Synthesis and analgesic activity of N-Arylhydrazone derivatives of mefenamic acid

A series of N-Arylhydrazone derivatives of mefenamic acid (a known non-steroidal anti-inflammatory drug) were synthesized in order to obtain new compounds with potential analgesic and anti-inflammatory activity. The structures of all synthesized compounds were confirmed by means of infrared, proton magnetic resonance and mass spectroscopy. All compounds were evaluated for their analgesic and anti-inflammatory activities by abdominal constriction test (writhing test) and carrageenan-induced rat paw edema test respectively. Most of the synthesized compounds induced significant reduction in the writhing response when compared to control. Among them, compounds 11, 12, 15, 16, 19, 20, and 21 were significantly more potent than mefenamic acid in the writhing test. The anti-inflammatory activity of these 7 compounds were evaluated and compounds 11, 12, 16, 19 and 20 showed significant anti-inflammatory activity in comparison to control but their effect was weaker than mefenamic acid. The antinociceptive relative activity of some of these newly synthesized compounds is greater than mefenamic acid but they are not potent anti-inflammatory agents.