Antimicrobial peptides (AMPs) are a large class of defense molecules in multicellular organisms that exhibit broad and potent activity. We investigated the use of N-substituted glycine oligomers, peptoids, as AMP mimics with similar low concentration antimicrobial activities. The mechanism of action of AMPs varies, but many penetrate bacterial cell membranes leading to leakage and death. Our antimicrobial cyclic peptoids demonstrate a similar pore-formation mechanism against methicillin-resistant Staphylococcus aureus. We observed that the minimum inhibitory concentrations of the peptoids increased with the addition of polyethylene glycol to the cell suspensions, which protected from a loss of osmotic balance. This decrease in antimicrobial activity was more significant with larger osmoprotectants indicating that peptoids formed pores with initial diameters greater than 3.8 nm. Scanning electron microscopy was used to analyze cell membrane damage after 24 hours of peptoid treatment. These images revealed extensive membrane deformities and pores reaching over 200 nm in diameter.

Antimicrobial cyclic peptoids inducing transmembrane pore formation in Staphylococcus aureus

245th National Meeting (2013)

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