The effect of flavonoids on the α-tocopherol compositions antioxidant activity

Introduction. Flavonoids are a family of biologically active substances, representatives of which are often found in the human diet, in particular quercetin, rutin, and morin. When ingested with food, these compounds exhibit their antioxidant properties within the biomolecular system, where α-tocopherol is an important component. Systems formed by antioxidants are characterized by a certain total antioxidant effect, which often differs from the simple sum of their antioxidant capacities to a greater extent in the case of synergy or to a lesser extent in the case of subadditive interaction. From this point of view, the nature of the studied flavonoid's interaction with the endogenous antioxidant α-tocopherol is interesting. The identified interaction effects can serve as a basis for improved antioxidant formulations, as well as the subsequent study of the cooperation mechanisms in vivo.

Aim. The study aims to determine the interaction effects of the α-tocopherol compositions with quercetin, rutin, and morin at their different ratios.

Material and methods. Solutions of individual substances and flavonoid–α-tocopherol compositions in ratios from 1:1 to 1:20 were assessed. The antioxidant capacity was evaluated by the ABTS/PP method, implemented in the form of decolorization and kinetic approaches.

Results. The values of the TEAC index of the studied flavonoids obtained by the decolorization and kinetic method are close and lie in the range of 0.85–3.73 (decolorization) and 0.94–3.22 (kinetic method). Antioxidant capacity increased in the next order: α-tocopherol, rutin, morin, and quercetin. In the first 10 minutes of incubation, flavonoids captured 50–80% of the total number of ABTS^•+ radical cations, while α-tocopherol showed the maximum of its antioxidant capacity already in the 1^st minute. The composition effects were additive and slightly subadditive for the studied compositions of rutin, morin, and quercetin with α-tocopherol demonstrating maximum values up to –13% in the composition of morin–α-tocopherol 1:10 and quercetin–α-tocopherol 1:20. No dependence of the component’s ratios on the composition effect was found.

Conclusions. The studied compositions of bioflavonoids and α-tocopherol exhibit additive and minor subadditive effects.