Structure–activity studies of echinomycin antibiotics against drug-resistant and biofilm-forming Staphylococcus aureus and Enterococcus faecalis

Four echinomycin antibiotics were isolated from the culture broth of a marine streptomycete, and their structures were determined by a combination of chemical and spectroscopic analyses. Antibiotic activities were measured against drug-resistant and biofilm-forming strains of Staphylococcus aureus and Enterococcus faecalis. Minimum inhibitory concentrations ranging from 0.01 μM to greater than 14 μM clearly defined structure–activity relationships for antibiotic potency. Echinomycin was the most active compound with a MIC of 0.03 μM against methicillin-resistant S. aureus and 0.01 μM against biofilm-forming E. faecalis.

Graphical abstractFour echinomycin antibiotics, including the new compound depsiechinoserine, were evaluated against antibiotic-resistant and biofilm-forming strains of Staphylococcus aureus and Enterococcus faecalis. Structure–activity relationships are presented.Figure optionsDownload full-size imageDownload as PowerPoint slide