Synthesis and pharmacological investigation of novel 4-(4-Ethyl phenyl)-1-substituted-4H-[1,2,4]triazolo[4,3-a]-quinazolin-5-ones as new class of H1-antihistaminic agents

✍ Scribed by V. Alagarsamy; P. Parthiban; V. Raja Solomon; K. Dhanabal; S. Murugesan; G. Saravanan; G. V. Anjana

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2008
• Tongue: English
• Weight: 312 KB
• Volume: 45
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570450312

✦ Synopsis

Abstract

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A series of novel 4‐(4‐ethylphenyl)‐1‐substituted‐4__H__‐[1,2,4]triazolo[4,3‐a]quinazolin‐5‐ones were synthesized by the cyclization of 2‐hydrazino intermediate with various electrophile. The starting material 2‐hydrazino compound was synthesized from 2‐ethyl aniline by a new innovative route with improved yield. When tested for their in vivo H~1~‐antihistaminic activity on conscious guinea pigs, all the test compounds significantly protected the animals from histamine induced bronchospasm. The compound II emerged as the most active compound of the series and it is more potent (73.93% protection) when compared to the reference standard, chlorpheniramine maleate (71% protection), it showed negligible sedation (10%) when compared to chlorpheniramine maleate (30%). Therefore compound II will serve as prototype molecule for further development as a new class of H~1~‐antihistamines