Synthesis and biological evaluation of a novel structural type of serotonin 5-HT3 receptor antagonists

A series of novel 3-substituted quinoxalin-2-carboxamides were designed as per the pharmacophoric requirement for 5-HT3 receptor antagonists and prepared by microwave irradiation and also by conventional method. The compounds were characterized by spectral data (IR, 1H NMR, and MS) and the purity was ascertained by microanalysis. The synthesized compounds were evaluated for 5-HT3 antagonisms in longitudinal muscle-myenteric plexus preparation from guinea pig ileum against 5-HT3 agonist, 2-methyl-5-HT. Among the test compounds, N-{3-[(4-methylpiperazin-1-yl)methyl]-4-hydroxyphenyl}-3-methoxyquinoxalin-2-carboxamide 4e showed most favorable 5-HT3 receptor antagonism.