ABSTRACT
The emergence of multidrug-resistant bacterial have caused severe burden for public health. Particularly, Staphylococcus aureus as one of ESKAPE pathogens have induced various infectious diseases and resulted in increasing deaths. Developing new antibacterial agents is still urgent and challenging. Fortunately, in this study, based on aggregation-induced emission (AIE) ruthenium complexes were designed and synthesized, which realized the high efficiency of reactive oxygen species generation and remarkably killed S. aureus unlike conventional antibiotics action. Significantly, owing to good singlet oxygen production ability, Ru1 at only 4 µg/mL of concentration displayed good antibacterial photodynamic therapy effect upon white light irradiation and could deplete essential coenzyme NADH to disrupt intracellular redox balance. Also, the electrostatic interaction between Ru1 and bacteria enhanced the possibility of antibacterial. Under light irradiation, Ru1 could efficiently inhibit the biofilm growth and avoid the development of drug-resistant. Furthermore, Ru1 possessed excellent biocompatibility and displayed remarkable therapy effect in treating mice-wound infections in vivo. These findings indicated that AIE-based ruthenium complexes as new antibacterial agent had great potential in photodynamic therapy of bacteria and addressing the drug-resistance crisis.
ABSTRACT
Quaternization of ruthenium complexes may be a promising strategy for the development of new antibiotics. In response to the increasing bacterial resistance, we integrated the quaternary amine structure into the design of ruthenium complexes and evaluated their antibacterial activity. All the ruthenium complexes showed good antibacterial activity against the tested Staphylococcus aureus (S. aureus). Ru-8 was the most effective antibacterial agent that displayed excellent antibacterial activity against S. aureus (MIC = 0.78-1.56 µg/mL). In vitro experiments showed that all nine ruthenium complexes had low hemolytic toxicity to rabbit erythrocytes. Notably, Ru-8 was found to disrupt bacterial cell membranes, alter their permeability, and induce ROS production in bacteria, all the above leading to the death of bacteria without inducing drug resistance. To further explore the antibacterial activity of Ru-8in vivo, we established a mouse skin wound infection model and a G. mellonella larvae infection model. Ru-8 exhibited significant antibacterial efficacy against S. aureus in vivo and low toxicity to mouse tissues. The Ru-8 showed low toxicity to Raw264.7 cells (mouse monocyte macrophage leukemia cells). This study indicates that the ruthenium complex ruthenium quaternary was a promising strategy for the development of new antibacterial agents.