Sugars with nitrogen in the ring isolated from the leaves of Morus bombycis

It is known that 1-deoxynojirimycin (1) is contained in the leaves and roots of Morus sp. The modified purification procedures of 1 from leaves of Morus bombycis led to the isolation of many polyhydroxylated alkaloids. These include 1, N-methyl-1-deoxynojirimycin (2), 2-O-α-d-galactopyranosyl-1-deoxynojirimycin (3), fagomine (4), 1,4-dideoxy-1,4-imino-d-arabinitol (5), 1,4-dideoxy-1,4-imino-(2-O-βB-d-glucopyranosyl)-d-arabinitol (6), and 1α,2β,3α,4β-tetrahydroxy-nor-tropane (7), designated nortropanoline. The isolation of 2 is the first report of its natural occurrence. Compounds 3 and 6 are the first naturally occurring glycosides of 1 and 5, respectively. Natural alkaloidal glycosidase inhibitors are classified into five structural types: namely polyhydroxylated piperidines, pyrrolidines, pyrrolines, indolizidines, and pyrrolizidines. Nortropanoline is a novel tropane alkaloid and a new type of polyhydroxylated alkaloid.