Hydrogen Peroxide Formation during Catechin Oxidation Is Inhibited by Superoxide Dismutase

We established a simple method to quantify hydrogen peroxide (H2O2) generated during the aerobic heating process of (+)-catechin solution. Using this method, we found that non-enzymatic H2O2 formation from catechin depended on pH, temperature, incubation time, and the presence of O2 in the solution. The formation of oxidized products of (+)-catechin, which was estimated by measuring the absorbance of the solution at 430 nm, also depended on these factors. The H2O2 formation was inhibited by various kinds of superoxide dismutase (SOD) with almost the same dose dependency. Although the oxidation of (+)-catechin was enhanced by superoxide (O2−), neither catalase nor H2O2 had any effects on the oxidation. These results suggest that O2−, rather than H2O2, participated in the autoxidation of (+)-catechin, which was coupled with the H2O2 formation.