A COMPARISON OF THE ANTIMUTAGENIC POTENTIAL OF GREEN, BLACK AND DECAFFEINATED TEAS - CONTRIBUTION OF FLAVANOLS TO THE ANTIMUTAGENIC EFFECT

The present study was undertaken to compare the antimutagenic activity of aqueous extracts, at the concentrations used for human consumption , from green, black and decaffeinated black tea. Antimutagenic potenti al was evaluated against three indirect-acting dietary carcinogens, Gl u-P-l, benzo(a)pyrene and nitrosopyrrolidine, All three types of tea g ave rise to strong and concentration-dependent suppression of the muta genicity of the three premutagens in the presence of an activation sys tem, No major difference in the antimutagenic potential of the three t ypes of tea could be discerned, Black tea, decaffeinated black tea and , to a lesser extent, green tea also antagonized the mutagenicity of t he direct-acting mutagen 9-aminoacridine. All three types of tea inhib ited markedly the NADPH-dependent reduction of cytochrome c and the O- dealkylations of ethoxy-, methoxy- and, to a much lesser extent, pento xy-resorufin. When the microsomal metabolism was terminated, after the metabolic activation of the premutagens, incorporation of the aqueous tea extracts into the activation system caused a concentration-depend ent suppression of mutagenic response, No significant difference in th e antimutagenic activity of the three types of tea in this system was evident. Bearing in mind the much higher concentration of flavanols in green tea compared with the black teas, it may be concluded either th at these compounds are unlikely to be the major tea components respons ible for the antimutagenic, and possibly anticarcinogenic, properties of tea or that their fermentation products are similarly active.