Optimization of compound enzyme-assisted ultrasound extraction for Polygonatum sibiricum polysaccharides with characterization and bioactivity evaluation

Polygonatum sibiricum (PS) is a medicinal plant with significant therapeutic value, and Polygonatum sibiricum polysaccharide (PSP) represent its core bioactive components. We developed an ultrasound-assisted mixed-enzyme extraction process for PSP preparation and optimized the parameters. Subsequently, PSP was characterized to determine its microstructure, functional groups, and crystalline structure. Its monosaccharide composition and molecular weight were also determined. Finally, oligoasthenospermia (OAS) mouse models were established to evaluate therapeutic effects. The results demonstrated optimal extraction conditions: 105 min extraction time, 61°C temperature, 1:25 material-liquid ratio, and an enzyme dosage of 3080 U g -1 of dry material. The PSP yield reached 28.26%. PSP presented as amorphous flakes with characteristic polysaccharide functional groups, containing arabinose (1.7 μg mg -1 ), galactose (7.61 μg mg -1 ), glucose (571.47 μg mg -1 ), mannose (17.4 μg mg -1 ), and fructose (25.83 μg mg -1 ), with a molecular weight of 25,444 Da (within the medium molecular weight range of 10-100 kDa). PSP significantly enhanced sperm quality in OAS mice and upregulated CYP17A1 and HSD3β2 expression ( p <0.05). This indicates PSP promotes testosterone synthesis by regulating key steroidogenic enzymes. Therefore, the established process enables the large-scale production of PSP, which demonstrates the potential to treat OAS by modulating molecular mechanisms, laying the foundation for the development of biological products for reproductive health.