Ruthenium Complexes with 2-Pyridin-2-yl-1H-benzimidazole as Potential Antimicrobial Agents: Correlation between Chemical Properties and Anti-Biofilm Effects

Antimicrobial resistance is a growing public health concern that requires urgent action. Biofilm-associated resistance to antimicrobials begins at the attachment phase and increases as the biofilms maturate. Hence, interrupting the initial binding process of bacteria to surfaces is essential to effectively prevent biofilm-associated problems. Herein, we have evaluated the antibacterial and anti-biofilm activities of three ruthenium complexes in different oxidation states with 2-pyridin-2-yl-1H-benzimidazole (L-1 = 2,2 '-PyBIm): [(eta(6)-p-cymene)(RuClL1)-Cl-II]PF6 (Ru(II) complex), mer-[(RuCl3)-Cl-III(CH3CN)L-1]center dot L-1 center dot 3H(2)O (Ru(III) complex), (H2L1)(2)[(RuCl4)-Cl-III(CH3CN)(2)](2)[(RuCl4)-Cl-IV(CH3CN)(2)]center dot 2Cl center dot 6H(2)O (Ru(III/IV) complex). The biological activity of the compounds was screened against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa strains. The results indicated that the anti-biofilm activity of the Ru complexes at concentration of 1 mM was better than that of the ligand alone against the P. aeruginosa PAO1. It means that ligand, in combination with ruthenium ion, shows a synergistic effect. The effect of the Ru complexes on cell surface properties was determined by the contact angle and zeta potential values. The electric and physical properties of the microbial surface are useful tools for the examined aggregation phenomenon and disruption of the adhesion. Considering that intermolecular interactions are important and largely define the functions of compounds, we examined interactions in the crystals of the Ru complexes using the Hirshfeld surface analysis.

Automated summary

Antimicrobial resistance is a significant public health concern that requires urgent action. Interrupting the initial binding process of bacteria to surfaces is essential to prevent biofilm-associated problems, and ruthenium complexes with 2-pyridin-2-yl-1H-benzimidazole demonstrate synergistic anti-biofilm effects.