A sea buckthorn pericarp polysaccharide: Structure and amelioration of ulcerative colitis by modulating gut microbiota.

Abstract

Ulcerative colitis (UC) is characterized by colonic mucosal injury, epithelial barrier disruption, and gut microbiota dysbiosis, yet lacks effective therapeutic interventions. Polysaccharides are emerging as promising natural candidates for UC intervention. Sea buckthorn, a traditional medicinal plant, has documented intestinal protective effects; however, its pericarp-derived bioactive components remain largely unexplored. To valorize this botanical resource, a bioactive homogeneous polysaccharide with potential efficacy against UC, designated SBPP-BI (Mw = 62.0 kDa), was isolated and purified from sea buckthorn pericarps in this study. Structural analysis revealed that SBPP-BI features a backbone of T-α-Galp-(1→6)-α-Galp-(1 → 6)-α-Galp-(1 → [4)-α-GalpA-(1 → 4)-α-GalpA-OMe-(1→] → 4)-α-GalpA-3-OAc-(1 → [2)-α-Rhap-(1 → 4)-α-GalpA-(1→]with branched chains including →3)-α-Araf-(1→, →5)-α-Araf-(1→, and T-α-Araf-(1→. In vivo evaluation demonstrated that SBPP-BI markedly ameliorated dextran sulfate sodium-mediated colitis, restored intestinal barrier function, and modulated inflammatory cytokine levels in UC model mice. Mechanistically, 16S rRNA sequencing and gas chromatography-mass spectrometry analysis showed that SBPP-BI modulated gut microbiota composition and restored short-chain fatty acid production. Furthermore, Western blot analysis demonstrated that SBPP-BI suppressed activation of the TLR4/NF-κB signaling pathway in colon tissues. This research elucidates the distinct structure of a polysaccharide from sea buckthorn pericarp with anti-UC activity and highlights its promise as a prebiotic potential for UC management.