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Antimutagenicity of green tea polyphenols in the liver of transgenic medaka.

Winn RN, Kling H, Norris MB

Aquatic Biotechnology and Environmental Laboratory, Warnell School of Forest Resources, University of Georgia, Athens, 30602, USA. rwinn@uga.edu

We examined the ability of a mixture of the predominant green tea polyphenolic compounds (GTP) to reduce benzo[a]pyrene (B[a]P)-induced mutations in the cII gene of the lambda transgenic medaka. Fish were treated with 50 ppb B[a]P for 24 hr, followed by exposure to 2 ppm or 10 ppm GTP for 28 days. cII mutations in livers of fish exposed to B[a]P were increased significantly, 2.6-fold above controls. In contrast, the addition of GTP significantly reduced the frequency of cII mutants by 84%, comparable to that of controls. The frequencies of mutations at G:C basepairs, mutations that are highly characteristic of B[a]P exposure, were elevated significantly in treated fish. By comparison, B[a]P-exposed fish also treated with GTP showed reductions in these mutations, demonstrating a protective effect of GTP against B[a]P-induced mutagenesis. The antioxidant mechanism of GTP possibly played an important role in the reduction of B[a]P mutagenicity. These results corroborate findings from rodent models, showing that the protective effects of green tea extend to different species, and suggesting that similar mechanisms of B[a]P mutagenesis and GTP antimutagenesis are shared among the models. These studies illustrate the utility of lambda transgenic medaka for in vivo mutation analyses and suggest that this fish may be a valuable model in chemoprevention studies.

Published 17 August 2005 in Environ Mol Mutagen, 46(2): 88-95.
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