Antioxidant and Antimicrobial Activity of 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one

Abstract

Cycloaddition of nitrile imines 4 generated in situ by the catalytic dehydrogenation of diphenyl hydrazones 3 using Chloramine-T (CAT) as oxidant in glacial acetic acid with enolic form of ethyl acetoacetate 5 afforded Ethyl 3-aryl-5-methyl-1-phenyl-1H-pyrazol-4-carboxylate 6 in 80% yield. The said pyrazoles 6 refluxed with 80% hydrazine hydrate using absolute alcohol as solvent for about 2-3 hours to produce the respective 5-methyl-1,3-diphenyl-1H-pyrazole-4-carboxylic acid hydrazide 7. The alcoholic solution of pyrazole acid hydrazides on heating with ethyl acetoacetate 5 to give the 5-methyl-2-(5-methyl-1,3-diphenyl-1H-pyrazole-4-carbonyl)-2,4-dihydro-pyrazol-3-one 8. The synthesized compounds were found to exhibit good antimicrobial and antioxidant activity as evaluated by 1,1-diphenyl-2-picryl Hydrazyl (DPPH) radical scavenging, reducing power and DNA protection assays.