Effects of two representative antitumor ruthenium(III) complexes on thermal denaturation profiles of DNA

Structural, spectral characterization and molecular docking analyses of mer-ruthenium (II) complexes containing the bidentate chelating ligands

In this study, we analyzed some monofunctional Ru (II) complexes containing chlorine, bromine and fluorine atoms around the central atom. The best calculation level among HF, B3LYP and M062X methods for [Ru (Cl-Ph-tpy)(NN)X]⁺ (X = F, Cl, Br) was determined in the light of Benchmark analysis and according to this analysis results, the best level is shown as B3LYP-LANL2DZ/6-31G(d). In addition to this, the spectroscopic data (IR, NMR and UV-Vis) were also obtained in agreement with experimental results. The tendency of anticancer activity and structural activity relationship (SAR) parameters are predicted with some quantum chemical methods. Surface and contour diagrams, as well as electron densities on mentioned complexes were interpreted through theoretically obtained results. Finally, the anticancer activity tendency of the relevant complexes on the human cervical carcinoma cell line (ID: 1 M17) is supported by molecular docking calculations.

Biological activity and binding properties of [Ru(II)(dcbpy)2Cl2] complex to bovine serum albumin, phospholipase A2 and glutathione

Ruthenium compounds are highly regarded as metallo-drug candidates. Many studies have focused their attention on the interaction between ruthenium complexes with their possible biological targets. The interaction of ruthenium complexes with transport proteins, enzymes and peptides is of great importance for understanding their biodistribution and mechanism of action, therefore, the development of an anti-cancer therapy involving ruthenium complexes has recently shifted from DNA targeting towards protein targeting. With the aim of gaining insight into possible interactions between ruthenium complexes with biologically relevant proteins, we have studied the interaction of cis-dichlorobis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) complex [Ru(II)(dcbpy)2Cl2], which previously showed good potency in photo-dynamic chemotherapy, with bovine serum albumin (BSA), phospholipase A2 (PLA2) and glutathione (GSH). Binding constants and possible number of binding sites to mentioned proteins and peptide are investigated by ultraviolet-visible spectroscopy and Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI TOF MS). The complex binding affinities were in the following order: PLA2 > BSA > GSH. Moreover, genotoxic profile of the complex, tested on peripheral blood lymphocytes as a model system, was also promising.

Anticancer Activities of Mononuclear Ruthenium(II) Coordination Complexes

Ruthenium compounds are highly regarded as potential drug candidates. The compounds offer the potential of reduced toxicity and can be tolerated in vivo. The various oxidation states, different mechanism of action, and the ligand substitution kinetics of ruthenium compounds give them advantages over platinum-based complexes, thereby making them suitable for use in biological applications. Several studies have focused attention on the interaction between active ruthenium complexes and their possible biological targets. In this paper, we review several ruthenium compounds which reportedly possess promising cytotoxic profiles: from the discovery of highly active compounds imidazolium [trans-tetrachloro(dmso)(imidazole)ruthenate(III)] (NAMI-A), indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)](KP1019), and sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (NKP-1339) to the recent work based on both inorganic and organometallic ruthenium(II) compounds. Half-sandwich organometallic ruthenium complexes offer the opportunity of derivatization at the arene moiety, while the three remaining coordination sites on the metal centre can be functionalised with various coordination groups of various monoligands. It is clear from the review that these mononuclear ruthenium(II) compounds represent a strongly emerging field of research that will soon culminate into several ruthenium based antitumor agents.

Ru binding to RNA following treatment with the antimetastatic prodrug NAMI-A in Saccharomyces cerevisiae and in vitro

[ImH][trans-Ru(III)Cl(4)(DMSO)(Im)] (where DMSO is dimethyl sulfoxide and Im is imidazole) (NAMI-A) is an antimetastatic prodrug currently in phase II clinical trials. The mechanisms of action of this and related Ru-based anticancer agents are not well understood, but several cellular targets have been suggested. Although Ru has been observed to bind to DNA following in vitro NAMI-A exposure, little is known about Ru-DNA interactions in vivo and even less is known about how this or related metallodrugs might influence cellular RNA. In this study, Ru accumulation in cellular RNA was measured following treatment of Saccharomyces cerevisiae with NAMI-A. Drug-dependent growth and cell viability indicate relatively high tolerance, with approximately 40% cell death occurring at 6 h for 450 μM NAMI-A. Significant dose-dependent accumulation of Ru in cellular RNA was observed by inductively coupled plasma mass spectrometry measurements on RNA extracted from yeast treated with NAMI-A. In vitro, binding of Ru species to drug-treated model DNA and RNA oligonucleotides at pH 6.0 and 7.4 was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the presence and absence of the reductant ascorbate. The extent of Ru-nucleotide interactions increases slightly with lower pH and significantly in the presence of ascorbate, with differences in observed species distribution. Taken together, these studies demonstrate the accumulation of aquated and reduced derivatives of NAMI-A on RNA in vitro and in cellulo, and enhanced binding with nucleic acid targets in a tumorlike acidic, reducing environment. To our knowledge, this is also the first study to characterize NAMI-A treatment of S. cerevisiae, a genetically tractable model organism.

In vitro and in vivo evaluation of ruthenium(II)-arene PTA complexes

The antitumor activity of the organometallic ruthenium(II)-arene complexes, RuCl(2)(eta(6)-arene)(PTA), (arene = p-cymene, toluene, benzene, benzo-15-crown-5, 1-ethylbenzene-2,3-dimethylimidazolium tetrafluoroborate, ethyl benzoate, hexamethylbenzene; PTA = 1,3,5-triaza-7-phosphaadamantane), abbreviated RAPTA, has been evaluated. In vitro biological experiments demonstrate that these compounds are active toward the TS/A mouse adenocarcinoma cancer cell line whereas cytotoxicity on the HBL-100 human mammary (nontumor) cell line was not observed at concentrations up to 0.3 mM, which indicates selectivity of these ruthenium(II)-arene complexes to cancer cells. Analogues of the RAPTA compounds, in which the PTA ligand is methylated, have also been prepared, and these prove to be cytotoxic toward both cell lines. RAPTA-C and the benzene analogue RAPTA-B were selected for in vivo experiments to evaluate their anticancer and antimetastatic activity. The results show that these complexes can reduce the growth of lung metastases in CBA mice bearing the MCa mammary carcinoma in the absence of a corresponding action at the site of primary tumor growth. Pharmacokinetic studies of RAPTA-C indicate that ruthenium is rapidly lost from the organs and the bloodstream.

Zinc complexes with cyclic derivatives of α-ketoglutaric acid thiosemicarbazone: Synthesis, X-ray structures and DNA interactions

Six new cyclic ligands derived from alpha-ketoglutaric acid thiosemicarbazone (H(3)ct) and their zinc complexes have been synthesized and characterized by analytical and spectroscopic (IR and NMR) studies. The X-ray structures of ligands Me-H(2)ct(C) (1), Allyl-H(2)ct(c) (3) and of complex [Zn(Me-Hct(C))(2)(OH(2))(2)].2H(2)O (7) have been determined. In complex (7) the zinc atom lies on a twofold axis and is surrounded in a tetrahedral coordination by two water molecules and two carboxylic oxygen donor atoms from the ligand. DNA titration in the UV-visible region and thermal denaturation have been employed to determine the details of DNA binding for the studied compounds. Studies of nuclease activity have also been performed with all our compounds through a gel electrophoresis experiment using plasmid pBR322 showing that no DNA breakings take place. Tests in vitro on human leukemia cell line U937 have been carried out on cell growth inhibition where solubility of the compounds allowed the experiments.

Copper(II) Complexes with Substituted Thiosemicarbazones of α-Ketoglutaric Acid: Synthesis, X-ray Structures, DNA Binding Studies, and Nuclease and Biological Activity

New alpha-ketoglutaric acid thiosemicarbazone (H(3)ct) derivatives and their copper complexes were synthesized and characterized by analytical and spectroscopic (IR and NMR) methods. For two of the ligands, Me-H(3)ct and Allyl-H(3)ct, and for a complex, [Cu(Me-Hct)(OH(2))](n) x 2nH(2)O, the X-ray structures were also determined. In the latter the copper atom shows a 4 + 1 pyramidal coordination, a water oxygen appears in the apical position, and three of the basal positions are occupied by the SNO tridentate ligand and the fourth by a carboxylic oxygen of an adjacent molecule that gives rise to a polymeric chain. DNA binding constants were determined, and studies of thermal denaturation profiles and nuclease activity were also performed. Tests in vitro on human leukemia cell line U937 were carried out on cell growth inhibition, cell cycle, and apoptosis induction.

Synthesis and Chemical−Pharmacological Characterization of the Antimetastatic NAMI-A-Type Ru(III) Complexes (Hdmtp)[trans-RuCl4(dmso-S)(dmtp)], (Na)[trans-RuCl4(dmso-S)(dmtp)], and [mer-RuCl3(H2O)(dmso-S)(dmtp)] (dmtp = 5,7-Dimethyl[1,2,4]triazolo[1,5-a]pyrimidine)

Ruthenium compounds have gained large interest for their potential application as chemotherapeutic agents, and in particular the complexes of the type (X)[trans-RuCl4(dmso-S)L] (X = HL or Na, NAMI-A or NAMI, respectively, for L = imidazole) are under investigation for their antimetastatic properties. The NAMI(-A)-like compounds are prodrugs that hydrolyze in vivo, and the investigation of their hydrolytic properties is therefore important for determining the nature of the potential active species. The NAMI-A-type Ru(III) complex 1, (Hdmtp)[trans-RuCl4(dmso-S)(dmtp)] (dmtp is 5,7-dimethyl[1,2,4]triazolo[1,5-a]pyrimidine), and the corresponding sodium analogue 2, (Na)[trans-RuCl4(dmso-S)(dmtp)], were synthesized. The hydrolyses of 1 and 2 in water as well as in buffered solutions were studied, and the first hydrolysis product, [mer-RuCl3(H2O)(dmso-S)(dmtp)].H2O (3), was isolated and characterized. The molecular structures of 1 and 3 were determined by single-crystal X-ray diffraction analyses and prove the importance of the hydrogen-bonding properties of dmtp to stabilize hydrolysis products. In vitro 1 (a) is not cytotoxic on tumor cells, following challenges from 1 to 72 h and concentrations up to 100 microM, (b) inhibits matrigel invasion at 0.1 mM and MMP-9 activity with an IC50 of about 1 mM, and (c) is devoid of pronounced effects on cell distribution among cell cycle phases. In vivo compound 1, similar to NAMI-A, significantly inhibits metastasis growth in mice bearing advanced MCa mammary carcinoma tumors. In the lungs, 1 is significantly less concentrated than NAMI-A, whereas no differences between these two compounds were found in other organs such as tumor, liver, and kidney. However, 1 caused edema and necrotic areas on liver parenchyma that are more pronounced than those caused by NAMI-A. Conversely, glomerular and tubular changes on kidney are less extensive than with NAMI-A. In conclusion, 1 confirms the excellent antimetastatic properties of this class of NAMI-A-type compounds and qualifies as an interesting alternative to NAMI-A for treating human cancers.

Interactions of two cytotoxic organotin(IV) compounds with calf thymus DNA

The reactions with DNA of two antitumor active organotin(IV) compounds, the dimer of bis[(di-n-butyl 3,6-dioxaheptanoato)tin] (C(52)H(108)Sn(4)O(1) x 2H(2)O), compound 1, and tri-n-butyltin 3,6,9-trioxodecanoate (C(19)H(40)SnO(5) x 1/2H(2)O), compound 2, were analysed by circular dichroism, DNA melting experiments and gel mobility shift assays. It is found that both complexes modify only slightly the B-type circular dichroism spectroscopy (CD) spectrum of calf thymus DNA. On the other hand, both complexes were found to affect significantly the parameters of the thermally induced helix-to-coil transition. Addition of 1 or 2 to calf thymus DNA samples does not favor DNA renaturation after melting ruling out formation of interstrand crosslinks. Moreover, the effects of both compounds on plasmid DNA gel mobility were investigated. From the analysis of the present results it is inferred that both organotin(IV) compounds do interact with DNA, probably at the level of the phosphate groups.