Intervention Of Echinacea Purpurea Polysaccharide On Gut Microbes And Alcoholic Liver Injury In Mice

Echinacea(Echinacea purpurea(L.)Moench)is known as an "immune stimulant" and "hepatoprotective agent" in the West and was successfully introduced in our country in the1990 s.Echinacea purpurea polysaccharide(EPP),as one of its main active components,has excellent anti-inflammatory,antioxidant and immunomodulatory effects.At present,more and more studies have shown that plant polysaccharides can be used as prebiotics to improve intestinal function,while there are few reports on the effects of EPP on intestinal health.Therefore,in this study,the digestive characteristics of EPP in vitro and its regulatory effect on the gut microbes of mice were studied by using a simulation of the gastrointestinal digestive system in vitro and the mouse model in vivo.At the same time,the intervention effect of EPP on alcoholic liver disease(ALD)in mice was explored from the perspective of the "gut-liver" axis.The main results are as follows:1.The optimal ultrasonic extraction parameters were as follows: temperature 70 ℃,power 360 W,solid-liquid ratio 1:28 g/m L,and time 58 min.Under these conditions,the actual yield of crude polysaccharides was 3.59 ± 0.017%.Three fractions of Echinacea purpurea polysaccharides(EPP40,EPP60,and EPP80)were isolated by gradient ethanol precipitation method with molecular weights of 174978,20009,and 11816 Da,respectively,and the monosaccharide content of the three was high in galactose.The in vitro antioxidant results showed that these three polysaccharide fractions all had strong antioxidant activities,among which EPP80 had the strongest antioxidant activity;in addition,in vitro alcohol dehydrogenase(ADH)activation experiments also showed that EPP80 had the strongest ADH activation activity.2.The results of simulated "stomach-small intestine" digestion in vitro showed that EPP80 was hardly decomposed in simulated gastric juice,while in simulated small intestinal juice,the content of reducing sugar increased due to a small amount of glycosidic bond breakage.The results of free monosaccharides confirmed that the digestion process did not have a great impact on the main structure of EPP80,so EPP80 could still enter the large intestine in a relatively "intact" way.3.The intervention results of EPP80 on gut microbes in mice showed that EPP80 markedly increased the concentration of fecal short-chain fatty acids(SCFAs),which mainly manifested as the increase of formic acid,acetate,and propionate.Besides,the effect of EPP80 on the microbiota of colonic contents in mice was consistent with recognized prebiotic inulin at the phylum level,demonstrated by an increase in the relative abundance of Bacteroidota and a decrease in Firmicutes.At the genus level,the relative abundances of Muribaculaceae,Lactobacillus,and Alloprevotella increased,while Lachnospiraceae NK4A136,Alistipes,and Eubacterium xylanophilum decreased after EPP80 intervention.Hence,EPP80 could improve intestinal microecology by proliferating beneficial bacteria,promoting the production of SCFAs,and inhibiting harmful bacteria.4.The intervention results of EPP80 on ALD mice showed that EPP80 could alleviate intestinal inflammation,increase intestinal tight junction protein expression,reduce serum endotoxin level,and increase fecal n-butyric acid content in ALD mice.Besides,the relative abundances of Muribaculaceae,Lactobacillus,and Bacteroides increased in the colonic contents of mice,while Escherichia＿Shigella,Enterococcus,and Akkermansia decreased after EPP80 intervention;Meanwhile,the measurement results of mouse serum and liver indicators also confirmed that EPP80 alleviated the liver damage caused by alcohol.Therefore,EPP80 could improve gut microbiota and regulate gut microbial metabolites,thereby alleviating alcohol-induced liver injury in mice via the "gut-liver" axis.In summary,EPP80 could promote gut health and alleviate alcoholic liver injury in mice via the "gut-liver" axis.Therefore,this study not only provides a theoretical basis for the development of EPP as the main component of prebiotics and liver-protecting products,but also has a certain academic significance and application value for promoting the development and utilization of domestic Echinacea resources.