Biological activities of 3,4,5-trihydroxypiperidines and their N- and O-derivatives

3,4,5-Trihydroxypiperidines belong to the family of 1,5-dideoxy-1,5-iminosugar natural products and are structural analogues of pentose monosaccharides in the pyranose form. The biological activities of these apparently structurally simple molecules and their N- and O-alkylated and -arylated derivatives are no less remarkable than their C-6 hydroxymethyl counterparts of the hexoses (such as 1-deoxynojirimycin, DNJ). Their biological profiles indicate that the hydroxymethyl branch is crucial to neither potency nor selectivity, with O-alkylation demonstrated to produce exquisite selectivity extending beyond glycosidase inhibition, to immunosuppressant and antibacterial activities.