Inhibitory Effect of Vegetables, Fruits and Herbs on α-Glucosidase in an Immobilized Enzyme Assay System

Abstract

A system using immobilized enzyme according to Oki et al., [Biol. Pharm. Bull. 23(9) 1084-1087 (2000)], which mimics the small intestinal membrane, was applied to the screening of several kinds of vegetables, fruits and herbs in terms of their inhibitory effects on α-glucosidase (AGH).
AGH was partially purified from hog intestinal membrane by salting out, followed by immobilization on CNBr-activated Sepharose 4B as a matrix. As substrate, p-nitrophenyl-α-D-glucopyranoside (PNPG) was employed, producing p-nitrophenol (p-NP) by enzymic hydrolysis. Seven vegetables (Japanese radish, cabbage, onion, Chinese cabbage, tomato, cucumber, and carrot), 5 fruits (mandarin, apple, watermelon, melon, and grapefruit) and 4 herbs (Italian parsley, rucola, mache, and dill) were subjected to evaluations of the inhibitory effect on AGH.
All of the test samples exerted an inhibitory effect on immobilized AGH (iAGH). Raw Chinese cabbage and boiled tomato among vegetables, mandarin among fruits and dill among herbs exerted the strongest inhibitory effect on iAGH.