Polysaccharides from Sargassum fusiforme after UV/H2O2 degradation effectively ameliorate dextran sulfate sodium-induced colitis.

In this study, degraded polysaccharides from Sargassum fusiforme (PSF-T2) were prepared by UV/H2O2 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/H2O2 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.