Antimicrobial and Antibiofilm Activity of Copper-Based Metallic Compounds Against Bacteria Related with Healthcare-Associated Infections.

Health care-associated infections (HAIs) contribute to a significant rate of morbidity, mortality, and financial burden on health systems. These infections are caused by multidrug-resistant bacteria that produce biofilm as the main virulence factor. This study aimed to evaluate the effect of the copper-based metallic compounds [Cu(phen)(pz)NO2]Cl (I), [Cu(bpy)(pz)(NO2)]Cl (II), and [Cu(phen)(INA)NO2]Cl (III), where phen = phenanthroline, bpy = bipyridine, pz = pyrazinamide, and INA = isonicotinic acid, against planktonic cells and biofilms formation of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli. The susceptibility of the microorganisms was evaluated by minimum inhibitory concentration (MIC), minimum bacterial concentration (MBC), and time-kill curve assay on planktonic cells. The biofilm formation was evaluated by biomass quantification through staining with crystal violet (CV), colony-forming units (CFUs) quantification, and biofilm metabolic activity determination by XTT assay. The compounds showed bacteriostatic and bactericidal activity on all microorganisms analyzed. Regarding the antibiofilm activity, all metallic compounds were able to reduce significantly the biofilm biomass, colony-forming units, and the metabolic activity of remaining cells, varying the efficient concentration according to the strain analyzed. Interestingly, compounds (I), (II) and (III) did not exhibit DNA degradation activity even with up to 100 µM of these metal complexes. On the other hand, complexes (I) and (III) showed a remarkable capacity to cleave DNA upon addition of glutathione, a reducing agent (CuII/CuI) that leads to reactive oxygen species (ROS) formation. The results presented in this study showed promising antimicrobial and antibiofilm effects.

Comparative study on the antioxidant and anti-Toxoplasma activities of vanillin and its resorcinarene derivative.

A resorcinarene derivative of vanillin, resvan, was synthesized and characterized by spectroscopic techniques. We measured the cytotoxicity (in vivo and in vitro), antioxidant and anti-Toxoplasma activities of vanillin and the resorcinarene compound. Here we show that vanillin has a dose-dependent behavior with IC50 of 645 µg/mL through an in vitro cytotoxicity assay. However, we could not observe any cytotoxic response at higher concentrations of resvan (IC50 > 2,000 µg/mL). The in vivo acute toxicity assays of vanillin and resvan exhibited a significant safety margin indicated by a lack of systemic and behavioral toxicity up to 300 mg/kg during the first 30 min, 24 h or 14 days after administration. The obtained derivative showed greater antioxidative activity (84.9%) when comparing to vanillin (19.4%) at 1,000 µg/mL. In addition, vanillin presents anti-Toxoplasma activity, while resvan does not show that feature. Our findings suggest that this particular derivative has an efficient antioxidant activity and a negligible cytotoxic effect, making it a potential target for further biological investigations.

Reactivity of a nitrosyl ruthenium complex and its potential impact on the fate of DNA - An in vitro investigation.

The role of metal complexes on facing DNA has been a topic of major interest. However, metallonitrosyl compounds have been poorly investigated regarding their reactivities and interaction with DNA. A nitrosyl compound, cis-[Ru(bpy)2(SO3)(NO)](PF6)(A), showed a variety of promising biological activities catching our attention. Here, we carried out a series of studies involving the interaction and damage of DNA mediated by the metal complex A and its final product after NO release, cis-[Ru(bpy)2(SO3)(H2O](B). The fate of DNA with these metal complexes was investigated upon light or chemical stimuli using electrophoresis, electronic absorption spectroscopy, circular dichroism, size-exclusion resin, mass spectrometry, electron spin resonance (ESR) and viscometry. Since many biological disorders involve the production of oxidizing species, it is important to evaluate the reactivity of these compounds under such conditions as well. Indeed, the metal complex B exhibited important reactivity with H2O2 enabling DNA degradation, with detection of an unusual oxygenated intermediate. ESR spectroscopy detected mainly the DMPO-OOH adduct, which only emerges if H2O2 and O2 are present together. This result indicated HOO• as a key radical likely involved in DNA damage as supported by agarose gel electrophoresis. Notably, the nitrosyl ruthenium complex did not show evidence of direct DNA damage. However, its aqua product should be carefully considered as potentially harmful to DNA deserving further in vivo studies to better address any genotoxicity.

A vanillin-based copper(ii) metal complex with a DNA-mediated apoptotic activity.

Vanillin (vanH) is the major component of vanilla and one of the most widely used flavoring agents. In this work the complex [Cu(phen)(van)2] was prepared and characterized by structural (X-ray), spectroscopic (IR, UV-Vis, EPR) and electrochemical techniques. This compound showed an octahedral geometry with an unusual arrangement of the vanillin ligands, where the methoxy groups of the vanillinate ions are coordinated opposite to each other. The compound promoted DNA cleavage in the presence of glutathione (GSH) and H2O2. At 40 µmol L-1 of complex with GSH (10 mmol L-1), there is a complete cleavage of DNA to nicked form II, while only at 10 µmol L-1 of this complex with H2O2 (1 mmol L-1) an extensive cleavage leading to form III took place. Additionally, we have evidences of superoxide generation upon reaction with GSH. Therefore, DNA fragmentation occurs likely through an oxidative pathway. MTT assays indicated that the complex is highly cytotoxic against three distinct cell lines: B16-F10 (IC50 = 3.39 ± 0.61 µmol L-1), HUH-7 (IC50 = 4.22 ± 0.31 µmol L-1) and 786-0 (IC50 = 10.38 ± 0.91 µmol L-1). Flow cytometry studies conducted with 786-0 cell line indicated cell death might occur by apoptosis. Cell cycle progression evaluated at 5 and 10 µmol L-1 resulted in a clear increase of 786-0 cells at G1 phase and depletion of G2/M, while higher doses showed an expressive increase of sub-G1 phase. Altogether, these results pointed out to a promising biological activity and potential as an anti-cancer agent.

The ruthenium NO donor, [Ru(bpy)2(NO)SO3](PF6), inhibits inflammatory pain: involvement of TRPV1 and cGMP/PKG/ATP-sensitive potassium channel signaling pathway.

The activation of nitric oxide (NO) production is an analgesic mechanism shared by drugs such as morphine and diclofenac. Therefore, the controlled release of low amounts of NO seems to be a promising analgesic approach. In the present study, the antinociceptive effect of the ruthenium NO donor [Ru(bpy)2(NO)SO3](PF6) (complex I) was investigated. It was observed that complex I inhibited in a dose (0.3-10mg/kg)-dependent manner the acetic acid-induced writhing response. At the dose of 1mg/kg, complex I inhibited the phenyl-p-benzoquinone-induced writhing response and formalin- and complete Freund's adjuvant-induced licking and flinch responses. Additionally, complex I also inhibited transient receptor potential cation channel subfamily V member 1 (TRPV1)-dependent overt pain-like behavior induced by capsaicin. Complex I also inhibited the carrageenin-induced mechanical hyperalgesia and increase of myeloperoxidase activity (MPO) in paw skin samples. The inhibitory effect of complex I in the carrageenin-induced hyperalgesia, MPO activity and formalin was prevented by the treatment with ODQ, KT5823 and glybenclamide, indicating that complex I inhibits inflammatory hyperalgesia by activating the cGMP/PKG/ATP-sensitive potassium channel signaling pathway. The present study demonstrates the efficacy of a novel ruthenium NO donor and its analgesic mechanisms.

Mechanism and biological implications of the NO release of cis-[Ru(bpy)2L(NO)](n+) complexes: a key role of physiological thiols.

Nitric oxide (NO) has a critical role in several physiological and pathophysiological processes. In this paper, the reactions of the nitrosyl complexes of [Ru(bpy)(2)L(NO)](n+) type, where L = SO(3)(2-) and imidazole and bpy = 2,2'-bipiridine, with cysteine and glutathione were studied. The reactions with cysteine and glutathione occurred through the formation of two sequential intermediates, previously described elsewhere, [Ru(bpy)(2)L(NOSR)](n+) and [Ru(bpy)(2)L(NOSR)(2)] (SR = thiol) leading to the final products [Ru(bpy)(2)L(H(2)O)](n+) and free NO. The second order rate constant for the second step of this reaction was calculated for cysteine k(2)(SR(-))=(2.20±0.12)×10(9) M(-1) s(-1) and k(2(RSH))=(154±2) M(-1) s(-1) for L = SO(3)(2-) and k(2)(SR(-))=(1.30±0.23)×10(9) M(-1) s(-1) and k(2)(RSH)=(0.84±0.02) M(-1) s(-1) for L = imidazole; while for glutathione they were k(2)(SR(-))=(6.70±0.32)×10(8) M(-1) s(-1) and k(2)(RSH)=11.8±0.3 M(-1) s(-1) for L = SO(3)(2-) and k(2)(SR(-))=(2.50±0.36)×10(8) M(-1) s(-1) and k(2)(RSH)=0.32±0.01 M(-1) s(-1) for L = imidazole. In all reactions it was possible to detect the release of NO from the complexes, which it is remarkably distinct from other ruthenium metallocompounds described elsewhere with just N(2)O production. These results shine light on the possible key role of NO release mediated by physiological thiols in reaction with these metallonitrosyl ruthenium complexes.