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 Km and Vmax 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
