Structural Characteristics and Efficacy of Polysaccharides from Fenjiu Vinasse in Alleviating DSS-Induced Ulcerative Colitis

Vinasse, a major by-product of Fenjiu liquor production, is enriched with polysaccharides. However, their structural characteristics and potential anti-inflammatory functions remain unclear. In this study, polysaccharides from Fenjiu vinasse (VPS) were extracted and fractionated into seven sub-fractions (VPS-20 to VPS-80) via sequential alcohol precipitation. The molecular weight (Mw) of the fractions gradually decreased with increasing ethanol concentration. Monosaccharide composition analysis revealed that VPS and its fractions were mainly composed of glucose, mannose, and galactose. Among them, VPS-30 exhibited the most potent anti-inflammatory activity in LPS-induced RAW 264.7 macrophages by significantly reducing NO, IL-1β, IL-6, and TNF-α production. Structural characterization by methylation analysis and NMR spectroscopy indicated that VPS-30 contained six major glycosidic linkages, including 2,3-Araf, T-Manp, 4-Manp, 3-Galp, 4-Glcp, and 4,6-Manp, and its detailed structure was predicted. Furthermore, in DSS-induced ulcerative colitis (UC) mice, VPS-30 markedly alleviated colonic inflammation, restored intestinal barrier integrity by upregulating MUC-2, occludin, and ZO-1, and reshaped gut microbiota diversity, particularly by increasing beneficial genera such as Limosilactobacillus, Butyricicoccus, and Ligilactobacillus. Overall, these findings suggest that Fenjiu vinasse polysaccharides exert significant anti-inflammatory effects and may serve as promising functional food candidates for UC intervention.