7-Deoxy-6-epi-castanospermine, a Trihydroxyindolizidine Alkaloid Glycosidase Inhibitor from Castanospermum australe

Abstract

A new indolizidine alkaloid has been isolated from the seeds of Castanospermum australe and identified as 7-deoxy-6-epi-castanospermine by ms and 1H- and 13C-nmr spectroscopy. The alkaloid is the first trihydroxylated indolizidine to be isolated from this plant and may represent an intermediate in the biosynthetic pathway to the tetrahydroxy-indolizidines and -pyrrolizidines. It inhibits amyloglucosidase and yeast .alpha.-glucosidase but is significantly less active as a glycosidase inhibitor than its isomer swainsonine and the tetrahydroxylated alkaloids castanospermine, 6-epi-castanospermine, and australine.