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-Rhap-(1 → 4)-α-D-GalAp-(1 → 6)-β-D-Galp-(1 → and branched at the O-3/O-4 positions of →3,6)-β-D-Galp-(1 → and →2,4)-α-L-Rhap-(1 →. The branch chains consist of →5)-α-L-Araf-(1 →, →3,5)-α-L-Araf-(1 →, →3)-β-D-Galp-(1 →, β-D-Galp-(1 →, and α-L-Araf-(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.