Elansolid A, a unique macrolide antibiotic from Chitinophaga sancti isolated as two stable atropisomers.

Bacterial species of the genera Flexibacter and Chitinophaga are known to produce biologically active peptides of relevance to anti-infective research because of their interesting mechanisms of action. For instance, the formadicins, monocyclic b-lactam antibiotics from Flexibacter alginoliquefaciens, act selectively against pseudomonads and have proven to be hydrolysis-resistant against various types of b-lactamases. The anti-MRSA dipeptides TAN-1057A–D isolated from Flexibacter sp. were shown to inhibit peptide elongation during the bacterial translation. Early work on Flexibacter strains by Steinmetz, Gerth, and H fle resulted in the isolation of a group of novel metabolites named elansolids. The planar structure of the major component was elucidated by spectroscopic methods, degradation by cross-methathesis with ethylene, and biosynthetic reasoning as elansolid A1 (1). Later, in the course of our biological screening of extracts from non-myxobacterial gliding bacteria we re-investigated in depth the family of elansolids produced by Flexibacter sancti, a species recently reclassified as Chitinophaga sancti (comb. nov.). The elansolids are the first polyketide-derived macrolides from the genus Chitinophaga.