Effects of nitro- and amino-group on the antioxidant activity of genistein: A theoretical study.

Five novel compounds (Gen-NO, Gen-2NO, Gen-NH, Gen-2NH and Gen-6NH) have been designed via introducing an electron-withdrawing group -NO and an electron-donating group -NH into the structure of genistein. The effects of -NO and -NH groups on the antioxidant ability of genistein were investigated via quantum chemistry method in gas and methanol phases. The crucial parameters related to three antioxidant mechanisms were calculated. Moreover, the frontier molecular orbital, natural bond orbital and global descriptive parameters were calculated to evaluate the reactivity of genistein and its derivatives. Calculated results indicate the antioxidant process of genistein and its derivatives inclines to the hydrogen atom transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms in gas and methanol phases, respectively. Moreover, introducing -NH group into genistein can improve its antioxidant activity owing to the outstanding activities of amino-substituents of genistein, which will provide valuable guidance for the synthesis of new antioxidants experimentally.