Radical Scavenging Activity of Antioxidants by Cyclic Voltammetry

This work investigates the reactivity of individual antioxidants with the free radicals generated by 2,2 '-azobis(isobutironitrile) (AIBN). The consumption of antioxidants was followed by cyclic voltammetry. The fitting of such decay with a kinetic model yielded the rate constant k(d) of radical formation and the rate constant k(inh) of radical inhibition exerted by each antioxidant. The antioxidant efficiency was defined as the ratio between k(inh) and k(d). The following ranking of antioxidants was obtained: alpha-tocopherol "catechin" retinyl acetate "hydroxytyrosol "oleuropein" caffeic acid. Overall, the approach shows the utility of cyclic voltammetry to investigate the kinetic rates at which antioxidants react with radicals.