A novel polysaccharide from Wisteriopsis eurybotrya: extraction optimization, structural characterization, and bioactivities

This study optimized the hot-water extraction conditions of Wisteriopsis eurybotrya polysaccharides (WEP) using single-factor tests and response surface methodology, establishing optimal conditions as an extraction temperature of 92 °C, an extraction time of 241 min, and a liquid-solid ratio of 43 mL/g. Subsequently, a purified fraction named WEP-1-1 was isolated from WEP, followed by structural characterization and assessment of its in vitro activities. Structure analysis revealed that WEP-1-1, with a weight-average molecular weight of 130.3 kDa, was composed of Glc, Ara, Gal, Rha, Xyl, and Man in a molar ratio of 74.72:11.31:9.50:1.76:1.70:1.00, featuring a backbone predominantly of α-D-Glcp residues linked by (1 → 6) glycosidic bonds. Furthermore, WEP-1-1 could significantly enhance the glucose uptake in C2C12 myotubes and L02 cells. It also exhibited potent immunostimulatory activity in RAW264.7 cells, significantly enhancing phagocytosis and promoting production of NO and TNF-α. In conclusion, our findings demonstrate that WEP-1-1 is a promising candidate for natural functional materials due to its concurrent hypoglycemic and immunomodulatory activities.