Study on Antioxidant Properties of Pueraria lobata Polysaccharides and Its Hypoglycemic Effect

Objective: To study the antioxidant activity of Pueraria lobata polysaccharide and its hypoglycemic effect. Method: The polysaccharides of Pueraria lobata were extracted by water extraction and alcohol precipitation method, and the polysaccharide content and the antioxidant capacity of Pueraria lobata polysaccharides were determined. Rats were intraperitoneally injected with streptozotocin (STZ) to establish a type 1 diabetes model (T1DM), which was divided into normal group (distilled water 100 mg/kg), model group (distilled water 100 mg/kg), high-dose Pueraria lobata polysaccharide group (100 mg/kg), Pueraria lobata polysaccharide low-dose group (50 mg/kg), positive group (metformin 100 mg/kg), the rats' body weight and fasting blood glucose (FBG) were measured regularly for 8 weeks. In the last week, an oral glucose tolerance (OGTT) test was performed, and rat serum and liver were taken to determine the changes in lipid metabolism indexes and related oxidases in rats. Results: The content of Pueraria lobata polysaccharide was 87.80%, and the scavenging abilities of DPPH·, ABTS⁺·, ·OH, and PTIO were 90.2%, 83.3%, 81.3%, and 89.0% at a concentration of 1000 μg/mL, respectively. Compared with the model group, Pueraria lobata polysaccharide could effectively alleviate the weight loss of T1DM rats, significantly reduced their FBG (P<0.05), and significantly increased the level of OGTT (P<0.05). After high-dose treatment with Pueraria lobata polysaccharide, TC, TG, the levels of LDL-C and MDA decreased significantly, and the levels of HDL-C, SOD, GSH and CAT increased significantly (P<0.05). All indicators were dose-dependent. Conclusion: Pueraria lobata polysaccharide has good antioxidant properties and can reduce blood sugar by improving lipid metabolism and oxidative stress in T1DM rats.