Study On The Protective Effect Of Schisandra Chinensis Polysaccharide On CCl₄-Induced Acute Liver Injury In Mice

The liver is the most important organ for the biological transformation of the body and plays a central role in metabolic control and detoxification,which is particularly important for liver protection from damage.Schisandra chinensis has good hepatoprotective effects,and Schisandra chinensis polysaccharide（SCP）is an important bioactive substance in Schisandra chinensis.In this study,we investigated the in vitro antioxidant activity of SCP and its protective effect against hepatic injury caused by CCl₄and its mechanism by extracting and purifying SCP.The main studies and results are as follows.In this study,the crude polysaccharide of Schisandra chinensis was obtained by aqueous extraction and alcoholic precipitation,combined with protein removal to obtain purified SCP-B.The polysaccharide content of SCP-B was detected by phenol-sulfuric acid method and was about 71.95%.The accuracy of this test was also verified by reproducibility test,precision test and stability test.The in vitro test showed that SCP-B had strong scavenging ability for hydroxyl radical（·OH）,1,1-diphenyl-2-trinitrophenylhydrazine（·DPPH）,superoxide anion（·O₂^-）,significant in vitro antioxidant activity,and positive correlation with polysaccharide concentration.In this experiment,a mouse model of acute liver injury was established by intraperitoneal injection of CCl₄,and the protective effects of different doses of SCP-B on CCl₄liver injury were investigated.50 mice were randomly divided into 5 groups:blank group,CCl₄group,LSCP-B group,MSCP-B group and HSCP-B group.The blank and CCl₄groups were gavaged with saline daily,and the LSCP-B,MSCP-B,and HSCP-B groups were gavaged with 100,200,and 400 mg/kg of SCP-B solution once a day for 7 days,respectively.After 2 h of the last gavage,all groups except the blank group received a single intraperitoneal injection of 0.1μl/g of CCl₄.16 h after CCl₄injection,serum and liver samples were collected for serum biochemical and other indices.The results showed that（1）the livers of the blank group were delicate and smooth with a deep red color;compared with the blank group,the livers of the CCl₄group were yellowish,swollen in size and less elastic;with the increase of polysaccharide concentration,the degree of liver lesions would be alleviated;（2）the serum levels of ALT and AST in the mice of the CCl₄group were extremely significant higher than those of the blank group,indicating that the model of acute liver injury in animals established with CCl₄was successful,and each group of SCP-B significantly reduced the levels of ALT and AST,indicating that SCP-B could alleviate liver injury;（3）SCP-B groups could significantly increase the activities of superoxide dismutase（SOD）,catalase（CAT）and glutathione peroxidase（GSH-Px）in the liver of mice,and the degree of increase of the three indexes was positively correlated with the concentration of polysaccharide;reduce the level of malondialdehyde（MDA）The above results indicate that polysaccharide can alleviate liver injury by inhibiting lipid peroxidation in the liver;（4）SCP-B groups can significantly down-regulate tumor necrosis factor-α（TNF-α）and interleukin-6（IL-6）levels in the liver,and the degree of reduction of TNF-αand IL-6 is positively correlated with polysaccharide concentration.（5）Histopathological observation of mouse liver,according to the results of HE staining,the cells in the liver of mice in the blank group were regularly arranged and morphologically normal,and the hepatocytes in the CCl₄group were heavily swollen and accompanied by inflammatory cell infiltration and cell necrosis,compared with the CCl₄group,the hepatocytes in the SCP-B group were relatively regularly arranged,the blister degeneration was significantly reduced,and the degree of cell damage was decreased,indicating that SCP-B could improve the SCP-B could improve the inflammatory cell infiltration and blister degeneration in mice,thus effectively reducing the damage caused by CCl₄to hepatocytes.In this study,two aspects of oxidative and inflammatory regulatory mechanisms in mouse liver were investigated by Western blot experiments.The Western blot results showed that the expression levels of somatostatin 3（NLRP3）and cysteine aspartate protease 1（Caspase1）as well as nuclear factorκB（NF-κB）and myeloid factor（My D88）were significantly elevated.In contrast,the liver NLRP3 and Caspase1 in the three groups of SCP-B-treated mice showed an inhibitory state,and NF-κB and My D88 also showed a decreasing trend,and the change trend was negatively correlated with the concentration of SCP-B;in addition,the liver of mice in the CCl₄group showed a significant decrease in the expression levels of nuclear factor E2-related factor 2（Nrf2）and Kelch-like epichlorohydrin-related protein（Keap1）expression levels were significantly reduced,while the SCP-B groups could significantly elevate the levels of Nrf2 and Keap1,and the elevation trend was positively correlated with the concentration of SCP-B.The above Western blot results suggest that SCP-B may alleviate the extent of CCl₄-induced liver injury by inhibiting the inflammatory response and enhancing the antioxidant mechanism.The above results indicate that SCP-B has a good protective effect against CCl₄-induced acute liver injury in mice,and the mechanism of action of SCP-B is related to its upregulation of Keap1 and Nrf2 expression to enhance the antioxidant effect of liver and inhibition of NF-κB-p65,My D88,NLRP3 and Caspase1 expression to exert anti-inflammatory effects.This study provides a theoretical basis for the application of SCP-B to alleviate liver injury and provides new research ideas for the intervention of Chinese medicine in liver injury.