Purification and structural characterization of an active polysaccharide from Dendrobium chrysotoxum Lindl. and its therapeutic effect on inflammatory bowel disease in mice

Inflammatory bowel disease (IBD), a chronic disease of gastrointestinal tract, has become a global public health challenge. Previous studies have suggested that Dendrobium chrysotoxum Lindl (DC) are effective in preventing IBD and polysaccharides a class of the major active constituents. In this study, two polysaccharide fractions were isolated and purified from DC, and the more abundant fraction named DCP was further investigated. Structural characterization revealed the molecular weight of DCP had an average molecular weight of 19.7 kDa and a main chain of →4)-β-ᴅ-Glcp (1→, →4)-β-ᴅ-Manp (1→, →4,6)-β-ᴅ-Manp (1→, →4)−3-O-acetyl- β-ᴅ-Manp-(1→ and →4)−2-O-acetyl- α-ᴅ-Manp-(1→, having a degree of branch 6.62 %. Further investigation of its bioactivity revealed significant anti-inflammatory properties, as demonstrated in dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD) mice. The polysaccharide ameliorated IBD symptoms, including attenuating weight loss, lowering disease activity index (DAI), s preventing DSS-induced colon shortening, and alleviating histological damage in the colon. These findings suggest that DCP may serve as a potential potential natural anti-inflammatory agent for IBD management.