Secondary metabolites by chemical screening, 39 - Acyl alpha-L-rhamnopyranosides, a novel family of secondary metabolites from Streptomyces sp.: Isolation and biosynthesis

Abstract

In the course of our chemical screening program, the novel acyl alpha-L-rhamnopyranosides (1-6) were detected as metabolites from five different strains of Streptomycetes. The structures of all these compounds were elucidated by chemical and spectroscopic methods. The biosynthesis of 1 and 3 was established by feeding C-13-labelled acetate, glycerol, and d-glucose to Streptomyces griseoviridis (strain Tu 3634), and resulted in a complete labelling pattern of the 2,4-dimethyl-3-furanylcarbonyl and benzoyl residues, as well as the rhamnose moiety. These results reveal biosynthetic pathways of general importance and give an insight into the generation of the hexose phosphates, from which deoxysugars are formed. The acyl rhamnosides are members of a novel family of microbial metabolites and are considered as rhamnoconjugates from Streptomycetes.