An acidic polysaccharide from Lycium barbarum L: Isolation, purification, structural characterization, and therapeutic effects on ulcerative colitis

Addressing microbial imbalance is a critical therapeutic strategy for ulcerative colitis (UC). Natural polysaccharides have attracted increasing attention for their potential in UC prevention. In this study, we purified and characterized an acidic heteropolysaccharide (LBP 2–1) from Lycium barbarum L. and systematically evaluated its therapeutic effects on UC. Monosaccharide composition analysis combined with methylation analysis and NMR spectroscopy revealed that LBP 2–1 possesses a complex structure. The backbone is →2)-α-L-Rha p -(1 → 4)-α-D-GalA p -(1 → 6)-β-D-Gal p -(1 → and branched at the O-3/O-4 positions of →3,6)-β-D-Gal p -(1 → and →2,4)-α-L-Rha p -(1 →. The branch chains consist of →5)-α-L-Ara f -(1 →, →3,5)-α-L-Ara f -(1 →, →3)-β-D-Gal p -(1 →, β-D-Gal p -(1 →, and α-L-Ara f -(1 →. Particularly, LBP 2–1 relieved the symptoms of weight loss and colon shortening, and reduced DAI and histopathological scores in UC mice. Furthermore, LBP 2–1 alleviated UC symptoms by enhancing microbiota diversity, increasing the abundance of beneficial bacteria (e.g., norank_f__Muribaculaceae ), and reducing harmful bacteria (e.g., Bacteroides ). These findings elucidate the structural characteristics of a novel acidic polysaccharide and confirm its therapeutic potential for UC treatment.