Study On The Mechanism Of Chlorella Extract On Carbon Tetrachloride - Induced Acute Liver Injury In Rats

The purpose of this study was to investigate the hepatoprotective effects and the detoxification mechanism of aqueous extract of Chlorella vulgaris（CA）on CCl₄ induced acute liver injury in rats.The nutrition Constituent ofCA was analysed by AOAC method.The results showed that CA was high in protein（52.46%）and carbon hydrates（36.27%）,but low in fat （0.12%）.The antioxidant activity of CA was evaluated by UV-Vis spectrophotometry.The content of total phenolic compounds of CA was 22.94±1.82 mg·g^-1（n=3）,while the EC₅₀ of the DPPH^·free radical scavenging activity was 20.08 mg·mL^-1（n=3）.HPLC method was applied to determine the content of xanthopyl in CA.The separation was performed on a Zorbax Eclipse XDB-C₁₈（150×4.6 mm i.d.,3.5μm） column.The mobile phase was composed of methanol,acetonitrile and water with gradient elution program.The detection wavelength was 446 nm and the flow rate was 0.8 L·min^-1. All of this process was performed at room temperature.The linear calibration curve was A =2.362·10⁵ C-1.256×10³ï¼ˆr=0.9999,n=6）,and the linear over range was 5.0-50.0μg·mL^-1,the average recoveries was 98.7%（RSD=1.4%,n=9）.In the experiment of acute toxicological assessment of CA,ICR mice were divided into 4 groups randomly and CA was injected intragastrolly.During the 7 days after CA injection,no adverse effects were observed and no mice died.The result showed that CA was innoxious substance.To investigate the hepatoprotective effects of CA on CCl₄ induced liver injury in rats, the SD rats were divided randomly into 6 groups as control group,model group,CA groups（high,middle and low dosage groups）and positive control group.The CA(10,5, 2.5 g·kg^-1)and sylimarin(0.3 g·kg^-1)was injected intragastrolly to CA groups and positive control group for 30 days respectively.The control group and model group were injected with solvent with the same volume.All the groups except the control group were injected CCl₄ corn oil solution（50%）at the dosage of 2 mL·kg^-1on the 27^thday and the 30^thday. The control group was injected with corn oil.The liver functional index,liver peroxidation, different detoxification phase and liver hepatology were studied.The data showed that rats of CA groups showed lower levels of serum ALT,AST,ALP, TC,TG,TL compared to model group（P＜0.05 or P＜0.01）.The contents of MDA and Ca²⁺ in liver tissue were decreased significantly compared to the model group（P＜0.05 or P＜0.01）.The SOD and GSH-Px activities increased significantly（P＜0.05 or P＜0.01）.The contents of CYP₄₅₀and the activities of CPR were decreased（P＜0.05 or P＜0.01）.The expression of CYP2E1 was also decreased by CA.The hepatic GSH content was restored （P＜0.05）and the activity of GST were increased（P＜0.05）.For the HE result,rats of CA groups showed slightly liver injury of different levels compared to the model group.Focus and the necrosis were decreased by CA.Cloudy swelling,balloon cell formation and inflammation of hepatocytes were ameliorated.High dosage of CA group showed the best result.MTT method was applied to investigate the effect of CA on proliferation of HepG2 cells.The data indicated that CA showed obviously antiproliferation effect on HepG2 cells.