This paper reports highly active analogues of clovibactin in which the rare, noncanonical amino acid d-hydroxyasparagine is replaced with the commercially available amino acid d-threonine. Sequential mutation of leucines 2, 7, and 8 to the more hydrophobic homologue cyclohexylalanine dramatically increases the antibiotic activity of d-Thr5-clovibactin. The resulting analogues (d-Cha2,d-Thr5-clovibactin, Cha7,d-Thr5-clovibactin, and Cha8,d-Thr5-clovibactin) are readily prepared by standard peptide synthesis techniques and exhibit excellent activity (≤1 μg/mL) against the Gram-positive, drug-resistant pathogens MRSA and VRE.

Vancomycin continues to be a widely used antibiotic of last resort in treating drug-resistant pathogens despite the emergence of vancomycin-resistant strains such as vancomycin-resistant Enterococci (...