Studies on the biosynthesis of the a-glucosidase inhibitor acarbose: Valienamine, a m-c7n unit not derived from the shikimate pathway

Abstract

Feeding experiments with Actinoplanes sp. SN223/29 showed that 3-amino-5-hydroxy-[7-13C]benzoic acid is not incorporated into acarbose (I). The valienamine moiety of I is thus not derived in the same way, from the shikimate pathway, as the m-C7N units in the ansamycin, mitomycin and ansamitocin antibiotics. Feeding experiments with [U-13C3]-glycerol followed by analysis of I by multiple quantum NMR spectroscopy support this con-clusion and point to formation of the valienamine moiety by cyclization of a heptulose phos-phate which arises from a triose phosphate via successive transfer of two 2-carbon fragments by transketolase, as proposed by pape and co-workers. © 1987, JAPAN ANTIBIOTICS RESEARCH ASSOCIATION. All rights reserved.