Selenium-containing tea polysaccharides ameliorate DSS-induced ulcerative colitis via enhancing the intestinal barrier and regulating the gut microbiota

Both tea polysaccharides and selenium have certain remission potential for ulcerative colitis (UC), but few reports focused on natural selenium-containing tea polysaccharides. The purpose of this study was to isolate a selenium-containing tea polysaccharide (ASeTP) and determine its structure and effects on UC. Results showed that ASeTP was primarily composed of three purified, β-pyranoside-linked, protein-binding polysaccharides (SeTP-1, SeTP-2, and SeTP-3) with SeOC, OSeO, and SeO linkages. Specifically, SeTP-1 was a neutral heteropolysaccharide principally composed of mannose, glucose, galactose, xylose, and arabinose, while SeTP-2 and SeTP-3 were acidic heteropolysaccharides due to the existence of glucuronic acid. ASeTP effectively alleviated the symptoms of weight loss, colon shortens, and disease activity index scores increase in dextran sodium sulfate (DSS)-induced colitis mice. ASeTP attenuated the histological damage and maintained the colonic mucosal barrier via up-regulating the expression of occludin, claudin-1, and zona occludens-1 (ZO-1). ASeTP suppressed the levels of pro-inflammatory cytokines and enhanced the antioxidant capacity of colon tissue. Besides, ASeTP beneficially increased the selenium content of the colon. Furthermore, ASeTP remodeled the gut microbiota by accelerating the proliferation of beneficial bacteria and inhibiting pathogenic microorganisms. Thus, ASeTP has the potential to be a functional food against colitis.