Structural characteristics of steamed Polygonatum cyrtonema polysaccharide and its bioactivity on colitis via improving the intestinal barrier and modifying the gut microbiota

Steamed Polygonatum cyrtonema has been commonly used clinically for its gaining effect, whose main active ingredient is a polysaccharide. A water-soluble polysaccharide named PSP-W-1 was isolated from steamed Polygonatum cyrtonema. PSP-W-1 was characterized as a galactan having a backbone consisting predominately of 1,4-β-linked Galp branched at the C-6 position by T-β-linked Galp with a molecular weight of 14.4 kDa. PSP-W-1 could inhibit the overproduction of inflammatory factors and inflammatory mediators (iNOS, IL-6, COX-2) in dextran sodium sulfate-induced colitis mice. Oral administration of PSP-W-1 dramatically alleviated colonic pathological damage, repaired the intestinal barrier (occludin and ZO-1) and regulated the intestinal microbiota by increasing the abundance of norank_f_Muribaculaceae, Lactobacillus and norank_f_norank_o_Clostridia UCG-014, while decreasing the abundance of Bacteroides and Escherichia-Shigella to alleviate colitis symptoms. Overall, our findings suggest that PSP-W-1 might be a therapeutic option for both the prevention and treatment of colitis.