Synthesis, Structure and Antiradical Activity of Functionally Substituted Hydrazides of Isonicotinic Acid

The purpose of this work is the synthesis of new isonicotinic acid hydrazones, the study of their structure, reactivity and biological screening of some synthesized compounds. The reactions leading to new N-arylidene(alkylidene) hydrazones via the condensation of isonicotinic acid hydrazide with various derivatives of aromatic aldehydes were studied. The structure of the new functionally substituted isonicotinic acid hydrazones was established by FTIR, 1H and 13C NMR, two-dimensional COSY (1H-1H) NMR spectroscopy and HMQC (1H-13C). The antiradical activity of the synthesized derivatives was studied using diphenylpycrylhydrazide radical (DPPH) assay. It was shown that N-(3- ethoxy-4-hydroxybenzylidene)isonicotinohydrazide possesses antiradical activity (IC50 (DPPH) 103.0 μM). The antiradical properties of compounds of phenolic nature are in agreement with the energies of homolytic O-H bond dissociation calculated with the use of density functional theory.