Evaluation of antioxidant activity of vanillin by using multiple antioxidant assays

BackgroundVanillin, a compound widely used in foods, beverages, cosmetics and drugs, has been reported to exhibit multifunctional effects such as antimutagenic, antiangiogenetic, anti-colitis, anti-sickling, and antianalgesic effects. However, results of studies on the antioxidant activity of vanillin are not consistent.MethodsWe systematically evaluated the antioxidant activity of vanillin using multiple assay systems. DPPH radical-, galvinoxyl radical-, and ABTS+-scavenging assays, ORAC assay and an oxidative hemolysis inhibition assay (OxHLIA) were used for determining the antioxidant activity.Results and conclusionVanillin showed stronger activity than did ascorbic acid and Trolox in the ABTS+-scavenging assay but showed no activity in the DPPH radical- and galvinoxyl radical-scavenging assays. Vanillin showed much stronger antioxidant activity than did ascorbic acid and Trolox in the ORAC assay and OxHLIA. In the ABTS+-scavenging assay, ORAC assay and OxHLIA, vanillin reacted with radicals via a self-dimerization mechanism. The dimerization contributed to the high reaction stoichiometry against ABTS+ and AAPH-derived radicals to result in the strong effect of vanillin. Oral administration of vanillin to mice increased the vanillin concentration and the antioxidant activity in plasma. These data suggested that antioxidant activity of vanillin might be more beneficial than has been thought for daily health care.General significanceBased on the results of the present study, we propose the addition of antioxidant capacity to the multifunctionality of vanillin.

Research Highlights
► Vanillin shows no activity in the DPPH and galvinoxyl radical-scavenging assays.
► Vanillin shows strong activity in the ABTS+-scavenging assay.
► Vanillin shows strong antioxidant activity in the ORAC assay and OxHLIA.
► Vanillin reacts with radicals via a self-dimerization mechanism.
► Oral administration of vanillin to mice increases the antioxidant activity in plasma.