Raman Spectroscopy on Free-Base Meso-tetra(4-pyridyl) Porphyrin under Conditions of Low Temperature and High Hydrostatic Pressure.

We present a Raman spectroscopy study of the vibrational properties of free-base meso-tetra(4-pyridyl) porphyrin polycrystals under various temperature and hydrostatic pressure conditions. The combination of experimental results and Density Functional Theory (DFT) calculations allows us to assign most of the observed Raman bands. The modifications in the Raman spectra when excited with 488 nm and 532 nm laser lights indicate that a resonance effect in the Qy band is taking place. The pressure-dependent results show that the resonance conditions change with increasing pressure, probably due to the shift of the electronic transitions. The temperature-dependent results show that the relative intensities of the Raman modes change at low temperatures, while no frequency shifts are observed. The experimental and theoretical analysis presented here suggest that these molecules are well represented by the C2v point symmetry group.

Ruthenium(II) complex with 2-mercaptothiazoline ligand induces selective cytotoxicity involving DNA damage and apoptosis in melanoma cells.

Melanoma is the most aggressive and lethal type of skin cancer due to its characteristics such as high metastatic potential and low response rate to existing treatment modalities. In this way, new drug prototypes are being studied to solve the problem of treating patients with melanoma. Among these, ruthenium-based metallopharmaceuticals may be promising alternatives due to their antitumor characteristics and low systemic toxicity. In this context, the present study evaluated the antineoplastic effect of the ruthenium complex [Ru(mtz)(dppe)2]PF6-2-mercaptothiazoline-di-1,2-bis(diphenylphosphine) ethaneruthenium(II), namely RuMTZ, on human melanoma (A-375) and murine (B16-F10) cells, considering different approaches. Through XTT colorimetric and clonogenic efficiency assays, the complex revealed the selective cytotoxic activity, with the lowest IC50 (0.4 µM) observed for A375 cells. RuMTZ also induced changes in cell morphology, increased cell population in the sub-G0 phase and inhibiting cell migration. The levels of γH2AX and cleaved caspase 3 proteins were increased in both cell lines treated with RuMTZ. These findings indicated that the cytotoxic activity of RuMTZ on melanoma cells is related, at least in part, to the induction of DNA damage and apoptosis. Therefore, RuMTZ exhibited promising antineoplastic activity against melanoma cells.

Cobalt(III)-py2en systems as potential carriers of ß-ketoester-based ligands.

Two cobalt(III) complexes containing different ß-ketoesters, namely [CoIII(L1)(py2en)](ClO4)2·H2O (1) and [CoIII(L2)(py2en)](ClO4)2 (2) (py2en = N,N'-bis(pyridin-2-ylmethyl)ethylenediamine; L1- = methylacetoacetate; L2- = ethyl 4-chloroacetoacetate) have been prepared and investigated as prototypes of bioreductive prodrugs. The presence of ß-ketoester and py2en ligands in 1 and 2, as well as the perchlorate counterions, was supported by IR spectroscopy and CHN elemental analysis. The composition molecular structure of both complexes was confirmed by NMR spectroscopy and ESI mass spectrometry. Structural information was also obtained for 2via X-ray diffraction analysis. The redox properties indicate that 1 and 2 are suitable for reduction under biological conditions. Investigation of DNA-interacting suggest that 1 and 2 bind DNA via electrostatic forces. Both complexes may be employed as possible platforms for the delivery of biologically active compounds, since their reaction with ascorbic acid in PBS at pH 6.2 and 7.4 at 37°C results in the release of the ß-ketoester ligands upon Co(III)/Co(II) reduction.

Nanoencapsulation of Ruthenium Complex Ru(ThySMet): A Strategy to Improve Selective Cytotoxicity Against Breast Tumor Cells in 2D and 3D Culture Models.

BACKGROUND: Ruthenium complexes have shown promise in treating many cancers, including breast cancer. Previous studies of our group have demonstrated the potential of the trans-[Ru(PPh3)2(N,N-dimethylN'-thiophenylthioureato-k2O,S)(bipy)]PF6 complex, the Ru(ThySMet), in the treatment of breast tumor cancers, both in 2D and 3D culture systems. Additionally, this complex presented low toxicity when tested in vivo. AIMS: Improve the Ru(ThySMet) activity by incorporating the complex into a microemulsion (ME) and testing its in vitro effects. METHODS: The ME-incorporated Ru(ThySMet) complex, Ru(ThySMet)ME, was tested for its biological effects in two- (2D) and three-dimensional (3D) cultures using different types of breast cells, MDA-MB-231, MCF-10A, 4T1.13ch5T1 and Balb/C 3T3 fibroblasts. RESULTS: An increased selective cytotoxicity of the Ru(ThySMet)ME for tumor cells was found in 2D cell culture, compared with the original complex. This novel compound also changed the shape of tumor cells and inhibited cell migration with more specificity. Additional 3D cell culture tests using the non-neoplastic S1 and the triple-negative invasive T4-2 breast cells have shown that Ru(ThySMet)ME presented increased selective cytotoxicity for tumor cells compared with the 2D results. The morphology assay performed in 3D also revealed its ability to reduce the size of the 3D structures and increase the circularity in T4-2 cells. CONCLUSION: These results demonstrate that the Ru(ThySMet)ME is a promising strategy to increase its solubility, delivery, and bioaccumulation in target breast tumors.

Novel Ru(II)-bipyridine/phenanthroline-lapachol complexes as potential anti-cancer agents.

For the first time, we herein report on the syntheses of two new Ru(II)/bipyridine/phenanthroline complexes containing lapachol as ligand: complex (1), [Ru (bipy)2(Lap)]PF6 and complex (2), [Ru(Lap)(phen)2]PF6, where bipy = 2,2'-bipyridine and ph en = 1,10-phenanthroline; Lap = lapachol (2-hydroxy-3-(3-methylbut-2-en-1- yl)naphthalene-1,4-dione). The complexes were synthesized and characterized by elemental analyses, molar conductivity, mass spectrometry, ultraviolet-visible and infrared spectroscopies, nuclear magnetic resonance (1H, 13C), and single crystal X-ray diffraction, for complex (2). In addition, in vitro cytotoxicity was tested against six cancer cells: A549 (lung carcinoma); DU-145 (human prostate carcinoma); HepG2 (human hepatocellular carcinoma), PC-3 (human prostate adenocarcinoma); MDA-MB-231 (human breast adenocarcinoma); Caco-2 (human colorectal adenocarcinoma), and against two non-cancer cells, FGH (human gingival normal fibroblasts) and PNT-2 (prostate epithelial cells). Complex (1) was slightly more toxic and selective than complex (2) for all cell lines, except against the A549 cells, where (2) was more potent than complex (1). The complexes induced an increase in the reactive oxygen species, and the co-treatment with N-acetyl-L-cysteine remarkably suppressed the ROS generation and prevented the reduction of cell viability, suggesting that the cytotoxicity of the complexes is related to the ROS-mediated pathway. Further studies indicated that the complexes may bind to DNA via minor groove interaction. Our studies also revealed that free Lap induces gene mutations in Salmonella Typhimurium, nevertheless, the complexes demonstrated the absence of genotoxicity by the Ames test. The present study provides a relevant contribution to understanding the anti-cancer potential and genetic toxicological events of new ruthenium complexes containing the lapachol molecule as a ligand.

Anti-melanoma effect of ruthenium(II)-diphosphine complexes containing naphthoquinone ligand.

The use of natural products as potential ligands has been explored as a strategy in the development of metal-based chemotherapy. Since ruthenium complexes are promising alternatives to traditional antitumor agents, this study evaluated the anti-melanoma potential of two ruthenium(II) complexes containing the naphthoquinone ligands lapachol (lap), [Ru(lap)(dppm)2]PF6, and lawsone (law), [Ru(law)(dppm)2]PF6, in addition to the bis(diphenylphosphino)methane (dppm) ligand, referred to as complexes (1) and (2), respectively, using a syngeneic murine melanoma model. Activation of the apoptotic pathway by the treatments was assessed by immunohistochemistry in tumor tissue. Additionally, toxicity of the treatments was evaluated by variation in body and organ weight, quantification of biochemical indicators of renal damage, and genotoxicity in bone marrow and hepatocytes. First, the antiproliferative activity of (1) and (2) was observed in B16F10 cells, with IC50 values of 2.78 and 1.68 µM, respectively. The results obtained in mice showed that, unlike complex (1), (2) possesses significant anti-melanoma activity demonstrated by a reduction in tumor volume and mass (88.42%), as well as in mitosis frequency (83.86%). Additionally, complex (2) increased the levels of cleaved caspase-3, inducing tumor cell apoptosis. When compared to the metallodrug cisplatin, complex (2) exhibited similar anti-melanoma activity and lower toxicity considering all parameters evaluated. In silico studies demonstrated no difference in the binding energy of the naphthoquinone complex between complexes (1) and (2). However, the complex containing the lawsone ligand has a lower molar volume, which may be important for interactions with minor DNA grooves. The present results demonstrate the antitumor efficiency of complex (2) and a significantly lower systemic toxicity compared to cisplatin.

A giant hybrid organic-inorganic octahedron from a narrow rim carboxylate calixarene.

Here we discovered an unprecedented giant octahedral coordination compound bearing 16 Zn2+, 12 Na+, 8 O2-, 4 OH-, 13 H2O and 6 L4- ligands [L4- = fully deprotonated tetra(carboxymethoxy)calix[4]arene]. Its structure was elucidated by single-crystal X-ray diffraction, wavelength-dispersive X-ray spectroscopy and MALDI-TOF mass spectrometry. This compound, Zn8Na6L6⊃Zn8Na6O8(OH)4(H2O)13 (external⊃internal), has eight tetrahedral zinc ions forming the coordination vertices of an outermost cube where carboxylate groups from the sodium calixarenes are anchored. Its core consists of eight Zn2+, six Na+, eight O2-, and four OH- distributed over three layers, besides thirteen coordinated H2O molecules.

A straightforward catalytic approach to obtain deuterated chloroform at room temperature.

We report the catalytic activity for the complexes-cis-[RuCl2 (dppb)(bipy)] (A), and [η6 -(p-cymene)Ru (dppb)Cl]PF6 (B), wherein dppb = 1,4-bis(diphenylphosphine)butane, and bipy = 2,2'-bipyridine-for the synthesis of CDCl3 from CHCl3 using D2 O as deuterium source. H/D exchange reactions were performed using a chloroform/D2 O, 1:2 molar ratio, vigorously stirred, at room temperature. One mole of KOH was dissolved in D2 O fraction and catalytic complexes from 0.002 to 0.05 mmol were dissolved in chloroform. The H/D exchange reactions were monitored using 13 C nuclear magnetic resonance sequences without proton decoupling. The reaction using 0.01 mmol of compound A reached approximately 55% of H/D conversion in 1 h. In the same time, the reactions with 0.002 mmol of compound A and without catalyst show approximately 28% and 3% H/D exchange, respectively. Without the catalysts, the H/D exchange was only 12.0% in 5 h. For compound B, 55% H/D conversion was observed in 1 h, only when 0.05 mmol was used, which is much higher catalyst concentration. After the isolation of the chloroform fraction and two more addition of D2 O, it was possible to obtain 95.0% H/D exchange in approximately 3 h, using 0.01 mmol of the compound A. Therefore, compound A is an efficient catalyst for a rapid and straightforward synthesis of CDCl3 from CHCl3 at room temperature and using D2 O as deuterium source.

Ruthenium(II)/Benzonitrile Complex Induces Cytotoxic Effect in Sarcoma-180 Cells by Caspase-Mediated and Tp53/p21-Mediated Apoptosis, with Moderate Brine Shrimp Toxicity.

Ruthenium(II)/benzonitrile complexes have demonstrated promising anticancer properties. Considering that there are no specific therapies for treating sarcoma, we decided to evaluate the cytotoxic, genotoxic, and lethal effects of cis-[RuCl(BzCN)(phen)(dppb)]PF6 (BzCN = benzonitrile; phen = 1,10-phenanthroline; dppb = 1,4-bis-(diphenylphosphino)butane), as well as the mechanism of cell death induction that occurs against murine sarcoma-180 tumor. Thus, MTT assay was applied to assess the ruthenium cytotoxicity, showing that the compound is a more potent inhibitor for the sarcoma-180 tumor cell viability than normal cells (lymphocytes). The comet assay indicated low genotoxic for normal cells. cis-[RuCl(BzCN)(phen)(dppb)]PF6 also showed moderate lethality in Artemia salina. The complex induced cell cycle arrest in the G0/G1 phase in sarcoma-180 cells. In addition, the complex caused S180 cells to die by apoptosis by an increase in Annexin-V-positive cells and morphological changes typical of apoptotic cells. Additionally, cis-[RuCl(BzCN)(phen)(dppb)]PF6 increased the gene expression of Bax, Casp3, and Tp53 in S180 cells. By using a western blot, we observed an increased protein level of TNF-R2, Bax, and p21. In conclusion, cis-[RuCl(BzCN)(phen)(dppb)]PF6 is active and selective for sarcoma-180 cells, leading to cell cycle arrest at the G0/G1 and cell death through a caspases-mediated and Tp53/p21-mediated pathway.

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.

Ru(II)-Based Amino Acid Complexes Show Promise for Leukemia Treatment: Cytotoxicity and Some Light on their Mechanism of Action.

Ruthenium is attracting considerable interest as the basis for new compounds to treat diseases, and studies have shown that complexes with different structures have significant antineoplastic and antimetastatic potential against several types of tumors, including tumors resistant to cisplatin drugs. We examined the cytotoxic, genotoxic, and pro-apoptotic activities of six ruthenium complexes containing amino acid with general formulation [Ru(AA)(bipy)(dppb)]PF6, where AA = amino acid (alanine, glycine, leucine, lysine, methionine, or tryptophan); bipy = 2,2´-bipyridine; and dppb = [1,4-bis(diphenylphosphine)butane], against A549 (lung carcinoma) and K562 (chronic myelogenous leukemia) cancer cells. The results show that the ruthenium complexes tested were able to induce cytotoxicity in A549 and K562 cancer cells. Complex 1 containing alanine inhibited the cell viability of A549 and K562 tumor cells by inducing apoptosis, as evidenced by an increased number of Annexin V-positive cells and the induction of DNA damage and cell cycle arrest. Complex 1 was able to induce caspase-mediated apoptosis in K562 cells through the mitochondrial dysfunction, the upregulation of apoptotic genes, and the downregulation of Bcl2 anti-apoptotic gene. Besides being cytotoxic to K562 and A549 cells, ruthenium complex containing alanine shows low cytotoxicity and genotoxicity against non-tumor cells. These results suggest that the ruthenium (II) complex is a potential safe and efficient antineoplastic candidate for leukemia treatment.

Corrigendum: A Nanostructured Lipid System to Improve the Oral Bioavailability of Ruthenium(II) Complexes for the Treatment of Infections Caused by Mycobacterium tuberculosis.

[This corrects the article DOI: 10.3389/fmicb.2018.02930.].

A Supramolecular Interaction of a Ruthenium Complex With Calf-Thymus DNA: A Ligand Binding Approach by NMR Spectroscopy.

Lawsone itself exhibits interesting biological activities, and its complexation with a metal center can improve the potency. In this context a cytotoxic Ru-complex, [Ru(law)(dppb)(bipy)] (law = lawsone, dppb = 1,4-bis(diphenylphosphino)butane and bipy = 2,2'-bipyridine), named as CBLAU, was prepared as reported. In this work, NMR binding-target studies were performed to bring to light the most accessible interaction sites of this Ru-complex toward Calf-Thymus DNA (CT-DNA, used as a model), in a similar approach used for other metallic complexes with anti-cancer activity, such as cisplatin and carboplatin. Advanced and robust NMR binding-target studies, among them Saturation Transfer Difference (STD)-NMR and longitudinal relaxometry (T1), were explored. The 1H and 31P -NMR data indicate that the structure of Ru-complex remains preserved in the presence of CT-DNA, and some linewidth broadening is also observed for all the signals, pointing out some interaction. Looking at the binding efficiency, the T1 values are highly influenced by the formation of the CBLAU-DNA adduct, decreasing from 11.4 s (without DNA) to 1.4 s (with DNA), where the difference is bigger for the lawsone protons. Besides, the STD-NMR titration experiments revealed a stronger interaction (KD = 5.9 mM) for CBLAU-DNA in comparison to non-complexed lawsone-DNA (KD = 34.0 mM). The epitope map, obtained by STD-NMR, shows that aromatic protons from the complexed lawsone exhibits higher saturation transfer, in comparison to other Ru-ligands (DPPB and bipy), suggesting the supramolecular contact with CT-DNA takes place by the lawsone face of the Ru-complex, possibly by a spatial π-π stacking involving π-bonds on nucleic acids segments of the DNA chain and the naphthoquinone group.

Corrigendum: A Nanostructured Lipid System to Improve the Oral Bioavailability of Ruthenium(II) Complexes for the Treatment of Infections Caused by Mycobacterium tuberculosis.

[This corrects the article DOI: 10.3389/fmicb.2018.02930.].

Novel lawsone-containing ruthenium(II) complexes: Synthesis, characterization and anticancer activity on 2D and 3D spheroid models of prostate cancer cells.

This study describes a series of newly synthesized phosphine/diimine ruthenium complexes containing the lawsone as bioligand with enhanced cytotoxicity against different cancer cells, and apoptosis induction in prostatic cancer cells DU-145. The complexes [Ru(law)(N-N)2]PF6 where N-N is 2,2'-bipyridine (1) or 1,10-phenanthroline (2) and [Ru(law)(dppm)(N-N)]PF6, where dppm means bis(diphenylphosphino)methane, N-N is 2,2'-bipyridine (3) or 1,10-phenanthroline (4), and law is lawsone, were synthesized and fully characterized by elemental analysis, molar conductivity, NMR, UV-vis, IR spectroscopies and cyclic voltammetry. The interaction of the complexes (1-4) with DNA was evaluated by circular dichroism, gel electrophoresis, and fluorescence, and the complexes presented interactions by the minor grooves DNA. The phosphinic series of complexes exhibited a remarkably broad spectrum of anticancer activity with approximately 34-fold higher than cisplatin and 5-fold higher than doxorubicin, inhibiting the growth of 3D tumor spheroids and the ability to retain the colony survival of DU-145 cells. Also, the complex (4) inhibits DU-145 cell adhesion and migration potential indicating antimetastatic properties. The mechanism of its anticancer activity was found to be related to increased reactive oxygen species (ROS) generation, increased the BAX/BCL-2 ratio and subsequent apoptosis induction. Overall, these findings suggested that the complex (4) could be a promising candidate for further evaluation as a chemotherapeutic agent in the prostate cancer treatment.

A Nanostructured Lipid System to Improve the Oral Bioavailability of Ruthenium(II) Complexes for the Treatment of Infections Caused by Mycobacterium tuberculosis.

Tuberculosis (TB) is an infectious, airborne disease caused by the bacterium Mycobacterium tuberculosis that mainly affects the lungs. Fortunately, tuberculosis is a curable disease, and in recent years, death rates for this disease have decreased. However, the existence of antibiotic-resistant strains and the occurrence of co-infections with human immunodeficiency virus (HIV), have led to increased mortality in recent years. Another area of concern is that one-third of the world's population is currently infected with M. tuberculosis in its latent state, serving as a potential reservoir for active TB. In an effort to address the failure of current TB drugs, greater attention is being given to the importance of bioinorganic chemistry as an ally in new research into the development of anti-TB drugs. Ruthenium (Ru) is a chemical element that can mimic iron (Fe) in the body. In previous studies involving the following heteroleptic Ru complexes, [Ru(pic)(dppb)(bipy)]PF6 (SCAR1), [Ru(pic)(dppb)(Me-bipy)]PF6 (SCAR2), [Ru(pic)(dppb)(phen)]PF6 (SCAR4), cis-[Ru(pic)(dppe)2]PF6 (SCAR5), and [Ru(pic)(dppe)(phen)]PF6 (SCAR7), we observed excellent anti-TB activity, moderate cell-toxicity, and a lack of oral bioavailability in an in vivo model of these complexes. Therefore, the objective of this study was to evaluate the toxicity and oral bioavailability of these complexes by loading them into a nanostructured lipid system. The nanostructured lipid system was generated using different ratios of surfactant (soybean phosphatidylcholine, Eumulgin®, and sodium oleate), aqueous phase (phosphate buffer with a concentration of 1X and pH 7.4), and oil (cholesterol) to generate a system for the incorporation of Ru(II) compounds. The anti-TB activity of the compounds was determined using a microdilution assay with Resazurin (REMA) against strains of M. tuberculosis H37Rv and clinical isolates resistant. Cytotoxicity assay using J774.A1 cells (ATCC TIB-67) and intra-macrophage activity were performed. The oral bioavailability assay was used to analyze blood collected from female BALB/C mice. Plasma collected from the same mice was analyzed via inductively coupled plasma mass spectrometry (ICP-MS) to quantify the number of Ru ions. The complexes loaded into the nanostructured lipid system maintained in vitro activity and toxicity was found to be reduced compared with the compounds that were not loaded. The complexes showed intra-macrophagic activity and were orally bioavailable.

Carbonyl-heterobimetallic Ru(II)/Fe(II)-complexes containing polypyridyl ligands: Synthesis, characterization, cellular viability assays and interactions with biomolecules.

This paper describes on the interaction studies of carbonyl heterobimetallic compounds of Ru(II)/Fe(II) containing polypyridyl ligands, with general formula ct-[RuCl(CO)(N-N)(dppf)]PF6, N-N = 1,10-phenanthroline (phen) 5; dipyrido[3,2-f:2',3'-h]quinoxaline (dpq) 6; dipyrido[3,2-a:2',3'-c]phenazine (dppz) 7; dipyrido[3,2-f:2',3'-h]quinoxalino[2,3-b]quinoxaline (dpqQX) 8 and dppf = 1,1'-bis(diphenylphosphino) ferrocene], with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA). Also, it describes the cellular viability assays of these complexes in tumorigenic and non-tumorigenic cell lines. The carbonyl complexes 5-8 and their respective precursors with formula cis-[RuCl2(N-N)(dppf)], N-N = phen (1), dpq (2), dppz (3) and dpqQX (4), were characterized by elemental analysis and spectroscopic techniques (FTIR, UV-vis, 1H and 31P{1H} NMR). Also, a cyclic voltammetry study was performed for all complexes. The crystal structure of the complex 3 is presented and discussed. Spectrofluorimetric titrations shows spontaneous and strong interaction of 5-8 with BSA, through a static quenching mechanism, resulting in binding constants in the order of 104-106 L mol-1, at 310 K. Viscosity measurements and circular dichroism spectra prompts interactions of 5-8 with ct-DNA via non-classical intercalations or by an electrostatic pathway. MTT assays in breast tumor cells MDA-MB-231 and in non-tumorigenic cells MCF-10A and V79-4 cell lines revealed IC50 values ranging from 0.19 to 1.11 µmol L-1, 1.07-3.18 µmol L-1 and 1.29-3.85 µmol L-1 respectively, for complexes 5-8.

Acute toxic effects of ruthenium (II)/amino acid/diphosphine complexes on Swiss mice and zebrafish embryos.

Anticancer potential of ruthenium complexes has been widely investigated, but safety evaluation studies are still scarce. Despite of ruthenium-based anticancer agents are known to cause fewer side effects compared to other metal-based drugs, these compounds are not fully free of toxicity, causing mainly nephrotoxicity. Based on the promising results from antitumor activity of the complexes [Ru(L-Met)(bipy)(dppb)]PF6 (RuMet) and [Ru(L-Trp)(bipy)(dppb)]PF6 (RuTrp), for the first time we investigated the toxicity profile of these complexes in rodent and zebrafish models. The acute oral toxicity was evaluated in Swiss mice. The mutagenic and genotoxic potential was determined by a combination of Micronucleus (MN) and Comet assay protocols, after exposure of Swiss mice to RuMet and RuTrp in therapeutic doses. Zebrafish embryos were exposed to these complexes, and their development observed up to 96 h post-fertilization. RuMet and RuTrp complexes showed low acute oral toxicity. Recorded behavioral changes were not recorded, nor were macroscopic morphological changes or structural modifications in the liver and kidneys. These complexes did not cause genetic toxicity, presenting a lack of micronuclei formation and low DNA damage induction in the cells from Swiss mice. In contradiction, cisplatin treatment exhibited high mutagenicity and genotoxicity. RuMet and RuTrp showed low toxicity in the embryo development of zebrafish. The RuMet and RuTrp complexes demonstrated low toxicity in the two study models, an interesting property in preclinical studies for novel anticancer agents.

The trans-[Ru(PPh3)2(N,N-dimethyl-N'-thiophenylthioureato-k2O,S)(bipy)]PF6 complex has pro-apoptotic effects on triple negative breast cancer cells and presents low toxicity in vivo.

Triple negative breast cancer (TNBC) is a heterogeneous subtype of breast tumors that does not exhibit the expression of estrogen and progesterone receptors, neither the amplification of the human epidermal growth factor receptor 2 (HER-2) gene. Despite all the advances in cancer treatments, the development of new anticancer drugs for TNBC tumors is still a challenge. There is an increasing interest in new agents to be used in cancer treatment. Ruthenium is a metal that has unique characteristics and important in vivo and in vitro results achieved for cancer treatment. Thus, in this work, with the aim to develop anticancer drugs, three new ruthenium complexes containing acylthiourea ligands have been synthesized and characterized: trans-[Ru(PPh3)2(N,N-dibutyl-N'-benzoylthioureato-k2O,S)(2,2'-bipyridine (bipy))]PF6(1), trans-[Ru(PPh3)2(N,N-dimethyl-N'-thiophenylthioureato-k2O,S)(bipy)]PF6(2) and trans-[Ru(PPh3)2(N,N-dimethyl-N'-benzoylthioureato-k2O,S)(bipy)]PF6(3). Then, the cytotoxicity of these three new ruthenium complexes was investigated in TNBC MDA-MB-231 and in non-tumor MCF-10A cells. Complex (2) was the most selective complex and was chosen for further studies to verify its effects on cell morphology, adhesion, migration, invasion, induction of apoptosis and DNA damage in vitro, as well as its toxicity and capacity of causing DNA damage in vivo. Complex (2) inhibited proliferation, migration, invasion, adhesion, changed morphology and induced apoptosis, DNA damage and nuclear fragmentation of TNBC cells at lower concentrations compared to non-tumor MCF-10A cells, suggesting an effective action for this complex on tumor cells. Finally, complex (2) did not induce toxicity or caused DNA damage in vivo when low doses were administered to mice.

Ru(II)-Thymine Complex Causes Cell Growth Inhibition and Induction of Caspase-Mediated Apoptosis in Human Promyelocytic Leukemia HL-60 Cells.

Ruthenium-based compounds represent a class of potential antineoplastic drugs. Recently, we designed, synthesized, and identified the Ru(II)-thymine complex [Ru(PPh3)2(Thy)(bipy)]PF6 (where PPh = triphenylphosphine, Thy = thymine and bipy = 2,2'-bipyridine) as a potent cytotoxic agent with the ability to bind to DNA and human and bovine serum albumins. In this study, the underlying cytotoxic mechanism of the [Ru(PPh3)2(Thy)(bipy)]PF6 complex was assessed. This complex displayed potent cytotoxicity in different cancer cell lines; the morphology that is associated with apoptotic cell death, increased internucleosomal DNA fragmentation without cell membrane permeability, loss of the mitochondrial transmembrane potential, increased phosphatidylserine externalization, and caspase-3 activation were observed in human promyelocytic leukemia HL-60 cells that were treated with the complex. Moreover, pretreatment of HL-60 cells with Z-VAD(OMe)-FMK, a pan-caspase inhibitor, partially reduced the apoptosis that was induced by the complex, indicating that the apoptotic cell death occurred through a caspase-mediated pathway. In conclusion, the [Ru(PPh3)2(Thy)(bipy)]PF6 complex displays potent cytotoxicity to different cancer cells and induces caspase-mediated apoptosis in HL-60 cells.