Elucidation of the Electrochemical Oxidation Mechanism of the Antioxidant Sesamol on a Glassy Carbon Electrode

Abstract

The dissociation constant of Sesamol (5-hydroxy-1,3-benzodioxol) was determined from the dependence of the UV-visible spectra with the medium acidity. A pK value of 10.1 ± 0.1, corresponding to the hydroxyl group, was obtained. The oxidation of sesamol was investigated on carbon electrodes using controlled-potential electrolysis, linear-sweep cyclic voltammetry and measurements at the foot of the first oxidation peak. Up to three oxidation peaks and one reduction peak were found. The dioxol ring of the dissociated sesamol undergoes a cleavage to give 3-substituted 1,4-benzoquinone, being the rate-determining step the second electron transfer. The formation of radicals in the ring cleavage explains in part the ability of sesamol to interact with reactive oxygen species (ROS).