Contribution of phenols, quinones and reactive oxygen species to the mutagenicity of white grape juice in the Ames test.

The purpose of this study was to evaluate the role of phenols, quinones and reactive oxygen species in the mutagenicity of white grape juice in the Ames mutagenicity test. Mutagenicity was markedly suppressed by reduced glutathione but was not influenced by superoxide dismutase or catalase. In the presence of grape polyphenol oxidase, the mutagenicity of grape juice was markedly increased. When hepatic cytosol from Aroclor 1254-induced rats, supplemented with a reduced nicotinamide adenine dinucleotide phosphate-generating system. served as an activation system, an increase in the mutagenicity of grape juice was observed. The cytosol-induced mutagenicity of grape juice was attenuated in the presence of superoxide dismutase, catalase and glutathione. It is concluded that polyphenol oxidase-catalysed oxidation of phenolic compounds generates genotoxic species that are, at least partly, responsible for the mutagenicity of grape juice. In the presence of hepatic cytosol, one-electron reduction of grape juice quinones leads to the production of reactive oxygen species resulting in an increase in the mutagenic response.