title: Modulation of tea and tea polyphenols on benzo(a)pyrene-induced DNA damage in Chang liver cells.
abstract: The protective effects of three tea extracts (green tea, GTE; oolong tea, OTE; and black tea, BTE) and five tea polyphenols (epicatechin, EC; epicatechin gallate, ECG; epigallocatechin, EGC; epigallocatechin gallate, EGCG; and theaflavins, THFs) on benzo[a]pyrene (B[a]P)-induced DNA damage in Chang liver cells were evaluated using the comet assay. B[a]P-induced DNA damage in Chang liver cells was significantly (p < 0.05) inhibited by GTE and OTE at a concentration of 10 microg/ml and by BTE at 25 microg/ml. At a concentration of 100 microg/ml, the % tail DNA was reduced from 33% (B[a]P treated only) to 10, 9, 13%, by GTE, OTE and BTE, respectively. EC and ECG did not cause DNA damage in cells according to the results of the comet assay; however, EGC, EGCG and theaflavins caused DNA damage in cells at a concentration of 100 microM. The results indicated that EC and ECG had protective effects against B[a]P-induced DNA damage in cells at a concentration of 10-100 microM. Although EGC, EGCG and the theaflavins caused DNA damage at a high concentration, but they had protective effects against B[a]P-induced DNA damage in cells at a low concentration of 10-50 microM. The results also showed that the DNA damage in cells induced by EGC, EGCG, and the theaflavins was due to the generation of superoxide during incubation with cells at a higher concentration. Therefore, tea catechins and THFs play an important role in enabling tea extracts to inhibit DNA damage in Chang liver cells.
authors.affiliation: Department of Food Science, National Chung Hsing University, 250 Kuokuang Road, Taichung 40227, Taiwan. gcyen@dragon.nchu.edu.tw
authors.forename: Gow-Chin
authors.initials: GC
authors.lastname: Yen
authors.forename: Jyh-Woei
authors.initials: JW
authors.lastname: Ju
authors.forename: Chi-Hao
authors.initials: CH
authors.lastname: Wu
mesh_terms: D016587:Antimutagenic Agents / Q000494:pharmacology; D001564:Benzo(a)pyrene / Q000037:antagonists & inhibitors / Q000633:toxicity; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology* / Q000633:toxicity; D005982:Glutathione Transferase / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D010636:Phenols / Q000494:pharmacology* / Q000633:toxicity; D010936:Plant Extracts / Q000494:pharmacology / Q000633:toxicity; D059808:Polyphenols; D013481:Superoxides / Q000378:metabolism; D013662:Tea / Q000737:chemistry*
chemical_list: D016587:Antimutagenic Agents; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea; D013481:Superoxides; D001564:Benzo(a)pyrene; D005982:Glutathione Transferase