Synthesis and characterization of (E)-N′-(substituted benzylidene)isonicotinohydrazide derivatives as potent antimicrobial and hydrogen peroxide scavenging agents

Abstract

A series of (E)-N′-(substituted benzylidene)isonicotinohydrazide derivatives were synthesized by coupling isoniazid with differently substituted aldehydes and benzophenones in the presence of absolute ethanol along with catalytic amount of glacial acetic acid. The structure of all the synthesized compounds were confirmed and characterized by using various spectral technique like IR, 1H NMR, 13C NMR and mass spectroscopy. All the synthesized compounds were evaluated for their antimicrobial activity in terms of zone of inhibition, minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration in camparison to the standard drugs. The results revealed that all synthesized compounds had shown potent to mild biological activity. Among the synthesized derivatives, (E)-N′-(3,4-dimethoxybenzylidene) isonicotinohydrazide 2e, (E)-N′-(3,4,5-trimethoxybenzylidene)isonicotinohydrazide 2f and (E)-N′-(4-hydroxy-3-methoxybenzylidene)isonicotinohydrazide 2g were found to be the most effective antimicrobial compounds, whereas compounds 2g and 2k were the most potent antioxidants with significant hydrogen peroxide scavenging activity.