Khaya Senegalensis inhibitory activity against α-glucosidase

Abstract

α-glucosidase is an enzyme responsible for the hydrolysis of oligosaccharides to simple absorbable sugars. The inhibition of the enzyme is implicated in the management of postprandial hyperglycaemia. The current study evaluates the α-glucosidase inhibitory potentials of Khaya senegalensis stem bark. The result of an in vitro analysis using α-glucosidase from Saccharomyces cerevisiae and p-nitrophenyl α-D-glucopyranoside as substrate showed that the stem bark extract of K. senegalensis (IC₅₀ = 7.7 ± 0.02 μg /ml), had a significant inhibitory effect on α-glucosidase in a concentration dependant manner. From the study of the enzyme kinetics, the stem bark extract of K. senegalensis exhibited a non-competitive inhibition with a Ki of 0.33μg/ml. In an in vivo study, using Wistar albino rats, the extract significantly attenuated postprandial hyperglycaemia of area under glucose curve (AUCGlucose) following maltose administration. Two hitherto unknown bioactive compounds with α-glucosidase inhibitory activity were obtained from the methanol partition of the aqueous extract. The study concludes that the blood glucose-lowering effect of K. senegalensis is partly mediated by inhibiting the α-glucosidase activity in the intestine.