A COSY spectrum has been used to determine the position of inter-residue linkage in 4-O-(β-D-glucopyranosyl) fagomine (1) an example of a new class of glycosides of polyhydroxylated piperidine alkaloids isolated from seed of the legume Xanthocercis zambesiaca. (Bak.) Dunn. Unlike a number of polyhydroxylated piperidines, neither the glucoside (1) nor free fagomine [1,2,5-trideoxy-1,5-imino-D-arabinohexitol] (3) showed any inhibitory activity towards glycosidase enzymes from a variety of sources. © 1985.