DNA agarose gel electrophoresis for antioxidant analysis: Development of a quantitative approach for phenolic extracts

•Both H2O2 and H2O2/FeCl3 are effective DNA degradation systems.•Ascorbic acid had both antioxidant and prooxidant effects.•Gallic acid prevented DNA oxidation and had no prooxidant effect.•The extract effectively prevented DNA oxidation and had no prooxidant effect.

Most of the fast in vitro assays proposed to determine the antioxidant capacity of a compound/extract lack either biological context or employ complex protocols. Therefore, the present work proposes the improvement of an agarose gel DNA electrophoresis in order to allow for a quantitative estimation of the antioxidant capacity of pure phenolic compounds as well as of a phenolic rich extract, while also considering their possible pro-oxidant effects. The result obtained demonstrated that the proposed method allowed for the evaluation of the protection of DNA oxidation [in the presence of hydrogen peroxide (H2O2) and an H2O2/iron (III) chloride (FeCl3) systems] as well as for the observation of pro-oxidant activities, with the measurements registering interclass correlation coefficients above 0.9. Moreover, this method allowed for the characterization of the antioxidant capacity of a blueberry extract while demonstrating that it had no perceived pro-oxidant effect.