Polysaccharides from Polygonatum kingianum improve glucose and lipid metabolism in rats fed a high fat diet

Objective: Polygonatum kingianum is a traditional Chinese medicine commonly used to treat diabetes and hyperlipidemia. Polysaccharides from Polygonatum kingianum could regulate glucose and lipid metabolism in high-fat diet (HFD) rats. Methods: The gel permeation chromatography (GPC), liquid chromatography (HPLC) and chemical analysis were used to determine the molecular weight, monosaccharide composition, protein, polysaccharide and uronic acid content of the polysaccharide from Polygonatum kingianum, respectively. Total (PS) and high molecular weight (PSF) polysaccharides (> 100 KDa) were isolated and treated HFD rats for a 14-week period. TC, TG contents in blood samples were measured every two weeks, and HDL-C, LDL-C was measured at 12 and 14 weeks evaluating of blood lipids regulation activity of polysaccharide. The stool samples were used for 16S rDNA V4 highly variable region measurement method to regulate the role of polysaccharide in the intestinal microflora. The content of short chain fatty acid (SCFAs) in faeces was determined by gas chromatography (GC) to investigate the effect of polysaccharides on the content of SCFAs in the intestinal tract of rats. The expression of tight junction protein ZO-1 and occludin of intestinal tissue, and detection of the key protein expression in the LPS-TLR4/NF kappa B signaling pathway were detected by Western blot technique. Results: We found that PS and PSF improved both diabetic symptoms and lipid metabolism. PS and PSF also modulated the gut microbiota composition, abundance and diversity of HFD rats, increased the relative abundance of short chain fatty acid (SCFA) producing bacteria and increased SCFA production, reduced intestinal permeability, relieved gastrointestinal inflammation, and improved lipid metabolism. Conclusion: Polygonatum kingianum polysaccharides regulated the abundance and diversity of the intestinal microbial community through increasing the relative abundance of SCFA-producing bacteria. This promotes recovery of the intestinal permeability barrier, inhibits LPS entry into the circulation, alleviates inflammation, and prevents glucose and lipid metabolic disorders.