Dose-dependent Incorporation of Tea Catechins, (–)-Epigallocatechin-3-gallate and (–)-Epigallocatechin, into Human Plasma

Nakagawa, Kiyotaka; Okuda, Shiho; Miyazawa, Teruo

doi:10.1271/bbb.61.1981

Cited by 293 publications

(174 citation statements)

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“…3. The bioavailability of catechins after oral administration is low: EGCG levels detected in plasma correspond to 0.2-2.0% of the ingested amount [47]; however, catechin plasma levels can increase under particular conditions. Isbrucker et al found that the plasma area under the curve (AUC) for EGCG was significantly higher in fasted (205.7 ng h/mL) than in pre-fed dogs (19.8 ng h/mL) after 2 weeks dosing at 300 mg/kg per day by dietary administration [48].…”

Section: Discussionmentioning

confidence: 99%

Hepatotoxicity from green tea: a review of the literature and two unpublished cases

Mazzanti

Menniti‐Ippolito²,

Moro

et al. 2009

Eur J Clin Pharmacol

351

251

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Purpose To review the current literature on suspected green tea-related hepatic reactions and to describe two new cases reported within the framework of the Italian surveillance system of natural health products. Results A literature search of publication between 1999 and October 2008 retrieved 34 cases of hepatitis. Histological examination of the liver revealed inflammatory reactions, cholestasis, occasional steatosis, and necrosis. A positive dechallenge was reported in 29 cases. There was one reported death. A positive rechallenge occurred in seven cases (20%). In the two new cases, the causality assessment was judged as "possible" according to the RUCAM score. Conclusions Our analysis of the published case reports suggests a causal association between green tea and liver damage. The hepatotoxicity is probably due to (-)-epigallocatechin gallate or its metabolites which, under particular conditions related to the patient's metabolism, can induce oxidative stress in the liver. In a few cases, toxicity related to concomitant medications could also be involved.

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Section: Discussionmentioning

confidence: 99%

Hepatotoxicity from green tea: a review of the literature and two unpublished cases

Mazzanti

Menniti‐Ippolito²,

Moro

et al. 2009

Eur J Clin Pharmacol

351

251

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“…Interestingly, inhibition of UVA-induced ROS (DHR oxidation) and DNA damage were achieved at the lowest concentration of EGCG used (10 M ) that is of the same order as concentrations attained in human plasma after diet supplementation with green tea extracts (4.4 M). 30,31 Although the UVA radical species that determine the endpoints of survival, DNA damage and mutagenesis and against which EGCG acts, are not known, they are clearly of a different makeup to those detected by the probe DCFH because it shows a pro-oxidant effect of EGCG after UVA.…”

Section: Discussionmentioning

confidence: 99%

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

Tobi

Gilbert

Paul

et al. 2002

Intl Journal of Cancer

102

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A number of biological activities have been ascribed to the major green tea polyphenol epigallocatechin-3-gallate (EGCG) to explain its chemopreventive properties. Its antioxidant properties emerge as a potentially important mode of action. We have examined the effect of EGCG treatment on the damaging oxidative effects of UVA radiation in a human keratinocyte line (HaCaT). Using the ROS-sensitive probes dihydrorhodamine 123 (DHR) and 2 ,7 -dichlorodihydrofluorescein diacetate (DCFH-DA), we detected a reduction in fluorescence in UVA-irradiated (100 kJ/m 2 ) cells in the case of the former but not the latter probe after a 24-hr treatment with EGCG (e.g., 14%, [p < 0.05] after 10 M EGCG). In the absence of UVA, however, both DHR and DCFH detected a pro-oxidant effect of EGCG at the highest concentration used of 50 M. Measurements of DNA damage in UVA-exposed cells using the single cell gel electrophoresis assay (comet assay) also showed the protective effects of EGCG. A concentration of 10 M EGCG decreased the level of DNA single strand breaks and alkali-labile sites to 62% of the level observed in non-EGCG, irradiated cells (p < 0.001) with a 5-fold higher concentration producing little further effect. Correspondingly, EGCG ablated the mutagenic effects of UVA (500 kJ/m 2 ) reducing an induced hypoxanthine-guanine phosphoribosyl transferase (HPRT) mutant frequency of (3.39 ؎ 0.73) ؋ 10 ؊6 to spontaneous levels (1.09 ؎ 0.19) ؋ 10 ؊6 . Despite having an antiproliferative effect in the absence of UVA, EGCG also served to protect against the cytotoxic effects of UVA radiation. Our data demonstrate the ability of EGCG to modify endpoints directly relevant to the carcinogenic process in skin. © 2002 Wiley-Liss, Inc. Key words: epigallocatechin-3-gallate; antioxidant; ultraviolet AThere has been considerable recent interest in the chemopreventive properties of the polyphenols or catechins of green tea that have been shown to inhibit tumorigenesis in a variety of organs in rodent models. 1-3 The major polyphenol component by mass, (Ϫ)-epigallocatechin-3-gallate (EGCG) is an effective protectant against the mutagenicity of a number of chemical carcinogens including benzo[a]pyrene (B[a]P), aflatoxin B1 and 3-hydroxyamino-1-methyl-5H-pyrido [4,3-b]indole. 4 -6 EGCG, together with other green tea polyphenols also exhibits growth inhibitory properties in a variety of tumour cell lines. 7-9 Several mechanisms have been proposed by which these compounds exert their anti-tumorigenic action: these include the blockade of growth factors binding to their receptors, 10 phosphorylation (activation) of mitogen-activated protein kinases (MAPKs) 11,12 possibly resulting in the observed induction of Phase II drug-metabolizing enzymes, 13,14 and the generation of oxidative stress leading to apoptosis. 7,9 In the face of an oxidative challenge, however, it is now well documented that green tea catechins act as antioxidants. For example, EGCG abrogates oxidation by hydrogen peroxide both in a cell free system 15 and in terms of DNA single-s...

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“…Several reports have shown that the concentration of EGCG in the blood after two or three cups of green tea can reach about 1 mM. 8,9) Furthermore, a high concentration of EGCG has been detected in rat small intestine and colon mucosa following oral administration. 10) These findings support our hypothesis; however, further investigation must be carried out to confirm it.…”

Section: Resultsmentioning

confidence: 99%

Epigallocatechin Gallate (EGCG) Inhibits the Sulfation of 1-Naphthol in a Human Colon Carcinoma Cell Line, Caco-2.

Isozaki

Tamura

2001

Biological & Pharmaceutical Bulletin

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Tea is a universally popular beverage, consumed by over two thirds of the world's population. Green tea is consumed mostly in Japan and China. The anti-mutagenic and anti-carcinogenic activity of green tea has been extensively examined. 1) Bioactivation of carcinogenic arylamine and heterocyclic amine metabolites by mammalian liver phenol sulfotransferases (P-STs) has been postulated as a key mechanism leading to aromatic carcinogenesis in humans. [2][3][4][5] To elucidate whether the anti-carcinogenic activity of green tea is related to ST activity, we previously investigated the effect of green tea on P-ST activity in the mouse intestine and in a human colon carcinoma cell line, Caco-2. We found that catechins, especially epigallocatechin gallate (EGCG), strongly inhibit in vitro P-ST activity in both types of cells. 6) In the present study, we examined the ability of catechins to inhibit P-ST activity in intact cells. We found that catechins, especially EGCG, inhibit the sulfation of 1-naphthol within intact cells as strongly as they do in vitro. MATERIALS AND METHODSMaterials 1-Naphthol and sulfate were obtained from Sigma (St. Louis, MO, U.S.A.). The catechins and reagents for HPLC were purchased from Wako Chemicals (Tokyo, Japan). Caco-2 cells were obtained at passage 40 from RIKEN Cell Bank, Japan.Cell Culture Caco-2 cells were grown in a 6-well plate (Iwaki, Japan) in 3 ml MEM supplemented with 10% fetal bovine serum, 2 mM glutamine, 10 U/ml penicillin, 10 U/ml streptomycin and additional non-essential amino acids. The cells were kept at 37°C in a humidified atmosphere, containing 5% CO 2 . Cells were seeded in 6-well plates at a concentration of 5ϫ10 5 cells/ml and grown until confluence (5-6 d). Cells were cultivated for up to 3 weeks and their media was changed every 4-5 d.Analysis of Sulfation of 1-Naphthol in Intact Caco-2 Cells In order to examine the sulfation of 1-naphthol in intact Caco-2 cells, 1-naphthol was added to the medium of each well at a concentration of 200 mM. This value was chosen in light of the transport efficiency of 1-naphthol across the cell membrane and the K m value of P-ST activity (50 mM) in vitro. Following this, cells were incubated at 37°C. An aliquot (100 ml) was removed at various intervals and mixed with 5 ml of 200 mM p-nitrophenyl sulfate to provide an internal standard, then 10 ml of the mixture was injected onto the HPLC. The analysis was performed on an ODS column (CAPCELL PAK C 18 UG80, 250ϫ4.5 mm, Shiseido, Japan) at room temperature. The mobile phase was composed of 2 mM tetrabutylammonium hydrogen sulfate in water and acetonitrile (65 : 35). The flow rate was 1.3 ml/min with detection at 285 nm. The retention times of 1-naphthol and 1-naphthyl sulfate were 13.5 and 11.8 min, respectively. Linearity of the standard curve for 1-naphthyl sulfate was observed up to 100 mM. The effect of catechins on the sulfation of 1-naphthol was measured by the addition of EGCG, EGC, or EC at various concentrations into the culture medium. The IC 50 value for the concentration-...

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Dose-dependent Incorporation of Tea Catechins, (–)-Epigallocatechin-3-gallate and (–)-Epigallocatechin, into Human Plasma

Cited by 293 publications

References 0 publications

Hepatotoxicity from green tea: a review of the literature and two unpublished cases

Hepatotoxicity from green tea: a review of the literature and two unpublished cases

The green tea polyphenol, epigallocatechin‐3‐gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation

Epigallocatechin Gallate (EGCG) Inhibits the Sulfation of 1-Naphthol in a Human Colon Carcinoma Cell Line, Caco-2.

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