Rosowsky A, Forsch R A, Queener S F
Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
J Med Chem. 1995 Jul 7;38(14):2615-20. doi: 10.1021/jm00014a014.
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.
以2,4-二氨基-6-(溴甲基)吡啶并[3,2 - d]嘧啶氢溴酸盐(11·HBr)为原料，在室温下于二甲基甲酰胺中，添加或不添加碳酸氢钠，分别与相应的苯胺或N - 甲基苯胺反应，合成了6种此前未知的2,4 - 二氨基-6-(苯胺甲基)-和2,4 - 二氨基-6-[(N - 甲基苯胺基)-甲基]吡啶并[3,2 - d]嘧啶(5 - 10)。作为发现兼具高酶选择性和高效力的亲脂性非经典抗叶酸剂这一更大研究工作的一部分，对化合物5 - 10进行了测试，以考察其对卡氏肺孢子虫、弓形虫和大鼠肝脏二氢叶酸还原酶的抑制活性。在所测试的6种类似物中，对弓形虫二氢叶酸还原酶最具活性和选择性的是2,4 - 二氨基-6-[(3',4',5'-三甲氧基-N - 甲基苯胺基)甲基]吡啶并[3,2 - d]嘧啶(7)，其对该酶的IC50为0.0047 μM，而对大鼠肝脏酶的IC50为0.026 μM。7对弓形虫二氢叶酸还原酶的效力与三甲曲沙(TMQ, 1)和吡利曲星(PTX, 2)相似，但比对甲氧苄啶(TMP, 3)的效力高500倍以上。然而，虽然7对该酶的选择性比TMQ(19倍)或PTX(63倍)都高，但其与TMP相比选择性低8倍。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(6)的活性比7低17倍，选择性也较低。2,4 - 二氨基-6-[(3',4'-二氯-N - 甲基苯胺基)甲基]吡啶并[3,2 - d]嘧啶(10)对卡氏肺孢子虫二氢叶酸还原酶的IC50为0.022 μM，效力与TMQ和PTX相当。10对卡氏肺孢子虫与大鼠肝脏二氢叶酸还原酶的物种选择性比TMQ(21倍)或PTX(31倍)都高。另一方面，尽管10对卡氏肺孢子虫酶的活性比TMQ略高，但其选择性比TMP低7倍。因此，在这个有限的系列中，将具有稠环化合物TMQ和PTX特征的高酶结合活性与具有单环化合物TMP特征的对弓形虫和卡氏肺孢子虫二氢叶酸还原酶相对于大鼠肝脏二氢叶酸还原酶的高选择性相结合的目标仍未实现。
