alpha-Glucosidase inhibitory activity was found in aqueous methanol extracts of dried hyssop (Hyssopus officinalis) leaves. Active principles against alpha-glucosidase, prepared from rat small intestine acetone powders, were isolated and characterized. The structures of these isolated compounds were determined to be (7S, 8S)-syringoylglycerol-9-O-(6'-O-cinnamoyl)-beta-D-glucopyranoside and (7S, 8S)-syringoylglycerol 9-O-beta-D-glucopyranoside by analysis of physical and spectroscopic data (FDMS, 1H NMR, 13C NMR, HMQC, and HMBC experiments) together with chemical syntheses.