Résumé
OBJECTIVE@#To investigate the phenolic composition, antioxidant properties, and hepatoprotective mechanisms of polyphenols from green tea extract (GTP) in carbon tetrachloride (CCl)-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 O, 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 CCl. Hepatoprotective effects of GTP were evaluated in a CCl-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 98.56 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-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 CCl-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 hepatoprotective effects by improving hepatic antioxidant status and preventing cell apoptosis through caspase-3-dependent signaling pathways.
Résumé
<p><b>OBJECTIVE</b>To study the protective effect of Sanhuangyinchi Fang drug serum (SF) against hydrogen peroxide-mediated DNA oxidative damage in LO2 cells.</p><p><b>METHODS</b>The LO2 cells were randomly divided into the control group, H(2)O(2) group, SF groups (5%, 10%, and 15%) and vitE group. The morphological features of the treated LO2 cells were observed under inverted microscope. The viability of the treated cells was assessed with CCK-8 method, and the activity of SOD, CAT and GSH-PX were detected biochemically. Reactive oxygen species (ROS) levels, the content of 8-OHdG, and DNA damage of the cells were evaluated by flow cytometry, ELISA, and Comet assay, respectively.</p><p><b>RESULTS</b>Compared with H(2)O(2) group, the cells in SF groups (10% and 15%) and vitE group showed higher cell survival rate (P<0.05) and higher SOD, CAT, GSH-PX (P<0.05) and ROS scavenging activities (P<0.01) with markedly decreases the content of 8-OHdG (P<0.01) and reduced tailing ratio, tail length, tail moment and Olive tail moment (P<0.05).</p><p><b>CONCLUSION</b>SF drug serum, especially at the concentration of 15%, can protect LO2 cells from H(2)O(2)-mediated DNA oxidative damage.</p>