In vitro anti-diabetic activity of Tribulus terrestrisL. fruits extracts

Purpose The purpose of this paper is to evaluate the inhibition activity of Tribulus terrestris L. (T. terrestris) fruits extracts with solvents of increasing polarity against α-glucosidase and α-amylase, and to determine the inhibition mode of the most effective extract against both enzymes. Design/methodology/approach Hexane, acetone, ethanol and aqueous extracts of T. terrestris fruits were prepared using ultrasonic sequential extraction and analyzed for their α-amylase and α-glucosidase inhibitory activities by specific assay for each enzyme. The modes of inhibitions were detected using Lineweaver–Burk plots. Findings T. terrestris fruits extracts showed inhibition activity against α-glucosidase and α-amylase which was in the dose-dependent manner. Hexane extract had the highest α-glucosidase inhibition activity (IC50 = 27.28 μg/ml, p = 0.003), followed by acetone and ethanol extracts (IC50 = 60.58 μg/ml and IC50 = 84.21 μg/ml, respectively). The inhibition mode of hexane extract was noncompetitive. While acetone extract showed the highest inhibition activity against α-amylase (IC50 = 6.18 mg/ml, p = 0.002), hexane and ethanol extracts showed no significant difference (IC50 = 13.04 mg/ml and IC50 = 14.20 mg/ml, respectively, p = 0.09). The inhibition mode of acetone extract was competitive. Originality/value T. terrestris fruits extracts had strong inhibition activity against α-glucosidase and α-amylase, and they can be used as a promising anti-diabetic agent.