Antimutagenic effects of black tea in the Salmonella typhimurium reverse mutation assay

Black tea (Camellia sinensis) is one of the most widely consumed beverages worldwide. Its chemopreventive effects are well documented in the literature. In the present set of investigations antimutagenic effects of aqueous black tea extract (ATE) and black tea polyphenols (BTP) were evaluated in the Ames test using Salmonella typhimurium tester strains TA 98 and TA 100. Addition of benzo(a)pyrene (BaP) and cyclophosphamide (CP), two well known mutagens, at the concentrations of 20 and 15 microg/plate, respectively, in an S-9 metabolically activated system resulted in significant induction of his+ revertant colonies. However, addition of 500 microl 1, 2 and 4% ATE to the BaP and CP treated plates resulted in a dose dependent inhibition in the number of his+ revertant colonies. Furthermore in another set of experiments, supplementation with BTP at the concentrations of 100, 200 and 400 microg/plate also led to a significant inhibition in BaP and CP induced colony formation. The antimutagenic activity of BTP was found to be higher than that of ATE, which may be attributable to the higher amount of polyphenolic ingredients. Hence the study revealed that black tea has a protective efficacy in suppressing BaP and CP induced mutagenicity in a microbial test system.