The cyclical nature of potential new antibiotics

The continuing emergence of antibiotic resistant bacterial strains has highlighted the importance of identifying and developing new therapeutic agents. In 26 July Nature Sara Fernadez-Lopez and colleagues from the Skaggs Institute for Chemical Biology, California describe six- and eight-residue cyclic D,L-α-peptides that preferentially act upon the membranes of both Gram positive and Gram negative bacteria.

Fernadez-Lopez et al. observed that amphiphilic D,L-α-peptides having three consecutive hydrophilic residues and repeating L-tryptophan and D-leucine residues can self-assemble into tubular structures that span synthetic membranes. These structures allow the highly efficient transport of ions and other small species across lipid bilayers (Nature 2001, 412:452-455).

By using single negatively charged amino acid substitutions they were able to modify the activity of individual peptides and used these against a variety of pathogenic bacteria. In vitro testing with multiple resistant Staphylococcus aureus (MRSA) and Escherichia coli showed up to 20-fold increased anti-bacterial activity....