Repeated dose studies with pure Epigallocatechin-3-gallate demonstrated dose and route dependant hepatotoxicity with associated dyslipidemia

Abstract

EGCG (Epigallocatechin-3-gallate) is the major active principle catechin found in green tea. Skepticism regarding the safety of consuming EGCG is gaining attention, despite the fact that it is widely being touted for its potential health benefits, including anti-cancer properties. The lack of scientific data on safe dose levels of pure EGCG is of concern, while EGCG has been commonly studied as a component of GTE (Green tea extract) and not as a single active constituent. This study has been carried out to estimate the maximum tolerated non-toxic dose of pure EGCG and to identify the treatment related risk factors. In a fourteen day consecutive treatment, two different administration modalities were compared, offering an improved [i.p (intraperitoneal)] and limited [p.o (oral)] bioavailability. A trend of dose and route dependant hepatotoxicity was observed particularly with i.p treatment and EGCG increased serum lipid profile in parallel to hepatotoxicity. Fourteen day tolerable dose of EGCG was established as 21.1 mg/kg for i.p and 67.8 mg/kg for p.o. We also observed that, EGCG induced effects by both treatment routes are reversible, subsequent to an observation period for further fourteen days after cessation of treatment. It was demonstrated that the severity of EGCG induced toxicity appears to be a function of dose, route of administration and period of treatment.

Keywords: ALP, alkaline phosphatase; ALT, alanine aminotransferase; AST, aspartate aminotransferase; Dose dependant toxicity; Dyslipidemia; EGCG; GTE, green tea extract; Green tea; Liver toxicity; Route dependant toxicity; Serum lipids; i.p, intraperitoneal; i.v, intravenous; p.o, oral.

Fig. 1

Comparison of plasma levels of EGCG administered through various administration modalities against time. Data show plasma concentration levels (μg/ml) of EGCG after a single treatment of 108 mg/kg either through i.v, i.p, p.o route and plotted against time and the data represented as Mean ± SEM (n = 5).

Fig. 2

Effect of 14 day repeated treatment of EGCG by i.p versus p.o route in a range of doses, on various biochemical parameters. Data represents Mean ± SEM (n = 5) and ^* indicates a significant difference from control, as assessed by one-way ANOVA plus Bonferroni post hoc test (^*p < 0.05), (^**p < 0.01), (^***p < 0.001).

Fig. 3

Photo micrographs (at 10X) of liver sections showing dose dependant toxic changes in response to 14 day consecutive treatment of EGCG. (a) Normal liver parenchyma; (b) fatty change with moderate lobular inflammation (arrow); (c) mildly congested liver (box); (d) mild periportal and mild lobular inflammation (arrow), mild kupfer cell hyperplasia. Mild ballooning degeneration (arrow head), focal acute inflammation; (e) congested liver with very mild periportal inflammation (arrow); (f) moderate periportal and mild lobular inflammation, with fatty change (arrow); (g) congested liver with fatty change (box); (h) congested liver parenchyma with moderate lobular acute inflammation, ballooning degeneration of hepatocytes (arrow), hepatocyte drop out areas (star), kupfer cell proliferation and calcification (acute hepatitis); (i) mild kupfer cell hyperplasia and congestion, mild to moderate periportal inflammation (arrow).