Objective:

2

To investigate the phenolic composition

antioxidant properties

and hepatoprotective mechanisms of polyphenols from green tea extract (GTP) in carbon tetrachloride (CCl

4

)-induced acute liver injury mouse model.

Methods:

2

High-performance liquid chromatography was used to analyze the chemical composition of the extract. Antioxidant activity of GTP was assessed by O

2

•-

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 CCl

4

-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:

2

GTP contained 98.56 μg 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 CCl

4

-exposed hepatocytes. Hepatoprotective effects of low-

medium-

and highdose 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 CCl

4

-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:

2

GTP achieves hepatoprotective effects by improving hepatic antioxidant status and preventing cell apoptosis through caspase-3-dependent signaling pathways.