Polygonatum sibiricum extract exerts inhibitory effect on diabetes in a rat model

Abstract

Purpose: To investigate the effect of Polygonatum sibiricum extract (PSE) on streptozotocin-induced diabetic rats. Methods: PSE was obtained by steeping the dried Polygonatum sibiricum in water at 60 oC three times, each for 1 h, before first drying in an oven at 100C and then freeze-drying the final extract, thus obtained. Diabetic model rats were prepared by a single intraperitoneal injection of a freshly prepared solution of streptozotocin (50 mg/kg). The rats were randomly divided into 6 groups of ten rats each: negative control, normal control, reference (glibenclamide1 mg/kg) as well as PSE groups, (35, 70 and 140 mg/kg). Blood glucose and plasma insulin levels were measured to determine antihyperglycemic effect. Oxidative stress was evaluated in liver and kidney by their antioxidant markers, viz, lipid peroxidation (LPO), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx) and catalase (CAT). Blood serum levels of creatinine and urea were determined in both diabetic control and treated rats. Results: Compared with diabetic rats, oral administration of PSE at a concentration of 120 mg/kg daily for 30 days showed a significant decrease in fasting blood glucose (118.34 ± 3.29 mg/dL) (p < 0.05) and increased insulin level (12.86± 0.62 uU/mL, p < 0.05). Furthermore, it significantly reduced biochemical parameters (serum creatinine, 0.83 ±0.21 mg/dL, p < 0.05) and serum urea (43.26±1.42 mg/dL, p < 0.05). Conclusion: The results suggest that PSE may effectively normalize impaired antioxidant status in streptozotocin-induced diabetes in a dose-dependent manner. Thus, PSE has a protective effect against lipid peroxidation by scavenging free radicals, restoration of insulin function, and reduction of the incidence of complications.