Polyphenols-rich Cyamopsis tetragonoloba (L.) Taub. beans show hypoglycemic and β-cells protective effects in type 2 diabetic rats

The aim of this study was to evaluate the antidiabetic activity of Cyamopsis tetragonoloba (L) Taub. (Fabaceae) beans in high-fat diet (HFD) fed-streptozotocin (STZ)-induced type 2 diabetic rats. Dose dependent response of oral treatment of C tetragonoloba beans' methanol extract (CTme) (200 and 400 mg/kg b wt.) was assessed by measuring fasting blood glucose, changes in body weight, plasma insulin, homeostasis model assessment of insulin resistance (HOMA-IR), total cholesterol, triglycerides, oral glucose tolerance, intraperitoneal insulin tolerance, hepatic glycogen, marker enzymes of carbohydrate metabolism in HFD fed-STZ-induced type 2 diabetic rats. Histology and immunohistochemical analysis of pancreatic islets were also performed. High-performance liquid chromatography (HPLC) analysis of CTme showed the presence of polyphenols such as gallic acid and caffeic acid in the concentrations of 2.46% (W/W) and 0.32% (W/W). CTme significantly reverted the altered biochemical parameters to near normal levels in diabetic rats. Furthermore CTme showed the protective effect on the beta-cells of pancreatic tissues in diabetic rats. These findings indicate that C. tetragonoloba beans have therapeutic potential in HFD fed-STZ-induced hyperglycemia; therefore this can be used in the management of type 2 diabetes. (C) 2014 Elsevier Ltd. All rights reserved.