From Structure to Function: How Amomum villosum Polysaccharides Exert Antidiabetic Potential by Reshaping the Gut Microbiota

This study extracted polysaccharides from Amomum villosum Lour. using a synergistic fermentation method with Bacillus subtilis and Aspergillus niger. The extract was purified by DEAE-52 and Sephadex G-100 chromatography to obtain a homogeneous fraction, designated AVLP1( Amomum villosum Lour. polysaccharide 1). AVLP1 has a molecular weight of 3247 Da and consists primarily of glucose (95.37%), along with minor amounts of mannose, rhamnose, and arabinose. Structural characterization revealed an amorphous lamellar structure containing pyranose/furanose rings and α/β-glycosidic bonds, with its triple-helix conformation confirmed by Congo red assay. In vitro hypoglycemic assays demonstrated its potent inhibition of α-amylase (97.92%) and α-glucosidase (71.54%) at 10.0 mg/mL. Notably, at 6 mg/mL, its α-amylase inhibitory activity matched that of acarbose, exhibiting strong dose-dependence. Simulated digestion indicated that AVLP1 undergoes partial acid hydrolysis in gastric environments. In vitro fermentation coupled with 16S rRNA sequencing showed that AVLP1 markedly enriches SCFA-producing Bacillota and Megamonas , while reducing the abundance of Pseudomonadota , thereby improving gut microecological balance. SCFA analysis revealed that AVLP1 substantially increased the production of acetate, propionate, and butyrate production, displaying a distinct spatiotemporal pattern: rapid propionate generation, specific butyrate enrichment, and sustained acetate release. Alpha diversity analysis showed significantly higher Shannon/Simpson indices in the AVLP1 group than in the inulin group. Venn diagrams and beta-diversity analyses confirmed significant differences in microbial composition between the AVLP1 group and the control. These findings elucidate a dual-pathway hypoglycemic mechanism for AVLP1, involving combined inhibition of digestive enzymes and enhancement of SCFA production via gut microbiota modulation. This work establishes a theoretical foundation for developing AVLP1 as a functional food ingredient. • A polysaccharide (AVLP1) from Amomum villosum Lour. shows potent hypoglycemic effects and gut microbiota modulation via SCFA production. • AVLP1 potently inhibits α-amylase/glucosidase and modulates gut microbiota to boost SCFA production, improving metabolic health. • The polysaccharide AVLP1 exerts anti-diabetic effects by inhibiting digestive enzymes and enriching SCFA-producing gut bacteria.