Search

Four new copper(II) complexes were synthesized and characterized with the general formula [Cu(N–N)(Th)(NO3)], where N–N corresponds to the N-heterocyclic ligands 1,10-phenanthroline (phen), 2,2′-bipyridine (bipy), 4,7-diphenyl-1,10-phenanthroline (dpp), and 4,4-dimethyl-2,2′-bipyridine (dmbp) and Th represents the N,N-dibenzyl-N′-benzoylthiourea. Cytotoxic activities of the complexes against HCT116 (human colon carcinoma), HepG2 (human hepatocellular carcinoma), and non-tumor MRC-5 (human lung fibroblast) cells were investigated. The copper(II) complexes 1–4 were characterized by spectroscopic techniques while complexes 1 and 2 were studied using single-crystal X-ray diffraction as well. The complexes possessed a five-coordinated structure with one nitrate ligand as a monodentate at the axial position and two bidentate ligands N-heterocyclic and N,N-dibenzyl-N′-benzoylthiourea. The complexes showed promising IC50 values, ranging from 0.3 to 9.0 μM. Furthermore, interaction studies with biomolecules such as calf thymus DNA (ct-DNA) and Bovine Serum Albumin (BSA), which can act as possible biological targets of the complexes, were carried out. The studies suggested that the compounds interact moderately with ct-DNA and BSA. Complexes 1, 2, and 4 did not lead to cell accumulation at any stage of the cell cycle but caused a significant increase in internucleosomal DNA fragmentation. Whereas, compound 3 caused cell cycle arrest in the S phase while doxorubicin caused cell cycle arrest in the G2/M phase. The effect of structural modifications on the metal compounds was correlated with their biological properties and it was concluded that an increase in biological activity occurred with increasing the extension of the diimine ligands. Thus, complex 3 was the most promising one. [ABSTRACT FROM AUTHOR]

The search for new metal-based anticancer drug candidates is a fundamental task in medicinal inorganic chemistry. In this work, we assessed the potential of two new Ru(II)–phosphine–mercapto complexes as potential anticancer agents. The complexes, with the formula [Ru(bipy)(dppen)(Lx)]PF6 [(1), HL1 = 2-mercapto–pyridine and (2), HL2 = 2-mercapto–pyrimidine, bipy = 2,2′-bipyridine, dppen = cis-1,2-bis(diphenylphosphino)-ethylene] were synthesized and characterized by nuclear magnetic resonance (NMR) [1H, 31P(1H), and 13C], high resolution mass spectrometry (HR-MS), cyclic voltammetry, infrared and UV-Vis spectroscopies. Complex 2 was obtained as a mixture of two isomers, 2a and 2b, respectively. The composition of these metal complexes was confirmed by elemental analysis and liquid chromatography-mass spectrometry (LC-MS). To obtain insights into their lipophilicity, their distribution coefficients between n-octanol/PBS were determined. Both complexes showed affinity mainly for the organic phase, presenting positive log P values. Also, their stability was confirmed over 48 h in different media (i.e., DMSO, PBS and cell culture medium) via HPLC, UV-Vis and 31P{1H} NMR spectroscopies. Since enzymes from the P-450 system play a crucial role in cellular detoxification and metabolism, the microsomal stability of 1, which was found to be the most interesting compound of this study, was investigated using human microsomes to verify its potential oxidation in the liver. The analyses by LC-MS and ESI-MS reveal three main metabolites, obtained by oxidation in the dppen and bipy moieties. Moreover, 1 was able to interact with human serum albumin (HSA). The cytotoxicity of the metal complexes was tested in different cancerous and non-cancerous cell lines. Complex 1 was found to be more selective than cisplatin against MDA-MB-231 breast cancer cells when compared to MCF-10A non-cancerous cells. In addition, complex 1 affects cell morphology and migration, and inhibits colony formation in MDA-MB-231 cells, making it a promising cytotoxic agent against breast cancer. [ABSTRACT FROM AUTHOR]

The cis-[Fe(cyclam)Cl2]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) complex reacts with quinizarin (1,4-dihydroxy-9,10-anthraquinone, Qz), a biologically relevant molecule, yielding the binuclear complex [(Fe(cyclam))2(Qz)]Cl(PF6)3. This new compound was characterized by means of elemental analysis, X-ray diffraction, cyclic voltammetry and spectroscopic techniques. Crystallographic and FTIR data indicated that the bridging ligand, quinizarin, is coordinated to the FeIII cation via the oxygen atoms of the carbonyl groups in the form of quinones. The effect of ancillary (cyclam) and bridging (Qz) ligands on the properties of the complex is reflected by the stabilization of the FeIII–FeIII configuration supported by Mössbauer spectroscopy. The efficiency of ROS generation and DNA cleavage activity for this binuclear complex, as well as for the free quinizarin ligand, were investigated. This metal complex exhibited very low photochemical activity; however, it revealed a great ability to cleave the DNA molecule in the presence of glutathione, which was associated with the production of ROS species. Thereafter, the cytotoxic activity of these compounds was evaluated using the MTS assay against human tumor cells, namely lung adenocarcinoma (A549) and prostate carcinoma (LNCaP clone FGC), and against normal fibroblasts (L929). Our findings indicated low cytotoxic effects in general, where only a slight reduction in A549 and L929 cell viability was observed after light irradiation. Despite the lack of any significant biological activity, this binuclear compound validates in vitro the essential role of metal binding to an anthracycline-like moiety in the generation of ROS. The latter may be responsible for some of the cardiotoxicity reported for anthracycline-based drugs. [ABSTRACT FROM AUTHOR]

We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF6, where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2′-bipyridine, and O,S = N,N-dimethyl-N′-(benzoyl)thiourea (1), N,N-dimethyl-N′-(furoyl)thiourea (2), and N,N-dimethyl-N′-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC50 values lie in the micromolar range (0.07–0.70 μM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1–3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment. [ABSTRACT FROM AUTHOR]

This study reports the synthesis, structural characterization and cytotoxic activity of four new palladium/pyridylporphyrin complexes, with the general formula {TPyP[PdCl(P–P)]4}(PF6)4, where P–P is 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)butane (dppb) or 1,1′-bis(diphenylphosphino)ferrocene (dppf). The complexes were characterized by elemental analysis, and by FT-IR, UV/Vis, 1H and 31P{1H} NMR (1D/2D) spectroscopy. The slow evaporation of a methanolic solution of {TPyP[PdCl(dppb)]4}(PF6)4 (in an excess of NaBF4 salt) resulted in single crystals suitable for X ray diffraction, allowing the determination of the tridimensional structure of this complex, which crystallized in the P21/a space group. The cytotoxicity of the complexes against MDA-MB-231 (breast cancer cells) and MCF-10A (non-tumor breast cancer cells), was determined by the colorimetric MTT method, which revealed that all four complexes show selective indexes close to 1.2, lower than that of cisplatin for the same cells (12.12). The interaction of the complexes with CT-DNA was evaluated by UV-visible and viscosity measurements and it was determined that the complexes interact moderately with CT-DNA, probably by H-bonding/π–π stacking and electrostatic interactions. [ABSTRACT FROM AUTHOR]

This work describes the synthesis of three new ruthenium(II) complexes with gallic acid and derivatives of the general formula [Ru(L)(dppb)(bipy)]PF6, where L = gallate (GAC), benzoate (BAC), and esterified-gallate (EGA), bipy = 2,2′-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. The complexes were characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis and IR spectroscopy, and two of them by X-ray crystallography. Cell viability assays show promising results, indicating higher cytotoxicity of the complexes in MDA-MB-231 cells, a triple-negative breast cancer (TNBC) cell line, compared with the hormone-dependent MCF-7 cell line. Studies in vitro with the MDA-MB-231 cell line showed that only Ru(BAC) and Ru(GAC) interacted with BSA. Besides that, the Ru(GAC) complex, which has a polyphenolic acid, interacted in an apo-Tf structure and function dependent manner and it was able to inhibit the formation of reactive oxygen species. Ru(GAC) was able to cause damage to the cellular cytoskeleton leading to inhibition of some cellular processes of TNBC cells, such as invasion, migration, and adhesion. [ABSTRACT FROM AUTHOR]

There is an urgent need for new antimicrobial compounds to combat the growing threat of widespread antibiotic resistance. Recently, metal complexes have been recognized as promising sources for new antibiotics since they exhibit unique modes of action such as ligand exchange or release, ROS generation, redox activation and catalytic generation of toxic species or depletion of essential substrates. In addition, it is known that gaseous nitric oxide exerts an antimicrobial effect. These observations led to the development of NO delivery systems that can harness the antimicrobial properties of this evanescent gas. Here, we investigate the antimicrobial activity of the ct-[RuCl(NO)(dppb)(4,4′-Mebipy)](PF6)2 nitrosyl complex along with its precursor cis-[RuCl2(dppb)(4,4′-Mebipy)] complex. A series of antimicrobial activity studies using Gram(+) and Gram(−) bacteria were carried out with these compounds. Unfortunately, these ruthenium complexes did not show any activity against Gram(−) bacteria P. aeruginosa and E. coli, even at the highest concentration tested (500 μg mL−1). Otherwise, both complexes showed promising antibacterial activity against Gram-positive bacterial strains of Staphylococcus aureus (ATCC25923, ATCC700698 and JKD6008) and Staphylococcus epidermidis (ATCC12228 and ATCC35984). However, the nitrosyl complex showed a greater antibiotic effect than its precursor, supporting the important role of NO in this process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Six new ruthenium(II) complexes with lapachol (Lap) and lawsone (Law) with the general formula [Ru(L)(P–P)(bipy)]PF6, where L = Lap or Law, P–P = 1,2′-bis(diphenylphosphino)ethane (dppe), 1,4′-bis(diphenylphosphino)butane (dppb), 1,1′-bis(diphenylphosphino)ferrocene (dppf) and bipy = 2,2′-bipyridine, were synthesized, fully characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis, IR spectroscopies and three of them by X-ray crystallography. All six complexes were active against breast (MCF-7 and MDA-MB-231) and prostate (DU-145) cancer cell lines with lower IC50 values than cisplatin. Complex [Ru(Lap)(dppe)(bipy)]PF6 (1a) showed significant selectivity for MDA-MB-231, a model of triple-negative breast cancer (TNBC), as compared to the "normal-like" human breast epithelial cell line, MCF-10A. Complex (1a) inhibited TNBC colony formation and induced loss of cellular adhesion. Furthermore, the complex (1a) induced mitochondrial dysfunction and generation of ROS, as is involved in the apoptotic cell death pathway. Preferential cellular uptake of complex (1a) was observed in MDA-MB-231 cells compared to MCF-10A cells, consistent with the observed selectivity for tumorigenic vs. non-tumorigenic cells. Taken together, these results indicate that ruthenium complexes containing lapachol and lawsone as ligands are promising candidates as chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

Ruthenium(II) diclofenac-based complexes of the general formula [Ru(dicl)(P–P)(bpy)]PF6 [dicl = diclofenac, bpy = 2,2′-bipyridine, and P–P = 1,4′-bis(diphenylphosphino)butane (dppb) (1), 1,2′-bis(diphenylphosphino)ethane (dppe) (2), 1,3′-bis(diphenylphosphino)propane (dppp) (3) and 1,1′-bis(diphenylphosphino)ferrocene (dppf) (4)] are synthesized. The complexes (1–4) are characterized by elemental analyses, infrared, NMR, and UV-vis spectroscopy and (3) and (4) are characterized by single crystal X-ray diffraction. The DNA binding of complexes (1–4), studied by circular dichroism (CD) and Hoechst 33 258 staining assay, indicates their binding with the minor grooves. The complexes interact with BSA with binding constants (Kb) in the range of 2.5 × 103–5.5 × 104 M−1. The complexes exhibit high cytotoxicity against the tumor cell lines A549, MDA-MB-231, and MCF-7 with IC50 values ranging from 0.56 to 15.28 μM. The complexes are more selective for the hormone-dependent MCF-7 breast tumor cell line and complex (1) is the most potent one. The study demonstrates the anticancer activity of ruthenium(II)/diclofenac-based complexes. [ABSTRACT FROM AUTHOR]

New palladium complexes with thiosemicarbazonate ligands derived from pyrene exhibit potent antiproliferative activity against A2780 and cisplatin-resistant A2780Cis human ovarian cancer cells, which is dependent on substituent groups of the thiosemicarbazone ligands. Cellular accumulation and distribution studies confirmed that palladium enters the cell nucleus. DNA and topoisomerase IB studies show that one complex is a potent TopIB inhibitor, with selectivity for cancer versus normal cells. [ABSTRACT FROM AUTHOR]

Herein we discuss five ruthenium(II) complexes with good cytotoxicity against cancer cells. These complexes are named [Ru(tzdt)(bipy)(dppb)]PF6 (1), [Ru(mmi)(bipy)(dppb)]PF6 (2), [Ru(dmp)(bipy)(dppb)]PF6 (3), [Ru(mpca)(bipy)(dppb)]PF6 (4) and [Ru(2mq)(bipy)(dppb)]PF6 (5), where tzdt = 1,3-thiazolidine-2-thione, mmi = mercapto-1-methyl-imidazole, dmp = 4,6-diamino-2-mercaptopyrimidine, mpca = 6-mercaptopyridine-3-carboxylic acid, 2mq = 2-mercapto-4(3H)-quinazolinone, bipy = 2,2′-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed significant cytotoxic activity for 1–5 against MDA-MB-231, MCF-7, A549, DU-145 and HepG2 tumor cells, higher than that for the standard anticancer drug cisplatin. Compound/DNA interaction studies were carried out showing that 1–5 interact with DNA by electrostatic force of attraction or by hydrogen bonding. Moreover, the complexes interact, moderately and spontaneously, with human serum albumin (HSA) through the hydrophobic region. The five complexes are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (TopIB), and complex 1 is found to be the most efficient TopIB inhibitor among the five compounds. The inhibitory effect and analysis of different steps of the TopIB catalytic cycle indicate that complex 1 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and has no effect on the religation step. Complexes 1, 2 and 3 did not show mutagenic activity when they were evaluated by the cytokinesis-block micronucleus cytome assay in HepG2 cells and the Ames test in the presence and absence of mouse liver S9 metabolic activation. Therefore, it is necessary to perform further in-depth analysis of the therapeutic potential of these promising ruthenium complexes as anticancer drugs. [ABSTRACT FROM AUTHOR]

In this paper, four new ruthenium complexes, [Ru(N–S)(dppm)2]PF6 (1), [Ru(N–S)(dppe)2]PF6 (2), [Ru(N–S)2(dppp)] (3) and [Ru(N–S)2(PPh3)2] (4) [dppm = 1,1-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, PPh3 = triphenylphosphine and N–S = 2-mercaptopyrimidine anion] were synthesized and characterized using spectroscopy techniques, molar conductance, elemental analysis, electrochemical techniques and X-ray diffraction. The DNA binding studies were investigated using voltammetry and spectroscopy techniques. The results show that all complexes exhibit a weak interaction with DNA. HSA interaction with the complexes was studied using fluorescence emission spectroscopy, where the results indicate a spontaneous interaction between the species by a static quenching mechanism. The cytotoxicity of the complexes was evaluated against A549, MDA-MB-231 and HaCat cells by MTT assay. Complexes (1) and (2), which are very active against triple negative MDA-MB-231, were subjected to further biological tests with this cell line. The cytotoxic activity triggered by the complexes was confirmed by clonogenic assay. Cell cycle analyses demonstrated marked anti-proliferative effects, especially at the G0/G1 and S phases. The morphological detection of apoptosis and necrosis – HO/PI and Annexin V-FITC/PI assay, elucidated that the type of cell death triggered by these complexes was probably by apoptosis. The in vivo toxicological assessment performed on zebrafish embryos revealed that complexes (1) and (2) did not present embryotoxic or toxic effects during embryonic and larval development showing that they are promising new prototypes of safer and more effective drugs for triple negative breast cancer treatment. [ABSTRACT FROM AUTHOR]

We report the preparation, X-ray structure, chemical properties, and electron paramagnetic resonance (EPR) studies at Q and X-bands and temperature (mainly) T = 293 K of powder and oriented single crystal samples of the new compound [Cu(N′,N′-dimethyl-N′-benzoylthiourea)(2,2′-bipyridine)Cl], called CuBMB. The EPR spectra of single crystal samples at the Q-band display abrupt merging and narrowing of the peaks corresponding to two rotated copper sites as a function of magnetic field (B0) orientation. This behaviour indicates a quantum transition from an array of quasi-isolated spins to a quantum-entangled spin array associated with exchange narrowing processes and produced by weak intermolecular exchange interactions Ji between neighbour copper spins. This transition occurs when the magnitudes of the anisotropic contributions to the Zeeman couplings, tuned with the direction of B0, approach these ☋Ji☋ and produce level crossings. The exchange couplings between neighbour spins are estimated from the angular variation of the single crystal EPR results at the Q-band. We analyse the quantum behaviour and phase transitions of the spin system and discuss the magnitudes of the exchange couplings in terms of the structure of the chemical paths connecting Cu neighbours. The single crystal data at the Q-band indicates an uncommon ground electronic state of CuII which is discussed and compared with the results of DFT calculations. The spectrum of polycrystalline (powder) samples at the Q-band is a sum of contributions of microcrystals in each phase, and the fraction F of the entangled phase depends on the microwave frequency. The X-band spectrum is compatible with the Q-band results, but does not display a transition, and the spin system is in the quantum-entangled phase for all field orientations. This behaviour is further studied with a simple geometric model giving basic predictions. The crystal structure of CuBMB is monoclinic, space group P21/n, with a = 11.9790(3) Å, b = 14.0236(5) Å, c = 12.1193(3) Å, β = 104.952(2)° and Z = 4, and the copper ions are equatorially bonded to the benzoylthiourea and bipyridine ligands in a heavily distorted square pyramidal structure. [ABSTRACT FROM AUTHOR]

Four new organoruthenium complexes with formula [RuCl(η6-p-cymene)(μ-FCZ)]2[Cl]2 (1), [RuCl(FCZ)(η6-p-cymene)(PPh3)]PF6 (2), [RuCl(CTZ)(η6-p-cymene)(PPh3)]PF6 (3) and [RuCl(KTZ)(η6-p-cymene)(PPh3)]PF6 (4) (where FCZ: 2-(2,4-difluorophenyl)-1,3-di(1H-1,2,4-triazol-1-yl)-2-propanol, CTZ: 1-[(2-chlorophenyl)-diphenylmethyl-1H-imidazole] and KTZ: cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) were synthesized, characterized and evaluated as potential inhibitors for Leishmania amazonensis growth by widely reported methods. Complexes 3 and 4 displayed effective IC50 activities against Leishmania amazonensis promastigotes and intracellular amastigotes in the range of nanomolar concentration. Scanning and transmission electron microscopy analysis of Leishmania amazonensis promastigotes after treatment with 300 or 500 nM of complexes 3 and 4 for 48 h showed morphological alterations in the cell surface, a shortening of the flagellum, loss of mitochondrial matrix, disorganization of the kDNA and abnormal chromatin condensation. Thus, our strategy of incorporating a ruthenium atom into the structure of clinical drugs to improve their efficacy continues to demonstrate suitability for metallodrug discovery purposes. [ABSTRACT FROM AUTHOR]

The new complexes [Cu(PPh3)2(KTZ)2]NO3 (1), [Cu(PPh3)2(CTZ)2]NO3 (2), [Au(KTZ)2]Cl (3), [Au(CTZ)2]Cl (4) and Pt(KTZ)2Cl2 (5) were prepared by reaction of KTZ, CTZ (where CTZ: 1-[(2-chlorophenyl)-diphenylmethyl]-1H-imidazole and KTZ: cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine) and their respective metal salts or metal complexes under mild conditions. They were characterized using NMR, UV-vis and IR spectroscopies, microanalytical analysis and mass spectrometry. Complex (5) was also investigated using computational methods (DFT) to evaluate the geometry configuration around the Pt(ii) coordination sphere; the results showed that the trans complex is the most stable one. The antifungal activities of these new compounds 1–5 and some of our reported metal-based azole drug derivatives such as Pt(CTZ)2Cl2 (6), [Au(PPh3)(KTZ)]PF6 (7) and [Au(PPh3)(CTZ)]PF6 (8) were evaluated against sporotrichosis agents (Sporothrix schenckii, Sporothrix brasiliensis and Sporothrix globosa). Their selectivities towards fungal cells were also evaluated. Complexes [Cu(PPh3)2(KTZ)2]NO3 (1), [Cu(PPh3)2(CTZ)2]NO3 (2), [Au(PPh3)(KTZ)]PF6 (7) and [Au(PPh3)(CTZ)]PF6 (8) inhibited fungal growth and killed fungi at concentrations in the nanomolar range and were more active than CTZ or KTZ alone. Microscopy analysis using scanning electron microscopy showed that the complexes 1, 2, 7 and 8 interfered with the cell shape. All the metal–azole complexes tested were more selective for fungi than for mammalian cells and human red blood cells, revealing that they are promising molecules for the development of new antifungal compounds. [ABSTRACT FROM AUTHOR]

Herein, we used thymine (HThy) as a ligand to form two new ruthenium(ii) complexes with formula [Ru(PPh3)2(Thy)(bipy)]PF6 (1) and [Ru(Thy)(bipy)(dppb)]PF6 (2). The complexes were characterized by spectroscopic, spectrometric and X-ray crystallography analyses. Complexes 1 and 2 can interact with ctDNA presenting binding constants, Kb, of 0.4 and 1.2 × 103 M−1, respectively. Their cytotoxic activities towards tumor cell lines (B16-F10, HepG2, K562 and HL-60) and non-tumor cells (PBMCs) were evaluated using the Alamar blue assay. Complex 1 exhibits high cytotoxicity against tumor cells, showing IC50 values of 0.01 and 1.81 μM against the HL-60 and HepG2 cell lines, respectively. Therefore, compound 1 can be considered as a promising antitumor metallodrug. [ABSTRACT FROM AUTHOR]

Metal-based compounds have emerged as a novel strategy to improve our arsenal of medicines. Among these compounds, carbon monoxide donor agents have been developed mainly as metal complexes. These compounds have shown exciting biological activities, among them strong anti-inflammatory, antibiotic, and anticancer activity, although some of those properties might be associated with the metal moiety as well. Aiming to prepare a new ruthenium complex containing CO, we prepared a cis-[RuCl(CO)(dppb)(dppz)]PF6 complex (dppb = 1,4-bis(diphenylphosphino)butane and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), which was fully characterized along with DFT studies. This compound exhibited great thermal stability in phosphate buffer solution, but showed fast and efficient release of CO upon light irradiation, including blue LED. Surprisingly, DNA binding was quite weak, despite the dppz ligand moiety, suggesting that steric effects prevented intercalation binding. Nonetheless, this compound exhibited promising antibiotic activity against S. aureus, S. epidermidis and C. albicans in a low micromolar range. However, there was no further improvement upon light irradiation suggesting that there is no role of CO. Additionally, cytotoxicity assay using cancer cells showed quite low IC50 (92 nM, HCT-116) along with moderate to low toxicity assayed in lymphocytes and Artemia. Altogether, these results supported that this compound has great potential as a biological agent, whereas neither CO release nor DNA binding seemed to have a direct role in its activity. [ABSTRACT FROM AUTHOR]

Organometallic ruthenium complexes as potential anticancer agents have been explored due to their suitable properties, such as stability in the solid state and in solution, water solubility and low toxicity. In this study, eight metal complexes of this class were synthesized, characterized and their important biological activities against a human breast tumor cell line (MDA-MB-231) were studied. Complexes 1–8 were obtained in good yields and have been characterized by satisfactory elemental analyses, IR, 1D and 2D 1H and 13C{1H} NMR, UV-Vis spectroscopy, cyclic voltammetry, ESI-MS and X-ray diffractometry (1, 2, 3 and 6). All complexes exhibit growth inhibition on human breast and lung tumor cell lines, with IC50 values ranging from 6.0 to 45.0 μM in 48 h. Four compounds were selected to evaluate the changes in the morphology, clonogenic, migration, cell cycle arrest and cell death in MDA-MB-231 cells. The complexes are able to induce morphological changes and inhibit the size, number of colonies and cell migration, and induce cell cycle arrest in the sub-G1 phase and apoptosis cell death. The interaction of the complexes with DNA was determined by performing spectroscopic titration, a competitive assay with thiazole orange, circular dichroism, gel electrophoresis and interactions with guanosine or guanosine monophosphate by 1H NMR, indicating the non-covalent interaction. The HSA binding affinity measured by spectrophotometric titration, revealed the hydrophobic and spontaneous association with the human protein. Overall, the studies indicated that these metal complexes are potential agents against MDA-MB-231 cells, encouraging us to continue studies of these types of compounds. [ABSTRACT FROM AUTHOR]

Insights into the structural basis of nucleoside molecular organization have been achieved from crystal engineering research. Here, we have investigated the role of differences at the 3'-position of the five-membered ring in the determination of the molecular conformation and crystal packing of quasienantiomeric cytidine-based nucleosides. Firstly, a hydrochloride salt of zalcitabine (2',3'-dideoxycytidine) isostructural to lamivudine (2',3'-dideoxy-3'-thiacytidine) hydrochloride was prepared. The R1/2(6) motif responsible for pairing between nucleosides and counterions as well as the assembly of chains and sheets with 21-screw axis symmetry-related ionic pairs were observed in both salts, even with lamivudine differing from zalcitabine in the opposite chirality of their C1' and C4' carbons and for a sulfur atom at the 3'-position rather than a methylene group. Based on the isostructurality between zalcitabine hydrochloride and lamivudine hydrochloride, but with crystal structures which are quasi-enantiomeric, a hydrochloride salt having both nucleosides in a single crystal form was designed in this study. The obtained hybrid structure is a quasi-racemate in which chains assembled with R1 2(6)-paired lamivudine and chloride can be related by pseudo inversion symmetry to that of zalcitabine and chloride but with an antiparallel growth direction. In addition, the first examples of ruthenium(II) coordination complexes with cytidine nucleosides are reported here. The trans-bis-(triphenylphosphine)(lamivudinate)(2,2'-bipyridine) ruthenium(II) perchlorate and trans-bis-(triphenylphosphine)(cytidinate)(2,2'-bipyridine)ruthenium(II) perchlorate complexes have the same coordination geometry and similar chains made up of complex units intercalated by water despite major molecular difference given by 2'-CH2 and 3'-S moieties in lamivudinate rather than CH2OH ones in both positions of cytidinate. [ABSTRACT FROM AUTHOR]

Four new copper(II) complexes were synthesized and characterized with the general formula [Cu(N-N)(Th)(NO 3 )], where N-N corresponds to the N-heterocyclic ligands 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy), 4,7-diphenyl-1,10-phenanthroline (dpp), and 4,4-dimethyl-2,2'-bipyridine (dmbp) and Th represents the N , N -dibenzyl- N '-benzoylthiourea. Cytotoxic activities of the complexes against HCT116 (human colon carcinoma), HepG2 (human hepatocellular carcinoma), and non-tumor MRC-5 (human lung fibroblast) cells were investigated. The copper(II) complexes 1-4 were characterized by spectroscopic techniques while complexes 1 and 2 were studied using single-crystal X-ray diffraction as well. The complexes possessed a five-coordinated structure with one nitrate ligand as a monodentate at the axial position and two bidentate ligands N-heterocyclic and N , N -dibenzyl- N '-benzoylthiourea. The complexes showed promising IC 50 values, ranging from 0.3 to 9.0 μM. Furthermore, interaction studies with biomolecules such as calf thymus DNA (ct-DNA) and Bovine Serum Albumin (BSA), which can act as possible biological targets of the complexes, were carried out. The studies suggested that the compounds interact moderately with ct-DNA and BSA. Complexes 1, 2, and 4 did not lead to cell accumulation at any stage of the cell cycle but caused a significant increase in internucleosomal DNA fragmentation. Whereas, compound 3 caused cell cycle arrest in the S phase while doxorubicin caused cell cycle arrest in the G2/M phase. The effect of structural modifications on the metal compounds was correlated with their biological properties and it was concluded that an increase in biological activity occurred with increasing the extension of the diimine ligands. Thus, complex 3 was the most promising one.

The search for new metal-based anticancer drug candidates is a fundamental task in medicinal inorganic chemistry. In this work, we assessed the potential of two new Ru(II)-phosphine-mercapto complexes as potential anticancer agents. The complexes, with the formula [Ru(bipy)(dppen)(Lx)]PF 6 [(1), HL1 = 2-mercapto-pyridine and (2), HL2 = 2-mercapto-pyrimidine, bipy = 2,2'-bipyridine, dppen = cis -1,2-bis(diphenylphosphino)-ethylene] were synthesized and characterized by nuclear magnetic resonance (NMR) [ 1 H, 31 P( 1 H), and 13 C], high resolution mass spectrometry (HR-MS), cyclic voltammetry, infrared and UV-Vis spectroscopies. Complex 2 was obtained as a mixture of two isomers, 2a and 2b, respectively. The composition of these metal complexes was confirmed by elemental analysis and liquid chromatography-mass spectrometry (LC-MS). To obtain insights into their lipophilicity, their distribution coefficients between n -octanol/PBS were determined. Both complexes showed affinity mainly for the organic phase, presenting positive log  P values. Also, their stability was confirmed over 48 h in different media ( i.e. , DMSO, PBS and cell culture medium) via HPLC, UV-Vis and 31 P{ 1 H} NMR spectroscopies. Since enzymes from the P-450 system play a crucial role in cellular detoxification and metabolism, the microsomal stability of 1, which was found to be the most interesting compound of this study, was investigated using human microsomes to verify its potential oxidation in the liver. The analyses by LC-MS and ESI-MS reveal three main metabolites, obtained by oxidation in the dppen and bipy moieties. Moreover, 1 was able to interact with human serum albumin (HSA). The cytotoxicity of the metal complexes was tested in different cancerous and non-cancerous cell lines. Complex 1 was found to be more selective than cisplatin against MDA-MB-231 breast cancer cells when compared to MCF-10A non-cancerous cells. In addition, complex 1 affects cell morphology and migration, and inhibits colony formation in MDA-MB-231 cells, making it a promising cytotoxic agent against breast cancer.

Palladium(II) complexes have stimulated research interest mainly due to their in vitro cytotoxicity against various cancer cell lines and their low cytotoxicity in healthy cells. Thus, in this work, we combined Pd(II)/phosphine systems with the natural product curcumin as a ligand, obtaining a series of complexes, [Pd(cur)(PPh 3 ) 2 ]PF 6 (A1), [Pd(cur)(dppe)]PF 6 (A2), [Pd(cur)(dppp)]PF 6 (A3), [Pd(cur)(dppb)]PF 6 (A4) and [Pd(cur)(dppf)]PF 6 (A5), where dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, dppb = 1,4-bis(diphenylphosphino)butane, and dppf = 1,1'-bis(diphenylphosphino)ferrocene (P-P), which were characterized by elemental analysis, molar conductivity analysis, and mass, NMR ( 1 H, 13 C, 31 P{ 1 H}), UV-vis, and IR spectroscopies, and four of them (A1, A2, A4, and A5) by X-ray crystallography. The in vitro cell viability of the complexes A1-A5, cisplatin, and the free ligand curcumin against MDA-MB-231 (human triple-negative breast tumor cells), SK-BR-3 (human breast tumor cells), A549 (human lung tumor cells), MRC-5 (non-tumor human lung cells), A2780 (human ovarian carcinoma cells), and A2780cis (cisplatin-resistant human ovarian carcinoma cells), was evaluated by the MTT colorimetric assay. For the tumor cell lines tested, the complexes showed good anticancer activities. The results showed that in general the complexes had lower IC 50 values than free curcumin and the precursors [PdCl 2 (P-P)]. IC 50 results obtained for the A1-A5 complexes, in the MCF-7 cell line, are similar to those that had already been observed for some Pd/bipy/curcumin complexes. In the MDA-MB-231 cell line, complexes A1 and A5 stood out, with their lowest IC 50 values, around 5 μmol L -1 , and the complexes appeared to be more active (lower IC 50 values) against the ovarian cell lines. Complex A1 was 23 and 22-fold more cytotoxic than cisplatin, against the A2780 and A2780cis cells, respectively. The complex A1 was studied on A2780cis cells and it was found that this complex inhibits colony formation and induces cell cycle arrest in the sub-G1 phase in a concentration-dependent manner and leads to cell death by apoptosis. The DCFDA assay revealed a potent ROS induction for complex A1.

We have synthesized and characterized three new ruthenium(II) diphosphine complexes containing an acylthiourea ligand, with the general formula [Ru(DPEPhos)(O,S)(bipy)]PF 6 , where DPEPhos = bis(2-(diphenylphosphino)phenyl)ether, bipy = 2,2'-bipyridine, and O,S = N , N -dimethyl- N '-(benzoyl)thiourea (1), N , N -dimethyl- N '-(furoyl)thiourea (2), and N , N -dimethyl- N '-(thiophenyl)thiourea (3), by several physicochemical techniques. We evaluated the ruthenium complexes for their cytotoxicity against two human cancer cell lines, A549 (lung) and MDA-MB-231 (breast), and two corresponding lines of non-cancer cells, MRC-5 (lung) and MCF-10A (breast). All the complexes are cytotoxic against the cancer cell lines; the IC 50 values lie in the micromolar range (0.07-0.70 μM). Ruthenium complex 1 is more selective (7 times more active) toward lung cancer cells (A549) than toward non-cancer cells (MRC-5) and is 160 times more cytotoxic than cisplatin against A549 cells. Investigations of the mechanism of action of complex 1 in A549 cells demonstrated that it inhibits colony formation and promotes cell cycle arrest in the G1 phase and apoptotic cell death. DNA binding studies revealed that complexes 1-3 interact with the biomolecule via minor grooves. These complexes also interact with human serum albumin (HSA) and have affinity for site I by hydrophobic forces. Therefore, this new class of ruthenium complexes can act as cytotoxic agents, mainly for lung cancer treatment.

This study reports the synthesis, structural characterization and cytotoxic activity of four new palladium/pyridylporphyrin complexes, with the general formula {TPyP[PdCl(P-P)] 4 }(PF 6 ) 4 , where P-P is 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)butane (dppb) or 1,1'-bis(diphenylphosphino)ferrocene (dppf). The complexes were characterized by elemental analysis, and by FT-IR, UV/Vis, 1 H and 31 P{ 1 H} NMR (1D/2D) spectroscopy. The slow evaporation of a methanolic solution of {TPyP[PdCl(dppb)] 4 }(PF 6 ) 4 (in an excess of NaBF 4 salt) resulted in single crystals suitable for X ray diffraction, allowing the determination of the tridimensional structure of this complex, which crystallized in the P 2 1 / a space group. The cytotoxicity of the complexes against MDA-MB-231 (breast cancer cells) and MCF-10A (non-tumor breast cancer cells), was determined by the colorimetric MTT method, which revealed that all four complexes show selective indexes close to 1.2, lower than that of cisplatin for the same cells (12.12). The interaction of the complexes with CT-DNA was evaluated by UV-visible and viscosity measurements and it was determined that the complexes interact moderately with CT-DNA, probably by H-bonding/π-π stacking and electrostatic interactions.

This work describes the synthesis of three new ruthenium(ii) complexes with gallic acid and derivatives of the general formula [Ru(L)(dppb)(bipy)]PF 6 , where L = gallate (GAC), benzoate (BAC), and esterified-gallate (EGA), bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. The complexes were characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis and IR spectroscopy, and two of them by X-ray crystallography. Cell viability assays show promising results, indicating higher cytotoxicity of the complexes in MDA-MB-231 cells, a triple-negative breast cancer (TNBC) cell line, compared with the hormone-dependent MCF-7 cell line. Studies in vitro with the MDA-MB-231 cell line showed that only Ru(BAC) and Ru(GAC) interacted with BSA. Besides that, the Ru(GAC) complex, which has a polyphenolic acid, interacted in an apo-Tf structure and function dependent manner and it was able to inhibit the formation of reactive oxygen species. Ru(GAC) was able to cause damage to the cellular cytoskeleton leading to inhibition of some cellular processes of TNBC cells, such as invasion, migration, and adhesion.

Six new ruthenium(ii) complexes with lapachol (Lap) and lawsone (Law) with the general formula [Ru(L)(P-P)(bipy)]PF6, where L = Lap or Law, P-P = 1,2'-bis(diphenylphosphino)ethane (dppe), 1,4'-bis(diphenylphosphino)butane (dppb), 1,1'-bis(diphenylphosphino)ferrocene (dppf) and bipy = 2,2'-bipyridine, were synthesized, fully characterized by elemental analysis, molar conductivity, NMR, cyclic voltammetry, UV-vis, IR spectroscopies and three of them by X-ray crystallography. All six complexes were active against breast (MCF-7 and MDA-MB-231) and prostate (DU-145) cancer cell lines with lower IC50 values than cisplatin. Complex [Ru(Lap)(dppe)(bipy)]PF6 (1a) showed significant selectivity for MDA-MB-231, a model of triple-negative breast cancer (TNBC), as compared to the "normal-like" human breast epithelial cell line, MCF-10A. Complex (1a) inhibited TNBC colony formation and induced loss of cellular adhesion. Furthermore, the complex (1a) induced mitochondrial dysfunction and generation of ROS, as is involved in the apoptotic cell death pathway. Preferential cellular uptake of complex (1a) was observed in MDA-MB-231 cells compared to MCF-10A cells, consistent with the observed selectivity for tumorigenic vs. non-tumorigenic cells. Taken together, these results indicate that ruthenium complexes containing lapachol and lawsone as ligands are promising candidates as chemotherapeutic agents.

Ruthenium(ii) diclofenac-based complexes of the general formula [Ru(dicl)(P-P)(bpy)]PF6 [dicl = diclofenac, bpy = 2,2'-bipyridine, and P-P = 1,4'-bis(diphenylphosphino)butane (dppb) (1), 1,2'-bis(diphenylphosphino)ethane (dppe) (2), 1,3'-bis(diphenylphosphino)propane (dppp) (3) and 1,1'-bis(diphenylphosphino)ferrocene (dppf) (4)] are synthesized. The complexes (1-4) are characterized by elemental analyses, infrared, NMR, and UV-vis spectroscopy and (3) and (4) are characterized by single crystal X-ray diffraction. The DNA binding of complexes (1-4), studied by circular dichroism (CD) and Hoechst 33 258 staining assay, indicates their binding with the minor grooves. The complexes interact with BSA with binding constants (Kb) in the range of 2.5 × 103-5.5 × 104 M-1. The complexes exhibit high cytotoxicity against the tumor cell lines A549, MDA-MB-231, and MCF-7 with IC50 values ranging from 0.56 to 15.28 μM. The complexes are more selective for the hormone-dependent MCF-7 breast tumor cell line and complex (1) is the most potent one. The study demonstrates the anticancer activity of ruthenium(ii)/diclofenac-based complexes.

New palladium complexes with thiosemicarbazonate ligands derived from pyrene exhibit potent antiproliferative activity against A2780 and cisplatin-resistant A2780Cis human ovarian cancer cells, which is dependent on substituent groups of the thiosemicarbazone ligands. Cellular accumulation and distribution studies confirmed that palladium enters the cell nucleus. DNA and topoisomerase IB studies show that one complex is a potent TopIB inhibitor, with selectivity for cancer versus normal cells.

Herein we discuss five ruthenium(ii) complexes with good cytotoxicity against cancer cells. These complexes are named [Ru(tzdt)(bipy)(dppb)]PF6 (1), [Ru(mmi)(bipy)(dppb)]PF6 (2), [Ru(dmp)(bipy)(dppb)]PF6 (3), [Ru(mpca)(bipy)(dppb)]PF6 (4) and [Ru(2mq)(bipy)(dppb)]PF6 (5), where tzdt = 1,3-thiazolidine-2-thione, mmi = mercapto-1-methyl-imidazole, dmp = 4,6-diamino-2-mercaptopyrimidine, mpca = 6-mercaptopyridine-3-carboxylic acid, 2mq = 2-mercapto-4(3H)-quinazolinone, bipy = 2,2'-bipyridine and dppb = 1,4-bis(diphenylphosphino)butane. In vitro cell culture experiments revealed significant cytotoxic activity for 1-5 against MDA-MB-231, MCF-7, A549, DU-145 and HepG2 tumor cells, higher than that for the standard anticancer drug cisplatin. Compound/DNA interaction studies were carried out showing that 1-5 interact with DNA by electrostatic force of attraction or by hydrogen bonding. Moreover, the complexes interact, moderately and spontaneously, with human serum albumin (HSA) through the hydrophobic region. The five complexes are able to inhibit the DNA supercoiled relaxation mediated by human topoisomerase IB (TopIB), and complex 1 is found to be the most efficient TopIB inhibitor among the five compounds. The inhibitory effect and analysis of different steps of the TopIB catalytic cycle indicate that complex 1 inhibits the cleavage reaction impeding the binding of the enzyme to DNA and has no effect on the religation step. Complexes 1, 2 and 3 did not show mutagenic activity when they were evaluated by the cytokinesis-block micronucleus cytome assay in HepG2 cells and the Ames test in the presence and absence of mouse liver S9 metabolic activation. Therefore, it is necessary to perform further in-depth analysis of the therapeutic potential of these promising ruthenium complexes as anticancer drugs.

In this paper, four new ruthenium complexes, [Ru(N-S)(dppm)2]PF6 (1), [Ru(N-S)(dppe)2]PF6 (2), [Ru(N-S)2(dppp)] (3) and [Ru(N-S)2(PPh3)2] (4) [dppm = 1,1-bis(diphenylphosphino)methane, dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, PPh3 = triphenylphosphine and N-S = 2-mercaptopyrimidine anion] were synthesized and characterized using spectroscopy techniques, molar conductance, elemental analysis, electrochemical techniques and X-ray diffraction. The DNA binding studies were investigated using voltammetry and spectroscopy techniques. The results show that all complexes exhibit a weak interaction with DNA. HSA interaction with the complexes was studied using fluorescence emission spectroscopy, where the results indicate a spontaneous interaction between the species by a static quenching mechanism. The cytotoxicity of the complexes was evaluated against A549, MDA-MB-231 and HaCat cells by MTT assay. Complexes (1) and (2), which are very active against triple negative MDA-MB-231, were subjected to further biological tests with this cell line. The cytotoxic activity triggered by the complexes was confirmed by clonogenic assay. Cell cycle analyses demonstrated marked anti-proliferative effects, especially at the G0/G1 and S phases. The morphological detection of apoptosis and necrosis - HO/PI and Annexin V-FITC/PI assay, elucidated that the type of cell death triggered by these complexes was probably by apoptosis. The in vivo toxicological assessment performed on zebrafish embryos revealed that complexes (1) and (2) did not present embryotoxic or toxic effects during embryonic and larval development showing that they are promising new prototypes of safer and more effective drugs for triple negative breast cancer treatment.

Organometallic ruthenium complexes as potential anticancer agents have been explored due to their suitable properties, such as stability in the solid state and in solution, water solubility and low toxicity. In this study, eight metal complexes of this class were synthesized, characterized and their important biological activities against a human breast tumor cell line (MDA-MB-231) were studied. Complexes 1-8 were obtained in good yields and have been characterized by satisfactory elemental analyses, IR, 1D and 2D 1 H and 13 C{ 1 H} NMR, UV-Vis spectroscopy, cyclic voltammetry, ESI-MS and X-ray diffractometry (1, 2, 3 and 6). All complexes exhibit growth inhibition on human breast and lung tumor cell lines, with IC 50 values ranging from 6.0 to 45.0 μM in 48 h. Four compounds were selected to evaluate the changes in the morphology, clonogenic, migration, cell cycle arrest and cell death in MDA-MB-231 cells. The complexes are able to induce morphological changes and inhibit the size, number of colonies and cell migration, and induce cell cycle arrest in the sub-G1 phase and apoptosis cell death. The interaction of the complexes with DNA was determined by performing spectroscopic titration, a competitive assay with thiazole orange, circular dichroism, gel electrophoresis and interactions with guanosine or guanosine monophosphate by 1 H NMR, indicating the non-covalent interaction. The HSA binding affinity measured by spectrophotometric titration, revealed the hydrophobic and spontaneous association with the human protein. Overall, the studies indicated that these metal complexes are potential agents against MDA-MB-231 cells, encouraging us to continue studies of these types of compounds.