Contribution of hydrogen peroxide to the cytotoxicity of green tea and red wines

Green tea and red wine are claimed to have health benefits because of their high content of polyphenolic compounds, but they have also been reported as mutagenic in some test systems. In this paper, we show that a commonly used cell culture medium, Dulbecco’s modified Eagle’s medium (DMEM), catalyses oxidation of green tea and red wines to generate H2O2. The level of H2O2 produced from green tea accounted for all of the cytotoxic effects of this beverage on PCl2 cells. By contrast, H2O2 was only responsible for part of the cytotoxicity of the red wines examined. Our data illustrate the danger of extrapolating from cell culture studies to predict the effects of complex beverages in vivo.