In vitro evaluation of antioxidant activity and synergistic effects between vitamin C, phenolic acids and flavonoids using FRAP.

Abstract

Introduction: Antioxidants properties depend on the interactions that may occur when two or three of these substances are combined. 
Materials and methods: This study is an in vitro ana
lytical, experimental, and cross-sectional study. Methanolic solutions of 100 µM gallic acid, ferulic acid, catechin, and epicatechin, as well as an aqueous solution of vitamin C, were used. To evaluate antioxidant activity, binary and ternary combinations of phenolic acids (100 µM) and flavonoids (100 µM) were prepared in the absence and presence of three concentrations of vitamin C: 100, 200, and 300 µM. 
Antioxidant activity was assessed using the FRAP technique, and the results are expressed as nmoles of Fe2+ released. A synergistic effect was considered present when the experimental antioxidant activity was greater than the theoretically calculated antioxidant activity, expressed as nmoles of Fe2+ released. All determinations were performed in triplicate on three different days. 
Results: The presence of vitamin C in the reaction medium had a slight effect on the antioxidant activity and greater synergistic effect; in the absence of vitamin C the binary combination gallic acid (100 µM) and catechin (100 µM) released + 5.51 nmoles of Fe2+, but in the presence of vitamin C (100 µM) it increased to + 6.73 nmoles of Fe2+, while in the ternary combination ferulic acid (100 µM), catechin (100 µM) and gallic acid (100 µM) the release of Fe2+ was + 2.41 nmoles, while in the presence of vitamin C (200 µM) it increased to + 6.92 nmoles of Fe2+ released. 
Conclusions: Vitamin C had a very slight effect on the an
tioxidant activity of the phenolic acids and flavonoids, as well as on the binary and ternary combinations of these compounds.