Protective Effect Of Sulfated Mesona Chinensis Polysaccharide On Cyclophosphamide Induced Liver Injury In Mice Based On Intestinal Flora And Metabonomics

Mesona chinensis Benth is a commonly used medicinal and edible plant resource in China,which has high nutritional value and potential health functions.Mesona chinensis Benth polysaccharide(MP)is one of the main active ingredients of Mesona chinensis Benth.Preliminary studies have shown that it has anti-oxidation,hypoglycemic,hypolipidemic,anti-hypertensive,anti-viral and other biological activities,and sulfated Mesona chinensis polysaccharide(SMP)can enhance its anti-oxidation and immunomodulatory activities.Cyclophosphamide(CTX)is an alkylating drug,which is widely used in various cancer chemotherapy in clinical practice.It is also a typical drug that causes drug-induced liver injury(DILI).They can trigger and aggravate liver toxicity through direct cytotoxicity,oxidative stress and inflammation,etc.The severe liver toxicity limits their clinical application.At present,there are few reports about the effects of MP and SMP on CTX-induced liver injury in mice.This thesis aims to investigate the protective effect of dietary treatment of MP and SMP on CTX-induced hepatotoxicity,and to explore the hepatotoxicity effect of CTX and the liver protective mechanism of MP and SMP from the intestinal flora and metabolites by using 16 S r RNA high-throughput technology and UPLC-Q-TOF/MS,and other molecular biological methods.The main findings are as follows:(1)Sulfated modification can enhance the protective effect of MP on liver,and this protective mechanism may be due to its ability to effectively scavenging free radicals,restoring the body’s antioxidant defense system,and effectively regulating the body’s inflammation level.CTX can cause liver injury in mice,reduce the weight and liver index of mice,increase the activity of liver function indicators AST and ALT,cause oxidative stress in the liver of mice,increase the content of MDA,as well as reduce the activity of GSH,SOD and GSH-px.After MP and SMP treatment,the growth state of mice with liver injury was improved,body weight and liver organ index were restored,the activities of GSH,SOD and GSH-Px were significantly increased,and the levels of pro-inflammatory factors IL-6 and TNF-α in liver were inhibited,while the contents of MDA,AST and ALT were significantly decreased in a dose-dependent manner,and the effect of sulfated modification is better.In addition,MP and SMP can reduce the release of LPS in serum.The introduction of sulfate group can effectively enhance the liver protection effect of MP and alleviate obvious histopathological damage of liver tissue caused by CTX.The optimal dose is 200mg/kg·(bw).(2)Sulfated modification significantly altered the structure of intestinal microflora at different taxonomic levels,increasing the relative abundance of beneficial bacteria and decreasing the relative abundance of harmful bacteria,but had no significant effect on the diversity of intestinal microflora in mice.Compared with MC group,MP significantly increased the diversity of intestinal microflora.Theβ-diversity structure showed the clustering of different treatment groups.MP can increase the relative abundance of Ruminococcaceae,Lachnospiraceae,Blautia,Coprococcus and Oscillospira.SMP increased the relative abundance of Lactobacillus and Bifidobacerium.MP and SMP inhibited the relative abundance of Bacteroidaceae and Bacteroides.The reason that SMP treatment reduces the diversity of intestinal flora may be due to the large increase of the two types of beneficial bacteria,Lactobacillus and Bifidobacerium,which leads to the decrease of other bacteria.In addition,the intervention of MP and SMP significantly increased the concentration of SCFAs in the colon contents and feces of mice,and the sulfated modification increases the content of xylose and uronic acid in the MP,and promotes the production of acetic acid,propionic acid and butyric acid,which is beneficial to be effectively utilized by intestinal microorganisms and exerts its beneficial effects.(3)Sulfated modification improves the effect of MP on biomarkers and metabolic pathways,and the introduction of sulfate group has a better therapeutic effect on metabolic disorders caused by CTX.Principal Component Analysis(PCA)and Orthogonal Partial Least Squares Discriminant Analysis(OPLS-DA)found that the concentration of many metabolites in the MC group changed significantly compared with the NC group,and 23 and 38 different metabolites were screened and identified in liver and fecal metabolic profiles of each treatment group,respectively.These endogenous metabolites may be considered to be biomarkers for liver protection.Through enrichment pathway analysis of differential metabolites,the liver injury group mainly involves α-linolenic acid metabolism,phenylalanine metabolism,arachidonic acid metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,and unsaturated fatty acid biosynthesis these five metabolic pathways.The intervention of MP significantly affects phenylalanine metabolism,arachidonic acid metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,taurine and hypotaurine metabolism,tryptophan metabolism and intestinal microbial metabolism to exert liver protection;intervention of SMP significantly affects phenylalanine metabolism,arachidonic acid metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,histidine metabolism,tryptophan metabolism and intestinal microbial metabolism and other pathways play a hepatoprotective effect.In addition,a common metabolite arachidonic acid was also found in liver and feces samples.This will help to further understand the mechanism of action of MP and SMP,and provide a basis for further research.