A series of novel 1-substituted-4-(3-methylphenyl)-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones were synthesized by the cyclization of 2-hydrazino-3-(3-methylphenyl) quinazolin-4(3H)-one with various one carbon donors. The starting material 2-hydrazino-3-(3-methylphenyl)quinazolin-4(3H)-one, was synthesized from 3-methylaniline by a novel innovative route. When tested for their in vivo H1-antihistaminic activity on conscious guinea pigs, all the test compounds protected the animals from histamine induced bronchospasm significantly, whereas the compound 1-methyl-4-(3-methylphenyl)-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-one II was found to be equipotent (percent protection 70.0%) with the reference standard chlorpheniramine maleate (percent protection 71%). Compound II show negligible sedation (7%) when compared to chlorpheniramine maleate (25%). Hence it could serve as prototype molecule for further development as a new class of H1-antihistamines.
通过2-
肼基-3-环化合成了一系列新型1-取代-4-(3-甲基苯基)-
1,2,4-三唑并[4,3-a]
喹唑啉-5(4H)-酮(3-甲基苯基)
喹唑啉-4(3H)-1与多种碳供体。以
3-甲基苯胺为原料,通过创新路线合成了起始原料2-
肼基-3-(3-甲基苯基)
喹唑啉-4(3H)-酮。当在清醒的豚鼠身上测试其体内 H1 抗
组胺活性时,所有测试化合物均显着保护动物免受
组胺诱导的支气管痉挛,而化合物 1-甲基-4-(3-甲基苯基)-
1,2,4-三唑并发现 [4,3-a]
喹唑啉-5(4H)-one II 与参考标准
马来酸氯苯那敏(保护百分比 71%)等效(保护百分比 70.0%)。与
马来酸氯苯那敏 (25%) 相比,化合物 II 的镇静作用可以忽略不计 (7%)。因此,它可以作为进一步开发新型 H1
抗组胺药的原型分子。