Mechanism Of Polygonatum Cyrtonema Polysaccharide In Reducing Nutritional Obesity By Regulating Intestinal Flora

Objective:Along with the rapid development of the social economy,high-calorie diets and inactive lifestyles are leading to an increasing number of overweight and obese people worldwide.Obesity is not only a health hazard,but also a social and economic burden,making its prevention and treatment a major public health challenge.Polygonatum cyrtonema HUA is a perennial herb from family Liliaceae,and has been used in China for more than 2000 years.The Chinese medicinal book "Mingyibielu" recorded that it had the effect of "lightening the body when taken for a long time",and modern pharmacological studies have found that P.cyrtonema has the effect of lowering lipids and blood sugar and regulating cardiovascular diseases.Polysaccharide is the main medicinal active ingredient in P.cyrtonema.The group’s preliminary non-target-based metabolomics study found that the obesity-regulating effect of P.cyrtonema polysaccharide is related to the metabolic pathways of glycerophospholipids and arachidonic acid,but the specific mechanism of action still needs to be further explored.Recent studies have shown that intestinal microbial dysbiosis is one of the main causes of obesity generation and development,and the mechanism of how P.cyrtonema polysaccharide regulates intestinal microbes to exert weight loss and lipidlowering effects is still unclear.Therefore,in this paper,using high-fat diet-induced nutritional obesity mice as an animal model,we investigated the effect mechanism of polysaccharide of P.cyrtonema by regulating metabolic disorders in obese mice based on intestinal flora.It is an important guide for the development and clinical application of Chinese medicine targeting intestinal flora..Methods:P.cyrtonema was extracted by hydro-alcoholic precipitation and vacuum freezedried to obtain the lyophilized powder of P.cyrtonema polysaccharide(PCP)for animal experiments.Before the experiment,C57BL/6 mice were randomly divided into normal group(NG),high-fat diet(HFD)group,P.cyrtonema polysaccharide lowdose group(300 mg/kg,PCP-L),P.cyrtonema polysaccharide high-dose group(600mg/kg,PCP-H)and positive control orlistat group(40 mg/kg,ORL).All groups were fed the high-fat diet D12492,except for the normal group which was fed the normal diet,and the animal experiment lasted for 12 weeks.Body weight changes and food intake were recorded weekly during the feeding period,and biological samples were collected at the end of the 12 weeks.The serum levels of total cholesterol(TC),triglycerides(TG),high-density lipoprotein cholesterol(HDL-C)and low-density lipoprotein cholesterol(LDL-C)in mice were measured using biochemical test kits.Serum levels of inflammatory factors tumour necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and interleukin-6(IL-6)were measured by enzyme-linked immunosorbent assay(ELISA).morphology.The effects of PCP on mouse intestinal microorganisms and metabolites of short-chain fatty acids(SCFAs)were investigated by GC-MS quantitative analysis of the concentration of SCFAs in mouse faeces.The expression of SREBP-1α,FAS,ACC,DGAT1,PPARα,CPT1α,HMGCR and CYP51 in mouse liver tissue and LPL,FAS,ACC and DGAT2 in adipose tissue were detected by RT-PCR to investigate the regulation of lipid metabolism by PCP in mice.The gene expression levels of TLR-4 and the inflammatory factors TNF-α,IL-1β and IL-6 were measured by RT-PCR,and the gene expression levels of intestinal tight junction proteins Claudin-1,Occludin and ZO-1 were also measured by Western blot.The gene expression levels of intestinal tight junction proteins Claudin-1,Occludin and ZO-1 were also examined.Results:1.There was no significant difference in the daily energy intake of the mice in each group(P > 0.05).PCP-H significantly reduced the body weight,serum fasting glucose,TC,TG and LDL-C levels in the HFD group compared to the NG group(P <0.01).PCP-H significantly reduced the body weight,serum fasting glucose,TC and TG levels in the HFD group(P < 0.01),and its effect was similar to that of the positive control drug orlistat,indicating that PCP has a significant effect on the regulation of obesity.2.The results of the gut microbial analysis showed that HFD induced a significant decrease in the relative abundance of the phylum Bacillus and a significant increase in the ratio of the thick-walled phylum to the phylum Bacillus compared to the NG group.SCFAs analysis showed that HFD significantly reduced the concentration of total short-chain fatty acids in intestinal microbial metabolites,while PCP significantly increased the concentration of short-chain fatty acids such as acetic acid,propionic acid and butyric acid and significantly reduced the concentration of isovaleric acid.Analysis of the association between gut microorganisms and SCFAs by the Spearman method showed that PCP enriched the number of SCFAs-producing bacteria such as Muribaculaceae and Prevotella,and reduced the number of isovaleric acid-producing bacteria such as Helicobacter pylori and Desulfovibrio,thereby improving the dysbiosis of the intestinal flora caused by HFD and exerting a weightloss and lipid-lowering effect.3.In this study,we further investigated the mechanism of weight loss and lipid reduction by PCP and found that the number of intestinal lipopolysaccharide(LPS)-producing bacteria was significantly increased in HFD mice compared to the NG group,resulting in local inflammation in the intestine and impaired intestinal barrier function.-4-mediated inflammatory factors TNF-α,IL-1β and IL-6,thereby reducing local inflammation in the gut.The reduced inflammatory response in the intestine leads to increased expression of the transmembrane proteins Cloudin-1,Occludin and cytoplasmic protein ZO-1,and restoration of intestinal barrier function and intestinal permeability,resulting in a reduction in the concentration of LPS and the number of harmful bacteria entering the bloodstream,leading to a reduction in the concentration of serum inflammatory factors TNF-α,IL-1β and IL-6,which in turn attenuates the systemic chronic The effect of PCP on weight loss and lipid reduction is ultimately achieved through the reduction of serum inflammatory factors TNF-α,IL-1β and IL-6.4.In this study,further investigation of the mechanism of weight loss and lipid reduction by PCP revealed that HFD induced a significant increase in the expression levels of fatty acid synthesis genes and a significant decrease in the expression levels of fatty acid metabolism genes compared to the NG group.PCP significantly decreased the expression of fatty acid ab initio synthesis genes SREBP-1α,FAS and ACC and increased the expression of fatty acid metabolism genes PPARα,CPT1α and DGAT1 through activation of the AMPK pathway.CPT1α and DGAT1 to reduce TG accumulation in the liver,which may be related to PCP increasing the relative abundance of Emmanuellae,and increasing the gene expression of HMGCR and CYP51 to reduce TC accumulation in the liver;PCP reduces TG accumulation in adipose tissue by decreasing the expression of the fatty acid ab initio synthesis genes FAS and ACC and increasing the expression of the TG biosynthesis genes LPL and DGAT2,which may be related to the fact that PCP increases the concentration of butyric acid in the intestine that slows fat deposition.Conclusion:PCP has a significant weight loss effect on high-fat diet-induced obesity.Further mechanistic studies have shown that PCP exerts a weight loss and lipid-lowering effect by regulating the structure and composition of intestinal microorganisms,increasing microbial richness and diversity,and enriching the number of acetic acid,propionic acid and butyric acid producing bacteria and beneficial bacteria,while reducing the number of isovaleric acid producing bacteria and pathogenic bacteria;PCP exerts a weight loss and lipid-lowering effect by reducing the number of harmful bacteria such as Helicobacter pylori,reducing local inflammation in the intestine,and restoring the function of the intestinal barrier,thus PCP plays a role in weight loss and fat reduction by reducing chronic low-level inflammation in the body;in addition,PCP reduces the accumulation of TC and TG in the liver,inhibits the de novo synthesis of TG in fat and promotes lipolysis,thus exerting a weight loss and lipidlowering effect.