Gem-diamine 1-N-iminosugars as versatile glycomimetics: synthesis, biological activity and therapeutic potential

Iminosugars, which carry a basic nitrogen in the carbohydrate ring, have attracted increasing interest as new glycomimetics. Gem-diamine 1-N-iminosugars, a new class of iminosugars, have a nitrogen atom in place of the anomeric carbon. Various kinds of 1-N-iminosugars have been synthesized from glyconolactones as a chiral source in a totally stereospecific manner and/or by the convergent strategy from siastatin B, a secondary metabolite of Streptomyces. The protonated form of 1-N-iminosugar mimics the charge at the anomeric position in the transition state of enzymatic glycosidic hydrolysis, resulting in a strong and specific inhibition of glycosidases and glycosyltransferases. They have been recently recognized as a new source of therapeutic drug candidates in a wide range of diseases associated with the carbohydrate metabolism of glycoconjugates, such as tumor metastasis, influenza virus infection, lysosomal storage disorder and so forth.