Iminosugars

Iminosugars are a class of carbohydrate mimetics in which the ring oxygen of a typical sugar is replaced by a nitrogen atom. The resulting azasugar frameworks are usually five- or six-membered rings, such as pyrrolidine or piperidine cores, bearing multiple hydroxyl groups that resemble the stereochemistry of hexoses or pentoses. They are often referred to as iminosugars or azasugars and are studied for their ability to interact with glycoside-processing enzymes.

Natural examples and derivatives include nojirimycin, 1-deoxynojirimycin (DNJ), swainsonine, and castanospermine. These compounds inhibit glycosidases by mimicking the oxocarbenium ion transition state of glycosidic bond hydrolysis, leading to broad or selective inhibition of enzymes such as glucosidases and mannosidases. Some derivatives have been developed as therapeutics; for example miglustat (N-butyldeoxynojirimycin) and related iminosugars are used as substrate-reduction therapies for lysosomal storage disorders and as antiviral leads.

Beyond pharmacology, iminosugars are used as tools in glycobiology and medicinal chemistry to study carbohydrate-processing pathways. They are typically synthesized from chiral pool sugar derivatives or via amino-alcohol building blocks, and their biological activity depends on ring size, substitution pattern, and stereochemistry.