Metal-ruthenium complex based on dipyridylamine group as membrane-active antibacterial agent effectively decrease the development of drug-resistance on Staphylococcus aureus

Staphylococcus aureus (S. aureus), one of the Gram-positive bacteria, is easily to develop drug-resistance. Drug-resistant S. aureus infection leads to high morbidity and mortality. The complexes, namely [Ru(dpa)2(PSPIP)](PF6)2 (Ru1), [Ru(dpa)2(TSPIP)](PF6)2 (Ru2), and [Ru(dpa)2(TBPIP)](PF6)2 (Ru3), were synthesized using 2, 2'-dipyridylamine as an auxiliary ligand and three main ligands PSPIP, TSPIP, TBPIP. In vitro studies demonstrated that the Ru1-3 exhibited excellent antibacterial activity against S. aureus while showing low hemolytic toxicity to rabbit red blood cells. Notably, Ru3 was found to disrupt the bacterial cell membrane and alter its permeability through fluorescence staining and scanning electron microscopy (SEM) analysis. Furthermore, Ru3 displayed low toxicity in G. mellonella Larvae. Ru3 exhibited good activity against S. aureus in G. mellonella Larvae infection model and mouse skin infection model.To some extent, Ru3 inhibited biofilm formation on S. aureus as well as hemolytic toxin production, thereby attenuating the development of drug resistance without cross-resistance with other antibiotics. In addition, complex Ru3 exhibited a synergistic effect when combined with antibiotics amikacin, kanamycin, tobramycin and chloramphenicol, making it a valuable antibiotics adjuvant.

Synthesis of ruthenium polypyridine complexes with benzyloxyl groups and their antibacterial activities against Staphylococcus aureus

Four new ruthenium polypyridyl complexes, [Ru(bpy)₂(BPIP)](PF₆)₂ (Ru(II)-1), [Ru(dtb)₂(BPIP)](PF₆)₂ (Ru(II)-2), [Ru(dmb)₂(BPIP)](PF₆)₂ (Ru(II)-3) and [Ru(dmob)₂(BPIP)](PF₆)₂ (Ru(II)-4) (bpy = 2,2'-bipyridine, dtb = 4,4'-di-tert-butyl-2,2'-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, dmob = 4,4'-dimethoxy-2,2'-bipyridine and BPIP = 2-(3,5-bis(benzyloxyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline) had been synthesized and characterized. Their antimicrobial activities were investigated against Staphylococcus aureus (S. aureus) and four complexes showed obvious antibacterial effect, especially the minimum inhibition concentration (MIC) value of Ru(II)-3 was only 4 μg/mL. In addition, Ru(II)-3 was able to kill bacteria quickly and inhibit the formation of biofilm. Meanwhile, the cooperative effect between Ru(II)-3 and general antibiotics were tested and the results showed that Ru(II)-3 could enhance the susceptibility of S. aureus to different types of antibiotics. Most importantly, Ru(II)-3 hardly showed cytotoxicity to mammalian erythrocytes both in homelysis experiment and G. mellonella model. After being injected with high doses of the Ru(II)-3in vivo, the G. mellonella worms still exhibited high survival rates. Finally, a mouse skin infection model and G. mellonella infection model was built to determine the antibacterial activity of Ru(II)-3in vivo. The antibacterial mechanism of Ru(II)-3 was probably related to the membrane-disruption. Taken together, ruthenium polypyridine complexes with benzyloxyl groups had the potential to develop an attractive and untraditional antibacterial agent with new mode of action.

Ruthenium polypyridine complexes with triphenylamine groups as antibacterial agents against Staphylococcus aureus with membrane-disruptive mechanism

Due to the emergence and wide spread of methicillin-resistant Staphylococcus aureus, the treatment of this kind of infection becomes more and more difficult. To solve the problem of drug resistance, it is urgent to develop new antibiotics to avoid the most serious situation of no drug available. Three new Ru complexes [Ru (dmob)₂PMA] (PF6)₂ (Ru-1) [Ru (bpy)₂PMA] (PF6)₂ (Ru-2) and [Ru (dmb)₂PMA] (PF6)₂ (Ru-3) (dmob = 4,4′-dimethoxy-2,2′-bipyridine, bpy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine and PMA = N-(4-(1H-imidazo [4,5-f] [1,10] phenanthrolin-2-yl) -4-methyl-N-(p-tolyl) aniline) were synthesized and characterized by 1H NMR, 13C NMR and HRMS. The detailed molecular structure of Ru-3 was determined by single crystal X-ray diffraction. Their antibacterial activities against Staphylococcus aureus (Staphylococcus aureus) were obvious and Ru-3 showed the best antibacterial effect with the minimum inhibitory concentration value of 4 μg ml⁻¹. Therefore, further study on its biological activity showed that Ru-3 can effectively inhibit the formation of biofilm and destroy cell membrane. In vitro hemolysis test showed that Ru-3 has almost negligible cytotoxicity to mammalian red blood cells. In the toxicity test of wax moth insect model, Ru-3 exhibited low toxicity in vivo. These results, combined with histopathological studies, strongly suggest that Ru-3 was almost non-toxic. In addition, the synergistic effect of Ru-3 with common antibiotics such as ampicillin, chloramphenicol, tetracycline, kanamycin and gentamicin on Staphylococcus aureus was detected by chessboard method. Finally, in vivo results revealed that Ru-3 could obviously promote the wound healing of Staphylococcus aureus infected mice.

Synthesis and antibacterial activity study of ruthenium-based metallodrugs with membrane-disruptive mechanism against Staphylococcus aureus

The wide spread of drug-resistant bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), have posed a tremendous threat to global health. Of particular concern, resistance to vancomycin, linezolid and daptomycin have already...

Synthesis and evaluation of sulfonyl-substituted ruthenium complex as potential antibacterial activity against Staphylococcus aureus

A new ruthenium complex was synthesized, which can effectively prevent the development of S. aureus drug-resistance and with high antibacterial activity in vitro and in vivo.

Synthesis and biological evaluation of ruthenium polypyridine complexes with 18β-glycyrrhetinic acid as antibacterial agents against Staphylococcus aureus

Four new ruthenium(II) polypyridine complexes bearing 18β-glycyrrhetinic acid derivatives, [Ru(bpy)₂L](PF₆)₂ (Ru1), [Ru(dmb)₂L](PF₆)₂ (Ru2), [Ru(dtb)₂L](PF₆)₂ (Ru3) and [Ru(phen)₂L](PF₆)₂ (Ru4) (bpy = 2,2-bipyridine, dmb = 4,4'-dimethyl-2,2'-bipyridine, dtb = 4,4'-di-tert-butyl-2,2'-bipyridine, phen = 1,10-phenanthroline and L is the GA modified new ligand) were designed and synthesized. Their antimicrobial activities against Staphylococcus aureus (S. aureus) were evaluated and all complexes showed an obvious inhibitory effect, especially, the minimum inhibitory concentration (MIC) value of Ru2 was 3.9 μg mL^-1. Moreover, Ru2 was found to significantly inhibit the formation of biofilms. The membrane-compromising action mode was suggested to be their potential antibactericidal mechanism. In hemolysis experiments, Ru2 hardly showed cytotoxicity to mammalian erythrocytes. Furthermore, the synergism between Ru2 and common antibiotics, such as ampicillin, chloramphenicol, tetracyclines and ofloxacin, against S. aureus was also detected using the checkerboard method. Finally, a mouse skin infection model was established to evaluate the antibacterial activity of Ru2in vivo, and the results showed that Ru2 could effectively promote wound healing in mice infected with S. aureus. Moreover, the results of histopathological research were consistent with the results of the hemolysis test, indicating that the Ru2 complex was almost non-toxic. Thus, it was demonstrated that the polypyridine ruthenium complexes modified with glycyrrhetinic acid (GA) are a promising strategy for developing interesting antibacterial agents.

Ruthenium Complexes in the Fight against Pathogenic Microorganisms. An Extensive Review

The widespread use of antibiotics has resulted in the emergence of drug-resistant populations of microorganisms. Clearly, one can see the need to develop new, more effective, antimicrobial agents that go beyond the explored 'chemical space'. In this regard, their unique modes of action (e.g., reactive oxygen species (ROS) generation, redox activation, ligand exchange, depletion of substrates involved in vital cellular processes) render metal complexes as promising drug candidates. Several Ru (II/III) complexes have been included in, or are currently undergoing, clinical trials as anticancer agents. Based on the in-depth knowledge of their chemical properties and biological behavior, the interest in developing new ruthenium compounds as antibiotic, antifungal, antiparasitic, or antiviral drugs has risen. This review will discuss the advantages and disadvantages of Ru (II/III) frameworks as antimicrobial agents. Some aspects regarding the relationship between their chemical structure and mechanism of action, cellular localization, and/or metabolism of the ruthenium complexes in bacterial and eukaryotic cells are discussed as well. Regarding the antiviral activity, in light of current events related to the Covid-19 pandemic, the Ru (II/III) compounds used against SARS-CoV-2 (e.g., BOLD-100) are also reviewed herein.

A New Piano-Stool Ruthenium(II) P-Cymene-Based Complex: Crystallographic, Hirshfeld Surface, DFT, and Luminescent Studies

A new complex (Ru(η6-p-cymene)(5-ASA)Cl2) (1) where 5-ASA is 5-aminosalicylic acid has been prepared by reacting the ruthenium arene precursors ((η6-arene)Ru(μ-Cl)Cl)2, with the 5-ASA ligands in a 1:1 ratio. Full characterization of complex 1 was accomplished by elemental analysis, IR, and TGA following the structure obtained from a single-crystal X-ray pattern. The structural analysis revealed that complex 1 shows a “piano-stool” geometry with Ru-C (2.160(5)- 2.208(5)Å), Ru-N (2.159(4) Å) distances, which is similar to equivalents sister complex. Density functional theory (DFT) was used to calculate the significant molecular orbital energy levels, binding energies, bond angles, bond lengths, and spectral data (FTIR, NMR, and UV–VIS) of complex 1, consistent with the experimental results. The IR and UV–VIS spectra of complex 1 were computed using all of the methods and choose the most appropriate way to discuss. Hirshfeld surface analysis was also executed to understand the role of weak interactions such as H⋯H, C⋯H, C-H⋯π, and vdW interactions, which play a significant role in the crystal environment’s stability. Moreover, the luminescence results at room temperature show that complex 1 gives a more intense emission band positioned at 465 nm upon excitation at 330 nm makes it a suitable candidate for the building of photoluminescent material.