Aqueous methanol extracts from the bulbs of Hyacinthus orientalis were subjected to various ion-exchange column chromatographic steps to give 2(R),5(R)-bis(hydroxymethyl)-3(R),4(R)-dihydroxypyrrolidine (DMDP) (1), 2,5- dideoxy-2,5-imino-DL-glycero-D-manno-heptitol (homoDMDP) (2), 2,5-imino- 2,5,6-trideoxy-D-manno-heptitol (6-deoxy-homoDMDP) (3), 2,5-imino-2,5,6- trideoxy-D-gulo-heptitol (4), 1-deoxynojirimycin (5), 1-deoxymannojirimycin (6), α-homonojirimycin (7), β-homonojirimycin (8), α-homomannojirimycin (9), β-homomannojirimycin (10), and 7-Oβ-D-glucopyranosyl-α- homonojirimycin (MDL 25,637) (11). The structures of the new natural products 3 and 4 were determined by spectroscopic analysis, including extensive 1D and 2D NMR studies. Compound 2 was found to be a potent inhibitor of bacterial β-glucosidase, mammalian β-galactosidases, and mammalian trehalases, while 3 was a potent inhibitor of rice α-glucosidase and rat intestinal maltase. Compound 4 was observed to be a good inhibitor of α-L-fucosidase.
