The acid polysaccharides extracted from Moringa leaf improve DSS-induced ulcerative colitis by targeting intestinal microbiota metabolism.

Ulcerative colitis (UC) represents a category of inflammatory bowel disease (IBD) that currently lacks curative therapeutic options. This study isolated acidic polysaccharides from Moringa leaves using water extraction and ethanol precipitation, and characterized their saccharide chain structure. The acidic polysaccharide MOLP-2-2 is primarily composed of monosaccharides such as Galacturonic acid (Gal-UA), Galactose (Gal), and arabinose (Ara), with an Mn of 20.353 kDa; Mw of 35.094 kDa. The main sugar chain structure primarily comprises →4)-α-D-GalpA-(1→, →4)-α-D-GalpA-6-OMe-(1→, →4)-β-D-Galp-(1→, and →2,4)-α-L-Rhap-(1 → units. The side chains are predominantly comprised 4-OMe-β-D-Galp-(1→, →3,6)-β-D-Galp-(1→, and →6)-β-D-Galp-(1 → units. The potential of these polysaccharides as functional prebiotics in ameliorating DSS-induced UC in mice was investigated, and the underlying molecular mechanisms were explored. The mechanism of action may involve increasing the relative abundance of probiotic strains such as Intestinimonas, thereby promoting the secretion of the metabolites such as DL-Lysine, further modulating the expression of proteins associated with the NF-κB/MAPK and Keap1-Nrf2-HO-1 signaling pathways, thereby suppressing the release of pro-inflammatory cytokines and enhancing antioxidant capacity in mice, ultimately alleviating DSS-induced ulcerative colitis. Overall, this study demonstrates that the novel polysaccharide MOLP-2 can serve as a functional prebiotic for UC prevention and treatment.