Amphiphilicity to α/γ Hybrid Foldamers through Post-Modification at Multiple Sites: Antimicrobial Design and Structure-Function Relationship.

Antimicrobial drug design is an active area of research. Drug resistance in microorganisms to conventional antibiotics imposes a huge burden on the healthcare and economy worldwide. Understanding the structural parameters controlling the antimicrobial activity enables researchers to develop effective antimicrobial agents. Post-modification of artificial peptides as a method to introduce amphiphilicity, a structural parameter to exhibit antimicrobial activity, is described in the current work. Using two hybrid sequences composed of 5-amino salicylic acid and natural amino acid leucine (Leu) or phenylalanine (Phe), the approach enabled us to prepare peptides varying in chain length, charge, and cationic groups. The peptides against the ESKAP panel of bacterial pathogens showed a broad spectrum of antibacterial activity. The structure-function relationship indicated that antimicrobial activity varied with chain length, and the peptides composed of Leu residues were more effective than peptides with Phe residues. The late-stage modification and functional diversification can be done at a large scale, and the approach simplifies the synthesis and reduces the cost of production.