Helianthus annuus Leaf Ameliorates Postprandial Hyperglycaemia by Inhibiting Carbohydrate Hydrolyzing Enzymes Associated with Type-2 Diabetes

Background: Diabetes mellitus is a chronic disease. Decreasing postprandial hyperglycemia by retarding glucose absorption through inhibiting carbohydrates digesting enzymes (α-amylase and α-glucosidase) is one of many approaches used for the management of this disease. This study was aimed at evaluating the normoglycaemic potential of Helianthus annuus leaf. Methods: The effect of the in vitro inhibitory of different extracts (acetone, ethyl acetate and hexane) of the plant was assessed on the activities of diabetes-related enzymes (α-amylase and α-glucosidase). Results: The hexane extract of H. annuus leaf displayed the best inhibitory activity against α- amylase and α-glucosidase as indicated by the IC50 values (3.92 ± 0.02 mg mL^-1) and (3.29 ± 0.12 mg mL^-1), respectively. Lineweaver-Burk plot of inhibition of α-amylase and α-glucosidase by this extract showed that it was competitive and non-competitive mode, respectively. Conclusion: H. annuus leaf possesses hypoglycaemic potential which may be due to the inhibition of pancreatic α-amylase and intestinal α-glucosidase.