Aminocyclitol

The aminocyclitol family of natural products is a class of sugar-derived microbial secondary metabolites that demonstrate significant biological activities. Aminocyclitols are found as a component of aminoglycoside antibiotics which is also called as pseudosugars or pseudosaccharides. Aminocyclitols have chemical structures of a carbon ring with amine functional group(s). The class of aminocyclitol containing natural products can be divided by ring sizes or types of precursors.

Sedoheptulose 7-phosphate, a pentose phosphate pathway intermediate, is a common precursor of C7N aminocyclitol moiety of natural products, such as acarbose,[6] validamycin A,[7] salbostatin,[8] cetoniacytone A,[9][10] and pyralomicin 1a.[11] 2-epi-5-epi-valiolone synthase (EEVS),[6][12][13] one of the sugar phosphate cyclase family enzyme[9] and which is a homolog of 3-dehydroquinate synthase in shikimate pathway, catalyzes the formation of a common intermediate, 2-epi-5-epi-valiolone from sedoheptulose 7-phosphate. After multiple enzyme reaction steps, which include phosphorylation,[14][15] epimerization,[16] dehydration, and keto-reduction reactions, valienol, an important core structure is formed which leads to the formation of C7N aminocyclitol containing natural products. In validamycin biosynthesis, the C-N linkage which connect the C7 cyclitol moiety to the other was found to be formed by unprecedented actions of nucleotidyltransferase[17] and glycosyltransferase-like enzymes[18][19][20] (which is termed pseudoglycosyltransferase).