Structural characterization of a polysaccharide from Alhagi honey and its protective effect against inflammatory bowel disease by modulating gut microbiota dysbiosis

The Alhagi honey polysaccharide (AHP) exhibits notable anti-inflammatory, antioxidant, and immunomodulatory properties, positioning it as a promising candidate in traditional Chinese medicine. In this investigation, we successfully isolated and purified a neutral AHP, designated AHPN50-1a, subsequently elucidating its structural attributes. AHPN50-1a was found to have a molecular weight of 1.756 × 106 Da, featuring a structural motif characterized by a recurring (1→6)-α-GlcP linker. To comprehensively evaluate its therapeutic potential, we explored the protective effects of AHPN50-1 in a murine model of dextran sodium sulfate-induced colitis. Administration of AHPN50-1 at doses of 200 and 400 mg/kg/day resulted in improved food intake, increased body weight, and increased colon length in mice with acute colitis. Simultaneously, a reduction in the disease activity index and histological scores was observed. AHPN50-1 effectively mitigated colon tissue damage, down-regulated the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) in colon tissue, restored intestinal microbiota diversity, and concentrations of short-chain fatty acids (SCFAs) of gut microbiota metabolites, thus alleviating intestinal inflammation in mice. In summary, our findings underscore the promise of AHPN50-1 as a valuable nutritional or dietary supplement for the treatment and prevention of inflammatory bowel disease.