A quantum chemical study on the antioxidant activity of bioactive polyphenols from peanut ( Arachis hypogaea) and the major metabolites of trans-resveratrol

Abstract

Trans-resveratrol, a polyphenolic compound, which is found in grape and red wine, exhibits inhibiting effect against tumour growth and shows strong antioxidant activity. In the human liver cells and intestinal epithelial ones this compound is converted to the following bioavailable metabolites: O-sulphates, O-disulphates, O-trisulphate and O-glucuronide conjugates. To explain the equilibrium structure–antioxidant radical scavenging capacity relationships of these metabolites and the major peanut polyphenols (arachidin-1, arachidin-2, arachidin-3 and trans-isopentadienylresveratrol), the accurate quantum-chemical calculations in the gas phase and water medium with the use of density functional theory have been performed for the first time. The hydrogen atom transfer mechanism for free radicals scavenging is found more preferable than the single-electron transfer mechanism in the media studied. The importance of 4′-OH group as a hydrogen atom donor is indicated. The metabolites and peanut polyphenols are found to be more active donors of hydrogen atoms in the gas phase than in water medium, in which the compounds studied are more susceptible to electron donation than in the gas phase. The calculations have shown that the O-sulphates, O-disulphates and O-trisulphate studied are more efficient hydrogen donors than trans-resveratrol. According to the phenolic O–H bond dissociation enthalpies of the peanut stilbenoids were found to be efficient antioxidants. It was found that arachidin-1 is the most effective antioxidant among the compounds studied. The metabolites of trans-resveratrol are shown to have a similar ability to scavenge free radicals as the parent compound and can synergistically reduce oxidative stress in human cells. This study provides rational approach for investigation of the antioxidant activity of other bioactive trans-resveratrol derivatives.