• dipeptide;
  • inhibitor;
  • RND-type efflux pumps;
  • Salmonella enterica

Multidrug efflux pump inhibitors have a great potential as pharmacological agents that increase the drug susceptibility of bacterial pathogens. Our study was focused on the synthesis and evaluation of the efficiency of resistance–nodulation–division (RND) family efflux pump inhibitors. The efficiency of these inhibitors was investigated on Salmonella enterica ser. typhimurium cells using tetraphenylphosphonium (TPP+) and ethidium cations as the efflux pump substrates. Results of our study indicated that efficiency of the inhibitors depends on the cell outer membrane permeability and method of the assay used. Temperature of the incubation medium and a solvent of the inhibitor used have only minor effect on results of the assay.