Synthesis and antinociceptive activity of methyl nicotinate
Methyl nicotinate (methyl-3-pyridinecarboxylate) is a methyl ester of nicotinic acid – a type of B vitamin called niacin. It was prepared by esterification of nicotinic acid by refluxing with methanol in the presence of concentrated sulphuric acid, esterification product obtained was extracted into organic solvent (chloroform) after neutralization of the reaction mixture with 10% sodium bicarbonate. The product was purified by column chromatography and purity ascertained by thin layer chromatography. Structure of the desired product was confirmed by NMR and Mass spectroscopy. Methyl nicotinate was obtained as a white powder (m.p. 40-42oC, 23.39% yield). The product was evaluated for its antinociceptive activity using the acetic acid-induced writhing and the hot plate test in mice. The synthesized compound exhibited effective peripheral and central antinociceptive activity. Oral doses of methyl nicotinate (5 and 10 mg/kg) caused a significant reduction in the number of writhes induced by acetic acid (P < 0.05) and prolonged the reaction latency to thermally-induced pain in mice.
Keywords: Methyl nicotinate, esterification, antinociceptive activity