Hepatic and intestinal cytochrome P450 and conjugase activities in rats treated with black tea theafulvins and theaflavins

Black Tea Theaflavins Suppress Dioxin-Induced Transformation of the Aryl Hydrocarbon Receptor

“…A previous study found that long-term ingestion of Tfs (20 mg/kg body weight) suppresses both expression and activity of CYP1A1 in the rat intestine. 27) Taking together the results of this study and previous reports, continual intake of black tea would lead to an increase in the physiological and intestinal levels of Tfs, and have a possibility of suppressing AhR transformation and CYP1A1 expression.…”

“…25) An intake of 700 mg of Tfs results in a plasma concentration of 1.0 mg/l and a concentration of 4.2 mg/l in urine after 2 h, 26) indicating that Tfs are, at least in part, absorbed into the body, whereafter they affect physiological functions. Recently, black tea Tfs and theafulvins were reported to suppress CYP1A1 expression and its activity in the rat intestine, 27) suggesting that these polyphenols suppress AhR transformation induced by halogenated and/or polycyclic aromatic hydrocarbons in the liver. In the present study, we investigated whether black tea suppresses transformation of the AhR in vitro.…”

The Chemopreventive Effect of Taxifolin Is Exerted through ARE-Dependent Gene Regulation

“…33) Theaflavins and catechins in black tea suppress CYP2E1 protein expression in rat intestinal microsomes after oral intake for four weeks. 34) Thus, the simultaneous inhibition of CYP2E1 and induction of NQO1 in our experiments implies that taxifolin exerts chemopreventive effects through modulating the balance between phase I and II detoxification reactions.…”

Oral thearubigins do not protect against acetaminopheninduced hepatotoxicity in mice

“…In addition, there is little research on black tea theaflavins and thearubigins regarding their gastrointestinal absorption, metabolism, and potential impact on health [22]. A similar contrast was reported by Catterall et al [23,24]. In the earlier study [23], they found that theafulvins, a fraction of black tea TRs, inhibited the hepatic CYP450 activity associated with the CYP2E subfamilies.…”