Protective Mechanism Of Soybean Hull Polysaccharide On Liver Injury

Liver injury is a common pathological state of various liver diseases.Its continuous deterioration will lead to cirrhosis,liver fibrosis and liver cancer.Therefore,the search for effective substances against liver injury has been widely concerned.Active polysaccharides widely exist in plants,microorganisms and animals,with the characteristics of high efficiency,low toxicity and small side effects.It has become a research hotspot in the field of natural drug preparations against liver injury,and has made more progress.In this study,soybean hull antioxidant polysaccharide（SP）was used for the research object to systematically study on its preparation technology,structural characterization,antioxidant activity,liver protection and protective mechanism against CCl₄ induced liver injury.The main research contents and results are as follows1.Different extraction methods have certain influence on the extraction efficiency of polysaccharides.The yield of polysaccharide obtained by microwave-assisted ammonium oxalate extraction（ASP）was the highest（9.3±0.5%）,followed by that by microwave-assisted sodium citrate extraction（SSP）,which was 3.6±0.4%.The extraction efficiency of polysaccharide obtained by hot water extraction was only 1.2±0.5%.The monosaccharide compositions of the three polysaccharides were composed mainly of mannose,galactose,arabinose,rhamnose,glucose and galacturonic acid,but each content was different.Compared with the other two kinds of polysaccharides,the content of arabinose,galacturonic acid and sulfate in ASP was higher,which content of protein was lower,and the molecular weight was 251 k Da.In addition,SEM results show that ASP,unlike SSP and HSP,has mainly flake structure with smoother surface.2.The scavenging efficiency of ASP,SSP on DPPH and ABTS⁺were 76.9±1.9%,63.6±3.3%and 85.3±3.8%,68.7±4.5%,respectively.The total reducing power of ASP,SSP was higher than that of HSP.The scavenging efficiency of DPPH and ABTS⁺was dose-dependent in the concentration range of 2-10 mg/m L.This may be closely related to the differences of structure.3.Establish CCl₄ induced liver injury model in mice,and explore the effect of three kinds of soybean hull polysaccharides on liver injury in vivo.The results showed that ASP and SSP could significantly regulate the relative content of alanine aminotransferase（ALT）/aspartate aminotransferase（AST）,reduce the content of malondialdehyde（MDA）and reactive oxygen species（ROS）,as well as increase the content of glutathione（GSH）.The results of liver tissue and section observation showed that ASP and SSP could effectively reduce tissue fibrosis and inflammation.In conclusion,SPs has a significant protective effect on liver injury.4.Based on 16S DNA high-throughput sequencing technology of mouse intestinal flora,the effect of soybean hull polysaccharide on intestinal flora of mice with CCl₄ induced liver injury was studied.The results showed that the content of Firmicute in the intestinal flora of mice treated with CCl₄ decreased,and the content of Bacteroidetes and Clostridium＿Ⅷ in the intestinal flora increased significantly,the increase of Bacteroidetes and the decrease of Firmicute were closely related to cholesterol content.SPs intervention can significantly reduce the content of Bacteroidetes and increase the content of Firmicute.In addition,ASP intervention could significantly increase Bifidobacterium content,SSP intervention could significantly increase Lactobacillus and Akkermansia content.In addition,Beta diversity results showed that CCl₄ could significantly differentiate intestinal flora from normal flora.However,ASP and SSP can significantly affect the intestinal microbial diversity of mice,making it close to the normal intestinal flora.These results showed that the intervention of SPs,especially SSP,can regulate the intestinal flora changed by CCl₄,make it develop to the normal direction,and have a positive impact on intestinal health.5.The results of qRT-PCR showed that SSP could up regulate the expression of Nrf2,down regulate the expression of Keap1,and indirectly up regulate the expression of HO-1 and NQO1.Through regulating Nrf2 signaling pathway,SSP could regulate the intracellular redox state,promote the expression of antioxidant genes,improve the ability of antioxidant stress of hepatocytes,and protect hepatocytes from oxidative damage induced by CCl₄.In this paper,the structure,physicochemical properties and antioxidant activity of soybean hull polysaccharides obtained by different extraction methods were analyzed,and their antioxidant activity was also proved can protect CCl₄ induced chemical liver injury in vivo and in vitro,and reveals the mechanism of liver protection,in hope to provide a theoretical basis for the development and comprehensive utilization of soybean resources,and to develop new ideas for the further development of natural,efficient,low toxic and side effects of liver protection functional food.