Antibiotics from gliding bacteria, LXXVIII: Ripostatin A, B, and C: Isolation and structure elucidation of novel metabolites from Sorangium cellulosum

Article abstract of DOI:10.1002/jlac.199619961026

Three closely related new metabolites named ripostatins were isolated from the myxobacterium Sorangium cellulosum and their structures elucidated by spectroscopic methods. Two of them, ripostatin A (1a, b) and B (2a), are 14-membered macrolides with an acetic acid and a phenylalkyl side chain, whereas the third metabolite ripostatin C (3a) is an acyclic derivative of ripostatin A. By application of the method of Helmchen the absolute stereochemistry could be determined as (11R,13A) for ripostatin A, 11R,13S,15R for ripostatin B and 11S for ripostatin C. The polyketide origin of A was revealed by feeding experiments with ¹³C-labeled precursors demonstrating the incorporation of one molecule of phenylacetic acid derived from phenylalanine, one propionate unit, and ten acetate units. VCH Verlagsgesellschaft mbH, 1996.