The Inhibitory Activity of α-Glucosidase in Methanol Extract of Some Antidiabetic Medicinal Plants in Sulaymaniyah Province

Control of hyperglycemia after meals is an important strategy in the management of type II diabetes, and the reduction of chronic complications associated with it. Therefore, inhibitors of carbohydrate-degrading enzymes such as α-glucosidase can be useful in the treatment of this disease. The aim of this study was to evaluate the α-glucosidase inhibitory activity in some traditional medicines in Sulaymaniyah province of Iraq.

Eight plant species were prepared with advisory from authentic spiceries in Sulaymaniyah. After air drying and preparation of their methanolic extracts, enzyme microplate assay was conducted on them in four different extract concentrations (1, 0.1, 0.01 and 0.001 mg/ml) along with negative and positive controls. Finally, enzyme kinetic analysis was performed on effective extracts.

Among the eleven studied plant species, Rubus idaeus L., Rheum ribes R. and Salix alba L. extracts at 1 mg/mL concentration showed highest inhibitory activity (98.13±1.05% (IC50=0.046 mg/mL), 93.39±2.11% (IC50=0.085 mg/mL) and 84.46±1.12% (IC50=0.125 mg/mL), respectively) against α-glucosidase,. After kinetic analysis of α-glucosidase inhibition, Rubus idaeus L., Rheum ribes R. extracts showed mixed type of inhibition (competitive- uncompetitive) while extract of Salix alba showed uncompetitive type of inhibition.

The leave extract from both Rubus idaeus, Salix alba and root extract of Rheum ribes are remarkable α-glucosidase inhibitors, and may be used in the treatment of type II diabetics after clinical tests.