenta[d]pyrimidines with a classical p-aminobenzoyl-L-glutamate side chain as inhibitors of bovine, murine, and human DHFR.
|
Concentration inhibiting Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminopyrido[3,2-d]pyrimidine inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 14
First Page : 2615
Last Page : 2620
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : Six previously unknown 2,4-diamino-6-(anilinomethyl)- and 2,4-diamino-6-[(N-methylanilino)-methyl]pyrido[3,2-d]pyrimidines (5-10) were synthesized from 2,4-diamino-6-(bromomethyl)-pyrido[3,2-d]pyrimidine hydrobromide (11.HBr) by treatment with the appropriate aniline or N-methylaniline in dimethylformamide at room temperature, with or without NaHCO3 present. Compounds 5-10 were tested as inhibitors of dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, and rat liver as a part of a larger effort directed toward the discovery of lipophilic nonclassical antifolates combining high enzyme selectivity and high potency. Of the six analogues tested, the most potent and selective against T. gondii DHFR was 2,4-diamino-6-[(3',4',5'-trimethoxy-N-methylanilono)methyl]pyrido[ 3,2-d d pyrimidine (7), which had an IC50 of 0.0047 microM against this enzyme as compared with 0.026 microM against the rat liver enzyme. The potency of 7 against T. gondii DHFR was similar to that of trimetrexate (TMQ, 1) and piritrexim (PTX, 2) but was > 500-fold greater than that of trimethoprim (TMP, 3). However, while 7 was more selective than either TMQ (19x) or PTX (63x) against this enzyme, its selectivity in comparison with TMP was 8-fold lower. 2,4-Diamino-6-[3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyri midin e (6) was 17-fold less active than 7 and was also less selective. 2,4-Diamino-6-[(3',4'-dichloro-N-methylanilino)methyl]pyrido[3, 2-d]pyrimidine (10) had an IC50 of 0.022 microM against P. carinii DHFR and was comparable in potency to TMQ and PTX. The species selectivity of 10 for P. carinii versus rat liver DHFR was greater than that of either TMQ (21-fold) or PTX (31-fold). On the other hand, even though 10 was slightly more active than TMQ against the P. carinii enzyme, its selectivity was 7-fold lower than that of TMP. Thus, the goal of combining high enzyme binding activity, which is characteristic of the fused-ring compounds TMQ and PTX, with high selectivity for T. gondii and P. carinii DHFR versus rat liver DHFR, which is characteristic of the monocyclic compound TMP, remained unmet in this limited series.
|
Inhibition of Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Inhibition of Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Conformationally restricted analogues of trimethoprim: 2,6-diamino-8-substituted purines as potential dihydrofolate reductase inhibitors from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 19
First Page : 3032
Last Page : 3039
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Twenty-two 2,6-diamino-8-substituted purines (2-23) were synthesized, in which rotation around the two flexible bonds of trimethoprim (TMP), linking the pyrimidine ring to the side chain phenyl ring, was restricted by incorporation into a purine ring, in an attempt to increase the potency and selectivity of TMP against dihydrofolate reductase (DHFR) from the organisms that often cause fatal opportunistic infections in patients with AIDS, i.e., Pneumocystis carinii (pc) and Toxoplasma gondii (tg). The syntheses of analogues 2-20 were achieved via a one-pot reaction of 2,4,5,6-tetraaminopyrimidine and the appropriately substituted benzaldehyde or phenyl acetaldehyde, in acidic methoxyethanol. Analogues 21-23 were synthesized via nucleophilic displacement of 2,6-diamino-8-(chloromethyl)purine with the appropriate anilines or 2-naphthalenethiol. The compounds were evaluated as inhibitors of pcDHFR and tgDHFR with rat liver (rl) DHFR as the mammalian reference enzyme. Compound 11, the 3',4'-dichlorophenyl analogue, was as potent as TMP and had a selectivity ratio of 13 for pcDHFR, which ranked it as one of the three most selective inhibitors of pcDHFR (compared to rlDHFR) known to date. It also displayed a selectivity ratio of 38 for tgDHFR. None of the other analogues showed any improvement compared to TMP in potency or selectivity. In the preclinical in vitro screening program of the National Cancer Institute, compound 11 showed a GI50 of 10(-6) M for the inhibition of the growth of 17 tumor cell lines.
|
Inhibition against Dihydrofolate reductase in Pneumocystis carinii
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Effect of N9-methylation and bridge atom variation on the activity of 5-substituted 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 7
First Page : 1173
Last Page : 1177
Authors : Gangjee A, Mavandadi F, Queener SF.
Abstract : The effect of N9-methylation and bridge atom variation on inhibitory potency and selectivity of 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases (DHFR) was studied. Specifically three nonclassical 2,4-diamino-5-((N-methylanilino)methyl)pyrrolo[2,3-d]pyrimidines with 2',5'-dimethoxyphenyl (2), 3',4'-dichlorophenyl (3), 1'-naphthyl (4), one classical analogue with a 4'-L-glutamate substituent (10), and four nonclassical 2,4-diamino-5-((phenylthio)methyl)pyrrolo[2,3-d]pyrimidines with 3',4'-dimethoxyphenyl (5), 3',4'-dichlorophenyl (6), 1'-naphthyl (7), and 2'-naphthyl (8) substituents were synthesized. The classical and nonclassical analogues were obtained by displacement of the intermediate 2,4-diamino-5-bromomethylpyrrolo[2,3-d]pyrimidine, 14, with appropriately substituted N-methylaniline, thiophenols, or 4-(N-methylamino)benzoyl-L-glutamate. Compounds 2-8 and 10 were evaluated against Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) DHFRs. The N-methyl and thiomethyl analogues were more inhibitory than their corresponding anilinomethyl analogues (previously reported) against all three DHFRs. The inhibitory potency of these analogues was greater against rlDHFR than against tgDHFR which resulted in a loss of selectivity for tgDHFR compared to the N9-H analogues. The classical N9-methyl analogue 10 was more potent and about 2-fold more selective against tgDHFR than its corresponding desmethyl analogue. All of the analogues, 2-8 and 10, were more selective than trimetrexate (TMQ) against pcDHFR (except 4) and significantly more selective than TMQ against tgDHFR.
|
Inhibition of Dihydrofolate reductase of Pneumocystis carinii
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-chloroquinazoline analogues of trimetrexate and piritrexim: synthesis and antifolate activity.
Year : 1994
Volume : 37
Issue : 26
First Page : 4522
Last Page : 4528
Authors : Rosowsky A, Mota CE, Wright JE, Queener SF.
Abstract : Ten heretofore undescribed 2,4-diamino-5-chloroquinazoline analogues of trimetrexate (TMQ) and piritrexim (PTX) were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from rat liver, Pneumocystis carinii, and Toxoplasma gondii. The most active quinazolines against both the P. carinii and the T. gondii enzyme were those with an ArCH2-NH or ArNHCH2 side chain. Among ArNH(CH2)n compounds with n = 1-3 and either 2',5'-dimethoxyphenyl or 3',4',5'-trimethoxyphenyl as the Ar moiety, activity decreased in the order n = 1 > n = 2 > n = 3. The best inhibitor of P. carinii DHFR, 2,4-diamino-5-chloro-6-[(N-methyl-3',4',5'-trimethoxyanilino)methy l] quinazoline (10) had an IC50 of 0.012 microM and was slightly more potent than TMQ and PTX. Compound 10 was also the best inhibitor of T. gondii DHFR, with an IC50 of 0.0064 microM corresponding again to a minor increase in activity over TMQ and PTX. However, as with these standard agents, 10 showed no appreciable selectivity for either the P. carinii or T. gondii enzyme relative to the rat liver enzyme. The highest selectivity achieved in this limited series was with 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl)-N-methylamino] quinazoline (17) against T. gondii DHFR. While 17 (IC50 = 0.016 microM) was somewhat less potent than 10, its selectivity, as defined by the ratio IC50(rat liver)/IC50(T. gondii) was ca. 30-fold higher than that of TMQ or PTX. Two compounds, 2,4-diamino-5-chloro-6-[(3',4',5'-trimethoxyanilino)methyl] quinazoline (9) and 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl) amino]quinazoline (15), were also tested against human DHFR and were found to have an IC50/[E] of 0.5, indicating that their binding was near-stoichiometric.
|
Concentration required to inhibit the Toxoplasma gondii Dihydrofolate reductase by 50% was determined; Range: 4.0-4.6
|
Toxoplasma gondii
|
4.3
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 2,4-diamino-6-[2'-O-(omega-carboxyalkyl)oxydibenz[b,f]azepin-5-yl]methylpteridines as potent and selective inhibitors of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductase.
Year : 2004
Volume : 47
Issue : 10
First Page : 2475
Last Page : 2485
Authors : Rosowsky A, Fu H, Chan DC, Queener SF.
Abstract : Six previously undescribed N-(2,4-diaminopteridin-6-yl)methyldibenz[b,f]azepines with water-solubilizing O-carboxyalkyloxy or O-carboxybenzyloxy side chains at the 2'-position were synthesized and compared with trimethoprim (TMP) and piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic organisms known to cause significant morbidity and mortality in patients with AIDS and other disorders of the immune system. The ability of the new analogues to inhibit reduction of dihydrofolate to tetrahydrofolate by Pc, Tg, Ma, and rat DHFR was determined, and the selectivity index (SI) was calculated from the ratio IC(50)(rat DHFR)/IC(50)(Pc, Tg, or Ma DHFR). The IC(50) values of the 2'-O-carboxypropyl analogue (10), with SI values in parentheses, were 1.1 nM (1300) against Pc DHFR, 9.9 nM (120) against Tg DHFR, and 2.0 nM (600) against Ma DHFR. The corresponding values for the 2'-O-(4-carboxybenzyloxy) analogue (12) were 1.0 nM (560), 22 nM (21), and 0.75 nM (630). By comparison, the IC(50) and SI values for TMP were Pc, 13 000 nM (14); Tg, 2800 nM (65); and Ma, 300 nM (610). For the prototypical potent but nonselective inhibitors PTX and TMX, respectively, these values were Pc, 13 nM (0.26) and 47 nM (0.17); Tg, 4.3 nM (0.76) and 16 nM (0.50); Ma, 0.61 nM (5.4) and 1.5 nM (5.3). Thus 10 and 12 met the criterion for DHFR inhibitors that combine the high selectivity of TMP with the high potency of PTX and TMX.
|
Inhibition of dihydrofolate reductase from Toxoplasma gondii.
|
None
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase and as antiopportunistic infection and antitumor agents.
Year : 2003
Volume : 46
Issue : 23
First Page : 5074
Last Page : 5082
Authors : Gangjee A, Adair OO, Queener SF.
Abstract : A series of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) dihydrofolate reductase (DHFR) and as inhibitors of the growth of tumor cell lines in culture. Compounds 4-15 were designed as part of a continuing effort to examine the effects of substitutions at the 5-position, in the two-atom bridge, and in the side chain phenyl ring on structure-activity/selectivity relationships of 2,4-diaminopyrido[2,3-d]pyrimidines against a variety of DHFRs. Reductive amination of the common intermediate 2,4-diaminopyrido[2,3-d]pyrimidine-6-carbonitrile 16 with the appropriate anilines afforded the target compounds 4-12. Nucleophilic substitution or reductive methylation afforded the N10-methyl target compounds 13-15. As predicted, compounds 4-15 were, in general, less potent against all three DHFRs compared to the corresponding 2,4-diamino-5-methyl analogues previously reported; however, the greater decrease in potency against rlDHFR compared to pcDHFR and tgDHFR resulted in appreciable selectivity toward pathogenic DHFRs from different pathogens. The 2',5'-dichloro analogue 8 showed selectivity ratios (IC(50) against rlDHFR/IC(50) against pcDHFR or tgDHFR) of 15.7 and 23 for pcDHFR and tgDHFR, respectively. Thus, the selectivity of 8 for pcDHFR is higher than the first line clinical agent trimethoprim (TMP). In a P. carinii cell culture study, analogue 8 exhibited 88% cell growth inhibition at a concentration of 10 muM and afforded marginal effects in an in vivo study in the T. gondii mouse model. Selected compounds were evaluated in the National Cancer Institute (NCI) in vitro preclinical antitumor screening program and inhibited the growth of tumor cells in culture at micromolar to submicromolar concentrations and were selected for evaluation in a NCI in vivo hollow fiber assay.
|
Inhibitory activity against dihydrofolate reductase in mammalians. (high potency)
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : New drug developments for opportunistic infections in immunosuppressed patients: Pneumocystis carinii.
Year : 1995
Volume : 38
Issue : 24
First Page : 4739
Last Page : 4759
Authors : Queener SF.
|
Inhibitory activity against Dihydrofolate reductase from Pneumocystis carinii
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines as inhibitors of dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1995
Volume : 38
Issue : 10
First Page : 1778
Last Page : 1785
Authors : Gangjee A, Vasudevan A, Queener SF, Kisliuk RL.
Abstract : The synthesis and biological activity of 15 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]-pyrimidines are reported. These compounds were synthesized in improved yields by modifications of procedures previously reported by us. Specifically, dimethoxyphenyl-substituted compounds with H and CH3 at the N-10 position and trimethoxyphenyl-substituted compounds with N-10 ethyl, isopropyl, and propargyl moieties were synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii, Toxoplasma gondii, and rat liver, and selected analogues were evaluated as inhibitors of the growth of T. gondii and tumor cells in culture. All the compounds showed increased selectivity (vs rat liver DHFR) for T. gondii DHFR compared to trimetrexate. In general, for the trimethoxy-substituted analogues, increasing the size of the N-10 substituent from a methyl group to larger groups resulted in a decrease in selectivity and potency for both P. carinii and T. gondii DHFR. For the dimethoxy-substituted analogues, N-10 methylation in general decreased potency but increased selectivity for T. gondii DHFR. In an attempt to improve the cell penetration of these analogues, the N-10 naphthyl-substituted analogues were also synthesized. These analogues displayed excellent cell penetration and inhibition of T. gondii cells in culture. Further, these analogues were potent inhibitors of the growth of tumor cells in the preclinical in-vitro screening program of the National Cancer Institute with IC50s in the nanomolar range.
|
Inhibition of Dihydrohydrofolate reductase(DHFR) of Pneumocystis carinii
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of Dihydrofolate Reductase of Pneumocystis carinii.
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of nonclassical 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines with novel side chain substituents as potential inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 4
First Page : 479
Last Page : 485
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2-10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase (pcDHFR) and Toxoplasma gondii dihydrofolate reductase (tgDHFR). Compounds 2-5 were designed as conformationally restricted analogues of trimetrexate (TMQ), in which rotation around tau 3 was constrained by incorporation of the side chain nitrogen as part of an indoline or an indole ring. Analogue 6, which has an extra atom between the side chain nitrogen and the phenyl ring, has its nitrogen as part of a tetrahydroisoquinoline ring. Analogues 7-9 are epiroprim (Ro 11-8958) analogues and contain a pyrrole ring as part of the side chain substitution on the phenyl ring similar to epiroprim. These analogues were designed to investigate the role of the pyrrole substitution on the phenyl ring of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines. Molecular modeling indicated that a pyrrole substituent in the ortho position of the side chain phenyl ring was most likely to interact with pcDHFR in a manner similar to the pyrrole moiety of epiroprim. Analogue 10, in which a phenyl ring replaced a methoxy group, was synthesized to determine the contribution of a phenyl ring on selectivity, lipophilicity, and cell penetration. The synthesis of analogues 2-4 was achieved via reductive amination of 2,4-diamino-5-methyl 6-carboxaldehyde with the appropriately substituted indolines. The indolines were obtained from the corresponding indoles via NaCNBH3 reductions. Analogues 5-10 were synthesized by nucleophilic displacement of 2,4-diamino-5-methyl-6-(bromomethyl)-pyrido[2,3-d]pyrimidine with the 5-methoxyindolyl anion, 6,7-dimethoxytetrahydroisoquinoline, the appropriately substituted pyrroloaniline or 2-methoxy-5-phenylaniline. The pyrroloanilines were synthesized in two steps by treating the substituted nitroanilines with 2,5-dimethoxy-tetrahydrofuran to afford the nitropyrrole intermediates, followed by reduction of the nitro group with Raney Ni. The analogues were more potent than trimethoprim and epiroprim and more selective than TMQ and piritrexim against pcDHFR and tgDHFR. Compounds 5 and 10 had IC50 values of 1 and 0.64 microM, respectively, for the inhibition of the growth of T. gondii cells in culture, and showed excellent culture IC50/enzyme IC50 ratios, which were correlated with their calculated log P values, indicating a direct relationship between calculated lipophilicity and cell penetration.
|
Inhibitory activity against dihydrofolate reductase (DHFR) from Pneumocystis carinii
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : 6-Substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues of piritrexim as inhibitors of dihydrofolate reductase from rat liver, Pneumocystis carinii, and Toxoplasma gondii and as antitumor agents.
Year : 1998
Volume : 41
Issue : 23
First Page : 4533
Last Page : 4541
Authors : Gangjee A, Zhu Y, Queener SF.
Abstract : The synthesis and biological activity are reported for 21 6-substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues (4-24) of piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) and as antitumor agents. Recombinant DHFR from Pneumocystis carinii (pc) and native DHFR from Toxoplasma gondii (tg) were the target enzymes tested; these organisms are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity for the pathogenic DHFR. The synthesis of S9-bridged compounds 4-6 was achieved by aryl displacement of 2,4-diamino-6-chloropyrido[3, 2-d]pyrimidine (27) with thiol nucleophiles. Oxidation of 4-6 with hydrogen peroxide in glacial acetic acid afforded the corresponding sulfone analogues 7-9. The N9-bridged compounds 10-24 were synthesized from their precursor 3-amino-6-(arylamino)-2-pyridinecarbonitriles via a thermal cyclization with chloroformamidine hydrochloride. Unlike the S9-bridged compounds, the arylamino side chains of the N9-bridged analogues were introduced prior to the formation of the 2, 4-diaminopyrido[3,2-d]pyrimidine nucleus. A reversed two-atom-bridged analogue (25) was also synthesized using a synthetic strategy similar to that utilized for compounds 10-24. The IC50 values of these compounds against pcDHFR ranged from 0.0023 x 10(-6) M for 2,4-diamino-6-(N-methyl-3',4'-dimethoxyanilino)pyrido[3, 2-d]pyrimidine (21), which was the most potent, to 90.4 x 10(-6) M for 2,4-diamino-6-(4'-methoxyanilino)pyrido[3,2-d]pyrimidine (12), which was the least potent. The three S9-bridged compounds tested were more potent than the corresponding sulfone-bridged compounds for all three DHFRs. N9-Methylation increased the potency by as much as 17 000-fold (compounds 15 and 21). None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was again 21 with an IC50 value of 0.00088 x 10(-6) M and the least potent was 12 with an IC50 of 2.8 x 10(-6) M. N9-Methylation afforded an increase in potency of up to 770-fold (compound 15 NH vs 21 N-CH3) compared to the corresponding N9-H analogue. In contrast to pcDHFR, several analogues had a greater selectivity ratio for tgDHFR compared to trimetrexate (TMQ) or PTX, most notably 2, 4-diamino-6-[(3',4'- dimethoxyphenyl)thio]pyrido[3,2-d]pyrimidine (4), 2,4-diamino-6-[(2'-methoxyphenyl)sulfonyl]pyrido[3, 2-d]pyrimidine (7), and 2,4-diamino-6-(2', 5'-dimethoxyanilino)pyrido[3,2-d]pyrimidine (14) which combined relatively high potency at 10(-7)-10(-8) M along with selectivity ratios of 3.97, 6.67, and 4.93, respectively. Several analogues synthesized had better selectivity ratios than TMQ or PTX for both pcDHFR and tgDHFR, and the potencies of the N9-methylated compounds were comparable to or greater than that of TMQ or PTX. Selected compounds were evaluated as inhibitors of the growth of a variety of tumor cells in culture. The N9-CH3 analogues were, in general, highly potent with GI50 values in the nanomolar range. The N9-H and S9 analogues were less potent with GI50 values in the millimolar to micromolar range.
|
Inhibitory activity against Dihydrofolate reductase from Pneumocystis carinii was evaluated using 90 uM dihydrofolic acid as substrate
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-5-aryl-6-ethylpyrimidine antifolates: activity as inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1997
Volume : 40
Issue : 19
First Page : 3040
Last Page : 3048
Authors : Robson C, Meek MA, Grunwaldt JD, Lambert PA, Queener SF, Schmidt D, Griffin RJ.
Abstract : Twelve novel 2,4-diamino-5-(4'-benzylamino)- and 2,4-diamino-5[4'-(N-methylbenzylamino)-3'-nitrophenyl]-6-ethylp yrimidines bearing 4-substituents on the benzylamino or N-methylbenzylamino aryl ring were synthesized and evaluated as nonclassical inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase (DHFR). Compounds were prepared by reaction of 2,4-diamino-5-(4'-chloro-3'-nitrophenyl)- (8) or 2,4-diamino-5-(4'-fluoro-3'-nitrophenyl)-6-ethylpyrimidine (15) with the appropriate 4-substituted (CO2H, CO2Me, SO2NH2, dioxolan-2-yl, CHO, dimethyloxazolin-2-yl) benzylamine or N-methylbenzylamine derivative. Compounds 25-29 were synthesized from 2,4-diamino-5-{4'-[N-(4"-carboxybenzyl)amino]-3'-nitrophenyl}-6- ethylpyrimidine (10) and the corresponding amine (NH3, MeNH2, Me2NH, piperidine, diethyl L-glutamate) via isobutyl mixed anhydride coupling; hydrolysis of the diethyl L-glutamate 29 afforded the L-glutamate analogue 30. The compounds exhibited potent inhibitory activity against T. gondii (IC50 values 0.0018-0.14 microM) and rat liver (IC50 values 0.0029-0.27 microM) DHFR, with a 4-substituent invariably enhancing binding to both enzymes relative to the unsubstituted benzoprim (5) or methylbenzoprim (6). Modest selectivity for T. gondii enzyme was observed with several analogues, whereas all of the compounds were relatively weak inhibitors of P. carinii DHFR and exhibited no selectivity. Selected analogues were evaluated for in vivo antitumor activity against the methotrexate-resistant M5076 murine reticulosarcoma, with 2,4-diamino-5-{4'-[N-[4"-(N"-methylcarbamoyl)benzyl]-N- methylamino]-3'-nitrophenyl}-6-ethylpyrimidine (14) (Ki for rat liver DHFR = 0.00035 +/- 0.00029 nM) combining significant antitumor activity with minimal toxicity.
|
Inhibitory activity against Pneumocystis carinii Dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-substituted-quinazolines as inhibitors of a human dihydrofolate reductase with a site-directed mutation at position 22 and of the dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 5
First Page : 745
Last Page : 752
Authors : Rosowsky A, Mota CE, Queener SF, Waltham M, Ercikan-Abali E, Bertino JR.
Abstract : 2,4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (p-aminobenzoyl)-L-glutamate side chain, were synthesized as potentially selective inhibitors of a site-directed mutant of human dihydrofolate reductase (DHFR) containing phenylalanine instead of leucine at position 22. This mutant enzyme is approximately 100-fold more resistant than native enzyme to the classical antifolate methotrexate (MTX), yet shows minimal cross resistance to the nonclassical antifolates piritrexim (PTX) and trimetrexate (TMQ). Although they were much less potent than trimetrexate and piritrexim, the lipophilic 5-substituted analogues were all found to bind approximately 10 times better to the mutant DHFR than to the wild-type enzyme. The potency of the analogue with a classical (p-aminobenzoyl)-L-glutamate side chain was similarly diminished in comparison with MTX, but the difference in its binding affinity to the two DHFR species was only 5-fold. Thus, by making subtle structural changes in the antifolate molecule, it may be possible to attack resistance due to mutational alterations in the active site of the target enzyme. Also, to test the hypothesis that DHFR from Pneumocystis carinii and Toxoplasma gondii may have a less sterically restrictive active site than the enzyme from mammalian cells, inhibition assays using several of the lipophilic analogues in the series were carried out against the P. carinii and T. gondii reductases in comparison with the enzyme from rat liver. In contrast to their preferential binding to mutant versus wild-type human DHFR, binding of these analogues to the P. carinii and T. gondii enzymes was weaker than binding to rat enzyme. It thus appears that, if the active site of the DHFR from these parasites is less sterically restrictive than the active site of the mammalian enzyme, this difference cannot be successfully exploited by moving the side chain from the 6-position to the 5-position.
|
Inhibitory activity against Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Lipophilic antifolates as agents against opportunistic infections. 1. Agents superior to trimetrexate and piritrexim against Toxoplasma gondii and Pneumocystis carinii in in vitro evaluations.
Year : 1996
Volume : 39
Issue : 6
First Page : 1271
Last Page : 1280
Authors : Piper JR, Johnson CA, Krauth CA, Carter RL, Hosmer CA, Queener SF, Borotz SE, Pfefferkorn ER.
Abstract : 2,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four 2,4-diaminoquinazolines, each with an aryl groups attached to the 6-position of the heterocyclic moiety through a two-atom bridge (either CH2NH, CH2N(CH3),CH2S, or CH2CH2), were synthesized and evaluated as inhibitors of the growth of Toxoplasma gondii in culture and as inhibitors of dihydrofolate reductase enzymes from T. gondii, Pneumocystis carinii, and rat liver. Exceptionally high levels of combined potency and selectivity as growth inhibitors of T. gondii and as inhibitors of the microbial enzymes relative to the mammalian enzyme were found among the 5-methyl-5-deazapteridines but not for the other heterocyclic types. Thirty of the 34 5-methyl-5-deaza compounds gave growth inhibition IC50 values lower than that of pyrimethamine (0.4 microM) with 14 compounds below 0.1 microM, values that compare favorably with those for piritrexim and trimetrexate (both near 0.02 microM). As inhibitors of T gondii DHFR, all but three of the 34 5-methyl-5-deaza compounds gave IC50 values in the order of magnitude with those of piritrexim (0.017 microM) and trimetrexate (0.010 microM), and 17 compounds of this group gave IC50 values versus P. carinii DHFR similarly comparable with those of piritrexim (0.031 microM) and trimetrexate (0.042 microM). Thirteen of these congeners gave both T. gondii growth inhibition and DHFR inhibition IC50 values of 0.10 microM or less, thus indicating facile penetration of the cell membrane. Eleven of these inhibitors of both T. gondii growth and DHFR have selectivity ratios (IC50 rat liver divided by IC50 T. gondii) of 5 or greater for the parasite DHFR. The highest selectivity ratio of nearly 100 belongs to the 5-methyl-5-deaza compound whose 6-substituent is CH2CH2C6H3(OCH3)2-2,5. This compound is over 10(3)-fold more selective for T. gondii DHFR than bridge homologue piritrexim (selectivity ratio 0.088), a compound now in clinical trials. The candidate with CH2NHC6H3(CH3)2-2,5 in the 6-position gave the highest P. carinii DHFR selectivity ratio of 4.0, which is about 60-fold more selective than trimetrexate (0.071) and 80-fold more selective than piritrexim (0.048) toward this enzyme. The 10 best compounds with respect to potency and selectivity includes six compounds bearing 2,5-disubstituted phenyl groups in the side chain (with little, if any, difference in effects of methyl, methoxy, or ethoxy), two side chains bearing 1-naphthyl groups, and two with 5,6,7,8-tetrahydro-1-naphthyl groups. Bridge groups represented in the 10 choice compounds are CH2NH, CH2N(CH3), CH2CH2, and CH2S. The high levels of both potency and selectivity among these agents suggest that in vivo studies now underway may lead to agents that could replace trimetrexate and piritrexim in treatment of toxoplasmosis and P. carinii pneumonia.
|
Inhibitory activity against dihydrofolate reductase in Pneumocystis carinii. (high potency)
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : New drug developments for opportunistic infections in immunosuppressed patients: Pneumocystis carinii.
Year : 1995
Volume : 38
Issue : 24
First Page : 4739
Last Page : 4759
Authors : Queener SF.
|
Inhibitory activity against dihydrofolate reductase in Pneumocystis carinii at 37 centigrade.
|
Pneumocystis carinii
|
19.0
nM
|
|
Journal : J. Med. Chem.
Title : New drug developments for opportunistic infections in immunosuppressed patients: Pneumocystis carinii.
Year : 1995
Volume : 38
Issue : 24
First Page : 4739
Last Page : 4759
Authors : Queener SF.
|
Inhibitory concentration against Dihydrofolate reductase from Pneumocystis carinii (pc)
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and dihydrofolate reductase inhibitory activities of 2,4-diamino-5-deaza and 2,4-diamino-5,10-dideaza lipophilic antifolates.
Year : 1997
Volume : 40
Issue : 4
First Page : 470
Last Page : 478
Authors : Gangjee A, Devraj R, Queener SF.
Abstract : Two series of nonclassical antifolates (2,4-diamino-5-deaza compounds 2-5 and 5,10-dideaza compounds 6-13) were synthesized as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) organisms that are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity. Syntheses of the target 5-deaza compounds were achieved by initial construction of the pivaloyl-protected 2,4-diamino-6-bromopyrido[2,3-d]-pyrimidine 17 via a cyclocondensation of 2,4,6-triaminopyrimidine with bromomalonaldehyde. Sequential Heck coupling of 17 with styrene followed by ozonolysis afforded the 6-formyl derivative 19. Reductive amination of 19 with 3,4,5-trimethoxyaniline afforded the N10-H analog. The N10-Me and N10-Et analogs were synthesized by nucleophilic displacement of the 6-bromomethyl derivative 22 (obtained from the 6-formyl derivative 19 by reduction and bromination) with the appropriate N-alkylaniline. The trans-5,10-dideaza analogs 6-8 were synthesized via a Heck coupling of the appropriate methoxystyrene with 17, and selective reduction of the resulting 9,10-double bond afforded target compounds 9-11. Further reduction to the tetrahydro derivatives afforded analogs 12 and 13. The 5-deaza N10-Me 3,4,5-trimethoxy analog 3 maintained the best balance of potency and selectivity against both tgDHFR and pcDHFR. Compared to trimethoprim, compound 3 was only slightly less selective but was 300-fold more potent against tgDHFR. The 5,10-dideaza analogs were generally less potent and selective than the 5-deaza compounds.
|
Inhibitory concentration against Pneumocystis carinii Dihydrofolate reductase
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological activities of conformationally restricted, tricyclic nonclassical antifolates as inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 12
First Page : 1930
Last Page : 1936
Authors : Gangjee A, Shi J, Queener SF.
Abstract : Seven novel tricyclic pyrimido[4,5-c][2,7]naphthyridones 5-8 and the corresponding naphthyridines 9-11 were synthesized as conformationally restricted inhibitors of dihydrofolate reductase (DHFR) and as antitumor and/or antiinfectious agents. The analogues were designed to orient the side chain trimethoxyphenyl group in different conformationally defined positions in order to explore the effect of the side chain orientation on binding affinity and selectivity for DHFR from various species. The semirigid orientations were achieved by bridging the C5 and N10 of compound 12 with a N-ethyl bridge and by variation of the position of double bonds in rings B and C as well as substitution at the 2',6'-positions of the phenyl ring. The synthesis of compounds 5-11 were accomplished by cyclocondensation of the appropriate keto ester (as the biselectrophile) with 2,4,6-triaminopyrimidine to afford the lactam 5. The dehydrolactams 6 and 7 were prepared by air oxidation and PtO2-catalyzed dehydrogenation of 7, respectively. The dichloro dehydro lactam 8 was obtained by refluxing lactam 5 and/or 6 in POCl3 or a mixture of POCl3/PCl5. Compounds 9-11 were obtained by two methods, direct borane reduction of lactam 5 or 6 or thiation of the dipivoylated lactam 15 followed by reductive dethiation. Compounds 9-11 were interconverted by air oxidation or PtO2-catalyzed reduction/oxidation, respectively. The compounds were evaluated as inhibitors of DHFR from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) with rat liver (rl) serving as the reference mammalian enzyme. In the lactam series 5-8, the most unsaturated analogue 7 showed an IC50 of 86 nM against rlDHFR, almost 100-fold more active than 5 and 3-fold more active than 6. The 2',6'-dichloro dehydro lactam 8 was less active than the corresponding dehydro lactam 6 against rlDHFR. In the naphthyridine series 9-11, the dehydro analogue 10 was more active than 9 against rlDHFR. The fully reduced analogue 11 (as a mixture of cis and trans isomers) was the most active in the naphthyridine series. The analogues were, in general, more inhibitory against rlDHFR than against pcDHFR, or tgDHFR, and thus lacked selectivity. In addition, they were less potent than the bicyclic compounds trimetrexate 3 (TMQ) and piritrixim 4 (PTX).
|
Inhibitory concentration against Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : Bioorg. Med. Chem. Lett.
Title : Preliminary in vitro studies on two potent, water-soluble trimethoprim analogues with exceptional species selectivity against dihydrofolate reductase from Pneumocystis carinii and Mycobacterium avium.
Year : 2004
Volume : 14
Issue : 7
First Page : 1811
Last Page : 1815
Authors : Forsch RA, Queener SF, Rosowsky A.
Abstract : 2,4-Diamino-5-[3',4'-dimethoxy-5'-(5-carboxy-1-pentynyl)]benzylpyrimidine (6) and 2,4-diamino-5-[3',4'-dimethoxy-5'-(4-carboxyphenylethynyl)benzylpyrimidine (7) were synthesized from 2,4-diamino-5-(5'-iodo-3',4'-dimethoxybenzyl)pyrimidine (9) via a Sonogashira reaction with appropriate acetylenic esters followed by saponification, and were tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat in comparison with the widely used antibacterial agent 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP). The selectivity index (SI) for each compound was calculated by dividing its 50% inhibitory concentration (IC(50)) against rat DHFR by its IC(50) against Pc, Tg, or Ma DHFR. The IC(50) of 6 against Pc DHFR was 1.0 nM, with an SI of 5000. Compound 7 had an IC(50) of 8.2 nM against Ma DHFR, with an SI of 11000. By comparison, the IC(50) of TMP was 12000 nM against Pc, 300 nM against Ma, and 180000 against rat DHFR. The potency and selectivity values of 6 and 7 were not as high against Tg as they were against Pc or Ma DHFR, but nonetheless exceeded those of TMP. Because of the outstanding selectivity of 6 against Pc and of 7 against Ma DHFR, these novel analogues may be viewed as promising leads for further structure-activity optimization.
|
Inhibitory concentration against dihydrofolate reductase dihydrofolate reductase from Pneumocystis carinii.
|
Pneumocystis carinii
|
34.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, computational prediction, and biological evaluation of ester soft drugs as inhibitors of dihydrofolate reductase from Pneumocystis carinii.
Year : 2001
Volume : 44
Issue : 15
First Page : 2391
Last Page : 2402
Authors : Graffner-Nordberg M, Kolmodin K, Aqvist J, Queener SF, Hallberg A.
Abstract : A series of lipophilic soft drugs structurally related to the nonclassical dihydrofolate reductase (DHFR) inhibitors trimetrexate and piritrexim have been designed, synthesized, and evaluated in DHFR assays, with special emphasis on the inhibition of P. carinii DHFR. The best inhibitors, encompassing an ester bond in the bridge connecting the two aromatic systems, were approximately 10 times less potent than trimetrexate and piritrexim. The metabolites were designed to be poor inhibitors. Furthermore, molecular dynamics simulations of three ligands in complex with DHFR from Pneumocystis carinii and from the human enzyme were conducted in order to better understand the factors determining the selectivity. A correct ranking of the relative inhibition of DHFR was achieved utilizing the linear interaction energy method. The soft drugs are intended for local administration. One representative ester was selected for a pharmacokinetic study in rats where it was found to undergo fast metabolic degradation to the predicted inactive metabolites.
|
The ability to inhibit Pneumocystis carinii Dihydrofolate reductase was tested
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and antiparasitic and antitumor activity of 2, 4-diamino-6-(arylmethyl)-5,6,7,8-tetrahydroquinazoline analogues of piritrexim.
Year : 1999
Volume : 42
Issue : 6
First Page : 1007
Last Page : 1017
Authors : Rosowsky A, Papoulis AT, Forsch RA, Queener SF.
Abstract : Nineteen previously undescribed 2,4-diamino-6-(arylmethyl)-5,6,7, 8-tetrahydroquinazolines (5a-m, 10-12) were synthesized as part of a larger effort to assess the therapeutic potential of lipophilic dihydrofolate reductase (DHFR) inhibitors against opportunistic infections of AIDS. Condensation of appropriately substituted (arylmethyl)triphenylphosphoranes with 4, 4-ethylenedioxycyclohexanone, followed by hydrogenation (H2/Pd-C) and acidolysis, yielded the corresponding 4-(arylmethyl)cyclohexanones, which were then condensed with cyanoguanidine to form the tetrahydroquinazolines. Three simple 2, 4-diamino-6-alkyl-5,6,7,8-tetrahydroquinazoline model compounds (9a-c) were also prepared in one step from commercially available 4-alkylcyclohexanones by this method. Enzyme inhibition assays against rat liver DHFR, Pneumocystis carinii DHFR, and the bifunctional DHFR-TS enzyme from Toxoplasma gondii were carried out, and the selectivity ratios IC50(rat)/IC50(P. carinii) and IC50(rat)/IC50(T. gondii) were compared. The three most potent inhibitors of P. carinii DHFR were the 2,5-dimethoxybenzyl (5j), 3, 4-dimethoxybenzyl (5k), and 3,4,5-trimethoxybenzyl (5l) analogues, with IC50 values of 0.057, 0.10, and 0.091 microM, respectively. The remaining compounds generally had IC50 values in the 0.1-1.0 microM range. However all the compounds were more potent against the rat liver enzyme than the P. carinii enzyme and thus were nonselective. The T. gondii enzyme was always more sensitive than the P. carinii enzyme, with most of the analogues giving IC50 values of 0.01-0.1 microM. Moderate 5-10-fold selectivity for T. gondii versus rat liver DHFR was observed with five compounds, the best combination of potency and selectivity being achieved with the 2-methoxybenzyl analogue 5d, which had an IC50 of 0.014 microM and a selectivity ratio of 8.6. One compound (5l) was tested for antiproliferative activity against P. carinii trophozoites in culture at a concentration of 10 microgram/mL and was found to completely suppress growth over 7 days. The suppressive effect of 5l was the same as that of trimethoprim (10 microgram/mL) + sulfamethoxazole (250 microgram/mL), a standard clinical combination for the treatment of P. carinii pneumonia in AIDS patients. Four compounds (5a,h,k,l) were tested against T. gondii tachyzoites in culture and were found to have a potency (IC50 = 0.1-0.5 microM) similar to that of pyrimethamine (IC50 = 0.69 microM), a standard clinical agent for the treatment of cerebral toxoplasmosis in AIDS patients. Compound 5h was also active against T. gondii infection in mice when given qdx8 by peritoneal injection at doses ranging from 62.5 (initial dose) to 25 mg/kg. Survival was prolonged to the same degree as with 25 mg/kg clindamycin, another widely used drug against toxoplasmosis. Three compounds (5j-l) were tested for antiproliferative activity against human tumor cells in culture. Among the 25 cell lines in the National Cancer Institute panel for which data were confirmed in two independent experiments, the IC50 for at least two of these compounds was <10 microM against 17 cell lines (68%) and in the 0. 1-1 microM range against 13 cell lines (52%). One compound (5j) had an IC50 of <0.01 microM against four of the cell lines. The activity profiles of 5k,l were generally similar to that of 5j except that there were no cells against which the IC50 was <0.01 microM.
|
Inhibition of dihydrofolate reductase (DHFR) from Pneumocystis carinii(pc)
|
Pneumocystis carinii
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase inhibitors and antitumor agents: synthesis and biological activities of 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl] pyrido[2,3-d]pyrimidines.
Year : 1999
Volume : 42
Issue : 13
First Page : 2447
Last Page : 2455
Authors : Gangjee A, Adair O, Queener SF.
Abstract : Thirteen 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl]pyrido[2,3-d]pyrimidines 5-17 were synthesized as potential Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR) inhibitors and as antitumor agents. Compounds 5-17 were designed to investigate the structure-activity relationship of monomethoxy and monohalide substitution in the phenyl ring and N10-methylation of the C9-N10 bridge. The synthetic route to compounds 5-12 involved the reductive amination of a common intermediate, 2,4-diamino-5-methylpyrido[2, 3-d]pyrimidine-6-carbonitrile (18), with the appropriate anilines. N10-Methylation was achieved by reductive methylation. In contrast to previous reports of trimethoprim, the removal of methoxy and chloro groups from the phenyl ring in the 2, 4-diamino-5-methyl-6-[(substituted anilino)methyl]pyrido[2, 3-d]pyrimidine series generally did not decrease DHFR inhibitory activity. The monosubstituted phenyl analogues 5-12 were as potent against pcDHFR and tgDHFR as the previously reported disubstituted phenyl analogues. N10-Methylation generally resulted in a marginal increase in potency against both pcDHFR and tgDHFR. Compounds 5, 7, and 9 were evaluated and shown to inhibit the growth of T. gondii cells in culture at nanomolar concentrations. Compounds 6-8, 9, 11, and 16 were selected by the National Cancer Institute for evaluation in an in vitro preclinical antitumor screening program. All six compounds showed GI50 values in the 10(-7)-10(-9) M range in more than 20 cell lines.
|
Binding affinity was reported with purified recombinant Pneumocystis carinii Dihydrofolate reductase
|
Pneumocystis carinii
|
0.143
nM
|
|
Journal : J. Med. Chem.
Title : New drug developments for opportunistic infections in immunosuppressed patients: Pneumocystis carinii.
Year : 1995
Volume : 38
Issue : 24
First Page : 4739
Last Page : 4759
Authors : Queener SF.
|
Inhibitory activity against Pneumocystis. carinii DHFR*
|
Pneumocystis carinii
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of dihydrofolate reductase in pneumocystis carinii.
|
None
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminothieno[2,3-d]pyrimidine analogues of trimetrexate and piritrexim as potential inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1993
Volume : 36
Issue : 21
First Page : 3103
Last Page : 3112
Authors : Rosowsky A, Mota CE, Wright JE, Freisheim JH, Heusner JJ, McCormack JJ, Queener SF.
Abstract : A series of eight previously undescribed 2,4-diaminothieno[2,3-d]pyrimidine analogues of the potent dihydrofolate reductase (DHFR) inhibitors trimetrexate (TMQ) and piritrexim (PTX) were synthesized as potential drugs against Pneumocystis carinii and Toxoplasma gondii, which are major causes of severe opportunistic infections in AIDS patients. 2,4-Diamino-5-methyl-6-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 3,4,5-trimethoxy or 2,5-dimethoxy substitution in the aryl/aralkyl moiety and 2,4-diamino-5-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 2,5-dimethoxy substitution in the aryl/aralkyl moiety were obtained by reaction of the corresponding 2-amino-3-cyanothiophenes with chloroformamidine hydrochloride. The aryl group in the 5,6-disubstituted analogues was either attached directly to the hetero ring or was separated from it by one or two carbons, whereas the aryl group in the 5-monosubstituted analogues was separated from the hetero ring by two or three carbons. 2-Amino-3-cyano-5-methyl-6-(aryl/alkyl)thiophene intermediates for the preparation of the 5,6-disubstituted analogues were prepared from omega-aryl-2-alkylidene-malononitriles and sulfur in the presence of a secondary amine, and 2-amino-3-cyano-4-(aryl/aralkyl)thiophene intermediates for the preparation of the 5-monosubstituted analogues were obtained from omega-aryl-1-chloro-2-alkylidenemalononitriles and sodium hydrosulfide. Synthetic routes to the heretofore unknown ylidenemalononitriles, and the ketone precursors thereof, were developed. The final products were tested in vitro as inhibitors of DHFR from Pneumocystis carinii, Toxoplasma gondii, rat liver, beef liver, and Lactobacillus casei. A selected number of previously known 2,4-diaminothieno[2,3-d]pyrimidines lacking the 3,4,5-trimethoxyphenyl and 2,5-dimethoxyphenyl substitution pattern of TMQ and PTX, respectively, were also tested for comparison. None of the compounds was as potent as TMQ or PTX, and while some of them showed some selectivity in their binding to Pneumocystis carinii and Toxoplasma gondii versus rat liver DHFR, this effect was not deemed large enough to warrant further preclinical evaluation.
|
Cytotoxic activity was evaluated against Daoy tumor cells
|
Homo sapiens
|
70.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Inhibition of partially purified dihydrofolate reductase (DHFR) from Toxoplasma gondii (Tg)
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Inhibition of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductases by 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines: marked improvement in potency relative to trimethoprim and species selectivity relative to piritrexim.
Year : 2002
Volume : 45
Issue : 1
First Page : 233
Last Page : 241
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : A series of previously undescribed 2,4-diamino-5-[2-methoxy-5-alkoxybenzyl]pyrimidines (3a-e) and 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines (3f-k) with up to eight CH2 groups in the alkoxy or omega-carboxyalkyloxy side chain were synthesized and tested for the ability to inhibit partially purified dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat liver in comparison with two standard inhibitors, trimethoprim (1) and piritrexim (2). The latter drug is known to be extremely potent but shows a marked preference for binding to mammalian DHFR, whereas the former is very selective for the parasite enzymes but is a much weaker inhibitor. The underlying strategy for the synthesis of compounds 3a-k was that a hybrid structure embodying some features of both 1 and 2 might possess a more favorable combination of potency and selectivity than either parent drug. The choice of analogues 3f-k was based on the idea that the acidic omega-carboxyl group might interact preferentially with a basic center in the active site of DHFR from any of the parasite species relative to the active site of mammalian DHFR. In addition, the omega-carboxyl group was expected to improve water solubility relative to 1 or 2. In standardized spectrophotometric assays with dihydrofolate as the substrate and NADPH as the cofactor, 2,4-diamino-5-[(2-methoxy-4-carboxybutyloxy)benzyl]pyrimidine (3g) inhibited Pc DHFR with an IC(50) of 0.049 microM and rat DHFR with IC(50) of 3.9 microM. Its potency against Pc DHFR was 140-fold greater than that of 1 and close to that of 2, and its selectivity index, defined as the ratio IC(50)(rat liver)/IC(50)(P. carinii), was 8-fold higher than that of 1 and >10(4)-fold higher than that of 2. Although it was less potent and less selective against Tg than Pc DHFR, it was very potent as well as highly selective against Ma DHFR, with an IC(50) of 0.0058 microM and an IC(50)(rat liver)/IC(50)(M. avium) ratio of >600. Because of this favorable combination of potency and selectivity relative to 1 and 2, compound 3g may be viewed as a promising lead in the search for new antifolates with potential clinical activity against P. carinii and other opportunistic pathogens in patients with AIDS.
|
Inhibition of Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 5-methyl-5-deaza nonclassical antifolates as inhibitors of dihydrofolate reductases and as potential antipneumocystis, antitoxoplasma, and antitumor agents.
Year : 1993
Volume : 36
Issue : 22
First Page : 3437
Last Page : 3443
Authors : Gangjee A, Shi J, Queener SF, Barrows LR, Kisliuk RL.
Abstract : A series of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines 4-9 were synthesized as 5-deaza nonclassical antifolates containing trimethoxy, dichloro-, or trichlorophenyl substitutions and a N-H, N-CH3, or N-CHO at the 10-position. The compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (P. carinii), Toxoplasma gondii (T. gondii), rat liver (RL), and Lactobacillus casei (L. casei); as inhibitors of T. gondii and P. carinii cell growth in culture; and as antitumor agents. The compounds were prepared by modifications of procedures for classical 5-deaza folates. 2,4-Diamino-5-methyl-6-[(3',4',5'-trimethoxy-N- methylanilino)methyl]pyrido[2,3-d]pyrimidine (5a) exhibited high potency as well as selectivity (compared to RL DHFR) for P. carinii and T. gondii DHFR. Compound 5a is one of the most potent and selective nonclassical folate inhibitors of T. gondii DHFR known. The N-10 formyl analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]pyrido-[2,3-d]pyrimidine (6a) had decreased potency, but it maintained high selectivity for T. gondii DHFR. The corresponding chloro-substituted analogues maintained potency or had decreased potency; N-10 substitution did not increase potency or selectivity to the extent observed in the 3',4',5'-trimethoxy series. Partial reduction of the B ring to afford the dihydro analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]-5,8-dihydropyrido[2,3-d]pyrimidine (7), its 5,6,7,8-tetrahydropyrido[2,3-d]pyrimidine analogue 8, and 2,4-diamino-5-methyl-6-[(3',4',5'-trimethoxyanilino)methyl]-5,6,7, 8- tetrahydropyrido[2,3-d]pyrimidine (9) resulted in a significant decrease in potency. In T. gondii cell culture inhibitory studies, 2,4-diamino-5-methyl-6-[(3',4',5'- trimethoxyanilino)methyl]pyrido[2,3-d]pyrimidine (4a), 5a, and 6a were less potent compared to their DHFR inhibitory potencies. Against P. carinii cells in culture, 4a and 5a at 10 micrograms/mL were as effective as the clinically used combination of trimethoprim/sulfamethoxazole (50/250 micrograms/mL). With the exception of the B ring reduced analogues 7-9, all of the compounds were significantly cytotoxic to leukemia CCRF-CEM cells in culture. The chloro-substituted analogues, in general, were more potent against a variety of other tumor cells in culture than the trimethoxy analogues. These results were corroborated by the preclinical tumor screening program at the National Cancer Institute where the most potent compound 2,4-diamino-5-methyl-6-[(3',4'-dichloroanilino)methyl]pyrido[2,3- d]pyrimidine (4b) was found to inhibit the growth of 26 tumor cell lines at an IG50 < 1.00 x 10(-8) M.
|
Inhibition of Toxoplasma gondii (tc) Dihydrofolate reductase
|
Toxoplasma gondii
|
10.0
nM
|
|
Journal : J. Med. Chem.
Title : Novel 2,4-diamino-5-substituted-pyrrolo[2,3-d]pyrimidines as classical and nonclassical antifolate inhibitors of dihydrofolate reductases.
Year : 1995
Volume : 38
Issue : 12
First Page : 2158
Last Page : 2165
Authors : Gangjee A, Mavandadi F, Queener SF, McGuire JJ.
Abstract : Eight novel, nonclassical, antifolate 2,4-diamino-5-(anilinomethyl)pyrrolo[2,3-d]pyrimidines, 1-8, with 3',4',5'-trimethoxyphenyl, 3',4'-dimethoxyphenyl, 2',5'-dimethoxyphenyl, 4'-methoxyphenyl, 2',5'-diethoxyphenyl, 3',4'-dichlorophenyl, 1'naphthyl, and phenyl substituents were synthesized as potential inhibitors of dihydrofolate reductases (DHFRs). The classical analogue N-[4-[N-[(2,4-diaminopyrrolo[2,3-d]pyrimidin- 5-yl)methyl]amino]benzoyl]-L-glutamic acid (9) was also synthesized as an inhibitor of DHFR and an antitumor agent. The classical and nonclassical analogues were obtained via reductive condensations of the key intermediate 2,4-diamino-5-cyanopyrrolo[2,3-d]pyrimidine (12) with the appropriate substituted aniline or (p-aminobenzoyl)-L-glutamate followed by reduction of the intermediate Schiff bases with NaCNBH3. Compounds 1-9 were evaluated in vitro as inhibitors of rat liver (rl), Pneumocystis carinii (pc), and Toxoplasma gondii (tg) DHFRs. The nonclassical analogues were significantly selective against tgDHFR (vs rat liver DHFR), ranging from 7- to 92-fold. The inhibitory activity was lower in pcDHFR and rlDHFR (IC50s > 10(-5) M) than in tgDHFR (IC50s = 10(-6) M). The classical analogue had inhibitory activity similar to that of methotrexate (MTX) against the growth of human leukemia CCRF-CEM, A253, and FaDu squamous cell carcinoma (SCC) of the head and neck cell lines. Further evaluation of 9 against CCRF-CEM and its sublines having defined mechanisms of MTX resistance demonstrated that the analogue utilizes the reduced folate/MTX-transport system and primarily inhibits DHFR and poly-gamma-glutamylation plays a role in its mechanism of action. Compound 9 was found to be 3-fold more efficient than aminopterin as a substrate for human folylpolyglutamate synthetase.
|
Inhibition of dihydrofolate reductase (DHFR) from Toxoplasma gondii(tg)
|
Toxoplasma gondii
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase inhibitors and antitumor agents: synthesis and biological activities of 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl] pyrido[2,3-d]pyrimidines.
Year : 1999
Volume : 42
Issue : 13
First Page : 2447
Last Page : 2455
Authors : Gangjee A, Adair O, Queener SF.
Abstract : Thirteen 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl]pyrido[2,3-d]pyrimidines 5-17 were synthesized as potential Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR) inhibitors and as antitumor agents. Compounds 5-17 were designed to investigate the structure-activity relationship of monomethoxy and monohalide substitution in the phenyl ring and N10-methylation of the C9-N10 bridge. The synthetic route to compounds 5-12 involved the reductive amination of a common intermediate, 2,4-diamino-5-methylpyrido[2, 3-d]pyrimidine-6-carbonitrile (18), with the appropriate anilines. N10-Methylation was achieved by reductive methylation. In contrast to previous reports of trimethoprim, the removal of methoxy and chloro groups from the phenyl ring in the 2, 4-diamino-5-methyl-6-[(substituted anilino)methyl]pyrido[2, 3-d]pyrimidine series generally did not decrease DHFR inhibitory activity. The monosubstituted phenyl analogues 5-12 were as potent against pcDHFR and tgDHFR as the previously reported disubstituted phenyl analogues. N10-Methylation generally resulted in a marginal increase in potency against both pcDHFR and tgDHFR. Compounds 5, 7, and 9 were evaluated and shown to inhibit the growth of T. gondii cells in culture at nanomolar concentrations. Compounds 6-8, 9, 11, and 16 were selected by the National Cancer Institute for evaluation in an in vitro preclinical antitumor screening program. All six compounds showed GI50 values in the 10(-7)-10(-9) M range in more than 20 cell lines.
|
Inhibitory activity against Toxoplasma gondii dihydrofolate reductase.
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-8-deazafolate analogues as inhibitors of dihydrofolate reductases from rat liver, Pneumocystis carinii, and Toxoplasma gondii.
Year : 1996
Volume : 39
Issue : 9
First Page : 1836
Last Page : 1845
Authors : Gangjee A, Zhu Y, Queener SF, Francom P, Broom AD.
Abstract : The synthesis and biological activity of 42 6-substituted-2,4-diaminopyrido[3,2-d]pyrimidines (2,4-diamino-8-deazafolate analogues) are reported. The compounds were synthesized in improved yields compared to previous classical analogues using modifications of procedures reported previously by us. Specifically, the S-phenyl-; mono-, di-, and trimethoxyphenyl-; and mono-, di-, and trichlorophenyl-substituted analogues with H or CH3 at the N10 position and methyl and trifluoromethyl phenyl ketone analogues with H, CH3, and CH2C identical to CH at the N10 position were synthesized. The S10 and N10 alpha- and beta-naphthyl analogues along with the N10 CH3 analogues were also synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg); selectivity ratios were determined against rat liver (rl) DHFR as the mammalian reference enzyme. Against pcDHFR the IC50 values ranged from 0.038 x 10-6 M for 2,4-diamino-6-[(N-methyl-2'-naphthylamino)methyl]pyrido[3,2-d]pyrimidine (28) to 5.5 x 10(-6) M for 2,4-diamino-6[(2',4'-dimethoxyanilino)methyl]pyrido[3,2-d]pyrim idi ne (15). N10 methylation in all instances increased potency. None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was 2,4-diamino-6-[(N-methylanilino)methyl]pyrido[3,2-d]pyrimidine (5) (IC50 0.0084 x 10(-6) M) and the least potent was 2,4-diamino-6[(2'-naphthylamino)methyl]-pyrido[3,2-d]pyrimidine (37) (IC50 0.16 x 10-6 M). N10 methylation afforded an increase in potency up to 10-fold. In contrast to pcDHFR, several of the 8-deaza analogues were significantly selective for tgDHFR, most notably 2,4-diamino-6-[(2'-chloro-N-methylanilino)-methyl]pyrido[3,2-d] pyrimidine (13), 2,4-diamino-6-[(3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyr pyrimidine (29), and 2,4-diamino-6-[(2',4',6'-trichloroanilino)methyl]pyrido[3,2-d] pyrimidine (32) which combined high potency at 10-8 M along with selectivities of 8.0, 5.0, and 12.4, respectively. The potency of these three analogues are comparable to the clinically used agent trimetrexate while their selectivities for tgDHFR are 17-43-fold better than trimetrexate.
|
Compound was tested for inhibition activity against Toxoplasma gondii (Toxoplasma gondii) Dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-6,7-dihydro-5H-cyclopenta[d]pyrimidine analogues of trimethoprim as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1998
Volume : 41
Issue : 6
First Page : 913
Last Page : 918
Authors : Rosowsky A, Papoulis AT, Queener SF.
Abstract : Three previously unreported (R,S)-2,4-diamino-5-[(3,4,5-trimethoxyphenyl) alkyl]-6,7-dihydro-5H-cyclopenta[d]pyrimidines 15a-c were synthesized as analogues of trimethoprim (TMP) and were tested as inhibitors of Pneumocystis carinii, Toxoplasma gondii, and rat liver dihydrofolate reductase (DHFR). The length of the alkyl bridge between the cyclopenta[d]pyrimidine and trimethoxyphenyl moiety ranged from one in 15a to three carbons in 15c. The products were tested as competitive inhibitors of the reduction of dihydrofolate by Pneumocystis carinii, Toxoplasma gondii, and rat liver DHFR. Compounds 15a-c had IC50 values of > 32, 1.8 and 1.3 microM, respectively, against P. carinii DHFR, as compared to 12 microM for TMP. Against the T. gondii enzyme, 15a-c had IC50 values of 21, 0.14 and 0.14 microM, respectively, as compared to 2.7 microM for TMP. Inhibitors 15b and 15c with two- and three-carbon bridges were significantly more potent than 15a against all three enzymes. Unlike TMP, 15b and 15c were better inhibitors of the rat liver enzyme than of the microbial enzymes. The potency of 15b and 15c against rat liver DHFR was less than has been reported for the corresponding 6,7-dihydro-5H-cyclopenta[d]pyrimidines with a classical p-aminobenzoyl-L-glutamate side chain as inhibitors of bovine, murine, and human DHFR.
|
Concentration inhibiting Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminopyrido[3,2-d]pyrimidine inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 14
First Page : 2615
Last Page : 2620
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : Six previously unknown 2,4-diamino-6-(anilinomethyl)- and 2,4-diamino-6-[(N-methylanilino)-methyl]pyrido[3,2-d]pyrimidines (5-10) were synthesized from 2,4-diamino-6-(bromomethyl)-pyrido[3,2-d]pyrimidine hydrobromide (11.HBr) by treatment with the appropriate aniline or N-methylaniline in dimethylformamide at room temperature, with or without NaHCO3 present. Compounds 5-10 were tested as inhibitors of dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, and rat liver as a part of a larger effort directed toward the discovery of lipophilic nonclassical antifolates combining high enzyme selectivity and high potency. Of the six analogues tested, the most potent and selective against T. gondii DHFR was 2,4-diamino-6-[(3',4',5'-trimethoxy-N-methylanilono)methyl]pyrido[ 3,2-d d pyrimidine (7), which had an IC50 of 0.0047 microM against this enzyme as compared with 0.026 microM against the rat liver enzyme. The potency of 7 against T. gondii DHFR was similar to that of trimetrexate (TMQ, 1) and piritrexim (PTX, 2) but was > 500-fold greater than that of trimethoprim (TMP, 3). However, while 7 was more selective than either TMQ (19x) or PTX (63x) against this enzyme, its selectivity in comparison with TMP was 8-fold lower. 2,4-Diamino-6-[3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyri midin e (6) was 17-fold less active than 7 and was also less selective. 2,4-Diamino-6-[(3',4'-dichloro-N-methylanilino)methyl]pyrido[3, 2-d]pyrimidine (10) had an IC50 of 0.022 microM against P. carinii DHFR and was comparable in potency to TMQ and PTX. The species selectivity of 10 for P. carinii versus rat liver DHFR was greater than that of either TMQ (21-fold) or PTX (31-fold). On the other hand, even though 10 was slightly more active than TMQ against the P. carinii enzyme, its selectivity was 7-fold lower than that of TMP. Thus, the goal of combining high enzyme binding activity, which is characteristic of the fused-ring compounds TMQ and PTX, with high selectivity for T. gondii and P. carinii DHFR versus rat liver DHFR, which is characteristic of the monocyclic compound TMP, remained unmet in this limited series.
|
Inhibition of Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Inhibition of Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Conformationally restricted analogues of trimethoprim: 2,6-diamino-8-substituted purines as potential dihydrofolate reductase inhibitors from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 19
First Page : 3032
Last Page : 3039
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Twenty-two 2,6-diamino-8-substituted purines (2-23) were synthesized, in which rotation around the two flexible bonds of trimethoprim (TMP), linking the pyrimidine ring to the side chain phenyl ring, was restricted by incorporation into a purine ring, in an attempt to increase the potency and selectivity of TMP against dihydrofolate reductase (DHFR) from the organisms that often cause fatal opportunistic infections in patients with AIDS, i.e., Pneumocystis carinii (pc) and Toxoplasma gondii (tg). The syntheses of analogues 2-20 were achieved via a one-pot reaction of 2,4,5,6-tetraaminopyrimidine and the appropriately substituted benzaldehyde or phenyl acetaldehyde, in acidic methoxyethanol. Analogues 21-23 were synthesized via nucleophilic displacement of 2,6-diamino-8-(chloromethyl)purine with the appropriate anilines or 2-naphthalenethiol. The compounds were evaluated as inhibitors of pcDHFR and tgDHFR with rat liver (rl) DHFR as the mammalian reference enzyme. Compound 11, the 3',4'-dichlorophenyl analogue, was as potent as TMP and had a selectivity ratio of 13 for pcDHFR, which ranked it as one of the three most selective inhibitors of pcDHFR (compared to rlDHFR) known to date. It also displayed a selectivity ratio of 38 for tgDHFR. None of the other analogues showed any improvement compared to TMP in potency or selectivity. In the preclinical in vitro screening program of the National Cancer Institute, compound 11 showed a GI50 of 10(-6) M for the inhibition of the growth of 17 tumor cell lines.
|
Inhibition against Dihydrofolate reductase in Toxoplasma gondii
|
Toxoplasma gondii
|
10.0
nM
|
|
Journal : J. Med. Chem.
Title : Effect of N9-methylation and bridge atom variation on the activity of 5-substituted 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 7
First Page : 1173
Last Page : 1177
Authors : Gangjee A, Mavandadi F, Queener SF.
Abstract : The effect of N9-methylation and bridge atom variation on inhibitory potency and selectivity of 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases (DHFR) was studied. Specifically three nonclassical 2,4-diamino-5-((N-methylanilino)methyl)pyrrolo[2,3-d]pyrimidines with 2',5'-dimethoxyphenyl (2), 3',4'-dichlorophenyl (3), 1'-naphthyl (4), one classical analogue with a 4'-L-glutamate substituent (10), and four nonclassical 2,4-diamino-5-((phenylthio)methyl)pyrrolo[2,3-d]pyrimidines with 3',4'-dimethoxyphenyl (5), 3',4'-dichlorophenyl (6), 1'-naphthyl (7), and 2'-naphthyl (8) substituents were synthesized. The classical and nonclassical analogues were obtained by displacement of the intermediate 2,4-diamino-5-bromomethylpyrrolo[2,3-d]pyrimidine, 14, with appropriately substituted N-methylaniline, thiophenols, or 4-(N-methylamino)benzoyl-L-glutamate. Compounds 2-8 and 10 were evaluated against Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) DHFRs. The N-methyl and thiomethyl analogues were more inhibitory than their corresponding anilinomethyl analogues (previously reported) against all three DHFRs. The inhibitory potency of these analogues was greater against rlDHFR than against tgDHFR which resulted in a loss of selectivity for tgDHFR compared to the N9-H analogues. The classical N9-methyl analogue 10 was more potent and about 2-fold more selective against tgDHFR than its corresponding desmethyl analogue. All of the analogues, 2-8 and 10, were more selective than trimetrexate (TMQ) against pcDHFR (except 4) and significantly more selective than TMQ against tgDHFR.
|
Inhibition of Dihydrofolate reductase of Toxoplasma gondii
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-chloroquinazoline analogues of trimetrexate and piritrexim: synthesis and antifolate activity.
Year : 1994
Volume : 37
Issue : 26
First Page : 4522
Last Page : 4528
Authors : Rosowsky A, Mota CE, Wright JE, Queener SF.
Abstract : Ten heretofore undescribed 2,4-diamino-5-chloroquinazoline analogues of trimetrexate (TMQ) and piritrexim (PTX) were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from rat liver, Pneumocystis carinii, and Toxoplasma gondii. The most active quinazolines against both the P. carinii and the T. gondii enzyme were those with an ArCH2-NH or ArNHCH2 side chain. Among ArNH(CH2)n compounds with n = 1-3 and either 2',5'-dimethoxyphenyl or 3',4',5'-trimethoxyphenyl as the Ar moiety, activity decreased in the order n = 1 > n = 2 > n = 3. The best inhibitor of P. carinii DHFR, 2,4-diamino-5-chloro-6-[(N-methyl-3',4',5'-trimethoxyanilino)methy l] quinazoline (10) had an IC50 of 0.012 microM and was slightly more potent than TMQ and PTX. Compound 10 was also the best inhibitor of T. gondii DHFR, with an IC50 of 0.0064 microM corresponding again to a minor increase in activity over TMQ and PTX. However, as with these standard agents, 10 showed no appreciable selectivity for either the P. carinii or T. gondii enzyme relative to the rat liver enzyme. The highest selectivity achieved in this limited series was with 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl)-N-methylamino] quinazoline (17) against T. gondii DHFR. While 17 (IC50 = 0.016 microM) was somewhat less potent than 10, its selectivity, as defined by the ratio IC50(rat liver)/IC50(T. gondii) was ca. 30-fold higher than that of TMQ or PTX. Two compounds, 2,4-diamino-5-chloro-6-[(3',4',5'-trimethoxyanilino)methyl] quinazoline (9) and 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl) amino]quinazoline (15), were also tested against human DHFR and were found to have an IC50/[E] of 0.5, indicating that their binding was near-stoichiometric.
|
Inhibitory activity against Dihydrofolate reductase from Toxoplasma gondii
|
Toxoplasma gondii
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines as inhibitors of dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1995
Volume : 38
Issue : 10
First Page : 1778
Last Page : 1785
Authors : Gangjee A, Vasudevan A, Queener SF, Kisliuk RL.
Abstract : The synthesis and biological activity of 15 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]-pyrimidines are reported. These compounds were synthesized in improved yields by modifications of procedures previously reported by us. Specifically, dimethoxyphenyl-substituted compounds with H and CH3 at the N-10 position and trimethoxyphenyl-substituted compounds with N-10 ethyl, isopropyl, and propargyl moieties were synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii, Toxoplasma gondii, and rat liver, and selected analogues were evaluated as inhibitors of the growth of T. gondii and tumor cells in culture. All the compounds showed increased selectivity (vs rat liver DHFR) for T. gondii DHFR compared to trimetrexate. In general, for the trimethoxy-substituted analogues, increasing the size of the N-10 substituent from a methyl group to larger groups resulted in a decrease in selectivity and potency for both P. carinii and T. gondii DHFR. For the dimethoxy-substituted analogues, N-10 methylation in general decreased potency but increased selectivity for T. gondii DHFR. In an attempt to improve the cell penetration of these analogues, the N-10 naphthyl-substituted analogues were also synthesized. These analogues displayed excellent cell penetration and inhibition of T. gondii cells in culture. Further, these analogues were potent inhibitors of the growth of tumor cells in the preclinical in-vitro screening program of the National Cancer Institute with IC50s in the nanomolar range.
|
Inhibitory activity against Dihydrohydrofolate reductase(DHFR) of Toxoplasma gondii
|
Toxoplasma gondii
|
43.0
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of Dihydrofolate Reductase of Toxoplasma gondii.
|
Toxoplasma gondii
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of nonclassical 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines with novel side chain substituents as potential inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 4
First Page : 479
Last Page : 485
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2-10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase (pcDHFR) and Toxoplasma gondii dihydrofolate reductase (tgDHFR). Compounds 2-5 were designed as conformationally restricted analogues of trimetrexate (TMQ), in which rotation around tau 3 was constrained by incorporation of the side chain nitrogen as part of an indoline or an indole ring. Analogue 6, which has an extra atom between the side chain nitrogen and the phenyl ring, has its nitrogen as part of a tetrahydroisoquinoline ring. Analogues 7-9 are epiroprim (Ro 11-8958) analogues and contain a pyrrole ring as part of the side chain substitution on the phenyl ring similar to epiroprim. These analogues were designed to investigate the role of the pyrrole substitution on the phenyl ring of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines. Molecular modeling indicated that a pyrrole substituent in the ortho position of the side chain phenyl ring was most likely to interact with pcDHFR in a manner similar to the pyrrole moiety of epiroprim. Analogue 10, in which a phenyl ring replaced a methoxy group, was synthesized to determine the contribution of a phenyl ring on selectivity, lipophilicity, and cell penetration. The synthesis of analogues 2-4 was achieved via reductive amination of 2,4-diamino-5-methyl 6-carboxaldehyde with the appropriately substituted indolines. The indolines were obtained from the corresponding indoles via NaCNBH3 reductions. Analogues 5-10 were synthesized by nucleophilic displacement of 2,4-diamino-5-methyl-6-(bromomethyl)-pyrido[2,3-d]pyrimidine with the 5-methoxyindolyl anion, 6,7-dimethoxytetrahydroisoquinoline, the appropriately substituted pyrroloaniline or 2-methoxy-5-phenylaniline. The pyrroloanilines were synthesized in two steps by treating the substituted nitroanilines with 2,5-dimethoxy-tetrahydrofuran to afford the nitropyrrole intermediates, followed by reduction of the nitro group with Raney Ni. The analogues were more potent than trimethoprim and epiroprim and more selective than TMQ and piritrexim against pcDHFR and tgDHFR. Compounds 5 and 10 had IC50 values of 1 and 0.64 microM, respectively, for the inhibition of the growth of T. gondii cells in culture, and showed excellent culture IC50/enzyme IC50 ratios, which were correlated with their calculated log P values, indicating a direct relationship between calculated lipophilicity and cell penetration.
|
Inhibitory activity against dihydrofolate reductase (DHFR) from Toxoplasma gondii
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : 6-Substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues of piritrexim as inhibitors of dihydrofolate reductase from rat liver, Pneumocystis carinii, and Toxoplasma gondii and as antitumor agents.
Year : 1998
Volume : 41
Issue : 23
First Page : 4533
Last Page : 4541
Authors : Gangjee A, Zhu Y, Queener SF.
Abstract : The synthesis and biological activity are reported for 21 6-substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues (4-24) of piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) and as antitumor agents. Recombinant DHFR from Pneumocystis carinii (pc) and native DHFR from Toxoplasma gondii (tg) were the target enzymes tested; these organisms are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity for the pathogenic DHFR. The synthesis of S9-bridged compounds 4-6 was achieved by aryl displacement of 2,4-diamino-6-chloropyrido[3, 2-d]pyrimidine (27) with thiol nucleophiles. Oxidation of 4-6 with hydrogen peroxide in glacial acetic acid afforded the corresponding sulfone analogues 7-9. The N9-bridged compounds 10-24 were synthesized from their precursor 3-amino-6-(arylamino)-2-pyridinecarbonitriles via a thermal cyclization with chloroformamidine hydrochloride. Unlike the S9-bridged compounds, the arylamino side chains of the N9-bridged analogues were introduced prior to the formation of the 2, 4-diaminopyrido[3,2-d]pyrimidine nucleus. A reversed two-atom-bridged analogue (25) was also synthesized using a synthetic strategy similar to that utilized for compounds 10-24. The IC50 values of these compounds against pcDHFR ranged from 0.0023 x 10(-6) M for 2,4-diamino-6-(N-methyl-3',4'-dimethoxyanilino)pyrido[3, 2-d]pyrimidine (21), which was the most potent, to 90.4 x 10(-6) M for 2,4-diamino-6-(4'-methoxyanilino)pyrido[3,2-d]pyrimidine (12), which was the least potent. The three S9-bridged compounds tested were more potent than the corresponding sulfone-bridged compounds for all three DHFRs. N9-Methylation increased the potency by as much as 17 000-fold (compounds 15 and 21). None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was again 21 with an IC50 value of 0.00088 x 10(-6) M and the least potent was 12 with an IC50 of 2.8 x 10(-6) M. N9-Methylation afforded an increase in potency of up to 770-fold (compound 15 NH vs 21 N-CH3) compared to the corresponding N9-H analogue. In contrast to pcDHFR, several analogues had a greater selectivity ratio for tgDHFR compared to trimetrexate (TMQ) or PTX, most notably 2, 4-diamino-6-[(3',4'- dimethoxyphenyl)thio]pyrido[3,2-d]pyrimidine (4), 2,4-diamino-6-[(2'-methoxyphenyl)sulfonyl]pyrido[3, 2-d]pyrimidine (7), and 2,4-diamino-6-(2', 5'-dimethoxyanilino)pyrido[3,2-d]pyrimidine (14) which combined relatively high potency at 10(-7)-10(-8) M along with selectivity ratios of 3.97, 6.67, and 4.93, respectively. Several analogues synthesized had better selectivity ratios than TMQ or PTX for both pcDHFR and tgDHFR, and the potencies of the N9-methylated compounds were comparable to or greater than that of TMQ or PTX. Selected compounds were evaluated as inhibitors of the growth of a variety of tumor cells in culture. The N9-CH3 analogues were, in general, highly potent with GI50 values in the nanomolar range. The N9-H and S9 analogues were less potent with GI50 values in the millimolar to micromolar range.
|
Inhibitory activity against Dihydrofolate reductase from Toxoplasma gondii was evaluated using 90 uM dihydrofolic acid as substrate
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-5-aryl-6-ethylpyrimidine antifolates: activity as inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1997
Volume : 40
Issue : 19
First Page : 3040
Last Page : 3048
Authors : Robson C, Meek MA, Grunwaldt JD, Lambert PA, Queener SF, Schmidt D, Griffin RJ.
Abstract : Twelve novel 2,4-diamino-5-(4'-benzylamino)- and 2,4-diamino-5[4'-(N-methylbenzylamino)-3'-nitrophenyl]-6-ethylp yrimidines bearing 4-substituents on the benzylamino or N-methylbenzylamino aryl ring were synthesized and evaluated as nonclassical inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase (DHFR). Compounds were prepared by reaction of 2,4-diamino-5-(4'-chloro-3'-nitrophenyl)- (8) or 2,4-diamino-5-(4'-fluoro-3'-nitrophenyl)-6-ethylpyrimidine (15) with the appropriate 4-substituted (CO2H, CO2Me, SO2NH2, dioxolan-2-yl, CHO, dimethyloxazolin-2-yl) benzylamine or N-methylbenzylamine derivative. Compounds 25-29 were synthesized from 2,4-diamino-5-{4'-[N-(4"-carboxybenzyl)amino]-3'-nitrophenyl}-6- ethylpyrimidine (10) and the corresponding amine (NH3, MeNH2, Me2NH, piperidine, diethyl L-glutamate) via isobutyl mixed anhydride coupling; hydrolysis of the diethyl L-glutamate 29 afforded the L-glutamate analogue 30. The compounds exhibited potent inhibitory activity against T. gondii (IC50 values 0.0018-0.14 microM) and rat liver (IC50 values 0.0029-0.27 microM) DHFR, with a 4-substituent invariably enhancing binding to both enzymes relative to the unsubstituted benzoprim (5) or methylbenzoprim (6). Modest selectivity for T. gondii enzyme was observed with several analogues, whereas all of the compounds were relatively weak inhibitors of P. carinii DHFR and exhibited no selectivity. Selected analogues were evaluated for in vivo antitumor activity against the methotrexate-resistant M5076 murine reticulosarcoma, with 2,4-diamino-5-{4'-[N-[4"-(N"-methylcarbamoyl)benzyl]-N- methylamino]-3'-nitrophenyl}-6-ethylpyrimidine (14) (Ki for rat liver DHFR = 0.00035 +/- 0.00029 nM) combining significant antitumor activity with minimal toxicity.
|
Inhibitory activity against Toxoplasma gondii Dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-substituted-quinazolines as inhibitors of a human dihydrofolate reductase with a site-directed mutation at position 22 and of the dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 5
First Page : 745
Last Page : 752
Authors : Rosowsky A, Mota CE, Queener SF, Waltham M, Ercikan-Abali E, Bertino JR.
Abstract : 2,4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (p-aminobenzoyl)-L-glutamate side chain, were synthesized as potentially selective inhibitors of a site-directed mutant of human dihydrofolate reductase (DHFR) containing phenylalanine instead of leucine at position 22. This mutant enzyme is approximately 100-fold more resistant than native enzyme to the classical antifolate methotrexate (MTX), yet shows minimal cross resistance to the nonclassical antifolates piritrexim (PTX) and trimetrexate (TMQ). Although they were much less potent than trimetrexate and piritrexim, the lipophilic 5-substituted analogues were all found to bind approximately 10 times better to the mutant DHFR than to the wild-type enzyme. The potency of the analogue with a classical (p-aminobenzoyl)-L-glutamate side chain was similarly diminished in comparison with MTX, but the difference in its binding affinity to the two DHFR species was only 5-fold. Thus, by making subtle structural changes in the antifolate molecule, it may be possible to attack resistance due to mutational alterations in the active site of the target enzyme. Also, to test the hypothesis that DHFR from Pneumocystis carinii and Toxoplasma gondii may have a less sterically restrictive active site than the enzyme from mammalian cells, inhibition assays using several of the lipophilic analogues in the series were carried out against the P. carinii and T. gondii reductases in comparison with the enzyme from rat liver. In contrast to their preferential binding to mutant versus wild-type human DHFR, binding of these analogues to the P. carinii and T. gondii enzymes was weaker than binding to rat enzyme. It thus appears that, if the active site of the DHFR from these parasites is less sterically restrictive than the active site of the mammalian enzyme, this difference cannot be successfully exploited by moving the side chain from the 6-position to the 5-position.
|
Inhibitory activity against Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Lipophilic antifolates as agents against opportunistic infections. 1. Agents superior to trimetrexate and piritrexim against Toxoplasma gondii and Pneumocystis carinii in in vitro evaluations.
Year : 1996
Volume : 39
Issue : 6
First Page : 1271
Last Page : 1280
Authors : Piper JR, Johnson CA, Krauth CA, Carter RL, Hosmer CA, Queener SF, Borotz SE, Pfefferkorn ER.
Abstract : 2,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four 2,4-diaminoquinazolines, each with an aryl groups attached to the 6-position of the heterocyclic moiety through a two-atom bridge (either CH2NH, CH2N(CH3),CH2S, or CH2CH2), were synthesized and evaluated as inhibitors of the growth of Toxoplasma gondii in culture and as inhibitors of dihydrofolate reductase enzymes from T. gondii, Pneumocystis carinii, and rat liver. Exceptionally high levels of combined potency and selectivity as growth inhibitors of T. gondii and as inhibitors of the microbial enzymes relative to the mammalian enzyme were found among the 5-methyl-5-deazapteridines but not for the other heterocyclic types. Thirty of the 34 5-methyl-5-deaza compounds gave growth inhibition IC50 values lower than that of pyrimethamine (0.4 microM) with 14 compounds below 0.1 microM, values that compare favorably with those for piritrexim and trimetrexate (both near 0.02 microM). As inhibitors of T gondii DHFR, all but three of the 34 5-methyl-5-deaza compounds gave IC50 values in the order of magnitude with those of piritrexim (0.017 microM) and trimetrexate (0.010 microM), and 17 compounds of this group gave IC50 values versus P. carinii DHFR similarly comparable with those of piritrexim (0.031 microM) and trimetrexate (0.042 microM). Thirteen of these congeners gave both T. gondii growth inhibition and DHFR inhibition IC50 values of 0.10 microM or less, thus indicating facile penetration of the cell membrane. Eleven of these inhibitors of both T. gondii growth and DHFR have selectivity ratios (IC50 rat liver divided by IC50 T. gondii) of 5 or greater for the parasite DHFR. The highest selectivity ratio of nearly 100 belongs to the 5-methyl-5-deaza compound whose 6-substituent is CH2CH2C6H3(OCH3)2-2,5. This compound is over 10(3)-fold more selective for T. gondii DHFR than bridge homologue piritrexim (selectivity ratio 0.088), a compound now in clinical trials. The candidate with CH2NHC6H3(CH3)2-2,5 in the 6-position gave the highest P. carinii DHFR selectivity ratio of 4.0, which is about 60-fold more selective than trimetrexate (0.071) and 80-fold more selective than piritrexim (0.048) toward this enzyme. The 10 best compounds with respect to potency and selectivity includes six compounds bearing 2,5-disubstituted phenyl groups in the side chain (with little, if any, difference in effects of methyl, methoxy, or ethoxy), two side chains bearing 1-naphthyl groups, and two with 5,6,7,8-tetrahydro-1-naphthyl groups. Bridge groups represented in the 10 choice compounds are CH2NH, CH2N(CH3), CH2CH2, and CH2S. The high levels of both potency and selectivity among these agents suggest that in vivo studies now underway may lead to agents that could replace trimetrexate and piritrexim in treatment of toxoplasmosis and P. carinii pneumonia.
|
Inhibitory concentration against Dihydrofolate reductase from Toxoplasma gondii (tg)
|
Toxoplasma gondii
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and dihydrofolate reductase inhibitory activities of 2,4-diamino-5-deaza and 2,4-diamino-5,10-dideaza lipophilic antifolates.
Year : 1997
Volume : 40
Issue : 4
First Page : 470
Last Page : 478
Authors : Gangjee A, Devraj R, Queener SF.
Abstract : Two series of nonclassical antifolates (2,4-diamino-5-deaza compounds 2-5 and 5,10-dideaza compounds 6-13) were synthesized as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) organisms that are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity. Syntheses of the target 5-deaza compounds were achieved by initial construction of the pivaloyl-protected 2,4-diamino-6-bromopyrido[2,3-d]-pyrimidine 17 via a cyclocondensation of 2,4,6-triaminopyrimidine with bromomalonaldehyde. Sequential Heck coupling of 17 with styrene followed by ozonolysis afforded the 6-formyl derivative 19. Reductive amination of 19 with 3,4,5-trimethoxyaniline afforded the N10-H analog. The N10-Me and N10-Et analogs were synthesized by nucleophilic displacement of the 6-bromomethyl derivative 22 (obtained from the 6-formyl derivative 19 by reduction and bromination) with the appropriate N-alkylaniline. The trans-5,10-dideaza analogs 6-8 were synthesized via a Heck coupling of the appropriate methoxystyrene with 17, and selective reduction of the resulting 9,10-double bond afforded target compounds 9-11. Further reduction to the tetrahydro derivatives afforded analogs 12 and 13. The 5-deaza N10-Me 3,4,5-trimethoxy analog 3 maintained the best balance of potency and selectivity against both tgDHFR and pcDHFR. Compared to trimethoprim, compound 3 was only slightly less selective but was 300-fold more potent against tgDHFR. The 5,10-dideaza analogs were generally less potent and selective than the 5-deaza compounds.
|
Inhibitory concentration against Toxoplasma gondii Dihydrofolate reductase
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological activities of conformationally restricted, tricyclic nonclassical antifolates as inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 12
First Page : 1930
Last Page : 1936
Authors : Gangjee A, Shi J, Queener SF.
Abstract : Seven novel tricyclic pyrimido[4,5-c][2,7]naphthyridones 5-8 and the corresponding naphthyridines 9-11 were synthesized as conformationally restricted inhibitors of dihydrofolate reductase (DHFR) and as antitumor and/or antiinfectious agents. The analogues were designed to orient the side chain trimethoxyphenyl group in different conformationally defined positions in order to explore the effect of the side chain orientation on binding affinity and selectivity for DHFR from various species. The semirigid orientations were achieved by bridging the C5 and N10 of compound 12 with a N-ethyl bridge and by variation of the position of double bonds in rings B and C as well as substitution at the 2',6'-positions of the phenyl ring. The synthesis of compounds 5-11 were accomplished by cyclocondensation of the appropriate keto ester (as the biselectrophile) with 2,4,6-triaminopyrimidine to afford the lactam 5. The dehydrolactams 6 and 7 were prepared by air oxidation and PtO2-catalyzed dehydrogenation of 7, respectively. The dichloro dehydro lactam 8 was obtained by refluxing lactam 5 and/or 6 in POCl3 or a mixture of POCl3/PCl5. Compounds 9-11 were obtained by two methods, direct borane reduction of lactam 5 or 6 or thiation of the dipivoylated lactam 15 followed by reductive dethiation. Compounds 9-11 were interconverted by air oxidation or PtO2-catalyzed reduction/oxidation, respectively. The compounds were evaluated as inhibitors of DHFR from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) with rat liver (rl) serving as the reference mammalian enzyme. In the lactam series 5-8, the most unsaturated analogue 7 showed an IC50 of 86 nM against rlDHFR, almost 100-fold more active than 5 and 3-fold more active than 6. The 2',6'-dichloro dehydro lactam 8 was less active than the corresponding dehydro lactam 6 against rlDHFR. In the naphthyridine series 9-11, the dehydro analogue 10 was more active than 9 against rlDHFR. The fully reduced analogue 11 (as a mixture of cis and trans isomers) was the most active in the naphthyridine series. The analogues were, in general, more inhibitory against rlDHFR than against pcDHFR, or tgDHFR, and thus lacked selectivity. In addition, they were less potent than the bicyclic compounds trimetrexate 3 (TMQ) and piritrixim 4 (PTX).
|
Inhibitory concentration against Toxoplasma gondii dihydrofolate reductase
|
Toxoplasma gondii
|
4.3
nM
|
|
Journal : Bioorg. Med. Chem. Lett.
Title : Preliminary in vitro studies on two potent, water-soluble trimethoprim analogues with exceptional species selectivity against dihydrofolate reductase from Pneumocystis carinii and Mycobacterium avium.
Year : 2004
Volume : 14
Issue : 7
First Page : 1811
Last Page : 1815
Authors : Forsch RA, Queener SF, Rosowsky A.
Abstract : 2,4-Diamino-5-[3',4'-dimethoxy-5'-(5-carboxy-1-pentynyl)]benzylpyrimidine (6) and 2,4-diamino-5-[3',4'-dimethoxy-5'-(4-carboxyphenylethynyl)benzylpyrimidine (7) were synthesized from 2,4-diamino-5-(5'-iodo-3',4'-dimethoxybenzyl)pyrimidine (9) via a Sonogashira reaction with appropriate acetylenic esters followed by saponification, and were tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat in comparison with the widely used antibacterial agent 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP). The selectivity index (SI) for each compound was calculated by dividing its 50% inhibitory concentration (IC(50)) against rat DHFR by its IC(50) against Pc, Tg, or Ma DHFR. The IC(50) of 6 against Pc DHFR was 1.0 nM, with an SI of 5000. Compound 7 had an IC(50) of 8.2 nM against Ma DHFR, with an SI of 11000. By comparison, the IC(50) of TMP was 12000 nM against Pc, 300 nM against Ma, and 180000 against rat DHFR. The potency and selectivity values of 6 and 7 were not as high against Tg as they were against Pc or Ma DHFR, but nonetheless exceeded those of TMP. Because of the outstanding selectivity of 6 against Pc and of 7 against Ma DHFR, these novel analogues may be viewed as promising leads for further structure-activity optimization.
|
Inhibitory concentration against dihydrofolate reductase DHFR from Toxoplasma gondii
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, computational prediction, and biological evaluation of ester soft drugs as inhibitors of dihydrofolate reductase from Pneumocystis carinii.
Year : 2001
Volume : 44
Issue : 15
First Page : 2391
Last Page : 2402
Authors : Graffner-Nordberg M, Kolmodin K, Aqvist J, Queener SF, Hallberg A.
Abstract : A series of lipophilic soft drugs structurally related to the nonclassical dihydrofolate reductase (DHFR) inhibitors trimetrexate and piritrexim have been designed, synthesized, and evaluated in DHFR assays, with special emphasis on the inhibition of P. carinii DHFR. The best inhibitors, encompassing an ester bond in the bridge connecting the two aromatic systems, were approximately 10 times less potent than trimetrexate and piritrexim. The metabolites were designed to be poor inhibitors. Furthermore, molecular dynamics simulations of three ligands in complex with DHFR from Pneumocystis carinii and from the human enzyme were conducted in order to better understand the factors determining the selectivity. A correct ranking of the relative inhibition of DHFR was achieved utilizing the linear interaction energy method. The soft drugs are intended for local administration. One representative ester was selected for a pharmacokinetic study in rats where it was found to undergo fast metabolic degradation to the predicted inactive metabolites.
|
Inhibitory concentration against dihydrofolate reductase of Toxoplasma gondii
|
Toxoplasma gondii
|
4.3
nM
|
|
Journal : J. Med. Chem.
Title : New 2,4-diamino-5-(2',5'-substituted benzyl)pyrimidines as potential drugs against opportunistic infections of AIDS and other immune disorders. Synthesis and species-dependent antifolate activity.
Year : 2004
Volume : 47
Issue : 6
First Page : 1475
Last Page : 1486
Authors : Rosowsky A, Forsch RA, Sibley CH, Inderlied CB, Queener SF.
Abstract : In a continuing effort to design small-molecule inhibitors of dihydrofolate reductase (DHFR) that combine the enzyme-binding selectivity of 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP) with the potency of 2,4-diamino-5-methyl-6-(2',5'-dimethoxybenzyl)pyrido[2,3-d]pyrimidine (piritrexim, PTX), seven previously undescribed 2,4-diamino-5-[2'-methoxy-5'-(substituted benzyl)]pyrimidines were synthesized in which the substituent at the 5'-position was a carboxyphenyl group linked to the benzyl moiety by a bridge of two or four atoms in length. The new analogues were all obtained from 2,4-diamino-5-(5'-iodo-2'-methoxybenzyl)pyrimidine via a Sonogashira reaction, followed, where appropriate, by catalytic hydrogenation. The new analogues were tested as inhibitors of DHFR from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three life-threatening pathogens often found in AIDS patients and individuals whose immune system is impaired as a result of treatment with immunosuppressive chemotherapy or radiation. The selectivity index (SI) of each compound was obtained by dividing its 50% inhibitory concentration (IC(50)) against Pc, Tg, or Ma DHFR by its IC(50) against rat DHFR. 2,4-Diamino-[2'-methoxy-5'-(3-carboxyphenyl)ethynylbenzyl]pyrimidine (28), with an IC(50) of 23 nM and an SI of 28 in the Pc DHFR assay, had about the same potency as PTX and was 520 times more potent than TMP. As an inhibitor of Tg DHFR, 28 had an IC(50) of 5.5 nM (510-fold lower than that of TMP and similar to that of PTX) and an SI value of 120 (2-fold better than TMP and vastly superior to PTX). Against Ma DHFR, 28 had IC(50) and SI values of 1.5 nM and 430, respectively, compared with 300 nM and 610 for TMP. Although it had 2.5-fold lower potency than 28 against Ma DHFR (IC(50) = 3.7 nM) and was substantially weaker against Pc and Tg DHFR, 2,4-diamino-[2'-methoxy-5'-(4-carboxyphenyl)ethynylbenzyl]pyrimidine (29), with the carboxy group at the para rather than the meta position, displayed 2200-fold selectivity against the Ma enzyme and was the most selective 2,4-diamino-5-(5'-substituted benzyl)pyrimidine inhibitor of this enzyme we have encountered to date. Additional bioassay data for these compounds are also reported.
|
The ability to inhibit Toxoplasma gondii Dihydrofolate reductase was tested
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and antiparasitic and antitumor activity of 2, 4-diamino-6-(arylmethyl)-5,6,7,8-tetrahydroquinazoline analogues of piritrexim.
Year : 1999
Volume : 42
Issue : 6
First Page : 1007
Last Page : 1017
Authors : Rosowsky A, Papoulis AT, Forsch RA, Queener SF.
Abstract : Nineteen previously undescribed 2,4-diamino-6-(arylmethyl)-5,6,7, 8-tetrahydroquinazolines (5a-m, 10-12) were synthesized as part of a larger effort to assess the therapeutic potential of lipophilic dihydrofolate reductase (DHFR) inhibitors against opportunistic infections of AIDS. Condensation of appropriately substituted (arylmethyl)triphenylphosphoranes with 4, 4-ethylenedioxycyclohexanone, followed by hydrogenation (H2/Pd-C) and acidolysis, yielded the corresponding 4-(arylmethyl)cyclohexanones, which were then condensed with cyanoguanidine to form the tetrahydroquinazolines. Three simple 2, 4-diamino-6-alkyl-5,6,7,8-tetrahydroquinazoline model compounds (9a-c) were also prepared in one step from commercially available 4-alkylcyclohexanones by this method. Enzyme inhibition assays against rat liver DHFR, Pneumocystis carinii DHFR, and the bifunctional DHFR-TS enzyme from Toxoplasma gondii were carried out, and the selectivity ratios IC50(rat)/IC50(P. carinii) and IC50(rat)/IC50(T. gondii) were compared. The three most potent inhibitors of P. carinii DHFR were the 2,5-dimethoxybenzyl (5j), 3, 4-dimethoxybenzyl (5k), and 3,4,5-trimethoxybenzyl (5l) analogues, with IC50 values of 0.057, 0.10, and 0.091 microM, respectively. The remaining compounds generally had IC50 values in the 0.1-1.0 microM range. However all the compounds were more potent against the rat liver enzyme than the P. carinii enzyme and thus were nonselective. The T. gondii enzyme was always more sensitive than the P. carinii enzyme, with most of the analogues giving IC50 values of 0.01-0.1 microM. Moderate 5-10-fold selectivity for T. gondii versus rat liver DHFR was observed with five compounds, the best combination of potency and selectivity being achieved with the 2-methoxybenzyl analogue 5d, which had an IC50 of 0.014 microM and a selectivity ratio of 8.6. One compound (5l) was tested for antiproliferative activity against P. carinii trophozoites in culture at a concentration of 10 microgram/mL and was found to completely suppress growth over 7 days. The suppressive effect of 5l was the same as that of trimethoprim (10 microgram/mL) + sulfamethoxazole (250 microgram/mL), a standard clinical combination for the treatment of P. carinii pneumonia in AIDS patients. Four compounds (5a,h,k,l) were tested against T. gondii tachyzoites in culture and were found to have a potency (IC50 = 0.1-0.5 microM) similar to that of pyrimethamine (IC50 = 0.69 microM), a standard clinical agent for the treatment of cerebral toxoplasmosis in AIDS patients. Compound 5h was also active against T. gondii infection in mice when given qdx8 by peritoneal injection at doses ranging from 62.5 (initial dose) to 25 mg/kg. Survival was prolonged to the same degree as with 25 mg/kg clindamycin, another widely used drug against toxoplasmosis. Three compounds (5j-l) were tested for antiproliferative activity against human tumor cells in culture. Among the 25 cell lines in the National Cancer Institute panel for which data were confirmed in two independent experiments, the IC50 for at least two of these compounds was <10 microM against 17 cell lines (68%) and in the 0. 1-1 microM range against 13 cell lines (52%). One compound (5j) had an IC50 of <0.01 microM against four of the cell lines. The activity profiles of 5k,l were generally similar to that of 5j except that there were no cells against which the IC50 was <0.01 microM.
|
Inhibitory activity against Toxoplasma gondii DHFR*
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of dihydrofolate reductase in Toxoplasma gondii.
|
None
|
11.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminothieno[2,3-d]pyrimidine analogues of trimetrexate and piritrexim as potential inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1993
Volume : 36
Issue : 21
First Page : 3103
Last Page : 3112
Authors : Rosowsky A, Mota CE, Wright JE, Freisheim JH, Heusner JJ, McCormack JJ, Queener SF.
Abstract : A series of eight previously undescribed 2,4-diaminothieno[2,3-d]pyrimidine analogues of the potent dihydrofolate reductase (DHFR) inhibitors trimetrexate (TMQ) and piritrexim (PTX) were synthesized as potential drugs against Pneumocystis carinii and Toxoplasma gondii, which are major causes of severe opportunistic infections in AIDS patients. 2,4-Diamino-5-methyl-6-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 3,4,5-trimethoxy or 2,5-dimethoxy substitution in the aryl/aralkyl moiety and 2,4-diamino-5-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 2,5-dimethoxy substitution in the aryl/aralkyl moiety were obtained by reaction of the corresponding 2-amino-3-cyanothiophenes with chloroformamidine hydrochloride. The aryl group in the 5,6-disubstituted analogues was either attached directly to the hetero ring or was separated from it by one or two carbons, whereas the aryl group in the 5-monosubstituted analogues was separated from the hetero ring by two or three carbons. 2-Amino-3-cyano-5-methyl-6-(aryl/alkyl)thiophene intermediates for the preparation of the 5,6-disubstituted analogues were prepared from omega-aryl-2-alkylidene-malononitriles and sulfur in the presence of a secondary amine, and 2-amino-3-cyano-4-(aryl/aralkyl)thiophene intermediates for the preparation of the 5-monosubstituted analogues were obtained from omega-aryl-1-chloro-2-alkylidenemalononitriles and sodium hydrosulfide. Synthetic routes to the heretofore unknown ylidenemalononitriles, and the ketone precursors thereof, were developed. The final products were tested in vitro as inhibitors of DHFR from Pneumocystis carinii, Toxoplasma gondii, rat liver, beef liver, and Lactobacillus casei. A selected number of previously known 2,4-diaminothieno[2,3-d]pyrimidines lacking the 3,4,5-trimethoxyphenyl and 2,5-dimethoxyphenyl substitution pattern of TMQ and PTX, respectively, were also tested for comparison. None of the compounds was as potent as TMQ or PTX, and while some of them showed some selectivity in their binding to Pneumocystis carinii and Toxoplasma gondii versus rat liver DHFR, this effect was not deemed large enough to warrant further preclinical evaluation.
|
In vitro inhibition of human dihydrofolate reductase
|
None
|
2.0
nM
|
|
Journal : J. Med. Chem.
Title : Selective inhibitors of Candida albicans dihydrofolate reductase: activity and selectivity of 5-(arylthio)-2,4-diaminoquinazolines.
Year : 1995
Volume : 38
Issue : 18
First Page : 3608
Last Page : 3616
Authors : Chan JH, Hong JS, Kuyper LF, Baccanari DP, Joyner SS, Tansik RL, Boytos CM, Rudolph SK.
Abstract : The recent increase in fungal infections, especially among AIDS patients, has resulted in the need for more effective antifungal agents. In our search for such agents, we focused on developing compounds which inhibit fungal dihydrofolate reductase (DHFR). A series of 25 5-(arylthio)-2,4-diaminoquinazolines were synthesized as potentially selective inhibitors of Candida albicans DHFR. The majority of the compounds were potent inhibitors of C. albicans DHFR and much less active against human DHFR. High selectivity, as defined by the ratio of the I50 values for human and C. albicans DHFR, was achieved by compounds with bulky and rigid 4-substituents in the phenylthio moiety. For example, 5-[(4-morpholinophenyl)thio]-2,4-diaminoquinazoline displayed a selectivity ratio of 540 and was the most selective inhibitor synthesized to date. Substitution in the 2- or 3-position of the 5-phenylthio group provided only marginal selectivity. 6-Substituted-5-[(4-tert-butylphenyl)thio]-2,4-diaminoquinazolines showed potent activity against the C. albicans enzyme but were equally active against human DHFR. Most of the selective compounds were also good inhibitors of C. albicans cell growth, with minimum inhibitory concentration values as low as 0.05 microgram/ mL.
|
Inhibitory concentration against dihydrofolate reductace enzyme of Pneumocystis carinii
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : New 2,4-diamino-5-(2',5'-substituted benzyl)pyrimidines as potential drugs against opportunistic infections of AIDS and other immune disorders. Synthesis and species-dependent antifolate activity.
Year : 2004
Volume : 47
Issue : 6
First Page : 1475
Last Page : 1486
Authors : Rosowsky A, Forsch RA, Sibley CH, Inderlied CB, Queener SF.
Abstract : In a continuing effort to design small-molecule inhibitors of dihydrofolate reductase (DHFR) that combine the enzyme-binding selectivity of 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP) with the potency of 2,4-diamino-5-methyl-6-(2',5'-dimethoxybenzyl)pyrido[2,3-d]pyrimidine (piritrexim, PTX), seven previously undescribed 2,4-diamino-5-[2'-methoxy-5'-(substituted benzyl)]pyrimidines were synthesized in which the substituent at the 5'-position was a carboxyphenyl group linked to the benzyl moiety by a bridge of two or four atoms in length. The new analogues were all obtained from 2,4-diamino-5-(5'-iodo-2'-methoxybenzyl)pyrimidine via a Sonogashira reaction, followed, where appropriate, by catalytic hydrogenation. The new analogues were tested as inhibitors of DHFR from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three life-threatening pathogens often found in AIDS patients and individuals whose immune system is impaired as a result of treatment with immunosuppressive chemotherapy or radiation. The selectivity index (SI) of each compound was obtained by dividing its 50% inhibitory concentration (IC(50)) against Pc, Tg, or Ma DHFR by its IC(50) against rat DHFR. 2,4-Diamino-[2'-methoxy-5'-(3-carboxyphenyl)ethynylbenzyl]pyrimidine (28), with an IC(50) of 23 nM and an SI of 28 in the Pc DHFR assay, had about the same potency as PTX and was 520 times more potent than TMP. As an inhibitor of Tg DHFR, 28 had an IC(50) of 5.5 nM (510-fold lower than that of TMP and similar to that of PTX) and an SI value of 120 (2-fold better than TMP and vastly superior to PTX). Against Ma DHFR, 28 had IC(50) and SI values of 1.5 nM and 430, respectively, compared with 300 nM and 610 for TMP. Although it had 2.5-fold lower potency than 28 against Ma DHFR (IC(50) = 3.7 nM) and was substantially weaker against Pc and Tg DHFR, 2,4-diamino-[2'-methoxy-5'-(4-carboxyphenyl)ethynylbenzyl]pyrimidine (29), with the carboxy group at the para rather than the meta position, displayed 2200-fold selectivity against the Ma enzyme and was the most selective 2,4-diamino-5-(5'-substituted benzyl)pyrimidine inhibitor of this enzyme we have encountered to date. Additional bioassay data for these compounds are also reported.
|
Inhibition of dihydrofolate reductase in Candida albicans (in vitro).
|
Candida albicans
|
40.0
nM
|
|
Journal : J. Med. Chem.
Title : Selective inhibitors of Candida albicans dihydrofolate reductase: activity and selectivity of 5-(arylthio)-2,4-diaminoquinazolines.
Year : 1995
Volume : 38
Issue : 18
First Page : 3608
Last Page : 3616
Authors : Chan JH, Hong JS, Kuyper LF, Baccanari DP, Joyner SS, Tansik RL, Boytos CM, Rudolph SK.
Abstract : The recent increase in fungal infections, especially among AIDS patients, has resulted in the need for more effective antifungal agents. In our search for such agents, we focused on developing compounds which inhibit fungal dihydrofolate reductase (DHFR). A series of 25 5-(arylthio)-2,4-diaminoquinazolines were synthesized as potentially selective inhibitors of Candida albicans DHFR. The majority of the compounds were potent inhibitors of C. albicans DHFR and much less active against human DHFR. High selectivity, as defined by the ratio of the I50 values for human and C. albicans DHFR, was achieved by compounds with bulky and rigid 4-substituents in the phenylthio moiety. For example, 5-[(4-morpholinophenyl)thio]-2,4-diaminoquinazoline displayed a selectivity ratio of 540 and was the most selective inhibitor synthesized to date. Substitution in the 2- or 3-position of the 5-phenylthio group provided only marginal selectivity. 6-Substituted-5-[(4-tert-butylphenyl)thio]-2,4-diaminoquinazolines showed potent activity against the C. albicans enzyme but were equally active against human DHFR. Most of the selective compounds were also good inhibitors of C. albicans cell growth, with minimum inhibitory concentration values as low as 0.05 microgram/ mL.
|
Inhibition of Dihydrofolate reductase enzyme from Candida albicans
|
Candida albicans
|
1.9
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Inhibition of human recombinant Dihydrofolate reductase enzyme
|
None
|
0.025
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Inhibitory activity against Leu22-Phe mutant human Dihydrofolate reductase
|
None
|
38.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-substituted-quinazolines as inhibitors of a human dihydrofolate reductase with a site-directed mutation at position 22 and of the dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 5
First Page : 745
Last Page : 752
Authors : Rosowsky A, Mota CE, Queener SF, Waltham M, Ercikan-Abali E, Bertino JR.
Abstract : 2,4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (p-aminobenzoyl)-L-glutamate side chain, were synthesized as potentially selective inhibitors of a site-directed mutant of human dihydrofolate reductase (DHFR) containing phenylalanine instead of leucine at position 22. This mutant enzyme is approximately 100-fold more resistant than native enzyme to the classical antifolate methotrexate (MTX), yet shows minimal cross resistance to the nonclassical antifolates piritrexim (PTX) and trimetrexate (TMQ). Although they were much less potent than trimetrexate and piritrexim, the lipophilic 5-substituted analogues were all found to bind approximately 10 times better to the mutant DHFR than to the wild-type enzyme. The potency of the analogue with a classical (p-aminobenzoyl)-L-glutamate side chain was similarly diminished in comparison with MTX, but the difference in its binding affinity to the two DHFR species was only 5-fold. Thus, by making subtle structural changes in the antifolate molecule, it may be possible to attack resistance due to mutational alterations in the active site of the target enzyme. Also, to test the hypothesis that DHFR from Pneumocystis carinii and Toxoplasma gondii may have a less sterically restrictive active site than the enzyme from mammalian cells, inhibition assays using several of the lipophilic analogues in the series were carried out against the P. carinii and T. gondii reductases in comparison with the enzyme from rat liver. In contrast to their preferential binding to mutant versus wild-type human DHFR, binding of these analogues to the P. carinii and T. gondii enzymes was weaker than binding to rat enzyme. It thus appears that, if the active site of the DHFR from these parasites is less sterically restrictive than the active site of the mammalian enzyme, this difference cannot be successfully exploited by moving the side chain from the 6-position to the 5-position.
|
Concentration required to inhibit the Mycobacterium avium Dihydrofolate reductase by 50% was determined; Range: 0.53-0.70
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 2,4-diamino-6-[2'-O-(omega-carboxyalkyl)oxydibenz[b,f]azepin-5-yl]methylpteridines as potent and selective inhibitors of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductase.
Year : 2004
Volume : 47
Issue : 10
First Page : 2475
Last Page : 2485
Authors : Rosowsky A, Fu H, Chan DC, Queener SF.
Abstract : Six previously undescribed N-(2,4-diaminopteridin-6-yl)methyldibenz[b,f]azepines with water-solubilizing O-carboxyalkyloxy or O-carboxybenzyloxy side chains at the 2'-position were synthesized and compared with trimethoprim (TMP) and piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic organisms known to cause significant morbidity and mortality in patients with AIDS and other disorders of the immune system. The ability of the new analogues to inhibit reduction of dihydrofolate to tetrahydrofolate by Pc, Tg, Ma, and rat DHFR was determined, and the selectivity index (SI) was calculated from the ratio IC(50)(rat DHFR)/IC(50)(Pc, Tg, or Ma DHFR). The IC(50) values of the 2'-O-carboxypropyl analogue (10), with SI values in parentheses, were 1.1 nM (1300) against Pc DHFR, 9.9 nM (120) against Tg DHFR, and 2.0 nM (600) against Ma DHFR. The corresponding values for the 2'-O-(4-carboxybenzyloxy) analogue (12) were 1.0 nM (560), 22 nM (21), and 0.75 nM (630). By comparison, the IC(50) and SI values for TMP were Pc, 13 000 nM (14); Tg, 2800 nM (65); and Ma, 300 nM (610). For the prototypical potent but nonselective inhibitors PTX and TMX, respectively, these values were Pc, 13 nM (0.26) and 47 nM (0.17); Tg, 4.3 nM (0.76) and 16 nM (0.50); Ma, 0.61 nM (5.4) and 1.5 nM (5.3). Thus 10 and 12 met the criterion for DHFR inhibitors that combine the high selectivity of TMP with the high potency of PTX and TMX.
|
Concentration required to inhibit the Pneumocystis carinii Dihydrofolate reductase by 50% was determined; Range: 9.0-17
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 2,4-diamino-6-[2'-O-(omega-carboxyalkyl)oxydibenz[b,f]azepin-5-yl]methylpteridines as potent and selective inhibitors of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductase.
Year : 2004
Volume : 47
Issue : 10
First Page : 2475
Last Page : 2485
Authors : Rosowsky A, Fu H, Chan DC, Queener SF.
Abstract : Six previously undescribed N-(2,4-diaminopteridin-6-yl)methyldibenz[b,f]azepines with water-solubilizing O-carboxyalkyloxy or O-carboxybenzyloxy side chains at the 2'-position were synthesized and compared with trimethoprim (TMP) and piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic organisms known to cause significant morbidity and mortality in patients with AIDS and other disorders of the immune system. The ability of the new analogues to inhibit reduction of dihydrofolate to tetrahydrofolate by Pc, Tg, Ma, and rat DHFR was determined, and the selectivity index (SI) was calculated from the ratio IC(50)(rat DHFR)/IC(50)(Pc, Tg, or Ma DHFR). The IC(50) values of the 2'-O-carboxypropyl analogue (10), with SI values in parentheses, were 1.1 nM (1300) against Pc DHFR, 9.9 nM (120) against Tg DHFR, and 2.0 nM (600) against Ma DHFR. The corresponding values for the 2'-O-(4-carboxybenzyloxy) analogue (12) were 1.0 nM (560), 22 nM (21), and 0.75 nM (630). By comparison, the IC(50) and SI values for TMP were Pc, 13 000 nM (14); Tg, 2800 nM (65); and Ma, 300 nM (610). For the prototypical potent but nonselective inhibitors PTX and TMX, respectively, these values were Pc, 13 nM (0.26) and 47 nM (0.17); Tg, 4.3 nM (0.76) and 16 nM (0.50); Ma, 0.61 nM (5.4) and 1.5 nM (5.3). Thus 10 and 12 met the criterion for DHFR inhibitors that combine the high selectivity of TMP with the high potency of PTX and TMX.
|
Inhibition of dihydrofolate reductase from pneumocystis carinii.
|
None
|
31.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase and as antiopportunistic infection and antitumor agents.
Year : 2003
Volume : 46
Issue : 23
First Page : 5074
Last Page : 5082
Authors : Gangjee A, Adair OO, Queener SF.
Abstract : A series of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) dihydrofolate reductase (DHFR) and as inhibitors of the growth of tumor cell lines in culture. Compounds 4-15 were designed as part of a continuing effort to examine the effects of substitutions at the 5-position, in the two-atom bridge, and in the side chain phenyl ring on structure-activity/selectivity relationships of 2,4-diaminopyrido[2,3-d]pyrimidines against a variety of DHFRs. Reductive amination of the common intermediate 2,4-diaminopyrido[2,3-d]pyrimidine-6-carbonitrile 16 with the appropriate anilines afforded the target compounds 4-12. Nucleophilic substitution or reductive methylation afforded the N10-methyl target compounds 13-15. As predicted, compounds 4-15 were, in general, less potent against all three DHFRs compared to the corresponding 2,4-diamino-5-methyl analogues previously reported; however, the greater decrease in potency against rlDHFR compared to pcDHFR and tgDHFR resulted in appreciable selectivity toward pathogenic DHFRs from different pathogens. The 2',5'-dichloro analogue 8 showed selectivity ratios (IC(50) against rlDHFR/IC(50) against pcDHFR or tgDHFR) of 15.7 and 23 for pcDHFR and tgDHFR, respectively. Thus, the selectivity of 8 for pcDHFR is higher than the first line clinical agent trimethoprim (TMP). In a P. carinii cell culture study, analogue 8 exhibited 88% cell growth inhibition at a concentration of 10 muM and afforded marginal effects in an in vivo study in the T. gondii mouse model. Selected compounds were evaluated in the National Cancer Institute (NCI) in vitro preclinical antitumor screening program and inhibited the growth of tumor cells in culture at micromolar to submicromolar concentrations and were selected for evaluation in a NCI in vivo hollow fiber assay.
|
Inhibition of partially purified dihydrofolate reductase (DHFR) from rat liver
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Inhibition of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductases by 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines: marked improvement in potency relative to trimethoprim and species selectivity relative to piritrexim.
Year : 2002
Volume : 45
Issue : 1
First Page : 233
Last Page : 241
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : A series of previously undescribed 2,4-diamino-5-[2-methoxy-5-alkoxybenzyl]pyrimidines (3a-e) and 2,4-diamino-5-[2-methoxy-5-(omega-carboxyalkyloxy)benzyl]pyrimidines (3f-k) with up to eight CH2 groups in the alkoxy or omega-carboxyalkyloxy side chain were synthesized and tested for the ability to inhibit partially purified dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat liver in comparison with two standard inhibitors, trimethoprim (1) and piritrexim (2). The latter drug is known to be extremely potent but shows a marked preference for binding to mammalian DHFR, whereas the former is very selective for the parasite enzymes but is a much weaker inhibitor. The underlying strategy for the synthesis of compounds 3a-k was that a hybrid structure embodying some features of both 1 and 2 might possess a more favorable combination of potency and selectivity than either parent drug. The choice of analogues 3f-k was based on the idea that the acidic omega-carboxyl group might interact preferentially with a basic center in the active site of DHFR from any of the parasite species relative to the active site of mammalian DHFR. In addition, the omega-carboxyl group was expected to improve water solubility relative to 1 or 2. In standardized spectrophotometric assays with dihydrofolate as the substrate and NADPH as the cofactor, 2,4-diamino-5-[(2-methoxy-4-carboxybutyloxy)benzyl]pyrimidine (3g) inhibited Pc DHFR with an IC(50) of 0.049 microM and rat DHFR with IC(50) of 3.9 microM. Its potency against Pc DHFR was 140-fold greater than that of 1 and close to that of 2, and its selectivity index, defined as the ratio IC(50)(rat liver)/IC(50)(P. carinii), was 8-fold higher than that of 1 and >10(4)-fold higher than that of 2. Although it was less potent and less selective against Tg than Pc DHFR, it was very potent as well as highly selective against Ma DHFR, with an IC(50) of 0.0058 microM and an IC(50)(rat liver)/IC(50)(M. avium) ratio of >600. Because of this favorable combination of potency and selectivity relative to 1 and 2, compound 3g may be viewed as a promising lead in the search for new antifolates with potential clinical activity against P. carinii and other opportunistic pathogens in patients with AIDS.
|
Compound was tested for inhibition activity against rat liver lipophilic Dihydrofolate reductase (DHFR).
|
None
|
15.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-6,7-dihydro-5H-cyclopenta[d]pyrimidine analogues of trimethoprim as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1998
Volume : 41
Issue : 6
First Page : 913
Last Page : 918
Authors : Rosowsky A, Papoulis AT, Queener SF.
Abstract : Three previously unreported (R,S)-2,4-diamino-5-[(3,4,5-trimethoxyphenyl) alkyl]-6,7-dihydro-5H-cyclopenta[d]pyrimidines 15a-c were synthesized as analogues of trimethoprim (TMP) and were tested as inhibitors of Pneumocystis carinii, Toxoplasma gondii, and rat liver dihydrofolate reductase (DHFR). The length of the alkyl bridge between the cyclopenta[d]pyrimidine and trimethoxyphenyl moiety ranged from one in 15a to three carbons in 15c. The products were tested as competitive inhibitors of the reduction of dihydrofolate by Pneumocystis carinii, Toxoplasma gondii, and rat liver DHFR. Compounds 15a-c had IC50 values of > 32, 1.8 and 1.3 microM, respectively, against P. carinii DHFR, as compared to 12 microM for TMP. Against the T. gondii enzyme, 15a-c had IC50 values of 21, 0.14 and 0.14 microM, respectively, as compared to 2.7 microM for TMP. Inhibitors 15b and 15c with two- and three-carbon bridges were significantly more potent than 15a against all three enzymes. Unlike TMP, 15b and 15c were better inhibitors of the rat liver enzyme than of the microbial enzymes. The potency of 15b and 15c against rat liver DHFR was less than has been reported for the corresponding 6,7-dihydro-5H-cyclopenta[d]pyrimidines with a classical p-aminobenzoyl-L-glutamate side chain as inhibitors of bovine, murine, and human DHFR.
|
Concentration inhibiting rat liver dihydrofolate reductase.
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminopyrido[3,2-d]pyrimidine inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 14
First Page : 2615
Last Page : 2620
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : Six previously unknown 2,4-diamino-6-(anilinomethyl)- and 2,4-diamino-6-[(N-methylanilino)-methyl]pyrido[3,2-d]pyrimidines (5-10) were synthesized from 2,4-diamino-6-(bromomethyl)-pyrido[3,2-d]pyrimidine hydrobromide (11.HBr) by treatment with the appropriate aniline or N-methylaniline in dimethylformamide at room temperature, with or without NaHCO3 present. Compounds 5-10 were tested as inhibitors of dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, and rat liver as a part of a larger effort directed toward the discovery of lipophilic nonclassical antifolates combining high enzyme selectivity and high potency. Of the six analogues tested, the most potent and selective against T. gondii DHFR was 2,4-diamino-6-[(3',4',5'-trimethoxy-N-methylanilono)methyl]pyrido[ 3,2-d d pyrimidine (7), which had an IC50 of 0.0047 microM against this enzyme as compared with 0.026 microM against the rat liver enzyme. The potency of 7 against T. gondii DHFR was similar to that of trimetrexate (TMQ, 1) and piritrexim (PTX, 2) but was > 500-fold greater than that of trimethoprim (TMP, 3). However, while 7 was more selective than either TMQ (19x) or PTX (63x) against this enzyme, its selectivity in comparison with TMP was 8-fold lower. 2,4-Diamino-6-[3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyri midin e (6) was 17-fold less active than 7 and was also less selective. 2,4-Diamino-6-[(3',4'-dichloro-N-methylanilino)methyl]pyrido[3, 2-d]pyrimidine (10) had an IC50 of 0.022 microM against P. carinii DHFR and was comparable in potency to TMQ and PTX. The species selectivity of 10 for P. carinii versus rat liver DHFR was greater than that of either TMQ (21-fold) or PTX (31-fold). On the other hand, even though 10 was slightly more active than TMQ against the P. carinii enzyme, its selectivity was 7-fold lower than that of TMP. Thus, the goal of combining high enzyme binding activity, which is characteristic of the fused-ring compounds TMQ and PTX, with high selectivity for T. gondii and P. carinii DHFR versus rat liver DHFR, which is characteristic of the monocyclic compound TMP, remained unmet in this limited series.
|
Concentration required to inhibit the rat liver Dihydrofolate reductase by 50% was determined; Range: 2.9-3.9
|
None
|
3.3
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 2,4-diamino-6-[2'-O-(omega-carboxyalkyl)oxydibenz[b,f]azepin-5-yl]methylpteridines as potent and selective inhibitors of Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium dihydrofolate reductase.
Year : 2004
Volume : 47
Issue : 10
First Page : 2475
Last Page : 2485
Authors : Rosowsky A, Fu H, Chan DC, Queener SF.
Abstract : Six previously undescribed N-(2,4-diaminopteridin-6-yl)methyldibenz[b,f]azepines with water-solubilizing O-carboxyalkyloxy or O-carboxybenzyloxy side chains at the 2'-position were synthesized and compared with trimethoprim (TMP) and piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic organisms known to cause significant morbidity and mortality in patients with AIDS and other disorders of the immune system. The ability of the new analogues to inhibit reduction of dihydrofolate to tetrahydrofolate by Pc, Tg, Ma, and rat DHFR was determined, and the selectivity index (SI) was calculated from the ratio IC(50)(rat DHFR)/IC(50)(Pc, Tg, or Ma DHFR). The IC(50) values of the 2'-O-carboxypropyl analogue (10), with SI values in parentheses, were 1.1 nM (1300) against Pc DHFR, 9.9 nM (120) against Tg DHFR, and 2.0 nM (600) against Ma DHFR. The corresponding values for the 2'-O-(4-carboxybenzyloxy) analogue (12) were 1.0 nM (560), 22 nM (21), and 0.75 nM (630). By comparison, the IC(50) and SI values for TMP were Pc, 13 000 nM (14); Tg, 2800 nM (65); and Ma, 300 nM (610). For the prototypical potent but nonselective inhibitors PTX and TMX, respectively, these values were Pc, 13 nM (0.26) and 47 nM (0.17); Tg, 4.3 nM (0.76) and 16 nM (0.50); Ma, 0.61 nM (5.4) and 1.5 nM (5.3). Thus 10 and 12 met the criterion for DHFR inhibitors that combine the high selectivity of TMP with the high potency of PTX and TMX.
|
Inhibition of rat liver dihydrofolate reductase
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Conformationally restricted analogues of trimethoprim: 2,6-diamino-8-substituted purines as potential dihydrofolate reductase inhibitors from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 19
First Page : 3032
Last Page : 3039
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Twenty-two 2,6-diamino-8-substituted purines (2-23) were synthesized, in which rotation around the two flexible bonds of trimethoprim (TMP), linking the pyrimidine ring to the side chain phenyl ring, was restricted by incorporation into a purine ring, in an attempt to increase the potency and selectivity of TMP against dihydrofolate reductase (DHFR) from the organisms that often cause fatal opportunistic infections in patients with AIDS, i.e., Pneumocystis carinii (pc) and Toxoplasma gondii (tg). The syntheses of analogues 2-20 were achieved via a one-pot reaction of 2,4,5,6-tetraaminopyrimidine and the appropriately substituted benzaldehyde or phenyl acetaldehyde, in acidic methoxyethanol. Analogues 21-23 were synthesized via nucleophilic displacement of 2,6-diamino-8-(chloromethyl)purine with the appropriate anilines or 2-naphthalenethiol. The compounds were evaluated as inhibitors of pcDHFR and tgDHFR with rat liver (rl) DHFR as the mammalian reference enzyme. Compound 11, the 3',4'-dichlorophenyl analogue, was as potent as TMP and had a selectivity ratio of 13 for pcDHFR, which ranked it as one of the three most selective inhibitors of pcDHFR (compared to rlDHFR) known to date. It also displayed a selectivity ratio of 38 for tgDHFR. None of the other analogues showed any improvement compared to TMP in potency or selectivity. In the preclinical in vitro screening program of the National Cancer Institute, compound 11 showed a GI50 of 10(-6) M for the inhibition of the growth of 17 tumor cell lines.
|
Inhibitory concentration against rat liver dihydrofolate reductase (DHFR)
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Conformationally restricted analogues of trimethoprim: 2,6-diamino-8-substituted purines as potential dihydrofolate reductase inhibitors from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 19
First Page : 3032
Last Page : 3039
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Twenty-two 2,6-diamino-8-substituted purines (2-23) were synthesized, in which rotation around the two flexible bonds of trimethoprim (TMP), linking the pyrimidine ring to the side chain phenyl ring, was restricted by incorporation into a purine ring, in an attempt to increase the potency and selectivity of TMP against dihydrofolate reductase (DHFR) from the organisms that often cause fatal opportunistic infections in patients with AIDS, i.e., Pneumocystis carinii (pc) and Toxoplasma gondii (tg). The syntheses of analogues 2-20 were achieved via a one-pot reaction of 2,4,5,6-tetraaminopyrimidine and the appropriately substituted benzaldehyde or phenyl acetaldehyde, in acidic methoxyethanol. Analogues 21-23 were synthesized via nucleophilic displacement of 2,6-diamino-8-(chloromethyl)purine with the appropriate anilines or 2-naphthalenethiol. The compounds were evaluated as inhibitors of pcDHFR and tgDHFR with rat liver (rl) DHFR as the mammalian reference enzyme. Compound 11, the 3',4'-dichlorophenyl analogue, was as potent as TMP and had a selectivity ratio of 13 for pcDHFR, which ranked it as one of the three most selective inhibitors of pcDHFR (compared to rlDHFR) known to date. It also displayed a selectivity ratio of 38 for tgDHFR. None of the other analogues showed any improvement compared to TMP in potency or selectivity. In the preclinical in vitro screening program of the National Cancer Institute, compound 11 showed a GI50 of 10(-6) M for the inhibition of the growth of 17 tumor cell lines.
|
Inhibition against Dihydrofolate reductase in rat liver
|
None
|
1.0
nM
|
|
Journal : J. Med. Chem.
Title : Effect of N9-methylation and bridge atom variation on the activity of 5-substituted 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1997
Volume : 40
Issue : 7
First Page : 1173
Last Page : 1177
Authors : Gangjee A, Mavandadi F, Queener SF.
Abstract : The effect of N9-methylation and bridge atom variation on inhibitory potency and selectivity of 2,4-diaminopyrrolo[2,3-d]pyrimidines against dihydrofolate reductases (DHFR) was studied. Specifically three nonclassical 2,4-diamino-5-((N-methylanilino)methyl)pyrrolo[2,3-d]pyrimidines with 2',5'-dimethoxyphenyl (2), 3',4'-dichlorophenyl (3), 1'-naphthyl (4), one classical analogue with a 4'-L-glutamate substituent (10), and four nonclassical 2,4-diamino-5-((phenylthio)methyl)pyrrolo[2,3-d]pyrimidines with 3',4'-dimethoxyphenyl (5), 3',4'-dichlorophenyl (6), 1'-naphthyl (7), and 2'-naphthyl (8) substituents were synthesized. The classical and nonclassical analogues were obtained by displacement of the intermediate 2,4-diamino-5-bromomethylpyrrolo[2,3-d]pyrimidine, 14, with appropriately substituted N-methylaniline, thiophenols, or 4-(N-methylamino)benzoyl-L-glutamate. Compounds 2-8 and 10 were evaluated against Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) DHFRs. The N-methyl and thiomethyl analogues were more inhibitory than their corresponding anilinomethyl analogues (previously reported) against all three DHFRs. The inhibitory potency of these analogues was greater against rlDHFR than against tgDHFR which resulted in a loss of selectivity for tgDHFR compared to the N9-H analogues. The classical N9-methyl analogue 10 was more potent and about 2-fold more selective against tgDHFR than its corresponding desmethyl analogue. All of the analogues, 2-8 and 10, were more selective than trimetrexate (TMQ) against pcDHFR (except 4) and significantly more selective than TMQ against tgDHFR.
|
Inhibition of Dihydrofolate reductase (DHFR) of in rat liver
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-chloroquinazoline analogues of trimetrexate and piritrexim: synthesis and antifolate activity.
Year : 1994
Volume : 37
Issue : 26
First Page : 4522
Last Page : 4528
Authors : Rosowsky A, Mota CE, Wright JE, Queener SF.
Abstract : Ten heretofore undescribed 2,4-diamino-5-chloroquinazoline analogues of trimetrexate (TMQ) and piritrexim (PTX) were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from rat liver, Pneumocystis carinii, and Toxoplasma gondii. The most active quinazolines against both the P. carinii and the T. gondii enzyme were those with an ArCH2-NH or ArNHCH2 side chain. Among ArNH(CH2)n compounds with n = 1-3 and either 2',5'-dimethoxyphenyl or 3',4',5'-trimethoxyphenyl as the Ar moiety, activity decreased in the order n = 1 > n = 2 > n = 3. The best inhibitor of P. carinii DHFR, 2,4-diamino-5-chloro-6-[(N-methyl-3',4',5'-trimethoxyanilino)methy l] quinazoline (10) had an IC50 of 0.012 microM and was slightly more potent than TMQ and PTX. Compound 10 was also the best inhibitor of T. gondii DHFR, with an IC50 of 0.0064 microM corresponding again to a minor increase in activity over TMQ and PTX. However, as with these standard agents, 10 showed no appreciable selectivity for either the P. carinii or T. gondii enzyme relative to the rat liver enzyme. The highest selectivity achieved in this limited series was with 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl)-N-methylamino] quinazoline (17) against T. gondii DHFR. While 17 (IC50 = 0.016 microM) was somewhat less potent than 10, its selectivity, as defined by the ratio IC50(rat liver)/IC50(T. gondii) was ca. 30-fold higher than that of TMQ or PTX. Two compounds, 2,4-diamino-5-chloro-6-[(3',4',5'-trimethoxyanilino)methyl] quinazoline (9) and 2,4-diamino-5-chloro-6-[N-(3',4',5'-trimethoxybenzyl) amino]quinazoline (15), were also tested against human DHFR and were found to have an IC50/[E] of 0.5, indicating that their binding was near-stoichiometric.
|
Inhibitory activity against Dihydrofolate reductase from rat liver
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines as inhibitors of dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1995
Volume : 38
Issue : 10
First Page : 1778
Last Page : 1785
Authors : Gangjee A, Vasudevan A, Queener SF, Kisliuk RL.
Abstract : The synthesis and biological activity of 15 6-substituted 2,4-diamino-5-methylpyrido[2,3-d]-pyrimidines are reported. These compounds were synthesized in improved yields by modifications of procedures previously reported by us. Specifically, dimethoxyphenyl-substituted compounds with H and CH3 at the N-10 position and trimethoxyphenyl-substituted compounds with N-10 ethyl, isopropyl, and propargyl moieties were synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii, Toxoplasma gondii, and rat liver, and selected analogues were evaluated as inhibitors of the growth of T. gondii and tumor cells in culture. All the compounds showed increased selectivity (vs rat liver DHFR) for T. gondii DHFR compared to trimetrexate. In general, for the trimethoxy-substituted analogues, increasing the size of the N-10 substituent from a methyl group to larger groups resulted in a decrease in selectivity and potency for both P. carinii and T. gondii DHFR. For the dimethoxy-substituted analogues, N-10 methylation in general decreased potency but increased selectivity for T. gondii DHFR. In an attempt to improve the cell penetration of these analogues, the N-10 naphthyl-substituted analogues were also synthesized. These analogues displayed excellent cell penetration and inhibition of T. gondii cells in culture. Further, these analogues were potent inhibitors of the growth of tumor cells in the preclinical in-vitro screening program of the National Cancer Institute with IC50s in the nanomolar range.
|
Inhibition Dihydrohydrofolate reductase(DHFR) of rat liver
|
Rattus norvegicus
|
3.3
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of Dihydrofolate Reductase of Rat Liver.
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of nonclassical 2,4-diamino-5-methylpyrido[2,3-d]pyrimidines with novel side chain substituents as potential inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 4
First Page : 479
Last Page : 485
Authors : Gangjee A, Vasudevan A, Queener SF.
Abstract : Nine novel 2,4-diamino-5-methyl-6-substituted-pyrido[2,3-d]pyrimidines, 2-10, were synthesized as potential inhibitors of Pneumocystis carinii dihydrofolate reductase (pcDHFR) and Toxoplasma gondii dihydrofolate reductase (tgDHFR). Compounds 2-5 were designed as conformationally restricted analogues of trimetrexate (TMQ), in which rotation around tau 3 was constrained by incorporation of the side chain nitrogen as part of an indoline or an indole ring. Analogue 6, which has an extra atom between the side chain nitrogen and the phenyl ring, has its nitrogen as part of a tetrahydroisoquinoline ring. Analogues 7-9 are epiroprim (Ro 11-8958) analogues and contain a pyrrole ring as part of the side chain substitution on the phenyl ring similar to epiroprim. These analogues were designed to investigate the role of the pyrrole substitution on the phenyl ring of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines. Molecular modeling indicated that a pyrrole substituent in the ortho position of the side chain phenyl ring was most likely to interact with pcDHFR in a manner similar to the pyrrole moiety of epiroprim. Analogue 10, in which a phenyl ring replaced a methoxy group, was synthesized to determine the contribution of a phenyl ring on selectivity, lipophilicity, and cell penetration. The synthesis of analogues 2-4 was achieved via reductive amination of 2,4-diamino-5-methyl 6-carboxaldehyde with the appropriately substituted indolines. The indolines were obtained from the corresponding indoles via NaCNBH3 reductions. Analogues 5-10 were synthesized by nucleophilic displacement of 2,4-diamino-5-methyl-6-(bromomethyl)-pyrido[2,3-d]pyrimidine with the 5-methoxyindolyl anion, 6,7-dimethoxytetrahydroisoquinoline, the appropriately substituted pyrroloaniline or 2-methoxy-5-phenylaniline. The pyrroloanilines were synthesized in two steps by treating the substituted nitroanilines with 2,5-dimethoxy-tetrahydrofuran to afford the nitropyrrole intermediates, followed by reduction of the nitro group with Raney Ni. The analogues were more potent than trimethoprim and epiroprim and more selective than TMQ and piritrexim against pcDHFR and tgDHFR. Compounds 5 and 10 had IC50 values of 1 and 0.64 microM, respectively, for the inhibition of the growth of T. gondii cells in culture, and showed excellent culture IC50/enzyme IC50 ratios, which were correlated with their calculated log P values, indicating a direct relationship between calculated lipophilicity and cell penetration.
|
Inhibition of Dihydrohydrofolate reductase(DHFR) of Mycobacterium avium
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibition of dihydrofolate reductase from rat liver.
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological evaluation of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines as inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase and as antiopportunistic infection and antitumor agents.
Year : 2003
Volume : 46
Issue : 23
First Page : 5074
Last Page : 5082
Authors : Gangjee A, Adair OO, Queener SF.
Abstract : A series of 2,4-diamino-6-(arylaminomethyl)pyrido[2,3-d]pyrimidines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc), Toxoplasma gondii (tg), and rat liver (rl) dihydrofolate reductase (DHFR) and as inhibitors of the growth of tumor cell lines in culture. Compounds 4-15 were designed as part of a continuing effort to examine the effects of substitutions at the 5-position, in the two-atom bridge, and in the side chain phenyl ring on structure-activity/selectivity relationships of 2,4-diaminopyrido[2,3-d]pyrimidines against a variety of DHFRs. Reductive amination of the common intermediate 2,4-diaminopyrido[2,3-d]pyrimidine-6-carbonitrile 16 with the appropriate anilines afforded the target compounds 4-12. Nucleophilic substitution or reductive methylation afforded the N10-methyl target compounds 13-15. As predicted, compounds 4-15 were, in general, less potent against all three DHFRs compared to the corresponding 2,4-diamino-5-methyl analogues previously reported; however, the greater decrease in potency against rlDHFR compared to pcDHFR and tgDHFR resulted in appreciable selectivity toward pathogenic DHFRs from different pathogens. The 2',5'-dichloro analogue 8 showed selectivity ratios (IC(50) against rlDHFR/IC(50) against pcDHFR or tgDHFR) of 15.7 and 23 for pcDHFR and tgDHFR, respectively. Thus, the selectivity of 8 for pcDHFR is higher than the first line clinical agent trimethoprim (TMP). In a P. carinii cell culture study, analogue 8 exhibited 88% cell growth inhibition at a concentration of 10 muM and afforded marginal effects in an in vivo study in the T. gondii mouse model. Selected compounds were evaluated in the National Cancer Institute (NCI) in vitro preclinical antitumor screening program and inhibited the growth of tumor cells in culture at micromolar to submicromolar concentrations and were selected for evaluation in a NCI in vivo hollow fiber assay.
|
Inhibitory activity against dihydrofolate reductase (DHFR) from rat liver
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 6-Substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues of piritrexim as inhibitors of dihydrofolate reductase from rat liver, Pneumocystis carinii, and Toxoplasma gondii and as antitumor agents.
Year : 1998
Volume : 41
Issue : 23
First Page : 4533
Last Page : 4541
Authors : Gangjee A, Zhu Y, Queener SF.
Abstract : The synthesis and biological activity are reported for 21 6-substituted 2,4-diaminopyrido[3,2-d]pyrimidine analogues (4-24) of piritrexim (PTX) as inhibitors of dihydrofolate reductase (DHFR) and as antitumor agents. Recombinant DHFR from Pneumocystis carinii (pc) and native DHFR from Toxoplasma gondii (tg) were the target enzymes tested; these organisms are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity for the pathogenic DHFR. The synthesis of S9-bridged compounds 4-6 was achieved by aryl displacement of 2,4-diamino-6-chloropyrido[3, 2-d]pyrimidine (27) with thiol nucleophiles. Oxidation of 4-6 with hydrogen peroxide in glacial acetic acid afforded the corresponding sulfone analogues 7-9. The N9-bridged compounds 10-24 were synthesized from their precursor 3-amino-6-(arylamino)-2-pyridinecarbonitriles via a thermal cyclization with chloroformamidine hydrochloride. Unlike the S9-bridged compounds, the arylamino side chains of the N9-bridged analogues were introduced prior to the formation of the 2, 4-diaminopyrido[3,2-d]pyrimidine nucleus. A reversed two-atom-bridged analogue (25) was also synthesized using a synthetic strategy similar to that utilized for compounds 10-24. The IC50 values of these compounds against pcDHFR ranged from 0.0023 x 10(-6) M for 2,4-diamino-6-(N-methyl-3',4'-dimethoxyanilino)pyrido[3, 2-d]pyrimidine (21), which was the most potent, to 90.4 x 10(-6) M for 2,4-diamino-6-(4'-methoxyanilino)pyrido[3,2-d]pyrimidine (12), which was the least potent. The three S9-bridged compounds tested were more potent than the corresponding sulfone-bridged compounds for all three DHFRs. N9-Methylation increased the potency by as much as 17 000-fold (compounds 15 and 21). None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was again 21 with an IC50 value of 0.00088 x 10(-6) M and the least potent was 12 with an IC50 of 2.8 x 10(-6) M. N9-Methylation afforded an increase in potency of up to 770-fold (compound 15 NH vs 21 N-CH3) compared to the corresponding N9-H analogue. In contrast to pcDHFR, several analogues had a greater selectivity ratio for tgDHFR compared to trimetrexate (TMQ) or PTX, most notably 2, 4-diamino-6-[(3',4'- dimethoxyphenyl)thio]pyrido[3,2-d]pyrimidine (4), 2,4-diamino-6-[(2'-methoxyphenyl)sulfonyl]pyrido[3, 2-d]pyrimidine (7), and 2,4-diamino-6-(2', 5'-dimethoxyanilino)pyrido[3,2-d]pyrimidine (14) which combined relatively high potency at 10(-7)-10(-8) M along with selectivity ratios of 3.97, 6.67, and 4.93, respectively. Several analogues synthesized had better selectivity ratios than TMQ or PTX for both pcDHFR and tgDHFR, and the potencies of the N9-methylated compounds were comparable to or greater than that of TMQ or PTX. Selected compounds were evaluated as inhibitors of the growth of a variety of tumor cells in culture. The N9-CH3 analogues were, in general, highly potent with GI50 values in the nanomolar range. The N9-H and S9 analogues were less potent with GI50 values in the millimolar to micromolar range.
|
Inhibitory activity against Dihydrofolate reductase from rat liver was evaluated using 90 uM dihydrofolic acid as substrate
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-5-aryl-6-ethylpyrimidine antifolates: activity as inhibitors of dihydrofolate reductase from Pneumocystis carinii and Toxoplasma gondii and as antitumor agents.
Year : 1997
Volume : 40
Issue : 19
First Page : 3040
Last Page : 3048
Authors : Robson C, Meek MA, Grunwaldt JD, Lambert PA, Queener SF, Schmidt D, Griffin RJ.
Abstract : Twelve novel 2,4-diamino-5-(4'-benzylamino)- and 2,4-diamino-5[4'-(N-methylbenzylamino)-3'-nitrophenyl]-6-ethylp yrimidines bearing 4-substituents on the benzylamino or N-methylbenzylamino aryl ring were synthesized and evaluated as nonclassical inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase (DHFR). Compounds were prepared by reaction of 2,4-diamino-5-(4'-chloro-3'-nitrophenyl)- (8) or 2,4-diamino-5-(4'-fluoro-3'-nitrophenyl)-6-ethylpyrimidine (15) with the appropriate 4-substituted (CO2H, CO2Me, SO2NH2, dioxolan-2-yl, CHO, dimethyloxazolin-2-yl) benzylamine or N-methylbenzylamine derivative. Compounds 25-29 were synthesized from 2,4-diamino-5-{4'-[N-(4"-carboxybenzyl)amino]-3'-nitrophenyl}-6- ethylpyrimidine (10) and the corresponding amine (NH3, MeNH2, Me2NH, piperidine, diethyl L-glutamate) via isobutyl mixed anhydride coupling; hydrolysis of the diethyl L-glutamate 29 afforded the L-glutamate analogue 30. The compounds exhibited potent inhibitory activity against T. gondii (IC50 values 0.0018-0.14 microM) and rat liver (IC50 values 0.0029-0.27 microM) DHFR, with a 4-substituent invariably enhancing binding to both enzymes relative to the unsubstituted benzoprim (5) or methylbenzoprim (6). Modest selectivity for T. gondii enzyme was observed with several analogues, whereas all of the compounds were relatively weak inhibitors of P. carinii DHFR and exhibited no selectivity. Selected analogues were evaluated for in vivo antitumor activity against the methotrexate-resistant M5076 murine reticulosarcoma, with 2,4-diamino-5-{4'-[N-[4"-(N"-methylcarbamoyl)benzyl]-N- methylamino]-3'-nitrophenyl}-6-ethylpyrimidine (14) (Ki for rat liver DHFR = 0.00035 +/- 0.00029 nM) combining significant antitumor activity with minimal toxicity.
|
Inhibitory activity against rat liver dihydrofolate reductase
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Lipophilic antifolates as agents against opportunistic infections. 1. Agents superior to trimetrexate and piritrexim against Toxoplasma gondii and Pneumocystis carinii in in vitro evaluations.
Year : 1996
Volume : 39
Issue : 6
First Page : 1271
Last Page : 1280
Authors : Piper JR, Johnson CA, Krauth CA, Carter RL, Hosmer CA, Queener SF, Borotz SE, Pfefferkorn ER.
Abstract : 2,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four 2,4-diaminoquinazolines, each with an aryl groups attached to the 6-position of the heterocyclic moiety through a two-atom bridge (either CH2NH, CH2N(CH3),CH2S, or CH2CH2), were synthesized and evaluated as inhibitors of the growth of Toxoplasma gondii in culture and as inhibitors of dihydrofolate reductase enzymes from T. gondii, Pneumocystis carinii, and rat liver. Exceptionally high levels of combined potency and selectivity as growth inhibitors of T. gondii and as inhibitors of the microbial enzymes relative to the mammalian enzyme were found among the 5-methyl-5-deazapteridines but not for the other heterocyclic types. Thirty of the 34 5-methyl-5-deaza compounds gave growth inhibition IC50 values lower than that of pyrimethamine (0.4 microM) with 14 compounds below 0.1 microM, values that compare favorably with those for piritrexim and trimetrexate (both near 0.02 microM). As inhibitors of T gondii DHFR, all but three of the 34 5-methyl-5-deaza compounds gave IC50 values in the order of magnitude with those of piritrexim (0.017 microM) and trimetrexate (0.010 microM), and 17 compounds of this group gave IC50 values versus P. carinii DHFR similarly comparable with those of piritrexim (0.031 microM) and trimetrexate (0.042 microM). Thirteen of these congeners gave both T. gondii growth inhibition and DHFR inhibition IC50 values of 0.10 microM or less, thus indicating facile penetration of the cell membrane. Eleven of these inhibitors of both T. gondii growth and DHFR have selectivity ratios (IC50 rat liver divided by IC50 T. gondii) of 5 or greater for the parasite DHFR. The highest selectivity ratio of nearly 100 belongs to the 5-methyl-5-deaza compound whose 6-substituent is CH2CH2C6H3(OCH3)2-2,5. This compound is over 10(3)-fold more selective for T. gondii DHFR than bridge homologue piritrexim (selectivity ratio 0.088), a compound now in clinical trials. The candidate with CH2NHC6H3(CH3)2-2,5 in the 6-position gave the highest P. carinii DHFR selectivity ratio of 4.0, which is about 60-fold more selective than trimetrexate (0.071) and 80-fold more selective than piritrexim (0.048) toward this enzyme. The 10 best compounds with respect to potency and selectivity includes six compounds bearing 2,5-disubstituted phenyl groups in the side chain (with little, if any, difference in effects of methyl, methoxy, or ethoxy), two side chains bearing 1-naphthyl groups, and two with 5,6,7,8-tetrahydro-1-naphthyl groups. Bridge groups represented in the 10 choice compounds are CH2NH, CH2N(CH3), CH2CH2, and CH2S. The high levels of both potency and selectivity among these agents suggest that in vivo studies now underway may lead to agents that could replace trimetrexate and piritrexim in treatment of toxoplasmosis and P. carinii pneumonia.
|
Inhibitory activity against rat liver dihydrofolate reductase.
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Nonclassical 2,4-diamino-8-deazafolate analogues as inhibitors of dihydrofolate reductases from rat liver, Pneumocystis carinii, and Toxoplasma gondii.
Year : 1996
Volume : 39
Issue : 9
First Page : 1836
Last Page : 1845
Authors : Gangjee A, Zhu Y, Queener SF, Francom P, Broom AD.
Abstract : The synthesis and biological activity of 42 6-substituted-2,4-diaminopyrido[3,2-d]pyrimidines (2,4-diamino-8-deazafolate analogues) are reported. The compounds were synthesized in improved yields compared to previous classical analogues using modifications of procedures reported previously by us. Specifically, the S-phenyl-; mono-, di-, and trimethoxyphenyl-; and mono-, di-, and trichlorophenyl-substituted analogues with H or CH3 at the N10 position and methyl and trifluoromethyl phenyl ketone analogues with H, CH3, and CH2C identical to CH at the N10 position were synthesized. The S10 and N10 alpha- and beta-naphthyl analogues along with the N10 CH3 analogues were also synthesized. These compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg); selectivity ratios were determined against rat liver (rl) DHFR as the mammalian reference enzyme. Against pcDHFR the IC50 values ranged from 0.038 x 10-6 M for 2,4-diamino-6-[(N-methyl-2'-naphthylamino)methyl]pyrido[3,2-d]pyrimidine (28) to 5.5 x 10(-6) M for 2,4-diamino-6[(2',4'-dimethoxyanilino)methyl]pyrido[3,2-d]pyrim idi ne (15). N10 methylation in all instances increased potency. None of the analogues were selective for pcDHFR. Against tgDHFR the most potent analogue was 2,4-diamino-6-[(N-methylanilino)methyl]pyrido[3,2-d]pyrimidine (5) (IC50 0.0084 x 10(-6) M) and the least potent was 2,4-diamino-6[(2'-naphthylamino)methyl]-pyrido[3,2-d]pyrimidine (37) (IC50 0.16 x 10-6 M). N10 methylation afforded an increase in potency up to 10-fold. In contrast to pcDHFR, several of the 8-deaza analogues were significantly selective for tgDHFR, most notably 2,4-diamino-6-[(2'-chloro-N-methylanilino)-methyl]pyrido[3,2-d] pyrimidine (13), 2,4-diamino-6-[(3',4',5'-trimethoxyanilino)methyl]pyrido[3,2-d]pyr pyrimidine (29), and 2,4-diamino-6-[(2',4',6'-trichloroanilino)methyl]pyrido[3,2-d] pyrimidine (32) which combined high potency at 10-8 M along with selectivities of 8.0, 5.0, and 12.4, respectively. The potency of these three analogues are comparable to the clinically used agent trimetrexate while their selectivities for tgDHFR are 17-43-fold better than trimetrexate.
|
Inhibitory activity against rat dihydrofolate reductase
|
None
|
3.3
nM
|
|
Journal : Bioorg. Med. Chem. Lett.
Title : Preliminary in vitro studies on two potent, water-soluble trimethoprim analogues with exceptional species selectivity against dihydrofolate reductase from Pneumocystis carinii and Mycobacterium avium.
Year : 2004
Volume : 14
Issue : 7
First Page : 1811
Last Page : 1815
Authors : Forsch RA, Queener SF, Rosowsky A.
Abstract : 2,4-Diamino-5-[3',4'-dimethoxy-5'-(5-carboxy-1-pentynyl)]benzylpyrimidine (6) and 2,4-diamino-5-[3',4'-dimethoxy-5'-(4-carboxyphenylethynyl)benzylpyrimidine (7) were synthesized from 2,4-diamino-5-(5'-iodo-3',4'-dimethoxybenzyl)pyrimidine (9) via a Sonogashira reaction with appropriate acetylenic esters followed by saponification, and were tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat in comparison with the widely used antibacterial agent 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP). The selectivity index (SI) for each compound was calculated by dividing its 50% inhibitory concentration (IC(50)) against rat DHFR by its IC(50) against Pc, Tg, or Ma DHFR. The IC(50) of 6 against Pc DHFR was 1.0 nM, with an SI of 5000. Compound 7 had an IC(50) of 8.2 nM against Ma DHFR, with an SI of 11000. By comparison, the IC(50) of TMP was 12000 nM against Pc, 300 nM against Ma, and 180000 against rat DHFR. The potency and selectivity values of 6 and 7 were not as high against Tg as they were against Pc or Ma DHFR, but nonetheless exceeded those of TMP. Because of the outstanding selectivity of 6 against Pc and of 7 against Ma DHFR, these novel analogues may be viewed as promising leads for further structure-activity optimization.
|
Inhibitory activity against rat liver Dihydrofolate reductase
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-substituted-quinazolines as inhibitors of a human dihydrofolate reductase with a site-directed mutation at position 22 and of the dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 5
First Page : 745
Last Page : 752
Authors : Rosowsky A, Mota CE, Queener SF, Waltham M, Ercikan-Abali E, Bertino JR.
Abstract : 2,4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (p-aminobenzoyl)-L-glutamate side chain, were synthesized as potentially selective inhibitors of a site-directed mutant of human dihydrofolate reductase (DHFR) containing phenylalanine instead of leucine at position 22. This mutant enzyme is approximately 100-fold more resistant than native enzyme to the classical antifolate methotrexate (MTX), yet shows minimal cross resistance to the nonclassical antifolates piritrexim (PTX) and trimetrexate (TMQ). Although they were much less potent than trimetrexate and piritrexim, the lipophilic 5-substituted analogues were all found to bind approximately 10 times better to the mutant DHFR than to the wild-type enzyme. The potency of the analogue with a classical (p-aminobenzoyl)-L-glutamate side chain was similarly diminished in comparison with MTX, but the difference in its binding affinity to the two DHFR species was only 5-fold. Thus, by making subtle structural changes in the antifolate molecule, it may be possible to attack resistance due to mutational alterations in the active site of the target enzyme. Also, to test the hypothesis that DHFR from Pneumocystis carinii and Toxoplasma gondii may have a less sterically restrictive active site than the enzyme from mammalian cells, inhibition assays using several of the lipophilic analogues in the series were carried out against the P. carinii and T. gondii reductases in comparison with the enzyme from rat liver. In contrast to their preferential binding to mutant versus wild-type human DHFR, binding of these analogues to the P. carinii and T. gondii enzymes was weaker than binding to rat enzyme. It thus appears that, if the active site of the DHFR from these parasites is less sterically restrictive than the active site of the mammalian enzyme, this difference cannot be successfully exploited by moving the side chain from the 6-position to the 5-position.
|
Inhibitory activity against rat DHFR*
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Further studies on 2,4-diamino-5-(2',5'-disubstituted benzyl)pyrimidines as potent and selective inhibitors of dihydrofolate reductases from three major opportunistic pathogens of AIDS.
Year : 2003
Volume : 46
Issue : 9
First Page : 1726
Last Page : 1736
Authors : Rosowsky A, Forsch RA, Queener SF.
Abstract : As part of an ongoing effort to discover novel small-molecule antifolates combining the enzyme-binding species selectivity of trimethoprim (TMP) with the potency of piritrexim (PTX), 10 previously unreported 2,4-diamino-5-(2'-methoxy-5'-substituted)benzylpyrimidines (2-11) containing a carboxyl group at the distal end of the 5'-substituent were synthesized and tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three of the opportunistic pathogens frequently responsible for life-threatening illness in people with impaired immune systems as a result of HIV infection or immunosuppressive chemotherapy. The selectivity index of DHFR inhibition was evaluated by comparing the potency of each compound against the parasite enzymes with its potency against rat liver DHFR. 2,4-Diamino-5-[5'-(5-carboxy-1-pentynyl)-2'-methoxybenzyl]pyrimidine (3) inhibited Pc DHFR with a selectivity index of 79 and was 430 times more potent than TMP. 2,4-Diamino-5-[5'-(4-carboxy-1-butynyl)-2'-methoxybenzyl]pyrimidine (2), with one less carbon than 3 in the side chain, had a selectivity index of 910 against Ma DHFR and was 43 times more potent than TMP. 2,4-Diamino-5-[5'-(5-carboxypentyl)-2'-methoxybenzyl]pyrimidine (6) had a selectivity index of 490 against Tg DHFR and was 320 times more potent than TMP. 2,4-Diamino-5-[5'-(6-carboxy-1-hexynyl)-2'-methoxybenzyl]pyrimidine (4), with one more carbon than 3, was less potent against all three of the parasite enzymes than either 3 or 6 and also had a lower selectivity index than 3 against the Pc enzyme. However, 4 was the only member of the series with a selectivity index of >300 against both Tg and Ma DHFR. Given that PTX is at least 10 times more potent against rat DHFR than against P. carinii or T. gondii DHFR and that the selectivity index of several of the compounds matches or exceeds that of TMP as well as PTX, our results suggest that it may be possible to develop clinically useful nonclassical antifolates that are both potent and selective against the major opportunistic pathogens of AIDS.
|
Inhibitory concentration against Dihydrofolate reductase from Rat liver (rl)
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and dihydrofolate reductase inhibitory activities of 2,4-diamino-5-deaza and 2,4-diamino-5,10-dideaza lipophilic antifolates.
Year : 1997
Volume : 40
Issue : 4
First Page : 470
Last Page : 478
Authors : Gangjee A, Devraj R, Queener SF.
Abstract : Two series of nonclassical antifolates (2,4-diamino-5-deaza compounds 2-5 and 5,10-dideaza compounds 6-13) were synthesized as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) organisms that are responsible for fatal opportunistic infections in AIDS patients. Rat liver (rl) DHFR served as the mammalian reference enzyme to determine selectivity. Syntheses of the target 5-deaza compounds were achieved by initial construction of the pivaloyl-protected 2,4-diamino-6-bromopyrido[2,3-d]-pyrimidine 17 via a cyclocondensation of 2,4,6-triaminopyrimidine with bromomalonaldehyde. Sequential Heck coupling of 17 with styrene followed by ozonolysis afforded the 6-formyl derivative 19. Reductive amination of 19 with 3,4,5-trimethoxyaniline afforded the N10-H analog. The N10-Me and N10-Et analogs were synthesized by nucleophilic displacement of the 6-bromomethyl derivative 22 (obtained from the 6-formyl derivative 19 by reduction and bromination) with the appropriate N-alkylaniline. The trans-5,10-dideaza analogs 6-8 were synthesized via a Heck coupling of the appropriate methoxystyrene with 17, and selective reduction of the resulting 9,10-double bond afforded target compounds 9-11. Further reduction to the tetrahydro derivatives afforded analogs 12 and 13. The 5-deaza N10-Me 3,4,5-trimethoxy analog 3 maintained the best balance of potency and selectivity against both tgDHFR and pcDHFR. Compared to trimethoprim, compound 3 was only slightly less selective but was 300-fold more potent against tgDHFR. The 5,10-dideaza analogs were generally less potent and selective than the 5-deaza compounds.
|
Inhibitory concentration against Rat liver Dihydrofolate reductase
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and biological activities of conformationally restricted, tricyclic nonclassical antifolates as inhibitors of dihydrofolate reductases.
Year : 1997
Volume : 40
Issue : 12
First Page : 1930
Last Page : 1936
Authors : Gangjee A, Shi J, Queener SF.
Abstract : Seven novel tricyclic pyrimido[4,5-c][2,7]naphthyridones 5-8 and the corresponding naphthyridines 9-11 were synthesized as conformationally restricted inhibitors of dihydrofolate reductase (DHFR) and as antitumor and/or antiinfectious agents. The analogues were designed to orient the side chain trimethoxyphenyl group in different conformationally defined positions in order to explore the effect of the side chain orientation on binding affinity and selectivity for DHFR from various species. The semirigid orientations were achieved by bridging the C5 and N10 of compound 12 with a N-ethyl bridge and by variation of the position of double bonds in rings B and C as well as substitution at the 2',6'-positions of the phenyl ring. The synthesis of compounds 5-11 were accomplished by cyclocondensation of the appropriate keto ester (as the biselectrophile) with 2,4,6-triaminopyrimidine to afford the lactam 5. The dehydrolactams 6 and 7 were prepared by air oxidation and PtO2-catalyzed dehydrogenation of 7, respectively. The dichloro dehydro lactam 8 was obtained by refluxing lactam 5 and/or 6 in POCl3 or a mixture of POCl3/PCl5. Compounds 9-11 were obtained by two methods, direct borane reduction of lactam 5 or 6 or thiation of the dipivoylated lactam 15 followed by reductive dethiation. Compounds 9-11 were interconverted by air oxidation or PtO2-catalyzed reduction/oxidation, respectively. The compounds were evaluated as inhibitors of DHFR from Pneumocystis carinii (pc) and Toxoplasma gondii (tg) with rat liver (rl) serving as the reference mammalian enzyme. In the lactam series 5-8, the most unsaturated analogue 7 showed an IC50 of 86 nM against rlDHFR, almost 100-fold more active than 5 and 3-fold more active than 6. The 2',6'-dichloro dehydro lactam 8 was less active than the corresponding dehydro lactam 6 against rlDHFR. In the naphthyridine series 9-11, the dehydro analogue 10 was more active than 9 against rlDHFR. The fully reduced analogue 11 (as a mixture of cis and trans isomers) was the most active in the naphthyridine series. The analogues were, in general, more inhibitory against rlDHFR than against pcDHFR, or tgDHFR, and thus lacked selectivity. In addition, they were less potent than the bicyclic compounds trimetrexate 3 (TMQ) and piritrixim 4 (PTX).
|
Inhibitory concentration against dihydrofolate reductase DHFR from rat liver.
|
None
|
4.4
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, computational prediction, and biological evaluation of ester soft drugs as inhibitors of dihydrofolate reductase from Pneumocystis carinii.
Year : 2001
Volume : 44
Issue : 15
First Page : 2391
Last Page : 2402
Authors : Graffner-Nordberg M, Kolmodin K, Aqvist J, Queener SF, Hallberg A.
Abstract : A series of lipophilic soft drugs structurally related to the nonclassical dihydrofolate reductase (DHFR) inhibitors trimetrexate and piritrexim have been designed, synthesized, and evaluated in DHFR assays, with special emphasis on the inhibition of P. carinii DHFR. The best inhibitors, encompassing an ester bond in the bridge connecting the two aromatic systems, were approximately 10 times less potent than trimetrexate and piritrexim. The metabolites were designed to be poor inhibitors. Furthermore, molecular dynamics simulations of three ligands in complex with DHFR from Pneumocystis carinii and from the human enzyme were conducted in order to better understand the factors determining the selectivity. A correct ranking of the relative inhibition of DHFR was achieved utilizing the linear interaction energy method. The soft drugs are intended for local administration. One representative ester was selected for a pharmacokinetic study in rats where it was found to undergo fast metabolic degradation to the predicted inactive metabolites.
|
Inhibitory concentration against dihydrofolate reductase of rat liver
|
None
|
3.3
nM
|
|
Journal : J. Med. Chem.
Title : New 2,4-diamino-5-(2',5'-substituted benzyl)pyrimidines as potential drugs against opportunistic infections of AIDS and other immune disorders. Synthesis and species-dependent antifolate activity.
Year : 2004
Volume : 47
Issue : 6
First Page : 1475
Last Page : 1486
Authors : Rosowsky A, Forsch RA, Sibley CH, Inderlied CB, Queener SF.
Abstract : In a continuing effort to design small-molecule inhibitors of dihydrofolate reductase (DHFR) that combine the enzyme-binding selectivity of 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP) with the potency of 2,4-diamino-5-methyl-6-(2',5'-dimethoxybenzyl)pyrido[2,3-d]pyrimidine (piritrexim, PTX), seven previously undescribed 2,4-diamino-5-[2'-methoxy-5'-(substituted benzyl)]pyrimidines were synthesized in which the substituent at the 5'-position was a carboxyphenyl group linked to the benzyl moiety by a bridge of two or four atoms in length. The new analogues were all obtained from 2,4-diamino-5-(5'-iodo-2'-methoxybenzyl)pyrimidine via a Sonogashira reaction, followed, where appropriate, by catalytic hydrogenation. The new analogues were tested as inhibitors of DHFR from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three life-threatening pathogens often found in AIDS patients and individuals whose immune system is impaired as a result of treatment with immunosuppressive chemotherapy or radiation. The selectivity index (SI) of each compound was obtained by dividing its 50% inhibitory concentration (IC(50)) against Pc, Tg, or Ma DHFR by its IC(50) against rat DHFR. 2,4-Diamino-[2'-methoxy-5'-(3-carboxyphenyl)ethynylbenzyl]pyrimidine (28), with an IC(50) of 23 nM and an SI of 28 in the Pc DHFR assay, had about the same potency as PTX and was 520 times more potent than TMP. As an inhibitor of Tg DHFR, 28 had an IC(50) of 5.5 nM (510-fold lower than that of TMP and similar to that of PTX) and an SI value of 120 (2-fold better than TMP and vastly superior to PTX). Against Ma DHFR, 28 had IC(50) and SI values of 1.5 nM and 430, respectively, compared with 300 nM and 610 for TMP. Although it had 2.5-fold lower potency than 28 against Ma DHFR (IC(50) = 3.7 nM) and was substantially weaker against Pc and Tg DHFR, 2,4-diamino-[2'-methoxy-5'-(4-carboxyphenyl)ethynylbenzyl]pyrimidine (29), with the carboxy group at the para rather than the meta position, displayed 2200-fold selectivity against the Ma enzyme and was the most selective 2,4-diamino-5-(5'-substituted benzyl)pyrimidine inhibitor of this enzyme we have encountered to date. Additional bioassay data for these compounds are also reported.
|
Inhibition of rat liver dihydrofolate reductase
|
Rattus norvegicus
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis of 5-methyl-5-deaza nonclassical antifolates as inhibitors of dihydrofolate reductases and as potential antipneumocystis, antitoxoplasma, and antitumor agents.
Year : 1993
Volume : 36
Issue : 22
First Page : 3437
Last Page : 3443
Authors : Gangjee A, Shi J, Queener SF, Barrows LR, Kisliuk RL.
Abstract : A series of 2,4-diamino-5-methyl-6-(anilinomethyl)pyrido[2,3-d]pyrimidines 4-9 were synthesized as 5-deaza nonclassical antifolates containing trimethoxy, dichloro-, or trichlorophenyl substitutions and a N-H, N-CH3, or N-CHO at the 10-position. The compounds were evaluated as inhibitors of dihydrofolate reductases (DHFR) from Pneumocystis carinii (P. carinii), Toxoplasma gondii (T. gondii), rat liver (RL), and Lactobacillus casei (L. casei); as inhibitors of T. gondii and P. carinii cell growth in culture; and as antitumor agents. The compounds were prepared by modifications of procedures for classical 5-deaza folates. 2,4-Diamino-5-methyl-6-[(3',4',5'-trimethoxy-N- methylanilino)methyl]pyrido[2,3-d]pyrimidine (5a) exhibited high potency as well as selectivity (compared to RL DHFR) for P. carinii and T. gondii DHFR. Compound 5a is one of the most potent and selective nonclassical folate inhibitors of T. gondii DHFR known. The N-10 formyl analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]pyrido-[2,3-d]pyrimidine (6a) had decreased potency, but it maintained high selectivity for T. gondii DHFR. The corresponding chloro-substituted analogues maintained potency or had decreased potency; N-10 substitution did not increase potency or selectivity to the extent observed in the 3',4',5'-trimethoxy series. Partial reduction of the B ring to afford the dihydro analogue 2,4-diamino-5-methyl-6-[(N-formyl-3',4',5'-trimethoxyanilino) methyl]-5,8-dihydropyrido[2,3-d]pyrimidine (7), its 5,6,7,8-tetrahydropyrido[2,3-d]pyrimidine analogue 8, and 2,4-diamino-5-methyl-6-[(3',4',5'-trimethoxyanilino)methyl]-5,6,7, 8- tetrahydropyrido[2,3-d]pyrimidine (9) resulted in a significant decrease in potency. In T. gondii cell culture inhibitory studies, 2,4-diamino-5-methyl-6-[(3',4',5'- trimethoxyanilino)methyl]pyrido[2,3-d]pyrimidine (4a), 5a, and 6a were less potent compared to their DHFR inhibitory potencies. Against P. carinii cells in culture, 4a and 5a at 10 micrograms/mL were as effective as the clinically used combination of trimethoprim/sulfamethoxazole (50/250 micrograms/mL). With the exception of the B ring reduced analogues 7-9, all of the compounds were significantly cytotoxic to leukemia CCRF-CEM cells in culture. The chloro-substituted analogues, in general, were more potent against a variety of other tumor cells in culture than the trimethoxy analogues. These results were corroborated by the preclinical tumor screening program at the National Cancer Institute where the most potent compound 2,4-diamino-5-methyl-6-[(3',4'-dichloroanilino)methyl]pyrido[2,3- d]pyrimidine (4b) was found to inhibit the growth of 26 tumor cell lines at an IG50 < 1.00 x 10(-8) M.
|
Inhibition of rat liver Dihydrofolate reductase
|
Rattus norvegicus
|
1.0
nM
|
|
Journal : J. Med. Chem.
Title : Novel 2,4-diamino-5-substituted-pyrrolo[2,3-d]pyrimidines as classical and nonclassical antifolate inhibitors of dihydrofolate reductases.
Year : 1995
Volume : 38
Issue : 12
First Page : 2158
Last Page : 2165
Authors : Gangjee A, Mavandadi F, Queener SF, McGuire JJ.
Abstract : Eight novel, nonclassical, antifolate 2,4-diamino-5-(anilinomethyl)pyrrolo[2,3-d]pyrimidines, 1-8, with 3',4',5'-trimethoxyphenyl, 3',4'-dimethoxyphenyl, 2',5'-dimethoxyphenyl, 4'-methoxyphenyl, 2',5'-diethoxyphenyl, 3',4'-dichlorophenyl, 1'naphthyl, and phenyl substituents were synthesized as potential inhibitors of dihydrofolate reductases (DHFRs). The classical analogue N-[4-[N-[(2,4-diaminopyrrolo[2,3-d]pyrimidin- 5-yl)methyl]amino]benzoyl]-L-glutamic acid (9) was also synthesized as an inhibitor of DHFR and an antitumor agent. The classical and nonclassical analogues were obtained via reductive condensations of the key intermediate 2,4-diamino-5-cyanopyrrolo[2,3-d]pyrimidine (12) with the appropriate substituted aniline or (p-aminobenzoyl)-L-glutamate followed by reduction of the intermediate Schiff bases with NaCNBH3. Compounds 1-9 were evaluated in vitro as inhibitors of rat liver (rl), Pneumocystis carinii (pc), and Toxoplasma gondii (tg) DHFRs. The nonclassical analogues were significantly selective against tgDHFR (vs rat liver DHFR), ranging from 7- to 92-fold. The inhibitory activity was lower in pcDHFR and rlDHFR (IC50s > 10(-5) M) than in tgDHFR (IC50s = 10(-6) M). The classical analogue had inhibitory activity similar to that of methotrexate (MTX) against the growth of human leukemia CCRF-CEM, A253, and FaDu squamous cell carcinoma (SCC) of the head and neck cell lines. Further evaluation of 9 against CCRF-CEM and its sublines having defined mechanisms of MTX resistance demonstrated that the analogue utilizes the reduced folate/MTX-transport system and primarily inhibits DHFR and poly-gamma-glutamylation plays a role in its mechanism of action. Compound 9 was found to be 3-fold more efficient than aminopterin as a substrate for human folylpolyglutamate synthetase.
|
Inhibition of rat liver dihydrofolate reductase.
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diaminothieno[2,3-d]pyrimidine analogues of trimetrexate and piritrexim as potential inhibitors of Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase.
Year : 1993
Volume : 36
Issue : 21
First Page : 3103
Last Page : 3112
Authors : Rosowsky A, Mota CE, Wright JE, Freisheim JH, Heusner JJ, McCormack JJ, Queener SF.
Abstract : A series of eight previously undescribed 2,4-diaminothieno[2,3-d]pyrimidine analogues of the potent dihydrofolate reductase (DHFR) inhibitors trimetrexate (TMQ) and piritrexim (PTX) were synthesized as potential drugs against Pneumocystis carinii and Toxoplasma gondii, which are major causes of severe opportunistic infections in AIDS patients. 2,4-Diamino-5-methyl-6-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 3,4,5-trimethoxy or 2,5-dimethoxy substitution in the aryl/aralkyl moiety and 2,4-diamino-5-(aryl/aralkyl)thieno[2,3-d]pyrimidines with 2,5-dimethoxy substitution in the aryl/aralkyl moiety were obtained by reaction of the corresponding 2-amino-3-cyanothiophenes with chloroformamidine hydrochloride. The aryl group in the 5,6-disubstituted analogues was either attached directly to the hetero ring or was separated from it by one or two carbons, whereas the aryl group in the 5-monosubstituted analogues was separated from the hetero ring by two or three carbons. 2-Amino-3-cyano-5-methyl-6-(aryl/alkyl)thiophene intermediates for the preparation of the 5,6-disubstituted analogues were prepared from omega-aryl-2-alkylidene-malononitriles and sulfur in the presence of a secondary amine, and 2-amino-3-cyano-4-(aryl/aralkyl)thiophene intermediates for the preparation of the 5-monosubstituted analogues were obtained from omega-aryl-1-chloro-2-alkylidenemalononitriles and sodium hydrosulfide. Synthetic routes to the heretofore unknown ylidenemalononitriles, and the ketone precursors thereof, were developed. The final products were tested in vitro as inhibitors of DHFR from Pneumocystis carinii, Toxoplasma gondii, rat liver, beef liver, and Lactobacillus casei. A selected number of previously known 2,4-diaminothieno[2,3-d]pyrimidines lacking the 3,4,5-trimethoxyphenyl and 2,5-dimethoxyphenyl substitution pattern of TMQ and PTX, respectively, were also tested for comparison. None of the compounds was as potent as TMQ or PTX, and while some of them showed some selectivity in their binding to Pneumocystis carinii and Toxoplasma gondii versus rat liver DHFR, this effect was not deemed large enough to warrant further preclinical evaluation.
|
The ability to inhibit rat liver Dihydrofolate reductase was tested
|
None
|
15.0
nM
|
|
Journal : J. Med. Chem.
Title : Synthesis and antiparasitic and antitumor activity of 2, 4-diamino-6-(arylmethyl)-5,6,7,8-tetrahydroquinazoline analogues of piritrexim.
Year : 1999
Volume : 42
Issue : 6
First Page : 1007
Last Page : 1017
Authors : Rosowsky A, Papoulis AT, Forsch RA, Queener SF.
Abstract : Nineteen previously undescribed 2,4-diamino-6-(arylmethyl)-5,6,7, 8-tetrahydroquinazolines (5a-m, 10-12) were synthesized as part of a larger effort to assess the therapeutic potential of lipophilic dihydrofolate reductase (DHFR) inhibitors against opportunistic infections of AIDS. Condensation of appropriately substituted (arylmethyl)triphenylphosphoranes with 4, 4-ethylenedioxycyclohexanone, followed by hydrogenation (H2/Pd-C) and acidolysis, yielded the corresponding 4-(arylmethyl)cyclohexanones, which were then condensed with cyanoguanidine to form the tetrahydroquinazolines. Three simple 2, 4-diamino-6-alkyl-5,6,7,8-tetrahydroquinazoline model compounds (9a-c) were also prepared in one step from commercially available 4-alkylcyclohexanones by this method. Enzyme inhibition assays against rat liver DHFR, Pneumocystis carinii DHFR, and the bifunctional DHFR-TS enzyme from Toxoplasma gondii were carried out, and the selectivity ratios IC50(rat)/IC50(P. carinii) and IC50(rat)/IC50(T. gondii) were compared. The three most potent inhibitors of P. carinii DHFR were the 2,5-dimethoxybenzyl (5j), 3, 4-dimethoxybenzyl (5k), and 3,4,5-trimethoxybenzyl (5l) analogues, with IC50 values of 0.057, 0.10, and 0.091 microM, respectively. The remaining compounds generally had IC50 values in the 0.1-1.0 microM range. However all the compounds were more potent against the rat liver enzyme than the P. carinii enzyme and thus were nonselective. The T. gondii enzyme was always more sensitive than the P. carinii enzyme, with most of the analogues giving IC50 values of 0.01-0.1 microM. Moderate 5-10-fold selectivity for T. gondii versus rat liver DHFR was observed with five compounds, the best combination of potency and selectivity being achieved with the 2-methoxybenzyl analogue 5d, which had an IC50 of 0.014 microM and a selectivity ratio of 8.6. One compound (5l) was tested for antiproliferative activity against P. carinii trophozoites in culture at a concentration of 10 microgram/mL and was found to completely suppress growth over 7 days. The suppressive effect of 5l was the same as that of trimethoprim (10 microgram/mL) + sulfamethoxazole (250 microgram/mL), a standard clinical combination for the treatment of P. carinii pneumonia in AIDS patients. Four compounds (5a,h,k,l) were tested against T. gondii tachyzoites in culture and were found to have a potency (IC50 = 0.1-0.5 microM) similar to that of pyrimethamine (IC50 = 0.69 microM), a standard clinical agent for the treatment of cerebral toxoplasmosis in AIDS patients. Compound 5h was also active against T. gondii infection in mice when given qdx8 by peritoneal injection at doses ranging from 62.5 (initial dose) to 25 mg/kg. Survival was prolonged to the same degree as with 25 mg/kg clindamycin, another widely used drug against toxoplasmosis. Three compounds (5j-l) were tested for antiproliferative activity against human tumor cells in culture. Among the 25 cell lines in the National Cancer Institute panel for which data were confirmed in two independent experiments, the IC50 for at least two of these compounds was <10 microM against 17 cell lines (68%) and in the 0. 1-1 microM range against 13 cell lines (52%). One compound (5j) had an IC50 of <0.01 microM against four of the cell lines. The activity profiles of 5k,l were generally similar to that of 5j except that there were no cells against which the IC50 was <0.01 microM.
|
Inhibition of dihydrofolate reductase (DHFR) from rat liver (rl)
|
None
|
1.5
nM
|
|
Journal : J. Med. Chem.
Title : Pneumocystis carinii and Toxoplasma gondii dihydrofolate reductase inhibitors and antitumor agents: synthesis and biological activities of 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl] pyrido[2,3-d]pyrimidines.
Year : 1999
Volume : 42
Issue : 13
First Page : 2447
Last Page : 2455
Authors : Gangjee A, Adair O, Queener SF.
Abstract : Thirteen 2,4-diamino-5-methyl-6-[(monosubstituted anilino)methyl]pyrido[2,3-d]pyrimidines 5-17 were synthesized as potential Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR) inhibitors and as antitumor agents. Compounds 5-17 were designed to investigate the structure-activity relationship of monomethoxy and monohalide substitution in the phenyl ring and N10-methylation of the C9-N10 bridge. The synthetic route to compounds 5-12 involved the reductive amination of a common intermediate, 2,4-diamino-5-methylpyrido[2, 3-d]pyrimidine-6-carbonitrile (18), with the appropriate anilines. N10-Methylation was achieved by reductive methylation. In contrast to previous reports of trimethoprim, the removal of methoxy and chloro groups from the phenyl ring in the 2, 4-diamino-5-methyl-6-[(substituted anilino)methyl]pyrido[2, 3-d]pyrimidine series generally did not decrease DHFR inhibitory activity. The monosubstituted phenyl analogues 5-12 were as potent against pcDHFR and tgDHFR as the previously reported disubstituted phenyl analogues. N10-Methylation generally resulted in a marginal increase in potency against both pcDHFR and tgDHFR. Compounds 5, 7, and 9 were evaluated and shown to inhibit the growth of T. gondii cells in culture at nanomolar concentrations. Compounds 6-8, 9, 11, and 16 were selected by the National Cancer Institute for evaluation in an in vitro preclinical antitumor screening program. All six compounds showed GI50 values in the 10(-7)-10(-9) M range in more than 20 cell lines.
|
Inhibitory concentration against Mycobacterium avium dihydrofolate reductase
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : Bioorg. Med. Chem. Lett.
Title : Preliminary in vitro studies on two potent, water-soluble trimethoprim analogues with exceptional species selectivity against dihydrofolate reductase from Pneumocystis carinii and Mycobacterium avium.
Year : 2004
Volume : 14
Issue : 7
First Page : 1811
Last Page : 1815
Authors : Forsch RA, Queener SF, Rosowsky A.
Abstract : 2,4-Diamino-5-[3',4'-dimethoxy-5'-(5-carboxy-1-pentynyl)]benzylpyrimidine (6) and 2,4-diamino-5-[3',4'-dimethoxy-5'-(4-carboxyphenylethynyl)benzylpyrimidine (7) were synthesized from 2,4-diamino-5-(5'-iodo-3',4'-dimethoxybenzyl)pyrimidine (9) via a Sonogashira reaction with appropriate acetylenic esters followed by saponification, and were tested as inhibitors of dihydrofolate reductase (DHFR) from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), Mycobacterium avium (Ma), and rat in comparison with the widely used antibacterial agent 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP). The selectivity index (SI) for each compound was calculated by dividing its 50% inhibitory concentration (IC(50)) against rat DHFR by its IC(50) against Pc, Tg, or Ma DHFR. The IC(50) of 6 against Pc DHFR was 1.0 nM, with an SI of 5000. Compound 7 had an IC(50) of 8.2 nM against Ma DHFR, with an SI of 11000. By comparison, the IC(50) of TMP was 12000 nM against Pc, 300 nM against Ma, and 180000 against rat DHFR. The potency and selectivity values of 6 and 7 were not as high against Tg as they were against Pc or Ma DHFR, but nonetheless exceeded those of TMP. Because of the outstanding selectivity of 6 against Pc and of 7 against Ma DHFR, these novel analogues may be viewed as promising leads for further structure-activity optimization.
|
Inhibitory concentration against dihydrofolate reductase of Mycobacterium avium
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : J. Med. Chem.
Title : New 2,4-diamino-5-(2',5'-substituted benzyl)pyrimidines as potential drugs against opportunistic infections of AIDS and other immune disorders. Synthesis and species-dependent antifolate activity.
Year : 2004
Volume : 47
Issue : 6
First Page : 1475
Last Page : 1486
Authors : Rosowsky A, Forsch RA, Sibley CH, Inderlied CB, Queener SF.
Abstract : In a continuing effort to design small-molecule inhibitors of dihydrofolate reductase (DHFR) that combine the enzyme-binding selectivity of 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine (trimethoprim, TMP) with the potency of 2,4-diamino-5-methyl-6-(2',5'-dimethoxybenzyl)pyrido[2,3-d]pyrimidine (piritrexim, PTX), seven previously undescribed 2,4-diamino-5-[2'-methoxy-5'-(substituted benzyl)]pyrimidines were synthesized in which the substituent at the 5'-position was a carboxyphenyl group linked to the benzyl moiety by a bridge of two or four atoms in length. The new analogues were all obtained from 2,4-diamino-5-(5'-iodo-2'-methoxybenzyl)pyrimidine via a Sonogashira reaction, followed, where appropriate, by catalytic hydrogenation. The new analogues were tested as inhibitors of DHFR from Pneumocystis carinii (Pc), Toxoplasma gondii (Tg), and Mycobacterium avium (Ma), three life-threatening pathogens often found in AIDS patients and individuals whose immune system is impaired as a result of treatment with immunosuppressive chemotherapy or radiation. The selectivity index (SI) of each compound was obtained by dividing its 50% inhibitory concentration (IC(50)) against Pc, Tg, or Ma DHFR by its IC(50) against rat DHFR. 2,4-Diamino-[2'-methoxy-5'-(3-carboxyphenyl)ethynylbenzyl]pyrimidine (28), with an IC(50) of 23 nM and an SI of 28 in the Pc DHFR assay, had about the same potency as PTX and was 520 times more potent than TMP. As an inhibitor of Tg DHFR, 28 had an IC(50) of 5.5 nM (510-fold lower than that of TMP and similar to that of PTX) and an SI value of 120 (2-fold better than TMP and vastly superior to PTX). Against Ma DHFR, 28 had IC(50) and SI values of 1.5 nM and 430, respectively, compared with 300 nM and 610 for TMP. Although it had 2.5-fold lower potency than 28 against Ma DHFR (IC(50) = 3.7 nM) and was substantially weaker against Pc and Tg DHFR, 2,4-diamino-[2'-methoxy-5'-(4-carboxyphenyl)ethynylbenzyl]pyrimidine (29), with the carboxy group at the para rather than the meta position, displayed 2200-fold selectivity against the Ma enzyme and was the most selective 2,4-diamino-5-(5'-substituted benzyl)pyrimidine inhibitor of this enzyme we have encountered to date. Additional bioassay data for these compounds are also reported.
|
Cytotoxic Activity was evaluated against H460 tumor cells
|
Homo sapiens
|
260.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic Activity was evaluated against HCT-8 tumor cells
|
Homo sapiens
|
68.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic activity was evaluated against L tumor cells
|
Mus musculus
|
76.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic activity was evaluated against P388D1 tumor cells
|
Mus musculus
|
21.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Inhibition of Toxoplasma gondii cell growth
|
Toxoplasma gondii
|
20.0
nM
|
|
Journal : J. Med. Chem.
Title : Lipophilic antifolates as agents against opportunistic infections. 1. Agents superior to trimetrexate and piritrexim against Toxoplasma gondii and Pneumocystis carinii in in vitro evaluations.
Year : 1996
Volume : 39
Issue : 6
First Page : 1271
Last Page : 1280
Authors : Piper JR, Johnson CA, Krauth CA, Carter RL, Hosmer CA, Queener SF, Borotz SE, Pfefferkorn ER.
Abstract : 2,4-Diaminopteridines (21 compounds) and 2,4-diamino-5-methyl-5-deazapteridines (34 compounds) along with three 2,4-diamino-5-unsubstituted-5-deazapteridines and four 2,4-diaminoquinazolines, each with an aryl groups attached to the 6-position of the heterocyclic moiety through a two-atom bridge (either CH2NH, CH2N(CH3),CH2S, or CH2CH2), were synthesized and evaluated as inhibitors of the growth of Toxoplasma gondii in culture and as inhibitors of dihydrofolate reductase enzymes from T. gondii, Pneumocystis carinii, and rat liver. Exceptionally high levels of combined potency and selectivity as growth inhibitors of T. gondii and as inhibitors of the microbial enzymes relative to the mammalian enzyme were found among the 5-methyl-5-deazapteridines but not for the other heterocyclic types. Thirty of the 34 5-methyl-5-deaza compounds gave growth inhibition IC50 values lower than that of pyrimethamine (0.4 microM) with 14 compounds below 0.1 microM, values that compare favorably with those for piritrexim and trimetrexate (both near 0.02 microM). As inhibitors of T gondii DHFR, all but three of the 34 5-methyl-5-deaza compounds gave IC50 values in the order of magnitude with those of piritrexim (0.017 microM) and trimetrexate (0.010 microM), and 17 compounds of this group gave IC50 values versus P. carinii DHFR similarly comparable with those of piritrexim (0.031 microM) and trimetrexate (0.042 microM). Thirteen of these congeners gave both T. gondii growth inhibition and DHFR inhibition IC50 values of 0.10 microM or less, thus indicating facile penetration of the cell membrane. Eleven of these inhibitors of both T. gondii growth and DHFR have selectivity ratios (IC50 rat liver divided by IC50 T. gondii) of 5 or greater for the parasite DHFR. The highest selectivity ratio of nearly 100 belongs to the 5-methyl-5-deaza compound whose 6-substituent is CH2CH2C6H3(OCH3)2-2,5. This compound is over 10(3)-fold more selective for T. gondii DHFR than bridge homologue piritrexim (selectivity ratio 0.088), a compound now in clinical trials. The candidate with CH2NHC6H3(CH3)2-2,5 in the 6-position gave the highest P. carinii DHFR selectivity ratio of 4.0, which is about 60-fold more selective than trimetrexate (0.071) and 80-fold more selective than piritrexim (0.048) toward this enzyme. The 10 best compounds with respect to potency and selectivity includes six compounds bearing 2,5-disubstituted phenyl groups in the side chain (with little, if any, difference in effects of methyl, methoxy, or ethoxy), two side chains bearing 1-naphthyl groups, and two with 5,6,7,8-tetrahydro-1-naphthyl groups. Bridge groups represented in the 10 choice compounds are CH2NH, CH2N(CH3), CH2CH2, and CH2S. The high levels of both potency and selectivity among these agents suggest that in vivo studies now underway may lead to agents that could replace trimetrexate and piritrexim in treatment of toxoplasmosis and P. carinii pneumonia.
|
Cytotoxic activity was evaluated against U87MG tumor cells
|
Homo sapiens
|
48.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic activity was evaluated against U373MG tumor cells
|
Homo sapiens
|
55.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Cytotoxic Activity was evaluated against Vero tumor cells
|
Chlorocebus sabaeus
|
30.0
nM
|
|
Journal : J. Med. Chem.
Title : High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size.
Year : 1996
Volume : 39
Issue : 4
First Page : 892
Last Page : 903
Authors : Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN.
Abstract : A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
|
Inhibitory activity against Wild-type human DHFR
|
None
|
33.0
nM
|
|
Journal : J. Med. Chem.
Title : 2,4-Diamino-5-substituted-quinazolines as inhibitors of a human dihydrofolate reductase with a site-directed mutation at position 22 and of the dihydrofolate reductases from Pneumocystis carinii and Toxoplasma gondii.
Year : 1995
Volume : 38
Issue : 5
First Page : 745
Last Page : 752
Authors : Rosowsky A, Mota CE, Queener SF, Waltham M, Ercikan-Abali E, Bertino JR.
Abstract : 2,4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (p-aminobenzoyl)-L-glutamate side chain, were synthesized as potentially selective inhibitors of a site-directed mutant of human dihydrofolate reductase (DHFR) containing phenylalanine instead of leucine at position 22. This mutant enzyme is approximately 100-fold more resistant than native enzyme to the classical antifolate methotrexate (MTX), yet shows minimal cross resistance to the nonclassical antifolates piritrexim (PTX) and trimetrexate (TMQ). Although they were much less potent than trimetrexate and piritrexim, the lipophilic 5-substituted analogues were all found to bind approximately 10 times better to the mutant DHFR than to the wild-type enzyme. The potency of the analogue with a classical (p-aminobenzoyl)-L-glutamate side chain was similarly diminished in comparison with MTX, but the difference in its binding affinity to the two DHFR species was only 5-fold. Thus, by making subtle structural changes in the antifolate molecule, it may be possible to attack resistance due to mutational alterations in the active site of the target enzyme. Also, to test the hypothesis that DHFR from Pneumocystis carinii and Toxoplasma gondii may have a less sterically restrictive active site than the enzyme from mammalian cells, inhibition assays using several of the lipophilic analogues in the series were carried out against the P. carinii and T. gondii reductases in comparison with the enzyme from rat liver. In contrast to their preferential binding to mutant versus wild-type human DHFR, binding of these analogues to the P. carinii and T. gondii enzymes was weaker than binding to rat enzyme. It thus appears that, if the active site of the DHFR from these parasites is less sterically restrictive than the active site of the mammalian enzyme, this difference cannot be successfully exploited by moving the side chain from the 6-position to the 5-position.
|
Inhibitory concentration against rat DHFR
|
Rattus norvegicus
|
3.3
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain.
Year : 2005
Volume : 48
Issue : 13
First Page : 4420
Last Page : 4431
Authors : Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A.
Abstract : As part of a search for dihydrofolate reductase (DHFR) inhibitors combining the high potency of piritrexim (PTX) with the high antiparasitic vs mammalian selectivity of trimethoprim (TMP), the heretofore undescribed 2,4-diamino-6-(2',5'-disubstituted benzyl)pyrido[2,3-d]pyrimidines 6-14 with O-(omega-carboxyalkyl) or omega-carboxy-1-alkynyl groups on the benzyl moiety were synthesized and tested against Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium DHFR vs rat DHFR. Three N-(2,4-diaminopteridin-6-yl)methyl)-2'-(omega-carboxy-1-alkynyl)dibenz[b,f]azepines (19-21) were also synthesized and tested. The pyridopyrimidine with the best combination of potency and selectivity was 2,4-diamino-5-methyl-6-[2'-(5-carboxy-1-butynyl)-5'-methoxy]benzyl]pyrimidine (13), with an IC(50) value of 0.65 nM against P. carinii DHFR, 0.57 nM against M. avium DHFR, and 55 nM against rat DHFR. The potency of 13 against P. carinii DHFR was 20-fold greater than that of PTX (IC(50) = 13 nM), and its selectivity index (SI) relative to rat DHFR was 85, whereas PTX was nonselective. The activity of 13 against P. carinii DHFR was 20 000 times greater than that of TMP, with an SI of 96, whereas that of TMP was only 14. However 13 was no more potent than PTX against M. avium DHFR, and its SI was no better than that of TMP. Molecular modeling dynamics studies using compounds 10 and 13 indicated a slight binding preference for the latter, in qualitative agreement with the IC(50) data. Among the pteridines, the most potent against P. carinii DHFR and M. avium DHFR was the 2'-(5-carboxy-1-butynyl)dibenz[b,f]azepinyl derivative 20 (IC(50) = 2.9 nM), whereas the most selective was the 2'-(5-carboxy-1-pentynyl) analogue 21, with SI values of >100 against both P. carinii and M. avium DHFR relative to rat DHFR. The final compound, 2,4-diamino-5-[3'-(4-carboxy-1-butynyl)-4'-bromo-5'-methoxybenzyl]pyrimidine (22), was both potent and selective against M. avium DHFR (IC(50) = 0.47 nM, SI = 1300) but was not potent or selective against either P. carinii or T. gondii DHFR.
|
Inhibitory concentration against Toxoplasma gondii DHFR
|
Toxoplasma gondii
|
4.3
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain.
Year : 2005
Volume : 48
Issue : 13
First Page : 4420
Last Page : 4431
Authors : Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A.
Abstract : As part of a search for dihydrofolate reductase (DHFR) inhibitors combining the high potency of piritrexim (PTX) with the high antiparasitic vs mammalian selectivity of trimethoprim (TMP), the heretofore undescribed 2,4-diamino-6-(2',5'-disubstituted benzyl)pyrido[2,3-d]pyrimidines 6-14 with O-(omega-carboxyalkyl) or omega-carboxy-1-alkynyl groups on the benzyl moiety were synthesized and tested against Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium DHFR vs rat DHFR. Three N-(2,4-diaminopteridin-6-yl)methyl)-2'-(omega-carboxy-1-alkynyl)dibenz[b,f]azepines (19-21) were also synthesized and tested. The pyridopyrimidine with the best combination of potency and selectivity was 2,4-diamino-5-methyl-6-[2'-(5-carboxy-1-butynyl)-5'-methoxy]benzyl]pyrimidine (13), with an IC(50) value of 0.65 nM against P. carinii DHFR, 0.57 nM against M. avium DHFR, and 55 nM against rat DHFR. The potency of 13 against P. carinii DHFR was 20-fold greater than that of PTX (IC(50) = 13 nM), and its selectivity index (SI) relative to rat DHFR was 85, whereas PTX was nonselective. The activity of 13 against P. carinii DHFR was 20 000 times greater than that of TMP, with an SI of 96, whereas that of TMP was only 14. However 13 was no more potent than PTX against M. avium DHFR, and its SI was no better than that of TMP. Molecular modeling dynamics studies using compounds 10 and 13 indicated a slight binding preference for the latter, in qualitative agreement with the IC(50) data. Among the pteridines, the most potent against P. carinii DHFR and M. avium DHFR was the 2'-(5-carboxy-1-butynyl)dibenz[b,f]azepinyl derivative 20 (IC(50) = 2.9 nM), whereas the most selective was the 2'-(5-carboxy-1-pentynyl) analogue 21, with SI values of >100 against both P. carinii and M. avium DHFR relative to rat DHFR. The final compound, 2,4-diamino-5-[3'-(4-carboxy-1-butynyl)-4'-bromo-5'-methoxybenzyl]pyrimidine (22), was both potent and selective against M. avium DHFR (IC(50) = 0.47 nM, SI = 1300) but was not potent or selective against either P. carinii or T. gondii DHFR.
|
Inhibitory concentration against Mycobacterium avium DHFR
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain.
Year : 2005
Volume : 48
Issue : 13
First Page : 4420
Last Page : 4431
Authors : Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A.
Abstract : As part of a search for dihydrofolate reductase (DHFR) inhibitors combining the high potency of piritrexim (PTX) with the high antiparasitic vs mammalian selectivity of trimethoprim (TMP), the heretofore undescribed 2,4-diamino-6-(2',5'-disubstituted benzyl)pyrido[2,3-d]pyrimidines 6-14 with O-(omega-carboxyalkyl) or omega-carboxy-1-alkynyl groups on the benzyl moiety were synthesized and tested against Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium DHFR vs rat DHFR. Three N-(2,4-diaminopteridin-6-yl)methyl)-2'-(omega-carboxy-1-alkynyl)dibenz[b,f]azepines (19-21) were also synthesized and tested. The pyridopyrimidine with the best combination of potency and selectivity was 2,4-diamino-5-methyl-6-[2'-(5-carboxy-1-butynyl)-5'-methoxy]benzyl]pyrimidine (13), with an IC(50) value of 0.65 nM against P. carinii DHFR, 0.57 nM against M. avium DHFR, and 55 nM against rat DHFR. The potency of 13 against P. carinii DHFR was 20-fold greater than that of PTX (IC(50) = 13 nM), and its selectivity index (SI) relative to rat DHFR was 85, whereas PTX was nonselective. The activity of 13 against P. carinii DHFR was 20 000 times greater than that of TMP, with an SI of 96, whereas that of TMP was only 14. However 13 was no more potent than PTX against M. avium DHFR, and its SI was no better than that of TMP. Molecular modeling dynamics studies using compounds 10 and 13 indicated a slight binding preference for the latter, in qualitative agreement with the IC(50) data. Among the pteridines, the most potent against P. carinii DHFR and M. avium DHFR was the 2'-(5-carboxy-1-butynyl)dibenz[b,f]azepinyl derivative 20 (IC(50) = 2.9 nM), whereas the most selective was the 2'-(5-carboxy-1-pentynyl) analogue 21, with SI values of >100 against both P. carinii and M. avium DHFR relative to rat DHFR. The final compound, 2,4-diamino-5-[3'-(4-carboxy-1-butynyl)-4'-bromo-5'-methoxybenzyl]pyrimidine (22), was both potent and selective against M. avium DHFR (IC(50) = 0.47 nM, SI = 1300) but was not potent or selective against either P. carinii or T. gondii DHFR.
|
Inhibitory concentration against Pneumocystis carinii DHFR
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain.
Year : 2005
Volume : 48
Issue : 13
First Page : 4420
Last Page : 4431
Authors : Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A.
Abstract : As part of a search for dihydrofolate reductase (DHFR) inhibitors combining the high potency of piritrexim (PTX) with the high antiparasitic vs mammalian selectivity of trimethoprim (TMP), the heretofore undescribed 2,4-diamino-6-(2',5'-disubstituted benzyl)pyrido[2,3-d]pyrimidines 6-14 with O-(omega-carboxyalkyl) or omega-carboxy-1-alkynyl groups on the benzyl moiety were synthesized and tested against Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium DHFR vs rat DHFR. Three N-(2,4-diaminopteridin-6-yl)methyl)-2'-(omega-carboxy-1-alkynyl)dibenz[b,f]azepines (19-21) were also synthesized and tested. The pyridopyrimidine with the best combination of potency and selectivity was 2,4-diamino-5-methyl-6-[2'-(5-carboxy-1-butynyl)-5'-methoxy]benzyl]pyrimidine (13), with an IC(50) value of 0.65 nM against P. carinii DHFR, 0.57 nM against M. avium DHFR, and 55 nM against rat DHFR. The potency of 13 against P. carinii DHFR was 20-fold greater than that of PTX (IC(50) = 13 nM), and its selectivity index (SI) relative to rat DHFR was 85, whereas PTX was nonselective. The activity of 13 against P. carinii DHFR was 20 000 times greater than that of TMP, with an SI of 96, whereas that of TMP was only 14. However 13 was no more potent than PTX against M. avium DHFR, and its SI was no better than that of TMP. Molecular modeling dynamics studies using compounds 10 and 13 indicated a slight binding preference for the latter, in qualitative agreement with the IC(50) data. Among the pteridines, the most potent against P. carinii DHFR and M. avium DHFR was the 2'-(5-carboxy-1-butynyl)dibenz[b,f]azepinyl derivative 20 (IC(50) = 2.9 nM), whereas the most selective was the 2'-(5-carboxy-1-pentynyl) analogue 21, with SI values of >100 against both P. carinii and M. avium DHFR relative to rat DHFR. The final compound, 2,4-diamino-5-[3'-(4-carboxy-1-butynyl)-4'-bromo-5'-methoxybenzyl]pyrimidine (22), was both potent and selective against M. avium DHFR (IC(50) = 0.47 nM, SI = 1300) but was not potent or selective against either P. carinii or T. gondii DHFR.
|
Concentration causing inhibition of CCRF-CEM human leukemic lymphoblasts growth in a 72 hr culture
|
Homo sapiens
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and antifolate activity of new analogues of piritrexim and other diaminopyrimidine dihydrofolate reductase inhibitors with omega-carboxyalkoxy or omega-carboxy-1-alkynyl substitution in the side chain.
Year : 2005
Volume : 48
Issue : 13
First Page : 4420
Last Page : 4431
Authors : Chan DC, Fu H, Forsch RA, Queener SF, Rosowsky A.
Abstract : As part of a search for dihydrofolate reductase (DHFR) inhibitors combining the high potency of piritrexim (PTX) with the high antiparasitic vs mammalian selectivity of trimethoprim (TMP), the heretofore undescribed 2,4-diamino-6-(2',5'-disubstituted benzyl)pyrido[2,3-d]pyrimidines 6-14 with O-(omega-carboxyalkyl) or omega-carboxy-1-alkynyl groups on the benzyl moiety were synthesized and tested against Pneumocystis carinii, Toxoplasma gondii, and Mycobacterium avium DHFR vs rat DHFR. Three N-(2,4-diaminopteridin-6-yl)methyl)-2'-(omega-carboxy-1-alkynyl)dibenz[b,f]azepines (19-21) were also synthesized and tested. The pyridopyrimidine with the best combination of potency and selectivity was 2,4-diamino-5-methyl-6-[2'-(5-carboxy-1-butynyl)-5'-methoxy]benzyl]pyrimidine (13), with an IC(50) value of 0.65 nM against P. carinii DHFR, 0.57 nM against M. avium DHFR, and 55 nM against rat DHFR. The potency of 13 against P. carinii DHFR was 20-fold greater than that of PTX (IC(50) = 13 nM), and its selectivity index (SI) relative to rat DHFR was 85, whereas PTX was nonselective. The activity of 13 against P. carinii DHFR was 20 000 times greater than that of TMP, with an SI of 96, whereas that of TMP was only 14. However 13 was no more potent than PTX against M. avium DHFR, and its SI was no better than that of TMP. Molecular modeling dynamics studies using compounds 10 and 13 indicated a slight binding preference for the latter, in qualitative agreement with the IC(50) data. Among the pteridines, the most potent against P. carinii DHFR and M. avium DHFR was the 2'-(5-carboxy-1-butynyl)dibenz[b,f]azepinyl derivative 20 (IC(50) = 2.9 nM), whereas the most selective was the 2'-(5-carboxy-1-pentynyl) analogue 21, with SI values of >100 against both P. carinii and M. avium DHFR relative to rat DHFR. The final compound, 2,4-diamino-5-[3'-(4-carboxy-1-butynyl)-4'-bromo-5'-methoxybenzyl]pyrimidine (22), was both potent and selective against M. avium DHFR (IC(50) = 0.47 nM, SI = 1300) but was not potent or selective against either P. carinii or T. gondii DHFR.
|
Inhibition of Pneumocystis carinii dihydrofolate reductase
|
Pneumocystis carinii
|
34.3
nM
|
|
Journal : J. Med. Chem.
Title : N9-substituted 2,4-diaminoquinazolines: synthesis and biological evaluation of lipophilic inhibitors of pneumocystis carinii and toxoplasma gondii dihydrofolate reductase.
Year : 2008
Volume : 51
Issue : 19
First Page : 6195
Last Page : 6200
Authors : Gangjee A, Adair OO, Pagley M, Queener SF.
Abstract : N9-substituted 2,4-diaminoquinazolines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR). Reduction of commercially available 2,4-diamino-6-nitroquinazoline 14 with Raney nickel afforded 2,4,6-triaminoquinazoline 15. Reductive amination of 15 with the appropriate benzaldehydes or naphthaldehydes, followed by N9-alkylation, afforded the target compounds 5- 13. In the 2,5-dimethoxybenzylamino substituted quinazoline analogues, replacement of the N9-CH 3 group of 4 with the N9-C2H5 group of 8 resulted in a 9- and 8-fold increase in potency against pcDHFR and tgDHFR, respectively. The N9-C2H5 substituted compound 8 was highly potent, with IC50 values of 9.9 and 3.7 nM against pcDHFR and tgDHFR, respectively. N9-propyl and N9-cyclopropyl methyl substitutions did not afford further increases in potency. This study indicates that the N9-ethyl substitution is optimum for inhibitory activity against pcDHFR and tgDHFR for the 2,4-diaminoquinazolines. Selectivity was unaffected by N9 substitution.
|
Inhibition of rat liver dihydrofolate reductase
|
Rattus norvegicus
|
4.4
nM
|
|
Journal : J. Med. Chem.
Title : N9-substituted 2,4-diaminoquinazolines: synthesis and biological evaluation of lipophilic inhibitors of pneumocystis carinii and toxoplasma gondii dihydrofolate reductase.
Year : 2008
Volume : 51
Issue : 19
First Page : 6195
Last Page : 6200
Authors : Gangjee A, Adair OO, Pagley M, Queener SF.
Abstract : N9-substituted 2,4-diaminoquinazolines were synthesized and evaluated as inhibitors of Pneumocystis carinii (pc) and Toxoplasma gondii (tg) dihydrofolate reductase (DHFR). Reduction of commercially available 2,4-diamino-6-nitroquinazoline 14 with Raney nickel afforded 2,4,6-triaminoquinazoline 15. Reductive amination of 15 with the appropriate benzaldehydes or naphthaldehydes, followed by N9-alkylation, afforded the target compounds 5- 13. In the 2,5-dimethoxybenzylamino substituted quinazoline analogues, replacement of the N9-CH 3 group of 4 with the N9-C2H5 group of 8 resulted in a 9- and 8-fold increase in potency against pcDHFR and tgDHFR, respectively. The N9-C2H5 substituted compound 8 was highly potent, with IC50 values of 9.9 and 3.7 nM against pcDHFR and tgDHFR, respectively. N9-propyl and N9-cyclopropyl methyl substitutions did not afford further increases in potency. This study indicates that the N9-ethyl substitution is optimum for inhibitory activity against pcDHFR and tgDHFR for the 2,4-diaminoquinazolines. Selectivity was unaffected by N9 substitution.
|
GSK_TCMDC: Inhibition of Plasmodium falciparum 3D7 in whole red blood cells, using parasite LDH activity as an index of growth. Test compounds present at 2uM
|
Plasmodium falciparum
|
92.0
%
|
|
Journal : Nature
Title : Thousands of chemical starting points for antimalarial lead identification.
Year : 2010
Volume : 465
Issue : 7296
First Page : 305
Last Page : 310
Authors : Gamo FJ, Sanz LM, Vidal J, de Cozar C, Alvarez E, Lavandera JL, Vanderwall DE, Green DV, Kumar V, Hasan S, Brown JR, Peishoff CE, Cardon LR, Garcia-Bustos JF.
Abstract : Malaria is a devastating infection caused by protozoa of the genus Plasmodium. Drug resistance is widespread, no new chemical class of antimalarials has been introduced into clinical practice since 1996 and there is a recent rise of parasite strains with reduced sensitivity to the newest drugs. We screened nearly 2 million compounds in GlaxoSmithKline's chemical library for inhibitors of P. falciparum, of which 13,533 were confirmed to inhibit parasite growth by at least 80% at 2 microM concentration. More than 8,000 also showed potent activity against the multidrug resistant strain Dd2. Most (82%) compounds originate from internal company projects and are new to the malaria community. Analyses using historic assay data suggest several novel mechanisms of antimalarial action, such as inhibition of protein kinases and host-pathogen interaction related targets. Chemical structures and associated data are hereby made public to encourage additional drug lead identification efforts and further research into this disease.
|
GSK_TCMDC: Inhibition of Plasmodium falciparum Dd2 in whole red blood cells, using parasite LDH activity as an index of growth. Test compounds present at 2uM
|
Plasmodium falciparum
|
97.0
%
|
|
Journal : Nature
Title : Thousands of chemical starting points for antimalarial lead identification.
Year : 2010
Volume : 465
Issue : 7296
First Page : 305
Last Page : 310
Authors : Gamo FJ, Sanz LM, Vidal J, de Cozar C, Alvarez E, Lavandera JL, Vanderwall DE, Green DV, Kumar V, Hasan S, Brown JR, Peishoff CE, Cardon LR, Garcia-Bustos JF.
Abstract : Malaria is a devastating infection caused by protozoa of the genus Plasmodium. Drug resistance is widespread, no new chemical class of antimalarials has been introduced into clinical practice since 1996 and there is a recent rise of parasite strains with reduced sensitivity to the newest drugs. We screened nearly 2 million compounds in GlaxoSmithKline's chemical library for inhibitors of P. falciparum, of which 13,533 were confirmed to inhibit parasite growth by at least 80% at 2 microM concentration. More than 8,000 also showed potent activity against the multidrug resistant strain Dd2. Most (82%) compounds originate from internal company projects and are new to the malaria community. Analyses using historic assay data suggest several novel mechanisms of antimalarial action, such as inhibition of protein kinases and host-pathogen interaction related targets. Chemical structures and associated data are hereby made public to encourage additional drug lead identification efforts and further research into this disease.
|
GSK_TCMDC: Inhibition of Plasmodium falciparum 3D7 LDH activity, using an LDH reporter assay. Test compounds present at 2uM
|
Plasmodium falciparum
|
5.0
%
|
|
Journal : Nature
Title : Thousands of chemical starting points for antimalarial lead identification.
Year : 2010
Volume : 465
Issue : 7296
First Page : 305
Last Page : 310
Authors : Gamo FJ, Sanz LM, Vidal J, de Cozar C, Alvarez E, Lavandera JL, Vanderwall DE, Green DV, Kumar V, Hasan S, Brown JR, Peishoff CE, Cardon LR, Garcia-Bustos JF.
Abstract : Malaria is a devastating infection caused by protozoa of the genus Plasmodium. Drug resistance is widespread, no new chemical class of antimalarials has been introduced into clinical practice since 1996 and there is a recent rise of parasite strains with reduced sensitivity to the newest drugs. We screened nearly 2 million compounds in GlaxoSmithKline's chemical library for inhibitors of P. falciparum, of which 13,533 were confirmed to inhibit parasite growth by at least 80% at 2 microM concentration. More than 8,000 also showed potent activity against the multidrug resistant strain Dd2. Most (82%) compounds originate from internal company projects and are new to the malaria community. Analyses using historic assay data suggest several novel mechanisms of antimalarial action, such as inhibition of protein kinases and host-pathogen interaction related targets. Chemical structures and associated data are hereby made public to encourage additional drug lead identification efforts and further research into this disease.
|
GSK_TCMDC: Percent inhibition of human HepG2 cell line. Test compounds present at 10uM.
|
Homo sapiens
|
68.0
%
|
|
Journal : Nature
Title : Thousands of chemical starting points for antimalarial lead identification.
Year : 2010
Volume : 465
Issue : 7296
First Page : 305
Last Page : 310
Authors : Gamo FJ, Sanz LM, Vidal J, de Cozar C, Alvarez E, Lavandera JL, Vanderwall DE, Green DV, Kumar V, Hasan S, Brown JR, Peishoff CE, Cardon LR, Garcia-Bustos JF.
Abstract : Malaria is a devastating infection caused by protozoa of the genus Plasmodium. Drug resistance is widespread, no new chemical class of antimalarials has been introduced into clinical practice since 1996 and there is a recent rise of parasite strains with reduced sensitivity to the newest drugs. We screened nearly 2 million compounds in GlaxoSmithKline's chemical library for inhibitors of P. falciparum, of which 13,533 were confirmed to inhibit parasite growth by at least 80% at 2 microM concentration. More than 8,000 also showed potent activity against the multidrug resistant strain Dd2. Most (82%) compounds originate from internal company projects and are new to the malaria community. Analyses using historic assay data suggest several novel mechanisms of antimalarial action, such as inhibition of protein kinases and host-pathogen interaction related targets. Chemical structures and associated data are hereby made public to encourage additional drug lead identification efforts and further research into this disease.
|
Antimicrobial activity against Toxoplasma gondii
|
Toxoplasma gondii
|
0.0
nM
|
|
Journal : Bioorg. Med. Chem.
Title : Multi-target spectral moment QSAR versus ANN for antiparasitic drugs against different parasite species.
Year : 2010
Volume : 18
Issue : 6
First Page : 2225
Last Page : 2231
Authors : Prado-Prado FJ, García-Mera X, González-Díaz H.
Abstract : There are many of pathogen parasite species with different susceptibility profile to antiparasitic drugs. Unfortunately, almost QSAR models predict the biological activity of drugs against only one parasite species. Consequently, predicting the probability with which a drug is active against different species with a single unify model is a goal of the major importance. In so doing, we use Markov Chains theory to calculate new multi-target spectral moments to fit a QSAR model that predict by the first time a mt-QSAR model for 500 drugs tested in the literature against 16 parasite species and other 207 drugs no tested in the literature using spectral moments. The data was processed by linear discriminant analysis (LDA) classifying drugs as active or non-active against the different tested parasite species. The model correctly classifies 311 out of 358 active compounds (86.9%) and 2328 out of 2577 non-active compounds (90.3%) in training series. Overall training performance was 89.9%. Validation of the model was carried out by means of external predicting series. In these series the model classified correctly 157 out 190, 82.6% of antiparasitic compounds and 1151 out of 1277 non-active compounds (90.1%). Overall predictability performance was 89.2%. In addition we developed four types of non Linear Artificial neural networks (ANN) and we compared with the mt-QSAR model. The improved ANN model had an overall training performance was 87%. The present work report the first attempts to calculate within a unify framework probabilities of antiparasitic action of drugs against different parasite species based on spectral moment analysis.
|
Antimicrobial activity against Pneumocystis carinii
|
Pneumocystis carinii
|
0.0
nM
|
|
Journal : Bioorg. Med. Chem.
Title : Multi-target spectral moment QSAR versus ANN for antiparasitic drugs against different parasite species.
Year : 2010
Volume : 18
Issue : 6
First Page : 2225
Last Page : 2231
Authors : Prado-Prado FJ, García-Mera X, González-Díaz H.
Abstract : There are many of pathogen parasite species with different susceptibility profile to antiparasitic drugs. Unfortunately, almost QSAR models predict the biological activity of drugs against only one parasite species. Consequently, predicting the probability with which a drug is active against different species with a single unify model is a goal of the major importance. In so doing, we use Markov Chains theory to calculate new multi-target spectral moments to fit a QSAR model that predict by the first time a mt-QSAR model for 500 drugs tested in the literature against 16 parasite species and other 207 drugs no tested in the literature using spectral moments. The data was processed by linear discriminant analysis (LDA) classifying drugs as active or non-active against the different tested parasite species. The model correctly classifies 311 out of 358 active compounds (86.9%) and 2328 out of 2577 non-active compounds (90.3%) in training series. Overall training performance was 89.9%. Validation of the model was carried out by means of external predicting series. In these series the model classified correctly 157 out 190, 82.6% of antiparasitic compounds and 1151 out of 1277 non-active compounds (90.1%). Overall predictability performance was 89.2%. In addition we developed four types of non Linear Artificial neural networks (ANN) and we compared with the mt-QSAR model. The improved ANN model had an overall training performance was 87%. The present work report the first attempts to calculate within a unify framework probabilities of antiparasitic action of drugs against different parasite species based on spectral moment analysis.
|
Inhibition of Mycobacterium avium DHFR
|
Mycobacterium avium
|
0.61
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and molecular modeling of novel pyrido[2,3-d]pyrimidine analogues as antifolates; application of Buchwald-Hartwig aminations of heterocycles.
Year : 2013
Volume : 56
Issue : 11
First Page : 4422
Last Page : 4441
Authors : Gangjee A, Namjoshi OA, Raghavan S, Queener SF, Kisliuk RL, Cody V.
Abstract : Opportunistic infections caused by Pneumocystis jirovecii (P. jirovecii, pj), Toxoplasma gondii (T. gondii, tg), and Mycobacterium avium (M. avium, ma) are the principal causes of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS). The absence of any animal models for human Pneumocystis jirovecii pneumonia and the lack of crystal structures of pjDHFR and tgDHFR make the design of inhibitors challenging. A novel series of pyrido[2,3-d]pyrimidines as selective and potent DHFR inhibitors against these opportunistic infections are presented. Buchwald-Hartwig coupling reaction of substituted anilines with pivaloyl protected 2,4-diamino-6-bromo-pyrido[2,3-d]pyrimidine was successfully explored to synthesize these analogues. Compound 26 was the most selective inhibitor with excellent potency against pjDHFR. Molecular modeling studies with a pjDHFR homology model explained the potency and selectivity of 26. Structural data are also reported for 26 with pcDHFR and 16 and 22 with variants of pcDHFR.
|
Inhibition of Pneumocystis carinii DHFR
|
Pneumocystis carinii
|
13.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and molecular modeling of novel pyrido[2,3-d]pyrimidine analogues as antifolates; application of Buchwald-Hartwig aminations of heterocycles.
Year : 2013
Volume : 56
Issue : 11
First Page : 4422
Last Page : 4441
Authors : Gangjee A, Namjoshi OA, Raghavan S, Queener SF, Kisliuk RL, Cody V.
Abstract : Opportunistic infections caused by Pneumocystis jirovecii (P. jirovecii, pj), Toxoplasma gondii (T. gondii, tg), and Mycobacterium avium (M. avium, ma) are the principal causes of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS). The absence of any animal models for human Pneumocystis jirovecii pneumonia and the lack of crystal structures of pjDHFR and tgDHFR make the design of inhibitors challenging. A novel series of pyrido[2,3-d]pyrimidines as selective and potent DHFR inhibitors against these opportunistic infections are presented. Buchwald-Hartwig coupling reaction of substituted anilines with pivaloyl protected 2,4-diamino-6-bromo-pyrido[2,3-d]pyrimidine was successfully explored to synthesize these analogues. Compound 26 was the most selective inhibitor with excellent potency against pjDHFR. Molecular modeling studies with a pjDHFR homology model explained the potency and selectivity of 26. Structural data are also reported for 26 with pcDHFR and 16 and 22 with variants of pcDHFR.
|
Inhibition of rat liver DHFR
|
Rattus norvegicus
|
3.3
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and molecular modeling of novel pyrido[2,3-d]pyrimidine analogues as antifolates; application of Buchwald-Hartwig aminations of heterocycles.
Year : 2013
Volume : 56
Issue : 11
First Page : 4422
Last Page : 4441
Authors : Gangjee A, Namjoshi OA, Raghavan S, Queener SF, Kisliuk RL, Cody V.
Abstract : Opportunistic infections caused by Pneumocystis jirovecii (P. jirovecii, pj), Toxoplasma gondii (T. gondii, tg), and Mycobacterium avium (M. avium, ma) are the principal causes of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS). The absence of any animal models for human Pneumocystis jirovecii pneumonia and the lack of crystal structures of pjDHFR and tgDHFR make the design of inhibitors challenging. A novel series of pyrido[2,3-d]pyrimidines as selective and potent DHFR inhibitors against these opportunistic infections are presented. Buchwald-Hartwig coupling reaction of substituted anilines with pivaloyl protected 2,4-diamino-6-bromo-pyrido[2,3-d]pyrimidine was successfully explored to synthesize these analogues. Compound 26 was the most selective inhibitor with excellent potency against pjDHFR. Molecular modeling studies with a pjDHFR homology model explained the potency and selectivity of 26. Structural data are also reported for 26 with pcDHFR and 16 and 22 with variants of pcDHFR.
|
Inhibition of Pneumocystis jirovecii recombinant DHFR
|
Pneumocystis jirovecii
|
1.6
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and molecular modeling of novel pyrido[2,3-d]pyrimidine analogues as antifolates; application of Buchwald-Hartwig aminations of heterocycles.
Year : 2013
Volume : 56
Issue : 11
First Page : 4422
Last Page : 4441
Authors : Gangjee A, Namjoshi OA, Raghavan S, Queener SF, Kisliuk RL, Cody V.
Abstract : Opportunistic infections caused by Pneumocystis jirovecii (P. jirovecii, pj), Toxoplasma gondii (T. gondii, tg), and Mycobacterium avium (M. avium, ma) are the principal causes of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS). The absence of any animal models for human Pneumocystis jirovecii pneumonia and the lack of crystal structures of pjDHFR and tgDHFR make the design of inhibitors challenging. A novel series of pyrido[2,3-d]pyrimidines as selective and potent DHFR inhibitors against these opportunistic infections are presented. Buchwald-Hartwig coupling reaction of substituted anilines with pivaloyl protected 2,4-diamino-6-bromo-pyrido[2,3-d]pyrimidine was successfully explored to synthesize these analogues. Compound 26 was the most selective inhibitor with excellent potency against pjDHFR. Molecular modeling studies with a pjDHFR homology model explained the potency and selectivity of 26. Structural data are also reported for 26 with pcDHFR and 16 and 22 with variants of pcDHFR.
|
Inhibition of human recombinant DHFR
|
Homo sapiens
|
3.0
nM
|
|
Journal : J. Med. Chem.
Title : Design, synthesis, and molecular modeling of novel pyrido[2,3-d]pyrimidine analogues as antifolates; application of Buchwald-Hartwig aminations of heterocycles.
Year : 2013
Volume : 56
Issue : 11
First Page : 4422
Last Page : 4441
Authors : Gangjee A, Namjoshi OA, Raghavan S, Queener SF, Kisliuk RL, Cody V.
Abstract : Opportunistic infections caused by Pneumocystis jirovecii (P. jirovecii, pj), Toxoplasma gondii (T. gondii, tg), and Mycobacterium avium (M. avium, ma) are the principal causes of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS). The absence of any animal models for human Pneumocystis jirovecii pneumonia and the lack of crystal structures of pjDHFR and tgDHFR make the design of inhibitors challenging. A novel series of pyrido[2,3-d]pyrimidines as selective and potent DHFR inhibitors against these opportunistic infections are presented. Buchwald-Hartwig coupling reaction of substituted anilines with pivaloyl protected 2,4-diamino-6-bromo-pyrido[2,3-d]pyrimidine was successfully explored to synthesize these analogues. Compound 26 was the most selective inhibitor with excellent potency against pjDHFR. Molecular modeling studies with a pjDHFR homology model explained the potency and selectivity of 26. Structural data are also reported for 26 with pcDHFR and 16 and 22 with variants of pcDHFR.
|
Inhibition of Pneumocystis carinii DHFR by spectrophotometric assay
|
Pneumocystis carinii
|
19.0
nM
|
|
Journal : Eur. J. Med. Chem.
Title : Recent advances in the chemistry and biology of pyridopyrimidines.
Year : 2015
Volume : 95
First Page : 76
Last Page : 95
Authors : Buron F, Mérour JY, Akssira M, Guillaumet G, Routier S.
Abstract : The interest in pyridopyrimidine cores for pharmaceutical products makes this scaffold a highly useful building block for organic chemistry. These derivatives have found applications in various areas of medicine such as anticancer, CNS, fungicidal, antiviral, anti-inflammatory, antimicrobial, and antibacterial therapies. This review mainly focuses on the progress achieved since 2004 in the chemistry and biological activity of pyridopyrimidines.
|
Inhibition of Toxoplasma gondii DHFR by spectrophotometric assay
|
Toxoplasma gondii
|
17.0
nM
|
|
Journal : Eur. J. Med. Chem.
Title : Recent advances in the chemistry and biology of pyridopyrimidines.
Year : 2015
Volume : 95
First Page : 76
Last Page : 95
Authors : Buron F, Mérour JY, Akssira M, Guillaumet G, Routier S.
Abstract : The interest in pyridopyrimidine cores for pharmaceutical products makes this scaffold a highly useful building block for organic chemistry. These derivatives have found applications in various areas of medicine such as anticancer, CNS, fungicidal, antiviral, anti-inflammatory, antimicrobial, and antibacterial therapies. This review mainly focuses on the progress achieved since 2004 in the chemistry and biological activity of pyridopyrimidines.
|
Inhibition of Pneumocystis jirovecii recombinant DHFR expressed in Escherichia coli Rosetta Gami B (DE3) competent cells using DHFA as substrate and NADPH
|
Pneumocystis jirovecii
|
41.0
nM
|
|
Journal : Bioorg Med Chem
Title : Targeting species specific amino acid residues: Design, synthesis and biological evaluation of 6-substituted pyrrolo[2,3-d]pyrimidines as dihydrofolate reductase inhibitors and potential anti-opportunistic infection agents.
Year : 2018
Volume : 26
Issue : 9
First Page : 2640
Last Page : 2650
Authors : Shah K, Lin X, Queener SF, Cody V, Pace J, Gangjee A.
Abstract : To combine the potency of trimetrexate (TMQ) or piritrexim (PTX) with the species selectivity of trimethoprim (TMP), target based design was carried out with the X-ray crystal structure of human dihydrofolate reductase (hDHFR) and the homology model of Pneumocystis jirovecii DHFR (pjDHFR). Using variation of amino acids such as Met33/Phe31 (in pjDHFR/hDHFR) that affect the binding of inhibitors due to their distinct positive or negative steric effect at the active binding site of the inhibitor, we designed a series of substituted-pyrrolo[2,3-d]pyrimidines. The best analogs displayed better potency (IC50) than PTX and high selectivity for pjDHFR versus hDHFR, with 4 exhibiting a selectivity for pjDHFR of 24-fold.
|
Inhibition of human recombinant DHFR expressed in Escherichia coli Rosetta Gami B (DE3) competent cells using DHFA as substrate and NADPH
|
Homo sapiens
|
2.0
nM
|
|
Journal : Bioorg Med Chem
Title : Targeting species specific amino acid residues: Design, synthesis and biological evaluation of 6-substituted pyrrolo[2,3-d]pyrimidines as dihydrofolate reductase inhibitors and potential anti-opportunistic infection agents.
Year : 2018
Volume : 26
Issue : 9
First Page : 2640
Last Page : 2650
Authors : Shah K, Lin X, Queener SF, Cody V, Pace J, Gangjee A.
Abstract : To combine the potency of trimetrexate (TMQ) or piritrexim (PTX) with the species selectivity of trimethoprim (TMP), target based design was carried out with the X-ray crystal structure of human dihydrofolate reductase (hDHFR) and the homology model of Pneumocystis jirovecii DHFR (pjDHFR). Using variation of amino acids such as Met33/Phe31 (in pjDHFR/hDHFR) that affect the binding of inhibitors due to their distinct positive or negative steric effect at the active binding site of the inhibitor, we designed a series of substituted-pyrrolo[2,3-d]pyrimidines. The best analogs displayed better potency (IC50) than PTX and high selectivity for pjDHFR versus hDHFR, with 4 exhibiting a selectivity for pjDHFR of 24-fold.
|
Inhibition of Pneumocystis jirovecii DHFR expressed in Escherichia coli Rosetta-gami B (DE3) assessed as reduction in consumption of NADPH using 18 uM DHFA as substrate
|
Pneumocystis jirovecii
|
1.6
nM
|
|
Journal : Bioorg Med Chem Lett
Title : Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection.
Year : 2019
Volume : 29
Issue : 15
First Page : 1874
Last Page : 1880
Authors : Shah K, Queener S, Cody V, Pace J, Gangjee A.
Abstract : Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC<sub>50</sub> of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.
|
Inhibition of recombinant human DHFR assessed as reduction in consumption of NADPH using 18 uM DHFA as substrate
|
Homo sapiens
|
3.0
nM
|
|
Journal : Bioorg Med Chem Lett
Title : Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection.
Year : 2019
Volume : 29
Issue : 15
First Page : 1874
Last Page : 1880
Authors : Shah K, Queener S, Cody V, Pace J, Gangjee A.
Abstract : Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC<sub>50</sub> of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.
|
Inhibition of Pneumocystis jirovecii DHFR expressed in Escherichia coli Rosetta-gami B (DE3) assessed as reduction in consumption of NADPH using 9 uM DHFA as substrate
|
Pneumocystis jirovecii
|
41.0
nM
|
|
Journal : Bioorg Med Chem Lett
Title : Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection.
Year : 2019
Volume : 29
Issue : 15
First Page : 1874
Last Page : 1880
Authors : Shah K, Queener S, Cody V, Pace J, Gangjee A.
Abstract : Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC<sub>50</sub> of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.
|
Inhibition of recombinant human DHFR assessed as reduction in consumption of NADPH using 9 uM DHFA as substrate
|
Homo sapiens
|
2.0
nM
|
|
Journal : Bioorg Med Chem Lett
Title : Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection.
Year : 2019
Volume : 29
Issue : 15
First Page : 1874
Last Page : 1880
Authors : Shah K, Queener S, Cody V, Pace J, Gangjee A.
Abstract : Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC<sub>50</sub> of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.
