Inhibitory effects of Launaea taraxacifolia and Strychnos spinosa leaves extract on an isolated digestive enzyme linked to type -2 -diabetes mellitus

Abstract

Background: The most prevalent type of diabetes mellitus (Type-2), is managed using many approaches, including the lowering of postprandial hyperglycaemia. Inhibition of key enzymes involved in carbohydrate breakdown such as α-glucosidase and α-amylase has been reported as a novel strategy to delay the absorption of glucose after meals. This study sought to determine the in vitro inhibitory potential of Launaea taraxacifolia and Strychnos spinosa leaf extracts on α-glucosidase enzyme and also determine their modes of inhibiting the enzyme.

Materials and Methods: Plant extracts were prepared using soxhlet apparatus. Inhibitory effect of extracts at different concentrations and mode of inhibition were carried out using α-glucosidase enzyme isolated from the small intestine of a guinea pig. Results: Extracts of Launaea taraxacifolia (LTE) and Strychnos spinosa (SSE) leaves showed α-glucosidase inhibitory potential of approximately 69 % and 79 % respectively as compared to 73 % for standard drug-acarbose at a maximum concentration of 1000 μg/mL. The IC₅₀ values recorded were 205.2±0.044 μg/mL, 129.4±0.094 μg/mL and 196.9±0.036 μg/mL for LTE, SSE and acarbose respectively. The Lineweaver Burk plot showed an uncompetitive mode of inhibition for both LTE and SSE as depicted by the lower K_m and V_max of enzyme inhibited by extracts compared to control. Conclusion: Extracts of Launaea taraxacifolia and Strychnos spinosa leaves showed significant inhibitory effect on an isolated intestinal α-glucosidase enzyme in an uncompetitive mode