Antioxidant and hepatoprotective effect of (-)-epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) from Chinese oolong tea.

(-)-Epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) has exhibited various biological activities in oolong tea. However, little information about its hepatoprotective activity is available. The objectives of the present study, therefore, were to determine the hepatoprotective activity of EGCG3″Me. First, high-purity EGCG3″Me was prepared from Chinese oolong tea by column chromatography. In antioxidant assay in vitro, EGCG3″Me exhibited potential antioxidant activity. For hepatoprotective activity in vitro, it was observed that EGCG3″Me effectively alleviated the changes induced by alcohol in a concentration-dependent manner. For hepatoprotective activity in vivo, the administration of EGCG3″Me at a dose of 100 mg/kg BW per day significantly decreased the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) from 64.6 ± 3.17 and 97.6 ± 3.78 to 39.6 ± 2.72 and 59.6 ± 3.02 U/L, decreased the liver level of malondialdehyde (MDA) from 1.14 ± 0.08 to 0.77 ± 0.03 nmol/mg protein, and remarkably restored the liver activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) from 247 ± 20.1 U/mg and 6.12 ± 0.17 nmol/mg protein to 261 ± 9.98 U/mg and 8.10 ± 0.03 nmol/mg protein, respectively, in alcohol-induced liver injury mice. This suggested that the protective effect of EGCG3″Me against alcohol-induced liver injury is possibly via its antioxidant activity to protect biological systems against oxidative stress.