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.
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.
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2,4-二氨基-5-取代的喹唑啉作为 22 位定点突变的人二氢叶酸还原酶以及来自卡氏肺孢子虫和弓形虫的二氢叶酸还原酶的抑制剂。
DOI：
10.1021/jm00005a002
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发表时间：
1995
影响因子：
7.3
通讯作者：
Bertino,JR
中科院分区：
文献类型：
--
作者：
Rosowsky,A;Mota,CE;Queener,SF;Waltham,M;Ercikan-Abali,E;Bertino,JR
合成了5位带有亲脂性侧链的2，4-二氨基喹唑啉对叶酸，在一例中含有典型的(邻氨基苯甲酰基)-L-谷氨酸侧链，作为人二氢叶酸还原酶定点突变体的潜在选择性抑制剂，该突变体在22位含有苯丙氨酸而不是亮氨酸。这种突变酶对经典的抗叶酸甲氨蝶呤(MTX)的抗性比天然酶高近100倍，但对非经典的抗叶酸甲氨蝶呤(PTX)和甲氨蝶呤(TMQ)的交叉耐药性最小。尽管它们的效力远低于曲美曲辛和匹立曲辛，但亲脂的5-取代类似物都被发现与突变的dhfr结合比与野生型酶结合好约10倍。经典的(对氨基苯甲酰基)-L-谷氨酸侧链类似物的效力与甲氨蝶呤相似，但其与两种DHFR物种的结合亲和力仅相差5倍。因此，通过在抗叶酸分子中进行微妙的结构变化，可能会由于靶酶活性部位的突变改变而攻击抗药性。此外，为了验证卡氏肺孢子虫和弓形虫DHFR可能具有比哺乳动物细胞的酶更少的空间限制性活性部位的假设，使用该系列中的几个亲脂类似物对卡氏肺孢子虫和弓形虫还原酶进行了抑制试验，并与大鼠肝脏的酶进行了比较。与它们与突变型和野生型人DHFR的优先结合相反，这些类似物与卡氏肺孢子虫和弓形虫酶的结合弱于与鼠酶的结合。因此，如果这些寄生虫的DHFR的活性部位的空间限制性低于哺乳动物酶的活性部位，这种差异不能通过将侧链从6位移动到5位来成功利用。2，4-二氨基喹唑类化合物在5位具有大量疏水基团，几年前由Hynes和他的同事合成并作为酶二氢叶酸还原酶(DHFR)的抑制剂进行了评估。1·2这一早期系列中研究的化合物一般类型为5-芳硫基、5-(芳硫基)-甲基、5-(2-芳基乙基)和5-(2-芳基乙基)衍生物；特殊芳基包括苯基、4-氯苯基、3，4-二氯苯基和2-萘基。还描述了一些5-芳硫基和5-(芳硫基)甲基衍生物的亚砜和亚砜。对大鼠肝脏和粪链球菌酶的活性进行了测定，发现几种化合物是有效的抑制剂，细菌酶通常比哺乳动物酶表现出更高的敏感性。随后，另一组3报道了一大系列的缓蚀剂，主要是5位上的非芳香基团，但也包括5-苄氧基和5-(2-苯乙基)衍生物。用这些化合物对DHFR进行了酶抑制试验。
2, 4-Diaminoquinazoline antifolates with a lipophilic side chain at the 5-position, and in one case with a classical (jo-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 ap-proximately 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 diminishedin comparison with MTX, but thedifference in itsbinding 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 theactive 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 chainfrom the 6-position to the 5-position.2, 4-Diaminoquinazolines with a bulky hydrophobic group at the 5-position were synthesized and evaluated as inhibitors of the enzyme dihydrofolate reductase (DHFR) from various species a number of years ago by Hynes and co-workers. 1· 2 General types of compounds studied in this early series were 5-arylthio, 5-(arylthio)-methyl, 5-(2-arylethenyl), and 5-(2-arylethyl) derivatives; specific aryl groups included phenyl, 4-chlorophe-nyl, 3, 4-dichlorophenyl, and 2-naphthyl. Sulfoxides and sulfones of some of the 5-arylthio and 5-(arylthio) methyl derivatives were also described. Activity was measured against rat liver andStreptococcus faecium enzyme, and several compounds were found to be potent inhibitors, with the bacterial enzyme generally showing greater sensitivity than the mammalian enzyme. Subsequently, another group3 reported a large series of inhibitors featuring mainly nonaromaticgroups at the 5-position, but also including a 5-benzyloxy and 5-(2-phenylethyl) derivative. Enzyme inhibition assays were carried out with thesecompounds against DHFR from several