Antimicrobial, anti-biofilm and cytotoxic properties of methallyl functionalized benzimidazolium-derived Ag(I)-N- heterocyclic carbene complexes

Purpose: To investigate the antimicrobial, antibiofilm, and cytotoxicity properties of methallyl substituted benzimidazolium-based, silver-bound N-heterocyclic carbene (Ag(I)-NHC) complexes, with respect to their potential to act as antimicrobial agents. Methods: The antimicrobial, antibiofilm, and cytotoxicity properties of the four complexes, the synthesis and characterization of which were carried out previously, were investigated. The antimicrobial properties were tested using the broth microdilution method, while their antibiofilm potential were determined by microtiter plate assay. The L-929 cell line was used for cytotoxic studies. Results: Strong antibiofilm and antimicrobial effects were produced by Ag(I)-NHC complexes. Compounds 2 and 3 showed potent activities against E. coli strain, with effects similar to that of positive control antibiotic, while compounds 1 and 4 exhibited antimicrobial activity at a concentration of 31.2 mu g/mL. The compounds were effective against biofilms formed at concentrations in the range of 32 - 84 %, and degraded mature biofilms at a concentration range of 14 -66 %. Compounds 1 and 2 did not significantly affect cell survival (p > 0.05), while compounds 3 and 4 significantly reduced cell survival, when compared with untreated cells in the control group (p < 0.001). Conclusion: This study may be one of the few studies on benzimidazolium-derived NHCs. The compounds which produced antimicrobial, antibiofilm, and cytotoxic properties in this study may be valuable and novel antimicrobial agents. Therefore, there is need for further in vivo and in vitro studies on these compounds.