Objective To investigate the phenolic composition,antioxidant properties,and hepatoprotective mechanisms of polyphenols from green tea extract(GTP)in carbon tetrachloride(CCl4)-induced acute liver injury mouse model.Methods High-performance liquid chromatography was used to analyze the chemical composition of the extract.Antioxidant activity of GTP was assessed by O2∙-,OH∙,DPPH∙,and ferric-reducing antioxidant power(FRAP)assay in vitro.Sixty Kunming mice were divided into 6 groups including control,model,low-,medium-,and high-doses GTP(200,400,800 mg/kg)and vitamin E(250 mg/kg)groups,10 in each group.GTP and vitamin E were administered at a level of abovementioned doses twice per day for 7 days prior to exposure to a single injection of CCl4.Hepatoprotective effects of GTP were evaluated in a CCl4-induced mouse model of acute liver injury,using commercial enzyme linked immunosorbent assay kits,histopathological observation,terminal deoxynucleotidyl transferase-mediated dUTPNick-end labeling(TUNEL)assay and Western blot.Results GTP contained 98.56µg gallic acid equivalents per milligram extract total polyphenols,including epicatechingallate,epigallocatechin gallate,epicatechin,and epigallocatechin.Compared with the model group,low-,medium-,or high doses GTP significantly decreased serum levels of alanine aminotransferase and aspartate transaminase(P<0.01).Histopathological observation confirmed that pretreatment of GTP prevented swelling and necrosis in CCl4-exposed hepatocytes.Hepatoprotective effects of low-,medium-,and high-dose GTP were associated with eliminating free radicals and improving superoxide dismutase,catalase,and glutathione peroxidase activity in the liver.Additionally,low-,medium-,and high-dose GTP decreased cell apoptosis in the CCl4-exposed liver(P<0.01).Phosphorylated nuclear factor kappa-B(NF-κB),p53,Bcl-2 associated x protein/B-cell lymphoma/leukemia-2 gene,cytochrome C,and cleaved caspase-3 levels were downregulated compared with the model group(P<0.01).Conclusion GTP achieves hepat
