Discovery of Peptide Antibiotics Composed of d-Amino Acids.

A paucity of viable programs and pipelines for the discovery of new antibiotics poses a significant public health threat. The emergence of resistant strains against vancomycin is particularly dangerous in hospital settings. Here, we report the design of enantiomeric targets based on bacterial cell wall biosynthesis precursors that allow for selection and identification of short linear, cyclic and bicyclic peptides that are composed of d-amino acids. These compounds are active against Staphylococcus aureus, Methicillin-resistant S. aureus, and vancomycin-resistant Enterococci that possess moderately high antibacterial activity and furthermore display no toxicity to both human red blood cells and mammalian cells at these concentrations. This 'mirror image phage display' approach yielded templates that can serve as scaffolds for further improvements in activity-based structural modifications. This strategy has the potential to provide a new class of antimicrobials that are metabolically stable and have the promise for oral delivery. The use of this platform combined with traditional medicinal chemistry approaches could rapidly yield large numbers of new therapeutic lead compounds.