Synergistic and antagonistic co-antioxidant effects of flavonoids with trolox or ascorbic acid in a binary mixture

Abstract By using the ORAC method, the values of the antiperoxyradical capacity of binary mixtures of bioflavonoids (quercetin, rutin, morin and naringin) with trolox or ascorbic acid, and individual antioxidants in the aqueous medium were determined. Through these values and the data of square wave voltammetry (SWV) method, the non-additive effects in the binary mixtures were revealed. Synergy in the binary mixtures was observed in the presence of flavonoids (rutin and naringin) having O-glucosyl group in the molecular structure. Flavonoids without a glucosyl group in the molecular structure (quercetin and morin), having relatively small values of the oxidation potential and low bond dissociation enthalpy (BDE) of the most reactive OH group in the mixtures with trolox or ascorbic acid, have shown antagonistic effects. In this work, ‘skeletal’ kinetic models are considered, explaining the non-additive effect of co-antioxidants under study, conditioned by the possibility of antioxidant regeneration with high (synergy) or low (antagonism) antiradical capacity.