Abstract: Objective: To investigate the effect of Dioscorea opposita Thunb. polysaccharide (DTP) extracted from the rhizomes of the ‘Foshou’ cultivar on glycolipid metabolism and oxidative stress in type 2 diabetic rats. Methods: A rat model of type 2 diabetes mellitus (T2DM) was constructed by feeding SD rats a high-fat diet and intraperitoneal injection of streptozocin into them at a dose of 40 mg/kg. The model rats were randomly divided into model control group (MC), positive control group (PC) (metformin at 150 mg/(kg·d)), DTP group (400 mg/(kg·d)), and normal control group (NC). During an administration period of six weeks, the general condition of rats was observed. Body weight, hepatic glycogen, blood glucose, and triacylglyceride (TG), low density lipoprotein cholesterol (LDL-C), HDL-C, malonaldehyde (MDA), nitric oxide (NO) and the activties of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) in serum were tested. Results: Compared with the model group, DTP effetively lowered fasting blood glucose levels in rats with experimental T2DM, highly significantly reduced serum TC and LDL-C levels, significantly decreased serum TG levels, and significantly enhanced the activities of SOD and CAT, but it had no significant impacts on hepatic glycogen, serum HDL-C, MDA and NO levels or serum GSH-Px activity. Conclusion: DTP shows a significant hypoglycemic effect on T2DM rats, and can regulate lipid metabolic disorders and the underlying mechanism may be associated with the enhanced activities of CAT and SOD.

Key words: Dioscorea opposita Thunb., polysaccharide, type 2 diabetes, blood glucose, blood lipids