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Two new ruthenium (II) polypyridyl complexes [Ru(MeIm)₄(pip)]²⁺ (1) and [Ru(MeIm)₄(4-npip)]²⁺ (2) were synthesized under the guidance of computational studies (DFT). Their binding property to human telomeric G-quadruplex studied by UV-Vis absorption spectroscopy, the fluorescent resonance energy transfer (FRET) melting assay and circular dichroism (CD) spectroscopy for validating the theoretical prediction. Both of them were evaluated for their potential anti-proliferative activity against four human tumor cell lines. Complex 2 shows growth inhibition against all the cell lines tested, especially the human lung tumor cell (A549). The RTCA analysis not only validated the inhibition activity but also showed the ability of reducing A549 cells' migration. DNA-flow cytometric analysis, mitochondrial membrane potential (ΔΨm) and the scavenger measurements of reactive oxygen species (ROS) analysis carried out to investigate the mechanism of cell growth inhibition and apoptosis-inducing effect of complex 2. The results demonstrated that complex 2 induces tumor cells apoptosis by acting on both mitochondrial homeostasis destruction and death receptor signaling pathways. And those suggested that complex 2 could be a candidate for further evaluation as a chemotherapeutic agent against human tumor. Show less

Variable, diversity and joining (V(D)J) recombination and immunoglobulin class switch recombination (CSR) are key processes in adaptive immune responses that naturally generate DNA double-strand breaks (DSBs) and trigger a DNA repair response. It is unclear whether this response is associated with distinct survival signals that protect T and B cells. Glycogen synthase kinase 3β (GSK3β) is a constitutively active kinase known to promote cell death. Here we show that phosphorylation of GSK3β on Ser(389) by p38 MAPK (mitogen-activated protein kinase) is induced selectively by DSBs through ATM (ataxia telangiectasia mutated) as a unique mechanism to attenuate the activity of nuclear GSK3β and promote survival of cells undergoing DSBs. Inability to inactivate GSK3β through Ser(389) phosphorylation in Ser(389)Ala knockin mice causes a decrease in the fitness of cells undergoing V(D)J recombination and CSR. Preselection-Tcrβ repertoire is impaired and antigen-specific IgG antibody responses following immunization are blunted in Ser(389)GSK3β knockin mice. Thus, GSK3β emerges as an important modulator of the adaptive immune response. Show less

Ruthenium-based anticancer complexes are promising antitumor agents for their low system toxicity and versatile chemical structures. Epidermal growth factor receptor (EGFR) has been found to be overexpressed in a broad range of tumor cells and is regarded as a drug target in developing novel antitumor drugs. In this work, five ruthenium(II) polypyridyl complexes containing EGFR-inhibiting 4-anilinoquinazoline pharmacophores were synthesized and characterized. These complexes showed both high EGFR-inhibiting activity and strong DNA minor groove-binding activity. In vitro antiproliferation screening demonstrated that the prepared ruthenium complexes are highly cytotoxic against a series of cancer cell lines, in particular non-small-cell lung A549 and human epidermoid carcinoma A431. Fluorescence-activated cell sorting analysis and fluorescence microscopy revealed that the most active complex, K4, induced much more late-stage cell apoptosis and necrosis than gefitinib, the first EGFR-targeting antitumor drug in clinical use. These results indicate that the ruthenium(II) polypyridyl complexes bearing EGFR-inhibiting 4-anilinoquinazolines possess highly active dual-targeting anticancer activity and are promising in developing new anticancer agents. Show less

Herein we report the synthesis, anticancer potency in vitro, biomolecule interaction, and preliminary mode of action studies of a series of cyclometalated 1,2,3-triazole-derived ruthenium(II) (2a-e) and osmium(II) (3a-e) organometallics of the general form [(η⁶-p-cym)RuCl(κ²-C^N-L)] with varying substituents in postion 1 of the 1,2,3-triazole moiety. These cyclometalates were characterized by standard analytical methods and their structures unambiguously assigned by single crystal X-ray crystallography. The anticancer activity of these novel compounds was tested in the human tumor cell lines A549 (non-small cell lung cancer), SW480 (colon adenocarcinoma), and CH1/PA-1 (ovarian teratocarcinoma), and preliminary structure-activity relationships were derived from the obtained data sets. Various representatives exhibit promising antineoplastic effects with IC₅₀ values down to the low micromolar range. The compounds readily formed stable DMSO adducts after aquation in DMSO-containing solution, but employing DMSO as solubilizer in cytotoxicity assays had no pronounced effect on the cytotoxicity, compared to analogous experiments with DMF for most compounds. We isolated and characterized selected DMSO adducts as triflate salts and found that they show activities in the same range as the parent chlorido metalacycles in MTT assays with the use of DMSO. Osmium(II) cyclometalates exhibited higher antiproliferative activities than their ruthenium(II) counterparts. The IC₅₀ values within each metal series decreased with increasing lipophilicity, which was attributed to higher cellular accumulation. Investigations on their mode of action revealed that the prepared organometallics were unable to inhibit topoisomerase IIα. Still, the most cytotoxic representatives 2b and 3b showed pronounced effects on cell cycle distribution. Show less

Organometallic iridium complexes are potent anticancer candidates which act through different mechanisms from cisplatin-based chemotherapy regimens. Here, ten phosphorescent cyclometalated iridium(III) complexes containing 2,2'-bipyridine-4,4'-dicarboxylic acid and its diester derivatives as ligands are designed and synthesized. The modification by ester group, which can be hydrolysed by esterase, facilitates the adjustment of drug-like properties. The quantum yields and emission lifetimes are influenced by variation of the ester substituents on the Ir(III) complexes. The cytotoxicity of these Ir(III) complexes is correlated with the length of their ester groups. Among them, 4a and 4b are found to be highly active against a panel of cancer cells screened, including cisplatin-resistant cancer cells. Mechanism studies in vitro indicate that they undergo hydrolysis of ester bonds, accumulate in mitochondria, and induce a series of cell-death related events mediated by mitochondria. Furthermore, 4a and 4b can induce pro-death autophagy and apoptosis simultaneously. Our study indicates that ester modification is a simple and feasible strategy to enhance the anticancer potency of Ir(III) complexes. Show less

Halogenido and carboxylato Ru(II) half-sandwich complexes of the general composition [Ru(η⁶-p-cym)(dpa)X]PF₆ (1-5) were prepared and thoroughly characterized with various techniques (e.g., mass spectrometry, NMR spectroscopy and X-ray analysis); dpa = 2,2'-dipyridylamine; p-cym = p-cymene; X = Cl^- (for 1), Br^- (for 2), I^- (for 3), valproate(1-) (for 4) or 4-phenylbutyrate(1-) (for 5). A single-crystal X-ray analysis showed a pseudo-octahedral piano-stool geometry of [Ru(η⁶-p-cym)(dpa)I]PF₆ (3), with a η⁶-coordinated p-cymene, bidentate N-donor dpa ligand and iodido ligand coordinated to the Ru(II) atom. The results of the ¹H-NMR solution behaviour studies proved that the complexes 1-5 hydrolyse were in the mixture of solvents used (10% MeOD-d₄/90% D₂O). Complexes 1-5 were in vitro inactive against the A2780 human ovarian carcinoma cell line, up to the highest tested concentration (IC₅₀ > 100 μM). Show less

Eight ruthenium(ii) compounds of the general formula [(η(5)-C5H5)Ru(N-N)(PPh3)][PF6] were rationally designed, exhibiting high cytotoxicity against HCT116 human colon cancer cells, with IC50 between 14.56 and 1.56 μM; importantly, compounds 5Ru and 6Ru are the first reported ruthenium glycoconjugates exploiting glucose transporters, widely overexpressed in cancer, for cellular uptake. Show less

The Ru(III) complexes indazolium [trans-RuCl4(1H-indazole)2] (KP1019) and sodium [trans-RuCl4(1H-indazole)2] (NKP-1339) are leading candidates for the next generation of metal-based chemotherapeutics. Trifluoromethyl derivatives of these compounds and their imidazole and pyridine analogues were synthesized to probe the effect of ligand lipophilicity on the pharmacological properties of these types of complexes. Addition of CF3 groups also provided a spectroscopic handle for (19)F NMR studies of ligand exchange processes and protein interactions. The lipophilicities of the CF3-functionalized compounds and their unsubstituted parent complexes were quantified by the shake-flask method to give the distribution coefficient D at pH 7.4 (log D7.4). The solution behavior of the CF3-functionalized complexes was characterized in phosphate-buffered saline (PBS) using (19)F NMR, electron paramagnetic resonance (EPR), and UV-vis spectroscopies. These techniques, along with fluorescence competition experiments, were also used to characterize interactions with human serum albumin (HSA). From these studies it was determined that increased lipophilicity correlates with reduced solubility in PBS but enhancement of noncoordinate interactions with hydrophobic domains of HSA. These protein interactions improve the solubility of the complexes and inhibit the formation of oligomeric species. EPR measurements also demonstrated the formation of HSA-coordinated species with longer incubation. (19)F NMR spectra show that the trifluoromethyl complexes release axial ligands in PBS and in the presence of HSA. In vitro testing showed that the most lipophilic complexes had the greatest cytotoxic activity. Addition of CF3 groups enhances the activity of the indazole complex against A549 nonsmall cell lung carcinoma cells. Furthermore, in the case of the pyridine complexes, the parent compound was inactive against the HT-29 human colon carcinoma cell line but showed strong cytotoxicity with CF3 functionalization. Overall, these studies demonstrate that lipophilicity may be a determining factor in the anticancer activity and pharmacological behavior of these types of Ru(III) complexes. Show less

The first examples of Ru^II and Rh^III piano-stool complex histone deacetylase (HDAC) inhibitors are presented. The novel complexes have antiproliferative activity against H460 non-small-cell lung carcinoma cells that is comparable to the clinically used HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Strong evidence for HDAC inhibition as a primary mechanism of action is provided. The complexes reported here represent an important step towards the design of highly active and selective HDAC inhibitors. Show less

Ruthenium (Ru) complexes are currently the focus of substantial interest because of their potential application as chemotherapeutic agents with broad anticancer activities. This study investigated the in vitro and in vivo anticancer activities and mechanisms of two Ru complexes-2,3,7,8,12,13,17,18-Octaethyl-21H,23H-porphine Ru(II) carbonyl (Ru1) and 5,10,15,20-Tetraphenyl-21H,23H-porphine Ru(II) carbonyl (Ru2)-against human hepatocellular carcinoma (HCC) cells. These Ru complexes effectively inhibited the cellular growth of three human hepatocellular carcinoma (HCC) cells, with IC50 values ranging from 2.7-7.3 μM. In contrast, the complexes exhibited lower toxicity towards L02 human liver normal cells with IC50 values of 20.4 and 24.8 μM, respectively. Moreover, Ru2 significantly inhibited HepG2 cell migration and invasion, and these effects were dose-dependent. The mechanistic studies demonstrated that Ru2 induced HCC cell apoptosis, as evidenced by DNA fragmentation and nuclear condensation, which was predominately triggered via caspase family member activation. Furthermore, HCC cell treatment significantly decreased the expression levels of Nrf2 and its downstream effectors,

Nad(p)h

quinone oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO1). Ru2 also exhibited potent in vivo anticancer efficacy in a tumor-bearing nude mouse model, as demonstrated by a time- and dose-dependent inhibition on tumor growth. The results demonstrate the therapeutic potential of Ru complexes against HCC via Nrf2 pathway regulation. Show less

Two ruthenium(II) complexes containing guanidinium ligands have been synthesized and characterized for the first time. It was found that the two complexes exhibit moderate antitumor activity in Hela, A549, CNE-2, MCF-7, and HepG2 human tumor cells. Flow cytometric analysis showed that both complexes arrested the cell cycle in the G2/M phase and induced apoptosis in Hela cells. Mechanism studies indicate that both complexes induced apoptosis through caspase- and reactive oxygen species (ROS)-dependent pathways. Additionally, the two complexes displayed higher phototoxicity to tumor cells and almost no influence on normal liver LO2 cells upon irradiation at 450nm. Show less

Mononuclear Ru(III) complexes of the type [Ru(LL)Cl2(H2O)] (LL = monobasic tridentate Schiff base anion: (1Z)-N'-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)-N-phenylethanimidamide [DAE], 4-[(1E)-N-{2-[(Z)-(4-hydroxy-3-methoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [HME], 4-[(1E)-N-{2-[(Z)-(3,4-dimethoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [MBE], and N-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)benzenecarboximidoyl chloride [DEE]) were synthesized and characterized using the microanalytical, conductivity measurements, electronic spectra, and FTIR spectroscopy. IR spectral studies confirmed that the ligands act as tridentate chelate coordinating the metal ion through the azomethine nitrogen and phenolic oxygen atom. An octahedral geometry has been proposed for all Ru(III)-Schiff base complexes. In vitro anticancer studies of the synthesized complexes against renal cancer cells (TK-10), melanoma cancer cells (UACC-62), and breast cancer cells (MCF-7) was investigated using the Sulforhodamine B assay. [Ru(DAE)Cl2(H2O)] showed the highest activity with IC50 valves of 3.57 ± 1.09, 6.44 ± 0.38, and 9.06 ± 1.18 μM against MCF-7, UACC-62, and TK-10, respectively, order of activity being TK-10 < UACC-62 < MCF-7. The antioxidant activity by DPPH and ABTS inhibition assay was also examined. Scavenging ability of the complexes on DPPH radical can be ranked in the following order: [Ru(DEE)Cl2(H2O)] > [Ru(HME)Cl2(H2O)] > [Ru(DAE)Cl2(H2O)] > [Ru(MBE)Cl2(H2O)]. Show less

The current work reports the synthesis, spectroscopic studies, antiradical and antiproliferative properties of four ruthenium(III) complexes of heterocyclic tridentate Schiff base bearing a simple 2',4'-dihydroxyacetophenone functionality and ethylenediamine as the bridging ligand with RCHO moiety. The reaction of the tridentate ligands with RuCl₃·3H₂O lead to the formation of neutral complexes of the type [Ru(L)Cl₂(H₂O)] (where L = tridentate NNO ligands). The compounds were characterized by elemental analysis, UV-vis, conductivity measurements, FTIR spectroscopy and confirmed the proposed octahedral geometry around the Ru ion. The Ru(III) compounds showed antiradical potentials against 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, with DPPH scavenging capability in the order: [(PAEBOD)RuCl₂] > [(BZEBOD)RuCl₂] > [(MOABOD)RuCl₂] > [Vit. C] > [rutin] > [(METBOD)RuCl₂], and ABTS radical in the order: [(PAEBOD)RuCl₂] < [(MOABOD)RuCl₂] < [(BZEBOD)RuCl₂] < [(METBOD)RuCl₂]. Furthermore, in vitro anti-proliferative activity was investigated against three human cancer cell lines: renal cancer cell (TK-10), melanoma cancer cell (UACC-62) and breast cancer cell (MCF-7) by SRB assay. Show less

This study performed in vitro and in vivo biological assays of the ruthenium (II) compound ct-[RuCl(CO)(dppb)(bipy)]PF₆ (where, dppb=1,4-bis(diphenylphosphine)butane and bipy=2,2'-bipyridine). The cytotoxic activity of this compound was evaluated against different tumor cell lines (HeLa, human cervical adenocarcinoma; MCF7, human breast adenocarcinoma; MO59J, human glioblastoma; HepG2, hepatocellular carcinoma and B16F10, murine melanoma) and healthy cell line (V79, Chinese hamster lung fibroblasts), by XTT (sodium 2,3'-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-3,4-tetrazolium-bis(4-methoxy-6-nitro)benzene-sulfonic acid hydrate) method. A syngeneic murine melanoma tumor model (B16F10) was used to evaluate its antitumor activity. Additionally, experiments were performed to assess the interactions with ctDNA (calf thymus DNA) and BSA (bovine serum albumin). The results showed that ct-[RuCl(CO)(dppb)(bipy)]PF₆ was cytotoxic against all tumor cell lines tested. Furthermore, the compound was more effective against tumor cells compared to the normal cell line, indicating selectivity, especially in B16F10 cells. Significant tumor growth reduction was observed in animals treated with the compound compared to the untreated control. Histopathological analysis of tumor tissue revealed a significant reduction of mitosis in animals treated with the compound compared to the untreated control. In the ctDNA and BSA interaction experiments, the compound in study showed weak interactions with ctDNA and hydrophobic interactions with BSA. The ruthenium compound investigated showed promising results in in vitro and in vivo biological assays. Show less

A series of Au(I) complexes (12, 13, 14, 15, 16) and Ag(I) complexes (17, 18, 19, 20) derived from imidazo[1,5‐a]pyridin‐3‐ylidenes were synthesized from AuCl(SMe2) or by reacting silver(I) acetate with 2,5‐dimethylimidazo[1,5‐a]pyridin‐2‐ium iodide or imidazo[1,5‐a]pyridin‐2‐ium salts, and were characterized using NMR spectroscopy, mass spectrometry and elemental analyses. In addition, the Au(I) complex 13 and the Ag(I) complex 19 were characterized using single‐crystal X‐ray diffraction. Using paclitaxel as a standard, all Au(I) and Ag(I) N‐heterocyclic carbene complexes were evaluated for their in vitro anti‐tumour activity against 12 cell lines using a monolayer cell survival and proliferation assay. The highest anticancer activity was found for complexes 15, 13 and 14 with mean IC50 values of 10.09, 10.42 and 12.28 μM, respectively. Copyright © 2016 John Wiley & Sons, Ltd. Show less

Multidrug resistance (MDR) is a major impediment to the success of chemotherapy in many cancer types. One particular MDR mechanism is the inherent or acquired adaptation of the cellular survival pathways that render malignant cells resistant to apoptotic cell death. Since most drugs act through apoptosis, compounds capable of inducing alternative forms of programmed cell death (PCD) can potentially be harnessed to bypass MDR. We investigated two organoruthenium complexes, RAS-1H and RAS-1T, and demonstrated that although they both induced non-apoptotic PCD through ER stress pathways, their modes-of-action were drastically different despite modest structural variations. RAS-1T acted through ROS-mediated ER stress while RAS-1H was ROS-independent. We further showed that they were more efficacious against apoptosis-resistant cells compared to clinical drugs including oxaliplatin. This work provides the basis for underpinning ER stress modulation using metal complexes to bypass apoptosis resistance. Show less

Two Ru(II) complexes [Ru(phen)2bppp](ClO4)2 (1) and [Ru(phen)27-Br-dppz](ClO4)2 (2) [phen=1,10 phenanthroline, 7-Br-dppz=7-fluorodipyrido[3,2-a:2',3'-c]phenazine, bppp=11-bromo-pyrido[2',3':5,6]pyrazino[2,3-f] [1,10]phenanthroline] have been synthesized and characterized by elemental analysis, ES-MS, (1)H-NMR, (13)C-NMR and IR. The in vitro cytotoxicity of the complexes examined against a panel of cancer cell lines (HeLa, Du145 and A549) by MTT method, both complexes show prominent anticancer activity against various cancer cells. Live cell imaging study and flow cytometric analysis demonstrate that both the complexes 1 and 2 could cross the cell membrane accumulating in the nucleus. Further, flow cytometry experiments showed that the cytotoxic Ru(II) complexes 1 and 2 induced apoptosis of HeLa tumor cell lines. Photo induced DNA cleavage studies have been performed and results indicate that both the complexes efficiently photo cleave pBR322 DNA. The binding properties of two complexes toward CT-DNA were investigated by various optical methods and viscosity measurements. The experimental results suggested that both Ru(II) complexes can intercalate into DNA base pairs. The complexes were docked into DNA-base pairs using the GOLD docking program. Show less

Four structurally related Ru(II)-halide-PTA complexes, of general formula trans- or cis-[Ru(PTA)4X2] (PTA=1,3,5-triaza-7-phosphaadamantane, X=Cl (1, 2), Br (3, 4), were prepared and characterized. Whereas compounds 1 and 2 are known, the corresponding bromo derivatives 3 and 4 are new. The Ru(III)-PTA compound trans-[RuCl4(PTAH)2]Cl (5, PTAH=PTA protonated at one N atom), structurally similar to the well-known Ru(III) anticancer drug candidates (Na)trans-[RuCl4(ind)2] (NKP-1339, ind=indazole) and (Him)trans-[RuCl4(dmso-S)(im)] (NAMI-A, im=imidazole), was also prepared and similarly investigated. Notably, the presence of PTA confers to all complexes an appreciable solubility in aqueous solutions at physiological pH. The chemical behavior of compounds 1-5 in water and in physiological buffer, their interactions with two model proteins - cytochrome c and ribonuclease A - as well as with a single strand oligonucleotide (5'-CGCGCG-3'), and their in vitro cytotoxicity against a human colon cancer cell line (HCT-116) and a myeloid leukemia (FLG 29.1) were investigated. Upon dissolution in the buffer, sequential halide replacement by water molecules was observed for complexes 1-4, with relatively slow kinetics, whereas the Ru(III) complex 5 is more inert. All tested compounds manifested moderate antiproliferative properties, the cis compounds 2 and 4 being slightly more active than the trans ones (1 and 3). Mass spectrometry experiments evidenced that all complexes exhibit a far higher reactivity towards the reference oligonucleotide than towards model proteins. The chemical and biological profiles of compounds 1-5 are compared to those of established ruthenium drug candidates in clinical development. Show less