Abstract

• Diabetes mellitusis a metabolic disorder characterized by chronic hyperglycemia. The management of the blood glucose level is a critical strategy in the control of diabetes complications. Low-cost herbal treatment is recommended due to their lesser side effect for treatment of diabetes. In this paper, tubers of D. bulbifera having significant traditional therapeutic potential were tested for their efficiency to inhibit α -amylase and α - glucosidase. In vitro α -amylase inhibitory activity of pet-ether, ethyl acetate, ethanol extracts as well as antidiabetic drugs, acarbose and metformin, were determined by starch iodine method and the 50 % inhibitory activity was found to be 172.50 μg/mL, 62.50 μg/mL, 65.00 μg/ mL, 60.50 μg/mL and 42.50 μg/mL respectively. In vitro α -glucosidase inhibitory activity was measured by glucose oxidase method and the IC50 values of acarbose, metformin, pet-ether, ethyl acetate and ethanol were found to be 35.75, 67.75, 137.50, 80.00 and 115.25 μg/mL respectively. From ethyl acetate extract which revealed significant inhibitory activity on both enzymes, compounds A, B and C were isolated by column and thin layer chromatography and identified by modern spectroscopic methods. From these assessments, the isolated compounds were ß-sitosterol (A) (0.0412 % yield, m.p 139 °C), diosbulbin B (B) (0.0012 % yield, m.p 217 °C) and 8-epidiosbulbin E-acetate (C) (0.0210 % yield, m.p 225 °C).