Prevention of heterocyclic amine formation by tea and tea polyphenols.
Heterocyclic amines (HCAs), formed during the cooking of meats and fish, are thought to be the genotoxic carcinogens associated with important types of human cancer in meat-eating populations, such as cancer of the breast, colon or pancreas. We studied the effect of black or green tea, and of the tea polyphenols theaflavine gallate (TFG, black tea) and epigallocatechin gallate (EGCG, green tea) on the formation of typical HCAs, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), using the model in vitro systems of Jägerstad. Green tea and black tea and solutions of TFG and EGCG lower the formation of PhIP by 62-85% during 1 h heating at 160 degrees C of 1 mmol creatinine, 1 mmol phenylalanine and 0.5 mmol glucose in 3.3 ml diethylene glycol-water (10:1), where the inhibitors replaced 0.3 ml of the water. The production of MeIQx and related HCAs, in the same system but with 1 mmol glycine instead of phenylalanine was likewise reduced, determined by amounts of mutagens formed. In the latter systems, the teas were not, or less effective, but the polyphenols were inhibitory. Thus, the tea products represent another approach to lower the formation of HCAs.