Structural Characterization of a Branched Polysaccharide Isolated from Thesium chinense Turcz. and Its Ameliorative Effects on Ulcerative Colitis

Ulcerative colitis (UC) is a chronic, complex inflammatory condition with a high global prevalence. Thesium chinense Turcz. is renowned for its antibacterial and anti-inflammatory properties. In this study, a novel branched polysaccharide (TP1) was isolated from Thesium chinense Turcz., primarily composed of fructose, glucose, and galactose with a molecular weight of 5377 Da. Its backbone includes →1)-β-D-Fruf-(2→, →1,6)-β-D-Fruf-(2→, →4)-α-D-Glcp-(1→, and →3,6)-β-D-Galp-(1→ residues, and the side chain is Fruf-(2→6)-β-D-Fruf-(2→ linked to the O-6 of the →1,6)-β-D-Fruf-(2→ residue, while β-D-Galp-(1→ linked to the O-6 of the →3,6)-β-D-Galp-(1→ residue. In DSS-induced UC mice, TP1 significantly ameliorated weight loss, colon shortening, and the intestinal barrier damage. Mechanistically, TP1 reestablished the gut microbiota, increased SCFAs concentrations, activated GPR41/43 receptors, and downregulated proteins expression in the IL-17/NF-κB/JAK2/STAT3 signaling axis. TP1 maintained Th17/Treg homeostasis may through the SCFAs-mediated GPR41/43 pathway and IL-17/NF-κB/JAK2/STAT3 pathway, thereby inhibiting intestinal inflammation to alleviate UC. This study provides new insights into therapeutic strategies for UC.