Naturally occurring iminosugars and related compounds: structure, distribution, and biological activity.

Alkaloids mimicking sugars in size and shape are now believed to be widespread in plants and microorganisms. Iminosugars are monosaccharide analogs in which the ring oxygen has been replaced by an imino group. Such iminosugars inhibit the glycosidases involved in a wide range of important biological processes because of their structural resemblance to the sugar moiety of the natural substrate and the presence of the nitrogen atom mimicking the positive charge of the glycosyl cation intermediate in the enzyme-catalyzed glycoside hydrolysis. These iminosugars and their derivatives are arousing considerable attention as potential therapeutic agents. In this review, the distribution of naturally occurring iminosugars and their biological activities and therapeutic applications will be reviewed and the prospects of iminosugars and their derivatives for new therapeutic applications will also be described.