Structural characteristics of a mannoglucan isolated from Chinese yam and its treatment effects against gut microbiota dysbiosis and DSS-induced colitis in mice.

A water-soluble polysaccharide named CYP-1 was isolated from Chinese yam. CYP-1 was characterized as a mannoglucan having a backbone consisting predominately of 1,4-α-linked Glcp branched at O-2, O-3, and O-6 position by t-α-linked Manp with a molecular weight of 2.86 kDa. CYP-1 could inhibit the overproduction of pro-inflammatory cytokines (such as TNF-α and IL-1β) in LPS-induced RAW 264.7 cells and DSS-induced colitis mice. Oral administration of CYP-1 dramatically alleviated colonic pathological damage, suppressed the activation of colonic inflammatory signaling pathways (such as NF-κB and NLRP3 inflammasome), recovered the mRNA expression of junctional proteins (such as ZO-1, claudin-1, occludin, and connexin-43), and modulated the gut microbiota by decreasing the abundances of Alistipes, Helicobacter, and an unidentified Enterobacteriaceae, in DSS-induced colitis mice. Overall, the present study elucidated that a new polysaccharide structure CYP-1 from Chinese yam and its therapeutic potential as a prebiotic for the prevention of inflammatory bowel disease.