The effects of Saponin derived from Tribulus terrestris on the activity and structure of α-Glucosidase

α-Glucosidase is a kind of hydrolase enzyme that catalyzes the hydrolysis of non-reducing terminal carbohydrates into α-glucose. Inhibition of this enzyme prevent the glucose absorption. Compounds that can inhibit α-glucosidase are widely used for the treatment of type 2 diabetes. Tribulus terrestris is a medicinal plant which is distributed around the world. Saponins in this plant are responsible for its biological activities. In the research, the α-glucosidase inhibitory activity of saponins extracted from Tribulus terrestris has been studied by ELISA reader, UV-Visible, and circular dichroism (CD) spectroscopies. The results of ELISA reader displayed that Saponins have functioned as uncompetitive inhibitory effects on α-glucosidase. The half maximal inhibitory concentration (IC50) value were 38 µM for saponin. The absorption of α-glucosidase increased with the addition of saponin concentrations. Comparison of the α-glucosidase and α-glucosidase-saponin complex displayed that the content of the α-helix structure decreased and the content of the β-sheets and random coils structure increased. Collectively, the results showed that saponins extracted from Tribulus terrestris can disrupt the α glucosidase enzyme structure and inhibit the enzyme activity. Altogether, the saponins extracted from Tribulus terrestris can be a good candidate for Type II diabetes treatment.