L-β-Galactoglucan alleviates loperamide-induced constipation in mice and regulates gut microbiota and metabolism.

Constipation is a common gastrointestinal disorder that affects millions of individuals worldwide. This study investigated the modulatory effects of L-β-galactoglucan, a novel exopolysaccharide derived from Agrobacterium sp. FN01, in a loperamide-induced murine constipation model. Mice were orally administered loperamide (10 mg/kg body weight) to induce constipation and subsequently received L-β-galactoglucan at doses of 0, 200, 400, or 800 mg/kg body weight for 14 days. The modulatory effects of L-β-galactoglucan were elucidated through an integrated approach combining histological, molecular, microbial, and metabolomic analyses. The results showed that L-β-galactoglucan significantly accelerated intestinal transit and increased fecal water content in constipated mice. Notably, L-β-galactoglucan reshaped gut microbiota composition, characterized by increased abundance of Muribaculaceae and decreased abundance of the Prevotellaceae_NK3B31_group and Prevotellaceae_UCG_001 group. Spearman correlation analysis revealed that the L-β-galactoglucan-induced alterations in the microbiota were closely associated with specific changes in colonic metabolic profiles. Furthermore, L-β-galactoglucan downregulated colonic aquaporins (AQP3 and AQP8) and upregulated tight junction proteins (claudin-3 and claudin-4), indicating a role in modulating water transport and regulating barrier-related molecular markers. Collectively, L-β-galactoglucan alleviated constipation phenotypes and reshaped the gut microbiota and metabolic profiles, highlighting its potential as a dietary bioactive resource for constipation management.