Effects Of Auricularia Cornea Var.Li.Polysaccharides On Blood Glucose Regulation And Intestinal Flora In Diabetic Mice

Auricularia cornea var.Li is rich in nutrition and contains a variety of bioactive components.According to the literature,Auricularia cornea var.Li polysaccharide has antioxidant,antitumor and immune regulating effects,but there are few studies on the hypoglycemic effect of Auricularia cornea var.Li polysaccharide and its effect on intestinal flora.In this thesis,the effects of Auricularia cornea var.Li.polysaccharides on blood glucose regulation and intestinal flora of diabetic mice were investigated.Firstly,the extraction,purification and structural characterization of Magnolia polysaccharide were carried out;the T2DM model was established in ICR male mice to study the hypoglycemic effect of Auricularia cornea var.Li.polysaccharide on diabetic mice.GC-MS was used to detect short-chain fatty acids in the intestine of mice,high-throughput sequencing was used to determine the species composition and abundance of intestinal flora,and the effects of body weight,blood glucose and blood lipids on intestinal flora and their metabolites were studied by combined multi-factor analysis to investigate the hypoglycemic effect and possible mechanism of action of Auricularia cornea var.Li.polysaccharide on mice with T2DM:(1)Extraction,separation,purification and structural characterization of the Auricularia cornea var.Li.polysaccharides.The crude polysaccharide was extracted by hot water extraction and ethanol precipitation,and the yield was(27.5±2.3)%.The proteins in the polysaccharide were removed by Sevage reagent and the small molecules were removed by dialysis,and then the polysaccharide with high purity was obtained.The sugar content of polysaccharide was 90.59%as measured by phenol-sulfuric acid method.The polysaccharides measured by liquid chromatography consist mainly of monosaccharides such as glucose(Glu),mannose(Man)and xylose(Xyl),the mass fractions were 40.23%,36.54%,and 10.08%,respectively;the heavy average molecular weight of the polysaccharides of M.japonica was measured by high performance gel permeation chromatography(HPGPC):Mw=4.784×10~6(±2.883%)had the highest content of 61.6%,followed by Mw=5.134×10~4(±3.574%)with 16.9%,Mw=3.165×10~5(±2.955%)with 16.6%,and Mw=1.527×10~5(±1.336%)with 4.9%;FTIR analysis showed that the polysaccharide had the general structure of common edible fungal polysaccharides with bothα-andβ-glycosidic bonds.The UV spectral analysis showed that the purified polysaccharide of Auricularia cornea var.Li.contained almost no protein and nucleic acid components,and the purity was high enough to be used in subsequent animal experiments.(2)Hypoglycemic effect of Auricularia cornea var.Li.polysaccharide on diabetic mice.ICR male mice were fed with high sugar and high fat diet combined with STZ intraperitoneal injection to successfully construct a T2DM model(modeling rate of 85%),and after 6 weeks of gavage intervention,the results showed that:Auricularia cornea var.Li.polysaccharide could effectively improve various symptoms of diabetic mice,including excessive drinking,excessive eating and weight loss,etc.The HDG group significantly reduced the fasting blood glucose of diabetic mice(p<0.01),significantly increased the body weight of mice(p<0.05),and its intervention effect was close to that of the PC group,which improved the overall health condition of mice;Auricularia cornea var.Li.polysaccharides could improve the symptoms of hyperglycemia in diabetic mice,significantly reduced the serum concentrations of TC,TG and LDL-c(p<0.01),enhanced the level of HDL-c content(p<0.05),significantly reduced the serum blood glucose content of mice and serum insulin(p<0.05),enhanced insulin and receptor sensitivity,significantly reduced insulin resistance(p<0.01),and made insulin secretion level converge to normal control group;pathological sections showed that Auricularia cornea var.Li.polysaccharides could improve the histopathological damage of liver and pancreas in T2DM mice,reduce cell irregularity,atrophy and vacuolation,and have certain protective and repairing effects on them;Auricularia cornea var.Li.polysaccharides intervention also could significantly increase the level of total short-chain fatty acid content in the intestine of mice(p<0.01),and improve the disorder of short-chain fatty acid in the intestine and regulate the balance of short-chain fatty acid content in the intestine.(3)Effect of Auricularia cornea var.Li.polysaccharide on intestinal flora of diabetic mice.OUT analysis of the Alpha and Beta diversity of mouse intestinal flora samples revealed that Auricularia cornea var.Li.polysaccharides could increase the abundance of intestinal flora in T2DM mice,among which the HDG group had the most significant effect in three polysaccharides dose gradients(p<0.01);The species composition of different mouse intestinal microflora was analyzed at the phylum level and genus level,and it was found that the intestinal flora of mice with T2DM was significantly disturbed.The abundance of Firmicutes and Proteobacteria in the intestine of NC group mice was significantly higher than that of BC group(p<0.01),while the abundance of Bacteroidot,Actinobacteriota and Patescibacteria was lower.By regulating the colony composition of intestinal microorganisms and up-regulating the abundance of Actinobacteriota,Patescibacteria and Bacteroidota,Auricularia cornea var.Li.polysaccharides improved the dysbiosis of intestinal flora in mice and improved the disorder of intestinal flora caused by T2DM.(4)Auricularia cornea var.Li.polysaccharides may promote the production of SCFAs in the intestine of mice by affecting the composition of intestinal flora,and It can improve abnormally elevated blood glucose and weight loss,regulate TC,TG,HDL-c,LDL-c and insulin levels,and reduce insulin resistance,thus alleviating diabetic symptoms and preventing complications;the number of intestinal OUT in mice was positively correlated with SCFAs,Weight and HDC＿c(Pearson correlation coefficient r>0,P<0.05),and with FBG,insulin,HOMA＿IR,TC,TG,and LDC＿c were negatively correlated(Pearson correlation coefficient r<0,P<0.05).In this thesis,it was shown that Auricularia cornea var.Li.polysaccharide had significant hypoglycemic effect and improved the symptoms of"three more and one less",and also reduced the tissue damage of pancreas and liver in T2DM mice.In addition,it also improved the intestinal flora and short-chain fatty acid disorders in diabetic mice,thus preventing and treating diabetes.This study provides some theoretical basis for the development and utilization of Magnolia polysaccharides.