Antimutagenic activity of selenium-enriched green tea toward the heterocyclic amine 2-amino-3-methylimidazo[4,5-f]quinoline

Both selenium and green tea have been reported to exhibit antigenotoxic and cancer chemopreventive properties. We compared the antimutagenic activities of regular green tea and selenium-enriched green tea obtained from Hubei Province, China, toward the heterocyclic amine, 2-amino-3-methylimidazo4,5-f]quinoline (IQ) in the Salmonella assay. Selenium-enriched green tea obtained by foliar application of selenite exhibited concentration-dependent inhibition of IQ-induced mutagenesis in the presence of rat liver S9 and was significantly more effective than regular green tea tested under the same conditions. Analytical studies revealed no major differences in the polyphenol or caffeine content between regular green tea and selenium-enriched green tea, but the latter tea contained approximately 60-fold higher concentrations of selenium compared with regular green tea. The only soluble form of selenium was identified as selenite. The antimutagenic effects of certain individual tea constituents, such as epicatechin gallate and catechin, were enhanced by the addition of selenite to the Salmonella assay. Sodium selenite, sodium selenate, seleno-dl-cysteine, seleno-l-methionine, and l-Se-methylselenocysteine were not antimutagenic toward IQ when tested alone, but augmented significantly the inhibitory potency of green tea. The results suggested an enhancing (“coantimutagenic”) effect of selenium in combination with green tea in vitro, but in vivo studies are needed to assess whether there is a synergistic effect of tea and selenium to protect against heterocyclic amine-induced mutagenesis and carcinogenesis.