They possess features of relative and absolute configuration that are characteristic of their class and have been extensively studied; but these features are not clearly displayed by general methods of stereochemical nomenclature, so that special methods of specifying their configuration are justified and have long been used.
[1] The aminocyclitol family of natural products is a class of sugar-derived microbial secondary metabolites that demonstrate significant biological activities.
The class of aminocyclitol containing natural products can be divided by ring sizes or types of precursors.
This class includes acarbose, validamycin, validoxylamine A,[2] salbostatin, cetoniacytone A,[3] pyralomicin 1a,[4] kirkamide[5] 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.
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).