Antioxidant properties of the dihydroquercetin with alpha-tocopherol combi-nations in free radical oxidation

Introduction. A significant factor in the manifestation of the compound antioxidant ability is a pattern of its interaction with other antioxidants, which affects the demonstrated final antioxidant effect. Flavonoids display different antioxidant capacities along with a wide range of biological activity, dihydroquercetin in particular. The role of the regenerating component in the cycles of mutual transformations in antioxidant systems is assumed for dihydroquercetin as it's a compound with a high profile of antiradical capacity. Here we focused on the nature of the antioxidant activity presentation in a composition consisting of dihydroquercetin and the essential antioxidant α-tocopherol. The combination was studied in a wide ratio range of the dihydroquercetin-α-tocopherol composition components from 1:1 to 1:20, based on the assumption that the concentration of the second component in living systems is excessive.

Aim. The work aimed to determine the nature of the dihydroquercetin-α-tocopherol composition antioxidant activity in vitro, both in general and in terms of the individual component’s action.

Material and methods. The antioxidant effects of the composition were studied within the framework of decolorization and kinetic methods based on the inhibition of model radical cations of 2,2'-azino-bis-(3-ethylbenzthiosoline-6-sulfonic acid) diammonium salt. To determine the nature of the individual components' action, high-resolution mass spectrometry was used, based on the analysis of the spectra of which kinetic curves of the consumption of the components of the composition were constructed.

Results. A study of the interaction of dihydroquercetin with α-tocopherol by the decolorization method showed that a slight subadditive effect was observed for all ratios of the components of the compositions. The kinetic method revealed a two-stage nature of the antioxidant activity manifestation of the composition, with the first stage of the induction period being attributed to the α–tocopherol action, and the second to dihydroquercetin. In support of the hypothesis expressed, it was shown by high-resolution mass spectrometry that a decrease in the concentration of dihydroquercetin in the composition begins only after almost complete α-tocopherol consumption.

Conclusions. α-Tocopherol prevents the oxidation of dihydroquercetin by radical cations ABTS•+ when acting together in the composition, and regeneration of one antioxidant by another does not occur.