Abstract
BACKGROUND/OBJECTIVES: Mori fructus polysaccharides are key bioactive components with diverse activities, but structural characterization of homogeneous fractions remains limited, hindering insights into structure-activity relationships. This study addresses this gap by isolating and characterizing a homogeneous polysaccharide (MFP-III) from M. fructus. METHODS: MFP-III, representing the final gel-filtration homogeneous fraction, was purified using defined procedures: DEAE-52 cellulose chromatography followed by Sephadex G-100 gel filtration. Purity and homogeneity were validated by high-performance liquid chromatography (HPLC). Structural characteristics were analyzed via HPLC, GC-MS, FTIR, and NMR spectroscopy. Meanwhile, hypoglycemic activity of MFP-III was evaluated. RESULTS: MFP-III (94.2 ± 2.6%) has a molecular weight of approximately 6.83 kDa, primarily composed of rhamnose, arabinose, galactose, glucose, mannose, and galacturonic acid. Its backbone structure is presumed to be →2,4)-α-L-Rhap-(1 → 4)-α-D-GalpA-(1→, with branching units potentially attached to O-4. MFP-III demonstrated significant inhibitory activity against α-glucosidase (IC(50) = 1.56 mg/mL) and α-amylase (IC(50) = 2.07 mg/mL), stronger than acarbose at equivalent concentrations. CONCLUSIONS: The findings provide preliminary insights into the hypoglycemic structure-activity relationship of MFP-III, providing data support for the development of blood glucose-lowering natural inhibitors, and offering a theoretical foundation for advancing the application of polysaccharides from other sources.