Gangjee A, Zhu Y, Queener S F, Francom P, Broom A D
Division of Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, USA.
J Med Chem. 1996 Apr 26;39(9):1836-45. doi: 10.1021/jm950918e.
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.
报道了42种6-取代-2,4-二氨基吡啶并[3,2-d]嘧啶（2,4-二氨基-8-去氮叶酸类似物）的合成及其生物活性。与之前的经典类似物相比，采用我们之前报道的方法进行改进后，这些化合物的合成产率有所提高。具体而言，合成了在N10位带有H或CH3的S-苯基、单甲氧基苯基、二甲氧基苯基、三甲氧基苯基、单氯苯基、二氯苯基和三氯苯基取代类似物，以及在N10位带有H、CH3和CH2C≡CH的甲基和三氟甲基苯基酮类似物。还合成了N10的α-和β-萘基类似物以及N10 CH3类似物。这些化合物被评估为卡氏肺孢子虫（pc）和弓形虫（tg）二氢叶酸还原酶（DHFR）的抑制剂；以大鼠肝脏（rl）DHFR作为哺乳动物参考酶测定了选择性比率。对于pcDHFR，IC50值范围从2,4-二氨基-6-[(N-甲基-2'-萘基氨基)甲基]吡啶并[3,2-d]嘧啶（28）的0.038×10-6 M到2,4-二氨基-6-[(2',4'-二甲氧基苯胺基)甲基]吡啶并[3,2-d]嘧啶（15）的5.5×10(-6) M。在所有情况下，N10甲基化均提高了活性。没有一种类似物对pcDHFR具有选择性。对于tgDHFR，最有效的类似物是2,4-二氨基-6-[(N-甲基苯胺基)甲基]吡啶并[3,2-d]嘧啶（5）（IC50 0.0084×10-6 M），最无效的是2,4-二氨基-6-[(2'-萘基氨基)甲基]吡啶并[3,2-d]嘧啶（37）（IC50 0.16×10-6 M）。N10甲基化使活性提高了10倍。与pcDHFR不同，几种8-去氮类似物对tgDHFR具有显著选择性，最显著的是2,4-二氨基-6-[(2'-氯-N-甲基苯胺基)-甲基]吡啶并[3,2-d]嘧啶（13）、2,4-二氨基-6-[(3',4',5'-三甲氧基苯胺基)甲基]吡啶并[3,2-d]嘧啶（29）和2,4-二氨基-6-[(2',4',6'-三氯苯胺基)甲基]吡啶并[3,2-d]嘧啶（32），它们在10-8 M时具有高效力，选择性分别为8.0、5.0和12.4。这三种类似物的效力与临床使用的药物三甲曲沙相当，而它们对tgDHFR的选择性比三甲曲沙高17 - 到43倍。
