Cereal-derived phenolic acids and intestinal alpha glucosidase activity inhibition: Structural activity relationship

Phenolic acids are thought to be involved in modulating the activity of intestinal alpha-glucosidase which is desirable in the treatment and management of diabetes. However, limited data exist on the structural activity relationship between phenolic acid derivatives and intestinal alpha-glucosidase activity inhibition. Thus five (5) hydroxycinnamic and six (6) hydroxybenzoic acid derivatives and four (4) hydroxycinnamic acid conjugates common in cereal grains were used to investigate the structural activity relationship and the kinetics of enzyme inhibition. alpha-Glucosidase activity was inhibited by 4%-55% in the presence of the phenolic acid derivatives. The inhibition potency was dependent on the number of hydroxyl and methoxy groups present in the aromatic ring. Conjugation to other compounds did not affect their inhibition potency. The Lineweaver-Burk plots suggest mixed, competitive and uncompetitive types of inhibition. These results suggest that some derivatives of phenolic acid could play a significant role in prevention and management of diabetes.