Production of hydrogen peroxide by polyphenols and polyphenol-rich beverages under quasi-physiological conditions

To investigate the ability of the production of H2O2 by polyphenols, we incubated various phenolic compounds and natural polyphenols under a quasi-physiological pH and temperature (pH 7.4, 37degreesC), and then measured the formation of H2O2 by the ferrous ion oxidation-xylenol orange assay. Pyrocatechol, hydroquinone, pyrogallol, 1,2,4-benzenetriol, and polyphenols such as catechins yielded a significant amount of H2O2. We also examined the effects of a metal chelator, pH, and O-2 on the H2O2-generating property, and the generation of H2O2 by the polyphenol-rich beverages, green tea, black tea, and coffee, was determined. The features of the H2O2-generating property of green tea, black tea, and coffee were in good agreement with that of phenolic compounds, suggesting that polyphenols are responsible for the generation of H2O2 in beverages. From the results, the possible significances of the H2O2-generating property of polyphenols for biological systems are discussed.