Purification and in Vitro Bioactivity of Polysaccharide from Wencheng Waxy Yam

Objective: To explore the potential of waxy yam polysaccharide in regulating glycolipid metabolism. Methods: Waxy yam polysaccharide (WCYP1) was purified using DEAE-52 cellulose chromatography, and its antioxidant, hypoglycemic, hypolipidemic activities and ability to improve insulin resistance (IR) were evaluated. Results: The total sugar content of WCYP1 was determined to be 96.90%, while the protein content was 2.78%. Infrared scanning revealed typical characteristic absorption peaks of polysaccharides. The weight-average molecular weight of WCYP1 was determined to be 145.693 kDa, while the number-average molecular weight was 45.628 kDa. WCYP1 consisted of 1.41% fucose, 5.89% rhamnose, 1.90% arabinose, 5.47% galactose, 13.49% glucose, 2.79% xylose, 67.89% mannose, and 1.17% glucuronic acid. At a concentration of 3 mg/mL, the DPPH and ABTS⁺ free radicals scavenging rates were 79.41%±0.47% and 81.14%±1.97%; the inhibition rates on α-amylase and α-glucosidase were 84.21%±5.26% and 36.67%±1.15%. When the WCYP1 concentration reached 4 mg/mL, the binding rates to sodium taurocholate and sodium glycocholate were 98.07%±0.02% and 98.03%±0.06%. And 200, 500, 800 µg/mL WCYP1 could significantly increase the glucose consumption of IR-HepG2 (P<0.05), and there was a positive correlation with the concentration. Meanwhile, 200 and 500 µg/mL WCYP1 administration for 24 h didn't affect the viability of IR-HepG2 cells. Conclusion: WCYP1 had certain in vitro antioxidant, hypoglycemic and hypolipidemic effects, and could effectively improve the state of IR. This provided theoretical support for the development and utilization of WCYP1.