Role of Amphiphilicity in the Design of Synthetic Mimics of Antimicrobial Peptides with Gram-negative Activity

Two new series of aryl SMAMPs (synthetic mimics of antimicrobial peptides) with facially amphiphilic (FA) and disrupted amphiphilic (DA) topologies were designed and synthesized to directly assess the role of amphiphilicity on their antimicrobial activity against gram-positive and gram-negative bacteria in closely related structures. The FA SMAMPs displayed broad spectrum antimicrobial activity against both gram-positive S. aureus and gram-negative E. coli, whereas the DA SMAMPs, which contained a polar amide bond in between the hydrophobic moieties, only exhibited activity towards S. aureus with increasing hydrophobicity. The integy moment (IW) was used to quantify the amphiphilicity of the SMAMPs and confirmed that it is critical for the design of SMAMPs with gram-negative activity.