Hypoglycemic effect of Polygonatum orientale Desf. rhizome extract on diabetes induced by streptozotocin in rat model

Background: Polygonatum orientale, an herbaceous and perennial plant from family Asparagaceae, is native to the forests of northern Iran. The hypoglycemic effects of other species of the Polygonatum have been proven. Objective: The aim of this study was to evaluate the hypoglycemic effect of P. orientale rhizome extract and its effects on the antioxidant enzymes in the plasma of the normal and streptozocin induced diabetic rats. Methods: 30 male rats were divided into 6 groups; healthy control, negative control, positive control (metformin, 500 mg/kg) and three groups of diabetic rats (200, 400 and 800 mg/kg) that received the ethanolic (70%) extract orally. After 28 days effects of the extract on blood glucose, superoxide dismutase (SOD) and catalase enzymes, as well as total antioxidant capacity of the plasma (by FRAP test) were investigated. Results: According to the results, the percentage of reduction in blood glucose in the groups of 400 (2%) and 800 (25%) mg/kg compared to the diabetic control group was significantly different, (P<0.05) and (P<0.001), respectively. The difference in blood glucose levels between 400 and 800 mg/kg and metformin was not significant (P>0.05). Also, 200 and 400 mg/kg of the extract reduced the amount of SOD in the plasma comparable to the normal group. Conclusion: It can be concluded that the ethanolic extract of rhizome of P. orientale exhibits a significant hypoglycemic effect that may be related to the presence of steroids, flavonoids and polysaccharides.