Investigation of the antimicrobial potential of imidazolium-based ionic liquids

Nowadays, infection diseases caused by pathogenic bacteria cause global major health problems. The major problem faced by antimicrobial agents used in the treatment of infections is that the microorganisms become resistance to antimicrobial agents in a short and very limited knowledge on biochemistry of these microorganisms. Therefore, this situation guides researcher to design and synthesize new and effective antimicrobial agents. Since benzoxanol ring systems of heterocyclic nucleus structures are similar to heterocyclic structures that are found in the structure of nucleic acids, it is believed that such conmpound groups may exhibit antimicrobial activity in this way. Imidazolium salts form an important part of structures bearing heterocyclic nucleus. It takes place in literature that the imidazolium derivatives have increased antimicrobial properties increase with the chain lengths. The aim of this study is to determine antibacterial and antibiofilm activity of imidazolium-bromide salts (NMI) compounds with different alkyl chain lengths [n-dodecyl (NMI-1Br), n-hexadecyl (NMI-2Br), n-tetradecyl (NMI-3Br)]. In addition, NMI compounds were labeled with 131I and it was demonstrated that the labeled compounds might have a potential of nuclear imaging for gram-positive Staphylococcus aureus (S. aureus) bacterial infection. In order to detect the antimicrobial activity of the NMI compounds against S. aureus and E. coli Minimum Inhibitor Concentration (MIC) values (for S. aureus ATCC 29213, NMI-1Br, NMI-2Br ve NMI-3Br respectively 10, 5, 1,25 µg/ml and for E. coli ATCC 25922, 312, 10, 2,5 µg/ml) were determined. It is observed that the compounds showed high antimicrobial activity against gram positive S. aureus and gram negative E. coli strains, NMI-1Br was found to be less effective in S. aureus and E. coli strains. Antibiofilm effect against the Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212 standart strains has been determined that the MIC/2 and MIC/4 concentrations of NMI compounds produced the biofilm and inhibited mature biofilm. All compounds were found to be effective on S. aureus strains at MIC/2 and MIC/4 concentrations. In the study, NMI compounds were labeled with 131I with the iodogen method. According to the quality control study results, it was determined that NMI compounds were labeled with 131I with high efficiency (NMI-1Br: 92,6±4,2%, NMI-2Br: 87,9±5,6%, NMI-3Br: 80,11±5,3%). The results obtained from in vitro binding experiments show that radiolabelled NMI-1Br, NMI-2Br, NMI-3Br compounds might have an agent potency to be used in nuclear imaging.