Synthesis and pharmacological investigation of 3-(substituted 1-phenylethanone)-4-(substituted phenyl)-1, 2, 3, 4-tetrahydropyrimidine-5-carboxylates

Fifteen new ethyl 6-methyl-2-methoxy-3-(substituted 1-phenylethanone)-4-(substituted phenyl)-1, 2, 3, 4-tetrahydropyrimidine-5-carboxylates (6a–o) have been synthesized in a two step reaction. In first step ethyl acetoacetate, s-methylisourea and appropriate benzaldehydes reacted in a single step reaction to obtain ethyl 6-methyl-2-methoxy-4-(substituted phenyl)-1, 4-dihydropyrimidine-5-carboxylates (4a–e). Second step involves synthesis of reaction between substituted phenacyl bromides and 1-4-dihydropyrimidine-5-carboxylates (6a–o). Their structures are confirmed by IR, 1H NMR, mass and elemental analyses. The compounds were tested for antihypertensive activity by non-invasive tail-cuff, and evaluated by carotid artery cannulation method for determining the diastolic blood pressure. Hypertension was induced by DOCA-salt. Anti-inflammatory activity was carried out by carrageenan induced rat-paw oedema method. Test compounds 6b, 6c, 6e, 6f, 6j, 6h, 6k, 6l, 6m, 6n and 6o exerted comparative antihypertensive activity at 10 mg/kg dose level compared to nifedipine. Compounds 6j, 6m and 6o showed excellent results on evaluation by direct method. Test compounds 6a–6h, 6l, 6m, 6n and 6o exerted moderate to comparative anti-inflammatory activity at the 100 mg/kg dose level compared to indomethacin. Their further investigation for analgesic activity and acute ulcerogenesis was carried out, compounds 6m, 6f, 6k, 6o showed excellent to good analgesic activity and low ulcerogenic activity.

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