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

Abstract

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.Graphical abstractSYNOPSIS The binary mixtures of bioflavonoids (quercetin, rutin, morin, naringin) with trolox or ascorbic acid in the aqueous medium have shown non-additive antioxidant effects. The non-additive effect of co-antioxidants, conditioned by the possibility to shift the quasi-equilibrium with the participation of phenoxyl radicals in the direction of regeneration of an antioxidant with high (synergy) or low (antagonism) antiperoxyradical capacity (f) in the trolox equivalent, respectively is discussed in this paper.