6-Hydroxyflavonoids as α-Glucosidase Inhibitors from Marjoram (<i>Origanum majorana</i>) Leaves

Abstract

A methanol extract of marjoram leaves strongly inhibited rat intestinal alpha-glucosidase. Five 6-hydroxyflavonoids, 6-hydroxyapigenin (scutellarein; IC50 for sucrose hydrolysis by rat intestinal alpha-glucosidase, 12 microM), 6-hydroxyapigenin-7-O-beta-D-glucopyranoside (> 500 microM), 6-hydroxyluteolin-7-O-beta-D-glucopyranoside (300 microM), 6-hydroxyapigenin-7-O-(6-O-feruloyl)-beta-D-glucopyranoside (>500 microM), and 6-hydroxyluteolin-7-O-(6-O-feruloyl)-beta-D-glucopyranoside (> 500 microM), were isolated as active principles and related compounds. The two feruloylglucosides are novel compounds.