Polysaccharides from Sargassum fusiforme after UV/H 2 O 2 degradation effectively ameliorate dextran sulfate sodium-induced colitis.

In this study, degraded polysaccharides from Sargassum fusiforme (PSF-T2) were prepared by UV/H ₂ O ₂ treatment for 2 h, and its effects on ameliorating dextran sulfate sodium-induced colitis were evaluated using a mouse model. Results showed that PSF-T2 relieved colitis symptoms, characterized by increasing the colon length and body weight, decreasing disease activity index and relieving colon damage. In addition, PSF-T2 decreased the secretion and expression of IL-1β, IL-6 and TNF-α, and increased the expression of MUC-2, ZO-1 and occludin. Besides, PSF-T2 promoted the production of short-chain fatty acids and modulated gut microbiota composition (increasing the abundance of Lactobacillaceae , Lachnospiraceae , Oscillospiraceae and Desulfovibrionaceae , and decreasing Bacteroidaceae and Erysipelotrichaceae ). These results suggested that polysaccharides from Sargassum fusiforme after UV/H ₂ O ₂ degradation could ameliorate colitis by decreasing inflammation, protecting the intestinal barrier and modulating gut microbiota. It can provide a theoretical basis for the preparation of bioactive polysaccharides by free radical degradation.