Harnessing Synergy: Investigation of the Antioxidant Interactions Between trans-Resveratrol and L-Ascorbic Acid by Spectroscopic and DFT Methods

The present study has employed a combination of UV-Vis, 13C NMR spectroscopic and computational methods to explore the antioxidant interactions between trans-resveratrol and L-ascorbic acid in the reaction with 2,2-diphenyl-1-picrylhydrazyl radical. Significant synergic and antagonistic effects were observed depending on the reaction conditions. Various molar ratios of antioxidants have been tested, and the highest synergistic interaction has been registered for the 1:1 ratio of antioxidants. 13C NMR spectral data argued on the dimerization of resveratrol producing the known natural trans-δ-viniferin as a crucial phenomenon involved in the synergetic antioxidant activity. The Density Functional Theory data completed the research, advancing the possibility of synergistic interactions through the regeneration of resveratrol's and its oligomer's radicals by the ascorbic acid via the hydrogen atom transfer pathway.