Four new polyhydroxypyrrolizidines, hyacinthacines A1, A2, A3 and B3, have been isolated from the bulbs of Muscari armeniacum (Hyacinthaceae) in addition to the known hyacinthacine C1, which was isolated from Hyacinthoides non-scripta (Hyacinthaceae). The structures of hyacinthacines A1, A2, A3 and B3 were identified on the basis of extensive NMR studies as (1S,2R,3R,7aR)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine, (1R,2R,3R,7aR)-1,2-dihydroxy-3-hydroxymethylpyrrolizidine, (1R,2R,3R,5R,7aR)-1,2-dihydroxy-3-hydroxymethyl-5-methylpyrrolizidine and (1S,2R,3R,5R,7R,7aR)-3-hydroxymethyl-5-methyl-1,2,7-trihydroxypyrrolizidine, respectively, or the corresponding enantiomers. The inhibitory activities of these new hyacinthacines against a variety of glycosidases are described. Copyright (C) 2000 Elsevier Science Ltd.
