Synthesis and H1-antihistaminic activity of some novel 1-substituted-4-(3-methylphenyl)-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-ones.

摘要: 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 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 from 3-methylaniline a innovative route. When tested for their in vivo H1-antihistaminic activity on conscious guinea pigs, all test compounds protected animals histamine induced bronchospasm significantly, whereas compound 1-methyl-4-(3-methylphenyl)-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-one II found to be equipotent (percent protection 70.0%) reference standard chlorpheniramine maleate 71%). Compound show negligible sedation (7%) when compared (25%). Hence it could serve as prototype molecule further development new class H1-antihistamines.