Analysis in vivo of antitumor activity, Cytotoxicity and Interaction between plasmid DNA and the cis-dichlorotetraammineruthenium(III) chloride

Schiff Bases and their Metal Complexes as Potential Anticancer Candidates: A Review of Recent Works

BACKGROUND

Schiff bases and their metal complexes are emerging as key classes of medicinal compounds, possessing an enormous potential of biological activities like anticancer, anticonvulsant and antioxidant etc. The aim of this review is to examine the anticancer activity of different classes of Schiff bases and their metal complexes.

METHODS

Anticancer activity of the already synthesized as well as the novel Schiff bases and their metal complexes was studied using different assays such as 3- [4,5-dimethyltiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT), PI staining, Sulforhodamine, Allium cepa, Sulfo- Rhodamine-B-stain(SRB), viability and potato disc against various human and animal cancer cell lines.

RESULTS

The test results indicated significant differences in anticancer activity between subclasses of Schiff base compounds as well as between the Schiff base ligands and their metal complexes. Quinazolines showed a very high activity against HepG2 and MCF-7 cell lines. Pyrazole-naphthalene derivatives exhibited high activity against numerous carcinoma cells while [Ni(HL1)2(OAc)2] showed the highest. Azosal and its tin(IV) complexes displayed high activity against U-1242 MG and excellent activity against HCT-116 cell lines. 2-thiouracil sulfonamides displayed high activity against MCF7, CaCo-2 carcinoma cells. Vitamin-B6 and its oxovanadium complex showed good activity against MCF-7, 3T3 and cervical cancer HeLa cancer cell lines in the presence of visible light. Indoles displayed high activity against AMJ13. Porphyrines derivatives exhibited good activity while its binuclear(Y and K) complexes displayed high activity against several carcinoma cells. Chitosan complexes of [Pd(II) and Pt(II)] showed a very high anticancer activity against MCF-7 carcinoma cell.

CONCLUSION

Schiff bases possess a high potential to inhibit carcinoma cells which enhanced with complexation, but the mechanism of their antitumor activity is still doubt.

Ruthenium (II) complexes with N, O-chelating proline and threonine ligands cause selective cytotoxicity by the induction of genomic instability, cell cycle arrest and apoptosis in breast and prostate tumor cells

Ruthenium complexes are being considered as novel chemotherapeutic alternatives for cancer treatment. In our study, we assessed the antitumoral activities of novel ruthenium complexes coupled to the amino acids proline (RuPro) and threonine (RuThr) in prostate tumor cell lines (DU145) and breast (MCF7), and normal cell lines of the lung fibroblast (GM07492A). Our results revealed that the EC₅₀ of the complexes for DU145 and MCF7 was two times lower than that GM07492A. Moreover, RuPro and RuThr were not able to induce significant genomic instability, cell cycle arrest or cell death in GM07492A, but could induce DNA damage, arrest in G2/M and apoptosis in DU145 and MCF7. Furthermore, BAX, TP53 and ATM were found to be upregulated in DU145 and MCF7 treated with RuPro and RuThr, in which, a higher ASCT2 gene expression was also observed. Using molecular docking, RuPro and RuThr interact with ASCT2, suggesting that this transporter might have a pivotal role in the execution of their activities. Hence, our results with RuPro and RuThr are capable of selectively inducing genetic damage, cell cycle arrest and apoptosis in DU145 and MCF7. We suggest that the selective action of the RuPro and RuThr complexes is related to the higher expression of ASCT2 in the tumor cells.

Anticancer activity and mechanism of bis-pyrimidine based dimetallic Ru(II)(η6-p-cymene) complex in human non-small cell lung cancer via p53-dependent pathway

Non-small cell lung cancer (NSCLC) is the most common cancer worldwide, which is related with poor prognosis and resistance to chemotherapy. Notably, ruthenium-based complexes have emerged as good alternative to the currently used platinum-based drugs for cancer therapy. In the present study, we synthesized a novel bis-pyrimidine based ligand 1,3-bis(2-methyl-6-(pyridin-2-yl)pyrimidin-4-yl)benzene (L) and used it in the synthesis of a dimetallic Ru(II) cymene complex [(Ru(η⁶-p-cymene)Cl)₂(1,3-bis(2-methyl-6-(pyridin-2-yl)pyrimidin-4-yl)benzene)] (L-Ru). We checked the stability of this complex in solution state in D₂O/DMSO‑d₆ mixture and found it to be highly stable under these conditions. We determined the anticancer activity and mechanism of action of L-Ru in human NSCLC A549 and A427 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and related biological analyses. These results revealed that L-Ru exerted a strong inhibitory effect on the cells proliferation,G0/G1-arrest, accompanied with upregulation of p53, p21, p15, cleaved Poly (ADP-ribose) polymerase (PARP) protein and downregulation of cell cycle markers. L-Ru inhibited cell migration and invasion. The mitochondria-mediated apoptosis of NSCLC induced by L-Ru was also observed followed by the increase of apoptosis regulator B-cell lymphoma 2 associated X (BAX), and activation of caspase-3/-9. The effects of L-Ru on the cell viability, Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positive cells and Annexin V-positive cells apoptosis induction were remarkably attenuated. This complex induced DNA damage, cell cycle arrest and cell death via caspase-dependent apoptosis involving PARP activation and induction of p53-dependent pathway. These findings suggested that this ruthenium complex might be a potential effective chemotherapeutic agent in NSCLC therapy.

Optical properties and antiangiogenic activity of a chalcone derivate

Chalcones and their derivatives exhibit numerous pharmacological activities such as antibacterial, antifungal, cytotoxic, antinociceptive and anti-inflammatory. Recently, they have been assessed aiming for novel application in nonlinear optics and in the treatment of immune diseases and cancers. In this study, we investigate the optical properties of synthetic chalcona 1E,4E-1-(4-chlorophenyl)-5-(2,6,6-trimethylcyclohexen-1-yl)penta-1,4-dien-3-one (CAB7β) and its antiangiogenic potential using the chorioallantoic membrane (CAM) with the S180 sarcoma cell line. Experimental and theoretical results show intense absorption in the UVA-UVC region, which is associated with a π → π* transition with intramolecular charge transfer from the trimethyl-cyclohexen-1-yl ring to the chlorophenyl ring. Quantum chemical calculations of the first hyperpolarizability, accounting for both solvent and frequency dispersion effects, are in very good concordance with hyper-Rayleigh scattering measurements. In addition, two-photon absorption allowed band centered at 650 nm was observed. Concerning antiangiogenic activity, CAB7β causes a significant reduction in the total number, junctions, length and caliber of blood vessels stimulated by S180 cells reducing the presence of blood vessels, inflammatory cells and others elements related to angiogenic process. It is found that CAB7β is a versatile compound and a promising candidate for linear and nonlinear optical applications, in therapy against sarcoma and phototherapy.

A thiol-reactive Ru(II) ion, not CO release, underlies the potent antimicrobial and cytotoxic properties of CO-releasing molecule-3

Carbon monoxide (CO)-releasing molecules (CORMs), mostly metal carbonyl compounds, are extensively used as experimental tools to deliver CO, a biological ‘gasotransmitter’, in mammalian systems. CORMs are also explored as potential novel antimicrobial drugs, effectively and rapidly killing bacteria in vitro and in animal models, but are reportedly benign towards mammalian cells. Ru-carbonyl CORMs, exemplified by CORM-3 (Ru(CO)₃Cl(glycinate)), exhibit the most potent antimicrobial effects against Escherichia coli. We demonstrate that CORM-3 releases little CO in buffers and cell culture media and that the active antimicrobial agent is Ru(II), which binds tightly to thiols. Thus, thiols and amino acids in complex growth media – such as histidine, methionine and oxidised glutathione, but most pertinently cysteine and reduced glutathione (GSH) – protect both bacterial and mammalian cells against CORM-3 by binding and sequestering Ru(II). No other amino acids exert significant protective effects. NMR reveals that CORM-3 binds cysteine and GSH in a 1:1 stoichiometry with dissociation constants, K_d, of about 5 μM, while histidine, GSSG and methionine are bound less tightly, with K_d values ranging between 800 and 9000 μM. There is a direct positive correlation between protection and amino acid affinity for CORM-3. Intracellular targets of CORM-3 in both bacterial and mammalian cells are therefore expected to include GSH, free Cys, His and Met residues and any molecules that contain these surface-exposed amino acids. These results necessitate a major reappraisal of the biological effects of CORM-3 and related CORMs.

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Carbon monoxide-releasing molecules (CORMs) are used for experimental CO delivery.

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CORM-3 is a potent antimicrobial, but is reportedly beneficial to mammalian cells.

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We demonstrate CORM-3 releases little CO in buffers and cell culture media.

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Redox-active Ru²⁺ is the biological agent, binding tightly to metabolites e.g. thiol.

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These results necessitate a major reappraisal of the biological effects of CORMs.

cis-[RuCl(BzCN)(bipy)(dppe)]PF6 induces anti-angiogenesis and apoptosis by a mechanism of caspase-dependent involving DNA damage, PARP activation, and Tp53 induction in Ehrlich tumor cells

Antimetastatic activities, low toxicity to normal cells and high selectivity for tumor cells make of the ruthenium complexes promising candidates in the search for develop new chemotherapeutic agents for the treatment of cancer. This study aimed to determine the cytotoxic, genotoxic and to elucidate the signaling pathway involved in the death cell process induced by cis-[RuCl(BzCN)(bipy)(dppb)]PF₆(1) and cis-[RuCl(BzCN)(bipy)(dppe)]PF₆(2) in Ehrlich ascites carcinoma (EAC) in vitro. Moreover, we report for the first time the anti-angiogenic potential on chick embryo chorioallantoic membrane (CAM) model. Peripheral blood mononuclear cells (PBMC) were isolated from healthy controls with an age range of 20-30 years and used to calculate the selectivity index (SI). The complex 2 (IC₅₀ = 8.5 ± 0.4/SI = 6.3) showed high cytotoxic and selectivity index against EAC cells than complex 1 (IC₅₀ = 14.9 ± 0.2/SI = 0.2) using the MTT assay. Complex 2 induced DNA damage on Ehrlich tumor cells at concentrations and time periods evalueted. In consequence, it was observed an increase of Tp53 gene expression, G0/G1-arrest cells, and increased levels of cleaved PARP protein. Beside that, the treatment of EAC with complex 2 led to an increase in Annexin V-positive cells and apoptosis induction by Caspase-7. Additionally, the complex 2 inhibited the angiogenesis caused by Ehrlich tumor cells in CAM model. This complex is active and selective for Ehrlich tumor cells, inducing DNA damage, cell cycle arrest and cell death by caspase-dependent apoptosis involving PARP activation (PARP1), and Tp53 induction.

Inhibition of human DNA topoisomerase IB by nonmutagenic ruthenium(II)-based compounds with antitumoral activity

Herein we synthesized two new ruthenium(II) compounds [Ru(pySH)(bipy)(dppb)]PF6 (1) and [Ru(HSpym)(bipy)(dppb)]PF6 (2) that are analogs to an antitumor agent recently described, [Ru(SpymMe2)(bipy)(dppb)]PF6 (3), where [(Spy) = 2-mercaptopyridine anion; (Spym) = 2-mercaptopyrimidine anion and (SpymMe2) = 4,6-dimethyl-2-mercaptopyrimidine anion]. In vitro cell culture experiments revealed significant anti-proliferative activity for 1-3 against HepG2 and MDA-MB-231 tumor cells, higher than the standard anti-cancer drugs doxorubicin and cisplatin. No mutagenicity is detected when compounds are evaluated by cytokinesis-blocked micronucleus cytome and Ames test in the presence and absence of S9 metabolic activation from rat liver. Interaction studies show that compounds 1-3 can bind to DNA through electrostatic interactions and to albumin through hydrophobic interactions. The three compounds are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (Top1). Compound 3 is the most efficient Top1 inhibitor and the inhibitory effect is enhanced upon pre-incubation with the enzyme. Analysis of different steps of Top1 catalytic cycle indicates that 3 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and slows down the religation reaction. Molecular docking shows that 3 preferentially binds closer to the residues of the active site when Top1 is free and lies on the DNA groove downstream of the cleavage site in the Top1-DNA complex. Thus, 3 can be considered in further studies for a possible use as an anticancer agent.

MDR1 and cytochrome P450 gene-expression profiles as markers of chemosensitivity in human chronic myelogenous leukemia cells treated with cisplatin and Ru(III) metallocomplexes

Leukemia is a major type of cancer affecting a significant segment of the population, and especially children. In fact, leukemia is the most frequent childhood cancer, with 26 % of all cases, and 20 % mortality. The multidrug resistance phenotype (MDR) is considered one of the major causes of failure in cancer chemotherapy. The present study aimed to investigate the relationship between the expression of MDR1 and CYP450 genes in human chronic myelogenous leukemia cells (K-562) treated with cisplatin (cisPt) and two ruthenium-based coordinated complexes [cisCRu(III) and cisDRu(III)]. The tested compounds induced apoptosis in K-562 tumor cells as evidenced by caspase 3 activation. Results also revealed that the amplification of P-gp gene is greater in K-562 cells exposed to cisPt and cisCRu(III) than cisDRu(III). Taken together, all these results strongly demonstrate that MDR-1 overexpression in K-562 cells could be associated to a MDR phenotype, and moreover, it is also contributing to the platinum and structurally related compound, resistance in these cells.

Cytotoxic effects of the compound cis-tetraammine(oxalato)ruthenium(III) dithionate on K-562 human chronic myelogenous leukemia cells

Chemotherapy is a common treatment for leukemia. Ruthenium complexes have shown potential utility in chemotherapy and photodynamic therapy. The identification of new chemotherapeutics agents is critical for further progress in the treatment of leukemia. Ruthenium complexes generally have lower toxicities compared to cisplatin attributed to their specific accumulation in cancer tissues. Based on these evidences, in the present work we studied the cytotoxic activity of the ruthenium(III) compound cis-tetraammine(oxalato)ruthenium(III) dithionate - {cis-[Ru(C2O4)(NH3)4]2(S2O6)} against human chronic myelogenous leukemia cells (K-562) tumor cell line. The tested compound induces cell death in a dose and time dependent manner on K-562 cells. It is found that the effect was improved linearly while prolonging the incubation time. Compared to the cell cycle profiles of untreated cells, flow cytometric analysis indicated the sub-G1 arresting effect of ruthenium compound on K-562 cells. In our study, {cis-[Ru(C2O4)(NH3)4]2(S2O6)} shows a significant increase in tailed cells in any of the concentrations tested compared with negative control. Consequently, the concentration of {cis-[Ru(C2O4)(NH3)4]2(S2O6)} might be associated cytotoxicity with direct effect on K-562 cells DNA. Thus, it can be deducted that ruthenium-based compounds present selectivity to enter both tumor and normal cells. Additional studies are needed to determine the molecular mechanisms of the active components and to evaluate the potential in vivo anticancer activity of the cis-tetraammine(oxalato)ruthenium(III) dithionate.

The ruthenium complexes cis-(dichloro)tetramineruthenium(III) chloride and cis-tetraammine(oxalato)ruthenium(III) dithionate overcome resistance inducing apoptosis on human lung carcinoma cells (A549)

Lung cancer is one of the leading causes of death in the world, and non-small cell lung carcinoma accounts for approximately 75-85 % of all lung cancers. In the present work, we studied the antitumor activity of the compound cis-(dichloro)tetramineruthenium(III) chloride {cis-[RuCl2(NH3)4]Cl} against human lung carcinoma tumor cell line A549. The present study aimed to investigate the relationship between the expression of MDR1 and CYP450 genes in human lung carcinoma cell lines A549 treated with cisCarboPt, cisCRu(III) and cisDRu(III). The ruthenium-based coordinated complexes presented low cytotoxic and antiproliferative activities, with high IC50 values, 196 (±15.49), 472 (±20.29) and 175 (±1.41) for cisCarboPt, cisCRu(III) and cisDRu(III), respectively. The tested compounds induced apoptosis in A549 tumor cells as evidenced by caspase 3 activation, but only at high concentrations. Results also revealed that the amplification of P-gp gene is greater in A549 cells exposed to cisCarboPt and cisCRu(III) than cisDRu(III). Taken together all these results strongly demonstrate that MDR-1 over-expression in A549 cells could be associated to a MDR phenotype of these cells and moreover, it is also contributing to the platinum, and structurally-related compound, resistance in these cells. The identification and characterization of novel mechanisms of drug resistance will enable the development of a new generation of anti-cancer drugs that increase cancer sensitivity and/or represent more effective chemotherapeutic agents.

Highly cytotoxic DNA-interacting copper(ii) coordination compounds

Copper complexes from Schiff-base ligands show high cytotoxicity against diverse cancer cell lines, with IC₅₀ values down to 0.23 μM.

Real-time infrared thermography detection of magnetic nanoparticle hyperthermia in a murine model under a non-uniform field configuration

PURPOSE

Magnetic nanoparticle hyperthermia consists of an increase of the temperature of magnetic nanoparticles (heat centres) due to the interaction of their magnetic moments with an alternating magnetic field. In vivo experiments using this method usually use a few fibre-optic thermometers inserted in the animal body to monitor the heat deposition. As a consequence, only a few points of the 3D temperature distribution can be monitored by this invasive procedure. It is the purpose of this work to show that non-invasive infrared thermography is able to detect, in real time, magnetic nanoparticle hyperthermia as well as monitor the harmful field-induced eddy currents in a murine model with a subcutaneous tumour. This surface temperature measurement method has the potential to give information about the intratumoral temperature.

MATERIALS AND METHODS

The non-invasive magnetic hyperthermia experiments were performed at 300 kHz in non-uniform field configuration conditions in healthy mice and murine tumour induced by sarcoma S180. A soft ferrite-based biocompatible magnetic colloid consisting of manganese-ferrite nanoparticles surface-coated with citric acid were used in the experiments, which were extensively characterised by several techniques (transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM)). The amplitude of the alternating magnetic fields was obtained from measurements using an AC field probe at similar experimental conditions. The temperature measurements were obtained from an infrared thermal camera and a fibre-optic thermometer.

RESULTS

Three-minute magnetic hyperthermia experiments revealed surface temperature increase as high as 11 °K in healthy and (5 °K in S180 tumour) animals when injecting subcutaneously 2 mg of magnetic nanoparticles (86 μL of magnetic fluid), in contrast to around 1.5 °K (for healthy) and 2.5 °K (for cancerous) animals in experiments without the colloid due to field-induced eddy currents at the animal surface. The thermographic temperature measurements were found to agree with the fibre-optic measurements within a 5% error, and were associated with the skin emissivity angle of dependence in the experimental set-up. On the other hand, a 30-min magnetic nanoparticle hyperthermia revealed surface temperature increases as high as 12 °K close to the injection site, while above 2-3 cm no significant temperature increase was observed. Curiously, the intratumoral temperature, monitored by a fibre-optic sensor, was found to be almost the same as the thermal camera surface temperature after achieving an equilibrium temperature regime. From the observed isotherms at the animal surface, using an analytical heat conduction model, taking into account surface conductance, we estimate a magnetic heating power of 0.45 W/cm(3) and a specific loss power (SLP) of 85 W/g for a field of the order of only 10 kA/m at the injection site region.

CONCLUSIONS

The results indicate that infrared thermography may be a promising tool for both early cancer detection and for hyperthermia treatment (at least for subcutaneous tumours), since the method permits access to information about the intratumoral temperature during a real-time magnetic hyperthermia as well as to estimate the in vivo nanoparticles SLP.

Induction of cell cycle arrest and apoptosis by ruthenium complex cis-(dichloro)tetramineruthenium(III) chloride in human lung carcinoma cells A549

Lung cancer is one of the leading causes of death in the world, and non-small cell lung carcinoma (NSCLC) accounts for approximately 75-85% of all lung cancers. In the present work, we studied the cytotoxic activity, cell cycle arrest and induction apoptosis of the compound cis-(dichloro)tetramineruthenium(III) chloride {cis-[RuCl(2)(NH(3))(4)]Cl} in human lung carcinoma tumor cell line A549. The results of MTT and trypan blue assays showed that cis-[RuCl(2)(NH(3))(4)]Cl causes reduction in the viability of A549 cells when treating with 95 and 383 μM of the compound for 48 and 72 h. Lower concentrations of the compound (19, 3.8 and 0.38 μM), however, only slightly affected cell viability. The IC(50) value for the compound was about 383 μM. Survival analysis of the A549 cells after treatment with ruthenium(III) compound using long term clonogenic assay showed that it reduced colony formation ability at concentrations of 0.38 and 3.8 μM, and at concentrations of 95 and 383 μM no colonies were observed. Cell cycle analysis showed that compound ruthenium led to an accumulation of A549 cells in S phase and increased in the sub-G1 peak. In addition, cis-(dichloro)tetramineruthenium(III) chloride treatment induced apoptosis, as observed by the increased numbers of annexin V-positive cells and increased messenger RNA expression of caspase-3.

Cell damage following carbon monoxide releasing molecule exposure: implications for therapeutic applications

The cytoprotective properties of carbon monoxide (CO) gas and CO-releasing molecules (CORMs) are well established. Despite promising pre-clinical results, little attention has been paid to the toxicological profile of CORMs. The effects of CORM-2 and its CO-depleted molecule (iCORM-2) (20-400 μM) were compared in primary rat cardiomyocytes and two cell lines [human embryonic kidney (HeK) and Madine-Darby canine kidney Cells (MDCK)]. Cells were assessed for cell viability, apoptosis, necrosis, cytology, mitochondrial energetics, oxidative stress and cell cycle arrest markers. In separate experiments, the anti-apoptotic effects of CORM-2 and i-CORM-2 treatment were compared against CO gas treatment in HeK and MDCK lines. H(2)O(2) -induced cellular damage, measured by lactate dehydrogenase (LDH) release from primary cardiomyocytes, was reduced by 20 μM CORM-2; LDH activity, however, was directly inhibited by 400 μM CORM-2. Both CORM-2/iCORM-2 and CO gas decreased cisplatin-induced caspase-3 activity in MDCK and HeK cells suggesting an anti-apoptotic effect. Conversely, both CORM-2 and iCORM-2 induced significant cellular toxicity in the form of decreased cell viability, abnormal cell cytology, increased apoptosis and necrosis, cell cycle arrest and reduced mitochondrial enzyme activity. Comparison of these markers after CO gas administration to MDCK cells found significantly less cellular toxicity than in 100 μM CORM-2/iCORM-2-treated cells. CO gas did not have an adverse effect on mitochondrial energetics and integrity. Release of CO by low concentrations of intact CORM-2 molecules provides cytoprotective effects. These results show, however, that the ruthenium-based CORM by-product, iCORM-2, is cytotoxic and suggest that the accumulation of iCORM-2 would seriously limit any clinical application of the ruthenium-based CORMs.

The compound cis-(dichloro)tetrammineruthenium(III) chloride induces caspase-mediated apoptosis in K562 cells

Ruthenium(III) complexes are increasingly attracting the interest of researchers due to their promising pharmacological properties. In the present study, we investigated the ability of cis-(dichloro)tetrammineruthenium(III) chloride to produce lethal effects in human chronic myelogenous leukemia K562 cells. The MTT tetrazolium reduction test and the trypan blue exclusion assay revealed that the IC(50) for the compound after 48 h of incubation with K562 cells was approximately 10.74 and 73.45 microM, respectively. Interestingly, it was observed that this compound exhibits mild cytotoxicity towards MRC-5 human fibroblast cells (IC(50)>383 microM). Flow cytometric analysis revealed that cis-(dichloro)tetrammineruthenium(III) chloride was capable of change cell cycle distribution since the percentage of cells in the G1, S and G2 phases decreased. In addition, treatment with this compound induced apoptotic cell death in K562 cells, demonstrated by increased DNA content in the sub-G1-peak and a significant increase in caspase-3 activity. Assay using cyclosporin A, an inhibitor of the mitochondrial permeability transition pore (MPT) showed that the preincubation of K562 cells with this inhibitor had not effect on cis-(dichloro)tetrammineruthenium(III) chloride induced caspase-3 activation. In summary, cis-(dichloro)tetrammineruthenium(III) chloride displayed a significant cytotoxic effect through cell cycle arrest and apoptotic induction in K562 cells, which suggests that cis-(dichloro)tetrammineruthenium(III) chloride might have therapeutic potential against leukemia.

The ruthenium complex cis-(dichloro)tetraammineruthenium(III) chloride presents selective cytotoxicity against murine B cell lymphoma (A-20), murine ascitic sarcoma 180 (S-180), human breast adenocarcinoma (SK-BR-3), and human T cell leukemia (Jurkat) tumor cell lines

The aim of present study was to verify the in vitro antitumor activity of a ruthenium complex, cis-(dichloro)tetraammineruthenium(III) chloride (cis-[RuCl(2)(NH(3))(4)]Cl) toward different tumor cell lines. The antitumor studies showed that ruthenium(III) complex presents a relevant cytotoxic activity against murine B cell lymphoma (A-20), murine ascitic sarcoma 180 (S-180), human breast adenocarcinoma (SK-BR-3), and human T cell leukemia (Jurkat) cell lines and a very low cytotoxicity toward human peripheral blood mononuclear cells. The ruthenium(III) complex decreased the fraction of tumor cells in G0/G1 and/or G2-M phases, indicating that this compound may act on resting/early entering G0/G1 cells and/or precycling G2-M cells. The cytotoxic activity of a high concentration (2 mg mL(-1)) of cis-[RuCl(2)(NH(3))(4)]Cl toward Jurkat cells correlated with an increased number of annexin V-positive cells and also the presence of DNA fragmentation, suggesting that this compound induces apoptosis in tumor cells. The development of new antineoplastic medications demands adequate knowledge in order to avoid inefficient or toxic treatments. Thus, a mechanistic understanding of how metal complexes achieve their activities is crucial to their clinical success and to the rational design of new compounds with improved potency.

The ruthenium complex cis-(Dichloro)Tetraammineruthenium(III) chloride presents immune stimulatory activity on human peripheral blood mononuclear cells

Ruthenium compounds in general are well suited for medicinal applications. They have been investigated as immunosuppressants, nitric oxide scavengers, antimicrobial agents, and antimalarials. The aim of this study is to evaluate the immunomodulatory activity of cis-(dichloro)tetraammineruthenium(III) chloride (cis-[RuCl(2)(NH(3))(4)]Cl) on human peripheral blood mononuclear cells (PBMC). The cytotoxic studies performed here revealed that the ruthenium(III) complex presents a cytotoxic activity towards normal human PBMC, only at very high concentration. Results also showed that cis-[RuCl(2)(NH(3))(4)]Cl presents a dual role on PBMC stimulating proliferation and interleukin-2 (IL-2) production at low concentration and inducing cytotoxicity, inability to proliferate, and inhibiting IL-2 production at high concentration. The noncytotoxic activity of cis-[RuCl(2)(NH(3))(4)]Cl at low concentration towards PBMC, which correlates with the small number of annexin V positive cells and also the absence of DNA fragmentation, suggest that this compound does not induce apoptosis on PBMC. For the first time, we show that, at low concentration (10-100 microg L(-1)), the cis-[RuCl(2)(NH(3))(4)]Cl compound induces peripheral blood lymphocytes proliferation and also stimulates them to IL-2 production. These results open a new potential applicability of ruthenium(III) complexes as a possible immune regulatory compound acting as immune suppressor at high concentration and as immune stimulator at low concentration.

Mutagenic and genotoxic effects of cis-(dichloro)tetraammineruthenium(III) chloride on human peripheral blood lymphocytes

Chemotherapeutic agents play an important role in cancer treatment mostly due their systemic action on human organism allowing access to liquid tumors and even metastases. Among these drugs, ruthenium compounds have been showing promising results to treat tumors and represent an important development of new antitumor therapy. This study presents the evaluation of cis-(dichloro)tetraammineruthenium(III) chloride, cis-[RuCl(2)(NH(3))(4)]Cl, genotoxic effects using human peripheral blood lymphocytes cultured in vitro. Mitotic index (MI), chromosome aberrations (CA), and DNA damage using the comet assay were analyzed. MI in human peripheral blood lymphocyte cultures treated with 1, 10, 100, and 1,000 microg mL(-1) cis-[RuCl(2)(NH(3))(4)]Cl were 5.9%, 4.6%, 3.9%, and 0%, respectively. Doxorubicin chloridate was used as the positive control. CA derived from 1, 10, and 100 microg mL(-1) concentrations were defined as spontaneous when compared with the negative control, and at the concentration of 1,000 microg mL(-1), the cell cycle was inhibited (IM = 0%). Results obtained for the comet assay using cis-[RuCl(2)(NH(3))(4)]Cl suggest that this compound has no genotoxic activity against cultured human peripheral blood lymphocytes.

Cytotoxic and genotoxic effects of cis-tetraammine(oxalato)ruthenium(III) dithionate on the root meristem cells of Allium cepa

Ruthenium complexes have attracted much attention as possible building blocks for new transition-metal-based antitumor agents. The present study examines the mitotoxic and clastogenic effects induced in the root tips of Allium cepa by cis-tetraammine(oxalato)ruthenium(III) dithionate {cis-[Ru(C(2)O(2))(NH(3))(4)](2)(S(2)O(6))} at different exposure durations and concentrations. Correlation tests were performed to determine the effects of the time of exposure and concentration of ruthenium complex on mitotic index (MI) and mitotic aberration index. A comparison of MI results of cis-[Ru(C(2)O(2))(NH(3))(4)](2)(S(2)O(6)) to those of lead nitrate reveals that the ruthenium complex demonstrates an average mitotic inhibition eightfold higher than lead, with the frequency of cellular abnormalities almost fourfold lower and mitotic aberration threefold lower. A. cepa root cells exposed to a range of ruthenium complex concentrations did not display significant clastogenic effects. Cis-tetraammine(oxalato)ruthenium(III) dithionate therefore exhibits a remarkable capacity to inhibit mitosis, perhaps by inhibiting DNA synthesis or blocking the cell cycle in the G2 phase. Further investigation of the mechanisms of action of this ruthenium complex will be important to define its clinical potential and to contribute to a novel and rational approach to developing a new metal-based drug with antitumor properties complementary to those exhibited by the drugs already in clinical use.

Effect of ruthenium complexes on the activities of succinate dehydrogenase and cytochrome oxidase

In this article, we report the effects of acute administration of ruthenium complexes, trans-[RuCl(2)(nic)(4)] (nic=3-pyridinecarboxylic acid) 180.7 micromol/kg (complex I), trans-[RuCl(2)(i-nic)(4)] (i-nic=4-pyridinecarboxylic acid) 13.6 micromol/kg (complex II), trans-[RuCl(2)(dinic)(4)] (dinic=3,5-pyridinedicarboxylic acid) 180.7 micromol/kg (complex III) and trans-[RuCl(2)(i-dinic)(4)]Cl (i-dinic=3,4-pyridinedicarboxylic acid) 180.7 micromol/kg (complex IV) on succinate dehydrogenase (SDH) and cytochrome oxidase (COX) activities in brain (hippocampus, striatum and cerebral cortex), heart, skeletal muscle, liver and kidney of rats. Our results showed that complex I inhibited SDH activity in hippocampus, cerebral cortex, heart and liver; and inhibited COX in heart and kidney. Complex II inhibited SDH in heart and hippocampus; COX was inhibited in hippocampus, heart, liver and kidney. SDH activity was inhibited by complex III in heart, muscle, liver and kidney. However, COX activity was increased in hippocampus, striatum, cerebral cortex and kidney. Complex IV inhibited SDH activity in muscle and liver; COX activity was inhibited in kidney and increased in hippocampus, striatum and cerebral cortex. In a general manner, the complexes tested in this work decrease the activities of SDH and COX in heart, skeletal muscle, liver and kidney. In brain, complexes I and II were shown to be inhibitors and complexes III and IV activators of these enzymes. In vitro studies showed that the ruthenium complexes III and IV did not alter COX activity in kidney, but activated the enzyme in hippocampus, striatum and cerebral cortex, suggesting that these complexes present a direct action on COX in brain.