Synthesis and Evaluation of Curcuminoid Analogues as Antioxidant and Antibacterial Agents

Diazocoupling reaction of curcumin with different diazonium salts of p-toluidine, 2-aminopyridine, and 4-aminoantipyrine in pyridine yielded the arylhydrazones 2a-c. Arylhydrazone of p-toluidine reacted with urea, thiourea, and guanidine nitrate to produce 5,6-dihydropyrimidines. Further reaction of 2a with 2,3-diaminopyrdine in sodium ethoxide solution yielded 1H-pyrido[2,3-b][1,4]diazepine derivative. Bis(2,5-dihydroisoxazole) is obtained from the reaction of 2a with hydroxylamine hydrochloride, while its reactions with hydrazines afforded the respective 4,5-dihydro-1H-pyrazoles. The target compounds were evaluated as antioxidant and antibacterial agents. The tested compounds showed good to moderate activities compared to ascorbic acid and chloramphenicol, respectively.