Biofilm-eradicating properties of quaternary ammonium amphiphiles: simple mimics of antimicrobial peptides.

Bacterial biofilms are difficult to eradicate because of reduced antibiotic sensitivity and altered metabolic processes; thus, the development of new approaches to biofilm eradication is urgently needed. Antimicrobial peptides (AMPs) and quaternary ammonium cations (QACs) are distinct, yet well-known, classes of antibacterial compounds. By mapping the general regions of charge and hydrophobicity of QACs onto AMP structures, we designed a small library of QACs to serve as simple AMP mimics.

Beyond paraquats: dialkyl 3,3'- and 3,4'-bipyridinium amphiphiles as antibacterial agents.

Dialkyl 4,4'-bipyridinium compounds, known as 'paraquats' (PQs), have a long history of use as herbicides, as redox indicators, and more recently as potent antibacterial agents. However, due to their ability to form reactive oxygen species (ROS) in vivo, PQs are also known to be toxic. We proposed that altering the electrochemical properties of PQ, specifically by preparing isomeric bipyridinium structures with 3,3'- and 3,4'-substitution of the nitrogen heteroatoms on the biaryl core, would maintain antibacterial activity, yet decrease toxicity.