Synthesis of some pyridazine derivatives as antioxidants and antimicrobial agents

Purpose: To prepare some pyridazine derivatives as antioxidant and antimicrobial agents. Methods: The coupling of aryl diazonium salts with diethyl 2-cyano-3-methylglutaconate afforded pyridazine-5-carbonitrile derivatives (3a-e). The methyl function in the pyridazine derivatives (3a-e) reacted with cinnamonitriles to yield phthalazine derivatives (6a-h). Imino-pyridazine derivatives (9a-h) were obtained by reacting 2-aminoprop-1-ene-1,1,3-tricarbonitrile along with aryl diazonium salts (1a-h). Structure elucidation was done by spectral analysis. The 1,1-diphenyl-2-picryl hydrazyl (DPPH) technique was employed to assess antioxidant effect, while evaluation of antimicrobial activity was carried out by serial dilution technique. Results: Compounds, 6f (IC50 = 12.68 mu g/mL; p < 0.05), 6a (IC50 = 14.23 mu g/mL; p < 0.05), and 3c (IC50 = 14.34 mu g/mL; p < 0.05) displayed good antioxidant activity compared to ascorbic acid (IC50 = 12.45 mu g/mL; p < 0.05). Based on the zone of inhibition, compound 6c (p < 0.05) displayed higher activity than ofloxacin (p < 0.05) against E. coli. Conclusion: The presence of an oxo group and carboxylate group plays an important role in the antioxidant activity of these compounds. Compounds 6a, 6f, and 3c can potentially serve as lead compounds for the development of promising antioxidants.