α-Glucosidase and α-Amylase Inhibitory Compounds from three African Medicinal Plants: An Enzyme Inhibition Kinetics Approach

The quest to find new lead compounds with anti-diabetic effects via the inhibition of α-glucosidase and α-amylase had led us to conduct bioassay guided isolation of three African medicinal plants which resulted in the identification of bicyclo[2.2.0]hexane-2,3,5-triol (1), 3β- O-acetyl betulinic acid (2) and 2,7-dihydroxy-4 H-1-benzopyran-4-one (3), as the bioactive compounds. The compounds demonstrated a significant (P < 0.05) inhibitory effect on α-glucosidase and α-amylase activities than acarbose. Steady state kinetic analysis revealed that compounds 1 and 2 inhibited both α-amylase and α-glucosidase in non-competitive patterns whilst compound 3 was an uncompetitive inhibitor of α-glucosidase and a non-competitive inhibitor of α-amylase. In conclusion, the study has identified three new active α-glucosidase and α-amylase inhibitory compounds that could have the potential to retard postprandial hyperglycemia.