Composition and enzyme inhibitory properties of finger millet (Eleusine coracana L.) seed coat phenolics: Mode of inhibition of α-glucosidase and pancreatic amylase

Inhibitors of alpha glucosidase and pancreatic amylase play a vital role in the clinical management of postprandial hyperglycemia. Although, powerful synthetic inhibitors are available, natural inhibitors are potentially safer. Phenolic compounds from the millet seed coat were extracted with acidified methanol and characterised by HPLC and ESI-MS. These phenolics showed strong inhibition towards alpha-glucosidase and pancreatic amylase and the IC50 values were 16.9 and 23.5 mu g of phenolics, respectively. The enzyme kinetic studies, using Michaelis-Menton and Lineweaver-Burk equations, indicated that, in the presence of millet phenolics, the Michaelis-Menton constant (K-m) remained constant but the maximal velocity (V-max) decreased, revealing a non-competitive type of inhibition. The study indicated the therapeutic potentiality of millet phenolics in the management of postprandial hyperglycemia. (C) 2009 Published by Elsevier Ltd.