Polysaccharide from Schisandra chinensis alleviates ulcerative colitis by improving intestinal microbiota abundance and inhibiting the TLR4/p65/IκBα pathway in Dextran sodium sulfate-induced mice

Schisandra chinensis polysaccharides (SCP) are isolated from Schisandra chinensis with a mean molecular weight of 32.401 kDa. Previous studies have demonstrated that Schisandra chinensis extract effectively prevented colitis and modulated gut microbiota in dextran sulfate sodium (DSS)-induced mice. In this study, 3% DSS was used to induce acute ulcerative colitis in mice, and then the SCP with different doses (50 mg/kg, 100 mg/kg, 200 mg/kg) and 5- aminosalicylic acid (5-ASA) were used to treat mice by oral gavage for one week. Here, we report for the first time that SCP presents outstanding protective effects on colon damage induced by DSS in mice. Firstly, SCP decreased oxidative stress, downregulated the expression of inflammatory factors, and inhibited the TLR4/p65/IκBα pathway in the colon. Then, SCP reversed DSS-induced intestinal barrier damage by improving the tight junction proteins. Moreover, SCP improved the levels of SCFA in the intestine of mice. Furthermore, SCP increased the diversity of gut microbiota and the abundance of beneficial bacteria, especially Lactobacillus and Akkermansia. Our results indicated that the protective effect of SCP on colitis caused by DSS may be due to inhibiting the TLR4/p65/IκBα pathway and the regulation of gut microbiota.