The current work illustrates a cost-effective post-modification approach using artificial peptides to generate synthetic oligomers as antimicrobial agents. The peptides against the ESKAP panel of bacterial strains showed a broad spectrum of antibacterial activity, and structure-function relationship studies were conducted considering parameters, such as charge and nature of hydrophilic and hydrophobic side chains.

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.