A Combination of Tea (Camellia senensis) Catechins Is Required for Optimal Inhibition of Induced CYP1A Expression by Green Tea Extract

Abstract

It was previously demonstrated that the commercial green tea extract Polyphenon 100 (P100), and to a lesser extent (-)-epigallocatechin-3-gallate (EGCG), partially antagonizes 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced transcription of human CYP1A1 (Williams, S. N.; Shih, H.; Guenette, D. K.; Brackney, W.; Denison, M. S.; Pickwell, G. V.; Quattrochi, L. C. Chem.-Biol. Interact. 2000, 128, 211-229). Here, P100 is compared to a reconstituted mixture of the four major tea catechins (referred to as P100R) to determine whether inhibition was due to additional polyphenols in the extract or from synergistic interactions among the tea catechins. It was found that cotreatment of cells with TCDD and either P100 or P100R inhibited TCDD-induced CYP1A promoter-driven luciferase reporter activity (HepG2 cells) and CYP1A expression (HepG2 and primary human hepatocytes), similarly. These results indicate that modulation of human CYP1A expression by P100 can be attributed entirely to the combination of the four tea catechins. These findings may be important in the evaluation of future chemoprevention strategies using green tea and single catechin agents.

Fourteen-Week Toxicity Study of Green Tea Extract in Rats and Mice

“…H. Wu et al 2003). In our study, male rats were more severely affected, which is consistent with previous studies (Raederstorff et al 2003; Takami et al 2008;S. N. Williams, Pickwell, and Quattrochi 2003; Yoshino et al 1994).…”

Epigallocatechin-3-gallate: a useful, effective and safe clinical approach for targeted prevention and individualised treatment of neurological diseases?

“…Interestingly, a mixture of the four tea catechins (Polyphenon 100) and individual tea catechins differently modulated human cytochrome P450 1A expression. The underlying mechanisms of increased effectiveness of green tea and a catechin mixture compared to single catechins were not elucidated in this study [242]. …”

Inhibitory effects of cocoa tea (Camellia ptilophylla) in human hepatocellular carcinoma HepG2 in vitro and in vivo through apoptosis

“…For instance, Horie et al reported that the EGCG worked synergistically with EC to inhibit the gastric carcinoma cells growth and induce apoptosis [35]. Besides, it was also found that the efficacy of the mixture of EGCG, EGC, ECG and EC was higher than EGCG alone in inhibiting HepG2 cell growth [36].…”