Structural characterization of an acetylated glucomannan from Aloe barbadensis and its alleviation of murine colitis via coordinated ECM repair and microbiota-metabolism actions.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease for which effective and durable therapeutic strategies remain limited. In this study, an acetylated glucomannan polysaccharide, Aloe barbadensis polysaccharide 7 (ABPA7), was isolated and purified from the gel of Aloe barbadensis with a purity of 97.65%. Structural characterization revealed that ABPA7 is a highly homogeneous β-(1 → 4)-linked mannan, low branching, site-specific O-acetylation at the O-2/O-2,3 positions, and a high molecular weight of approximately 647 kDa. Functionally, ABPA7 markedly alleviated disease severity in a dextran sulfate sodium (DSS)-induced mouse colitis model. Mechanistic investigations demonstrated that ABPA7 reinforced intestinal barrier integrity by restoring tight junction protein expression and suppressing pro-inflammatory cytokine production. In parallel, ABPA7 was associated with alterations in gut microbiota composition and microbial metabolic networks. Transcriptomic analyses further indicated that ABPA7 upregulates the extracellular matrix (ECM) related gene expression of the intestinal. Collectively, these findings support the involvement of a coordinated "microbiota-metabolism-host" regulatory framework underlying the anti-colitis effects of ABPA7, encompassing inflammation attenuation, barrier reinforcement, and controlled ECM remodeling. This study underscores the therapeutic potential of structurally defined aloe polysaccharides and provides a mechanistic reference for the rational development of polysaccharide-based interventions for ulcerative colitis.