Ruthenium-based chemotherapeutics: are they ready for prime time?

The role of ancillary ligands on benzodipyridophenazine-based Ru(II)/Ir(III) complexes in dark and light toxicity against TNBC cells

In this study, we investigated the impact of ancillary ligands on the anticancer activity of benzodipyridophenazine-based Ru(II) and Ir(III) complexes (Ru1, Ru2, Ir1, and Ir2). These metal complexes displayed three significant absorption bands attributed to the ligand-centered (LC) transitions, ligand-to-ligand charge transfer (LLCT), and metal-to-ligand charge transfer (MLCT). Binding studies of biomolecules were performed with the complexes along with the ligand, and it was found that after binding with Ru(II)/Ir(III), the properties of the ligands were enhanced. In vitro screening revealed that complex [(η5-Cp*)IrIIICl(κ2-N,N-benzo[i]dipyrido[3,2-a:2',3'-c])phenazine] (Ir1) exhibited the highest potency and selectivity (IC50 ∼ 2.14 μM, PI > 13) under yellow light irradiation. The photo-toxicity trend was Ir1 > Ru1 > Ir2 ≫ Ru2, which was found to be directly correlated with the singlet oxygen quantum yield (1O2). Chloro-substituted complexes (Ir1 and Ru1) were effective for hypoxic tumor treatment, particularly Ir1, which could generate high amounts of reactive oxygen species (ROS, type I PDT) in cells under photo irradiation. The high value of fluorescence quantum yield (fφ = 0.26) and significant emission at λ = 571 nm of Ir1 were certainly useful for bio-imaging applications. Colocalisation and DCFDA studies of Ir1 revealed that it can accumulate in the mitochondria, leading to depolarization of the mitochondrial membrane. These studies confirm that the complex Ir1 is a promising candidate for TNBC treatment in hypoxic tumors, with efficacy comparable to the current PDT drug Photofrin.

Hybrid Materials Based on Reduced Graphene Oxide; Synthesis and Characterization of V and Ru Metal Complexes

The unique material graphene, which can find its place in many areas such as pharmaceutical industry, medical field, aviation and space industry, and elimination of environmental pollution; was obtained from graphite using strong oxidants within the scope of this study. rGO was obtained by thermal reduction of oxygen-containing groups in the GO material layer. Hybrid materials were synthesized by binding 4-aminobenzoic acid (C) and 3-aminobenzoic acid (D) to the rGO material. Ru metal complexes, which stand out with their superior photophysical properties, and V metal complexes, which are harmful to the environment and human health, were formed with the hybrid materials. The synthesized hybrid and complex materials were characterized by methods such as FTIR, UV-vis, XRD, SEM and EDX and TEM. In addition, the photoluminescence properties of the materials were analyzed. The potential of Ru and V complexes of the obtained hybrid materials for use in the environment and human health was evaluated.

Chloride and Acetonitrile Ruthenium(IV) Complexes: Crystal Architecture, Chemical Characterization, Antibiofilm Activity, and Bioavailability in Biological Systems

Due to the emergence of drug resistance, many antimicrobial medications are becoming less effective, complicating the treatment of infections. Therefore, it is crucial to develop new active agents. This article aims to explore the ruthenium(IV) complexes with the following formulas: (Hdma)2(HL)2[RuIVCl6]·2Cl·2H2O (1), where Hdma is protonated dimethylamine and L is 2-hydroxymethylbenzimidazole, and [RuIVCl4(AN)2]·H2O (2), where AN is acetonitrile. This paper delves into the physicochemical characteristics and crystal structures of these complexes, employing various techniques such as spectroscopy (IR, UV-Vis), electrochemistry (CV, DPV), and X-ray crystallography. Hirshfeld surface analysis was also performed to visualize intermolecular interactions. Furthermore, the potential antibiofilm activity of the complexes against Pseudomonas aeruginosa PAO1 was investigated and the effect of the compounds on the production of pyoverdine, one of the virulence factors of the Pseudomonas strain, was assessed. The results show that particularly complex 1 reduces biofilm formation and pyoverdine production. Additionally, the bioavailability of these complexes in biological systems (by fluorescence quenching of human serum albumin (HSA) and molecular docking studies) is discussed, assessing how their chemical properties influence their interactions with biological molecules and their potential therapeutic applications.

Necrosis inducing tetranuclear Ru(II)-Re(I) metal complex for anticancer therapy

Chemotherapy is one of the most widely used anticancer treatments worldwide. However, despite its clinical effectiveness, most chemotherapeutic agents are associated with severe side effects. To address this limitation, there is an urgent need for the development of novel anticancer agents. Among the promising alternatives, Ruthenium and Rhenium complexes have garnered significant attention in the scientific literature. This study proposes combining these two metal moieties into a single tetranuclear complex, bridged by a 2,2'-bipyrimidine ligand. Cytotoxicity tests revealed broad activity of the novel metal complex against multiple cancer cell lines. Mechanistic studies suggested that the complex induces cell death by necrosis. Further analyses demonstrated its ability to eradicate colon carcinoma tumor spheroids at micromolar concentrations. To the best of our knowledge, this represents the first example of a Ru(II)-Re(I) tetranuclear metal complex as an anticancer agent.

Antimetastatic activity of (arene)ruthenium(II) complex of 4-aryl-4H-naphthopyran

Metastatic cancer remains a formidable challenge in anticancer therapy. Despite efforts to develop effective antimetastasis drugs over the past half-century, currently approved treatments fall short of expectations. This report highlights the promising antiproliferative activity of a ruthenium-based therapeutic agent, namely dichlorido(p-cymene)[2-amino-4-(pyridin-3-yl)-4H-benzo[h]-chromene-3-carbonitrile]ruthenium(II) (complex 1) against metastatic cell lines. Complex 1 shows significant efficacy in metastatic LoVo and Du-145 cell lines at nanomolar concentrations, being markedly more active than clinically used anticancer cisplatin. Studies on the MDA-MB-231 cell line, which displays invasive characteristics, demonstrated that 1 significantly reduces cell invasion. This efficacy was confirmed by its impact on matrix metalloproteinase production in MDA-MB-231 cells. Given that cell migration drives cancer invasion and metastasis, complex 1's effect on MDA-MB-231 cell migration was evaluated via wound healing assay and vimentin network analysis. Results indicated a strong reduction in migration. A re-adhesion assay further demonstrated that 1 significantly lowers the re-adhesion ability of MDA-MB-231 cells compared to cisplatin. To better simulate the human body environment, a 3D spheroid invasion assay was used. This method showed that 1 effectively inhibits tumor spheroids from infiltrating the surrounding extracellular matrix. This study underscores the potential of (arene)ruthenium(II) complexes with naphthopyran ligands as potent antimetastatic agents for chemotherapy.

Not All Binding Sites Are Equal: Site Determination and Folding State Analysis of Gas-Phase Protein-Metallodrug Adducts

Modern approaches in metallodrug research focus on compounds that bind protein targets rather than DNA. However, the identification of protein targets and binding sites is challenging. Using intact mass spectrometry and proteomics, we investigated the binding of the antimetastatic agent RAPTA-C to the model proteins ubiquitin, cytochrome c, lysozyme, and myoglobin. Binding to cytochrome c and lysozyme was negligible. However, ubiquitin bound up to three Ru moieties, two of which were localized at Met1 and His68 as [Ru(cym)], and [Ru(cym)] or [Ru(cym)(PTA)] adducts, respectively. Myoglobin bound up to four [Ru(cym)(PTA)] moieties and five sites were identified at His24, His36, His64, His81/82 and His113. Collision-induced unfolding (CIU) studies via ion-mobility mass spectrometry allowed measuring protein folding as a function of collisional activation. CIU of protein-RAPTA-C adducts showed binding of [Ru(cym)] to Met1 caused a significant compaction of ubiquitin, likely from N-terminal S-Ru-N chelation, while binding of [Ru(cym)(PTA)] to His residues of ubiquitin or myoglobin induced a smaller effect. Interestingly, the folded state of ubiquitin formed by His functionalization was more stable than Met1 metalation. The data suggests that selective metalation of amino acids at different positions on the protein impacts the conformation and potentially the biological activity of anticancer compounds.

Exploring the cytotoxicity of dinuclear Ru(II) p-cymene complexes appended N,N'-bis(4-substituted benzoyl)hydrazines: insights into the mechanism of apoptotic cell death

Cancer is a perilous life-threatening disease, and attempts are constantly being made to create multinuclear transition metal complexes that could lead to the development of potential anticancer medications and administration procedures. Hence, this work aims to design, synthesize, characterize, and assess the anticancer efficacy of ruthenium p-cymene complexes incorporating N,N'-bis(4-substituted benzoyl)hydrazine ligands. The formation of the new complexes (Ru2H1-Ru2H3) has been thoroughly established by elemental analysis, and FT-IR, UV-vis, NMR, and HR-MS spectral techniques. The solid-state molecular structures of the complexes Ru2H1 and Ru2H3 have been determined using the SC-XRD study, which confirms the N, O, and Cl-legged piano stool pseudo-octahedral geometry of each ruthenium(II) ion. The stability of these complexes in the solution state and their lipophilicity profile have been determined. Furthermore, the title complexes were tested for their in vitro anticancer activity against cancerous H460 (lung cancer cells), SkBr3 (breast cancer cells), HepG2 (liver cancer cells), and HeLa (cervical cancer cells) along with non-cancerous (HEK-293) cells. The IC50 results revealed that complex Ru2H3 exhibits potent activity against the proliferation of all four cancer cells and outscored the effect of the standard metallodrug cisplatin. This may be attributed to the presence of a couple of lipophilic electron-donating methoxy groups in the ligand scaffold and also the ruthenium(II) p-cymene motifs. Advantageously, all the complexes (Ru2H1-Ru2H3) displayed cytotoxic specificity only towards cancerous cells by leaving the off-target non-cancerous cells undamaged. Acridine orange/ethidium bromide (AO/EB) staining, Hoechst 33342, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) staining assays were used to investigate the apoptotic pathway and ROS levels in mitochondria. The results of western blot analysis confirmed that the complexes triggered apoptosis through an intrinsic mitochondrial pathway by upregulating Bax and downregulating Bcl-2 proteins. Finally, the extent of apoptosis triggered by the complex Ru2H3 was quantified with the aid of flow cytometry using the Annexin V-FITC/propidium iodide (PI) double-staining technique.

A review on metal complexes and its anti-cancer activities: Recent updates from in vivo studies

Research into cancer therapeutics has uncovered various potential medications based on metal-containing scaffolds after the discovery and clinical applications of cisplatin as an anti-cancer agent. This has resulted in many metallodrugs that can be put into medical applications. These metallodrugs have a wider variety of functions and mechanisms of action than pure organic molecules. Although platinum-based medicines are very efficient anti-cancer agents, they are often accompanied by significant side effects and toxicity and are limited by resistance. Some of the most studied and developed alternatives to platinum-based anti-cancer medications include metallodrugs based on ruthenium, gold, copper, iridium, and osmium, which showed effectiveness against many cancer cell lines. These metal-based medicines represent an exciting new category of potential cancer treatments and sparked a renewed interest in the search for effective anti-cancer therapies. Despite the widespread development of metal complexes touted as powerful and promising in vitro anti-cancer therapeutics, only a small percentage of these compounds have shown their worth in vivo models. Metallodrugs, which are more effective and less toxic than platinum-based drugs and can treat drug-resistant cancer cells, are the focus of this review. Here, we highlighted some of the most recently developed Pt, Ru, Au, Cu, Ir, and Os complexes that have shown significant in vivo antitumor properties between 2017 and 2023.

Insights into the binding of half-sandwich phosphino Ir(III) and Ru(II) complexes to deoxyribonucleic acid, albumin and apo-transferrin: Experimental and theoretical investigation

A group of cytotoxic half-sandwich iridium(III) (Ir(η5-Cp*)Cl2PPh2CH2OH (IrPOH)), (Ir(η5-Cp*)Cl2P(p-OCH3Ph)2CH2OH (IrMPOH)), and ruthenium(II) (Ru(η6-p-cymene)Cl2PPh2CH2OH (RuPOH), Ru(η6-p-cymene)Cl2P(p-OCH3Ph)2CH2OH (RuMPOH)) complexes with phosphine ligands exhibit the ability to (i) slow hydrolysis which is reversed by adding a high NaCl concentration; (ii) oxidation of NADH to NAD+; (iii) induction of cytotoxicity towards various cancer cell lines. Furthermore, we found that RuPOH and RuMPOH selectively inhibit the proliferation of skin cancer cells (WM266-4) while Ir(III) complexes were found to be moderate against prostate cancer cells (DU-145). Herein, to elucidate the cytotoxic effects, we investigated the interaction of these complexes with DNA and serum proteins by gel electrophoresis, fluorescence spectroscopy, and molecular docking studies. Fluorescence spectroscopic data (calf thymus DNA: CT-DNA titration), together with analysis of DNA fragmentation (gel electrophoresis) and molecular docking provided evidence for the multimodal interaction of Ir(III) and Ru(III) complexes with DNA with predominance of intercalation and minor groove binding. All examined complexes caused single-stranded cleavage of the sugar-phosphate backbone of plasmid DNA. The affinity of the complexes for apo-transferrin (apo-Tf) and human serum albumin (HSA) was evaluated by fluorescence emission spectroscopy to calculate the binding constants which suggested a tight and reversible binding. Moreover, ruthenium complexes can mimic the binding of iron compounds to specific biomolecules such as albumin and transferrin better than iridium complexes. In silico study indicate that complexes mostly bind to (i) apo-Tf with a preference for a single binding site and/or (ii) to dock within all the four predicted binding sites of HSA with the predominance of site I which include tryptophan residues of HSA. This class of ruthenium(II) and iridium(III) complexes has unusual features worthy of further exploration in the design of novel anticancer drugs.

Design, synthesis and anticancer evaluation of novel half-sandwich Ru(II) complexes bearing pyrazalone moiety: Apoptosis inducers based on mitochondrial dysfunction and G0/G1 arrest

Six half-sandwich Ru(II) complexes (Ru1-Ru6), integrated with 5-phenyl-2-(pyridin-2-yl)-2,4-dihydro-3H-pyrazol-3-one (PDPO1-PDPO6) ligands, were synthesized and spectroscopically characterized. The structure of Ru3 that crystallized as a monoclinic crystal with P21/c space group was further confirmed by X-ray single crystal diffraction. Prototropic tautomerism within the complexes transformed OH-form ligands to NH-form, forming a hydrogen bond (Cl1---H-N3). The complexes and ligands' cytotoxicity was assessed against several cancerous (HepG2, A549, MCF-7) and normal Vero cell lines. Relative to the ligands and Cisplatin, complexes (Ru2, Ru3, Ru5, Ru6) exhibited potent cytotoxicity against cancer cells, with IC50 values from 2.05 to 15.69 μM/L, excluding Ru1 and Ru4. Specifically, Ru2, Ru3, and Ru5 demonstrated superior anti-HepG2 properties. Compared to Cisplatin, Ru2 and Ru5 were less toxic to Vero cells, highlighting their enhanced selectivity in toxicity. Structure-activity relationship (SAR) studies indicated that t-butyl substitution (in Ru2) or -Cl (in Ru5) on the benzene ring significantly improved the selective toxicity. These complexes manifested substantial lipophilicity, cellular uptake, and were quickly hydrolyzed to Ru-H2O species. Roughly positive correlations were observed between hydrolysis rate, lipophilicity, cellular uptake, and anticancer activities. Ru2, investigated specifically, induced apoptosis in HepG2 cells at concentrations of 10 and 20 μM/L through ROS-mediated mitochondrial dysfunction and G0/G1phase arrest, associated with altered P21, cyclin D, and CDK4 expression levels.

Synthesis and Characterization of Ruthenium-Paraphenylene-Cyclopentadienyl Full-Sandwich Complexes: Cytotoxic Activity against A549 Lung Cancer Cell Line and DNA Binding Properties

Novel full-sandwich (η5-Cp)-Ru-paraphenylene complexes with the general formula [(η5-Cp)nRu(η6-L)](PF6)n where n = 1-3 and L = biphenyl, p-terphenyl and p-quaterphenyl, were synthesized and characterized by means of spectroscopic and analytical techniques. The structures of the complexes [(η5-Cp)Ru(η6-biphenyl)](PF6) (1), [(η5-Cp)Ru(η6-terphenyl)](PF6) (3) and [(η5-Cp)2Ru(η6-terphenyl)](PF6)2 (4) was determined by X-ray single crystal methods. The interaction of the complexes [(η5-Cp)Ru(η6-quaterphenyl)]Cl, (6)Cl, and [(η5-Cp)2Ru(η6-quaterphenyl)]Cl2, (7)Cl2, with the DNA duplex d(5'-CGCGAATTCGCG-3')2 was studied using NMR techniques. The results showed that both complexes interacted non-specifically with both the minor and major grooves of the helix. Specifically, (6)Cl exhibited partial binding through intercalation between the T7 and T8 bases of the sequence without disrupting the C-G and A-T hydrogen bonds. Fluorometric determination of the complexes' binding constants revealed a significant influence of the number of connected phenyl rings in the paraphenylene ligand (L) on the binding affinity of their complexes with the d(5'-CGCGAATTCGCG-3')2. The complexes (6)Cl and (7)Cl2 were found to be highly cytotoxic against the A549 lung cancer cell line, with complex (6) being more effective than (7) (IC50 for (6)Cl: 17.45 ± 2.1 μΜ, IC50 for (7)Cl2: 65.83 ± 1.8 μΜ) and with a selectivity index (SI) (SI for (6)Cl: 1.1 and SI for (7)Cl2: 4.8).

Research Progress of Metal Anticancer Drugs

Cancer treatments, including traditional chemotherapy, have failed to cure human malignancies. The main reasons for the failure of these treatments are the inevitable drug resistance and serious side effects. In clinical treatment, only 5 percent of the 50 percent of cancer patients who are able to receive conventional chemotherapy survive. Because of these factors, being able to develop a drug and treatment that can target only cancer cells without affecting normal cells remains a big challenge. Since the special properties of cisplatin in the treatment of malignant tumors were accidentally discovered in the last century, metal anticancer drugs have become a research hotspot. Metal anticancer drugs have unique pharmaceutical properties, such as ruthenium metal drugs with their high selectivity, low toxicity, easy absorption by tumor tissue, excretion, and so on. In recent years, efficient and low-toxicity metal antitumor complexes have been synthesized. In this paper, the scientific literature on platinum (Pt), ruthenium (Ru), iridium (Ir), gold (Au), and other anticancer complexes was reviewed by referring to a large amount of relevant literature at home and abroad.

Synthesis and Preclinical Evaluation of Radiolabeled [103Ru]BOLD-100

The first-in-class ruthenium-based chemotherapeutic agent BOLD-100 (formerly IT-139, NKP-1339, KP1339) is currently the subject of clinical evaluation for the treatment of gastric, pancreatic, colorectal and bile duct cancer. A radiolabeled version of the compound could present a helpful diagnostic tool. Thus, this study investigated the pharmacokinetics of BOLD-100 in more detail to facilitate the stratification of patients for the therapy. The synthesis of [103Ru]BOLD-100, radiolabeled with carrier added (c.a.) ruthenium-103, was established and the product was characterized by HPLC and UV/Vis spectroscopy. In order to compare the radiolabeled and non-radioactive versions of BOLD-100, both complexes were fully evaluated in vitro and in vivo. The cytotoxicity of the compounds was determined in two colon carcinoma cell lines (HCT116 and CT26) and biodistribution studies were performed in Balb/c mice bearing CT26 allografts over a time period of 72 h post injection (p.i.). We report herein preclinical cytotoxicity and pharmacokinetic data for BOLD-100, which were found to be identical to those of its radiolabeled analog [103Ru]BOLD-100.

Silver, Its Salts and Application in Medicine and Pharmacy

The healing properties of silver have been used since ancient times. The main aim of the study was to collect and review the literature on the clinical potential of silver, its salts and complex compounds. The second goal was to present an outline of the historical use of silver in medicine and pharmacy, taking into account the possibility of producing pharmaceutical drug forms on the premises of pharmacies. In the context of the growing resistance of microorganisms to available, widely used antibiotics, silver plays a key role. There is only one known case of bacterial resistance to silver-the Pseudomonas stutzeri strain, which naturally occurs in silver mines. The development of research in the field of coordination chemistry offers great opportunities in the design of new substances in which silver ions can be incorporated. These substances exhibit increased potency and often an extended antimicrobial spectrum. Silver-based compounds are, however, only limited to external applications, as opposed to their historic oral administration. Advanced studies of their physicochemical, microbiological, cytotoxic and genotoxic properties are ongoing and full of challenges. The improvement of the methods of synthesis gives the possibility of applying the newly synthesized compounds ex tempore, as was the case with the complex of metronidazole with silver (I) nitrate. Some of these experimental efforts performed in vitro are followed with clinical trials. The third and final goal of this study was to present the possibility of obtaining an ointment under the conditions of an actual pharmacy using silver (I) salts and a ligand, both of which are active substances with antimicrobial properties.

Comparative studies on in vitro antitumor activities and apoptosis-inducing effects of enantiomeric ruthenium(II) complexes

On the basis of our previous comparative studies on the DNA binding of a pair of ruthenium(II) complex enantiomers, Δ-[Ru(bpy)2PBIP]2+ and Λ-[Ru(bpy)2PBIP]2+ {bpy = 2,2'-bipyridine, PBIP = 2-(4-bromophenyl)imidazo[4,5-f]1,10-phenanthroline}, in this study, their antitumor activities and mechanisms were further investigated comparatively. The cytotoxicity assay demonstrated that both the enantiomers exerted selective antiproliferative effects on cancer cell lines A2780 and PC3. Fluorescence localization experiments suggested that both the enantiomers effectively permeated the nucleus of HeLa cells and co-localized with DNA, resulting in their DNA damage and apoptosis. Flow cytometry experiments showed that the apoptosis was enhanced by increasing the concentration of each enantiomer. Western blotting analyses indicated that both extrinsic and intrinsic apoptosis pathways were activated by the two enantiomers. miRNA microarray analyses displayed that both the enantiomers up- and downregulated multiple miRNAs, some of which were predicted to be associated with carcinogenesis. The above experimental results also showed that the Δ-enantiomer exerted a more potent antitumor activity, a higher efficiency of entering cancer cells and a stronger apoptosis-inducing effect compared with the Λ-enantiomer. Combined with the previously published research results, experimental results from this study implied that the antitumor activity of a metal complex might have originated from the conformation change of DNA in tumor cells caused by the intercalation of the complex, that the antitumor mechanism of a metal complex could be related to its DNA-binding mode, and that the antitumor efficiency of a metal complex could result from its DNA-binding strength.

Study on the Multimodal Anticancer Mechanism of Ru(II)/Ir(III) Complexes Bearing a Poly(ADP-ribose) Polymerase 1 Inhibitor

A series of novel ruthenium(II) and iridium(III) complexes (Ru1-Ru3 and Ir1-Ir3) with different ancillary ligands and a PARP-1-inhibitory chelating ligand 2-(2,3-dibromo-4,5-dimethoxybenzylidene)hydrazine-1-carbothioamide (L1) were designed and prepared. The target complexes were structurally characterized by NMR and ESI-MS techniques. Among them, the crystal and molecular structures of Ir1 and Ir2 were also determined by X-ray crystallography. These complexes retained the PARP-1 enzyme inhibitory effect of L1 and showed potent antiproliferative activity on the tested cancer cell lines. The ruthenium(II) complexes Ru1-Ru3 were found to be more cytotoxic than the iridium(III) complexes Ir1-Ir3. Further investigations revealed that the most active complex Ru3 induced apoptosis in MCF-7 cells by multiple modes, inclusive of inducing DNA damage, suppressing DNA damage repair, disturbing cell cycle distribution, decreasing the mitochondrial membrane potential, and increasing the intracellular reactive oxygen species levels.

Cytotoxicity of Ruthenium(II) Arene Complexes Containing Functionalized Ferrocenyl β-Diketonate Ligands

The synthesis and characterization of 24 ruthenium(II) arene complexes of the type [(p-cym)RuCl(Fc-acac)] (where p-cym = p-cymene and Fc-acac = functionalized ferrocenyl β-diketonate ligands) are reported, including single-crystal X-ray diffraction for 21 new complexes. Chemosensitivity studies have been conducted against human pancreatic carcinoma (MIA PaCa-2), human colorectal adenocarcinoma p53-wildtype (HCT116 p53+/+) and normal human retinal epithelial cell lines (APRE-19). The most active complex, which contains a 2-furan-substituted ligand (4), is 5x more cytotoxic than the analogs 3-furan complex (5) against MIA PaCa-2. Several complexes were screened under hypoxic conditions and at shorter-time incubations, and their ability to damage DNA was determined by the comet assay. Compounds were also screened for their potential to inhibit the growth of both bacterial and fungal strains.

Triarylphosphine-Coordinated Bipyridyl Ru(II) Complexes Induce Mitochondrial Dysfunction

While cancer cells rely heavily upon glycolysis to meet their energetic needs, reducing the importance of mitochondrial oxidative respiration processes, more recent studies have shown that their mitochondria still play an active role in the bioenergetics of metastases. This feature, in combination with the regulatory role of mitochondria in cell death, has made this organelle an attractive anticancer target. Here, we report the synthesis and biological characterization of triarylphosphine-containing bipyridyl ruthenium (Ru(II)) compounds and found distinct differences as a function of the substituents on the bipyridine and phosphine ligands. 4,4'-Dimethylbipyridyl-substituted compound 3 exhibited especially high depolarizing capabilities, and this depolarization was selective for the mitochondrial membrane and occurred within minutes of treatment in cancer cells. The Ru(II) complex 3 exhibited an 8-fold increase in depolarized mitochondrial membranes, as determined by flow cytometry, which compares favorably to the 2-fold increase observed by carbonyl cyanide chlorophenylhydrazone (CCCP), a proton ionophore that shuttles protons across membranes, depositing them into the mitochondrial matrix. Fluorination of the triphenylphosphine ligand provided a scaffold that maintained potency against a range of cancer cells but avoided inducing toxicity in zebrafish embryos at higher concentrations, displaying the potential of these Ru(II) compounds for anticancer applications. This study provides essential information regarding the role of ancillary ligands for the anticancer activity of Ru(II) coordination compounds that induce mitochondrial dysfunction.

A monoadduct generating Ru(ii) complex induces ribosome biogenesis stress and is a molecular mimic of phenanthriplatin

Ruthenium complexes are often investigated as potential replacements for platinum-based chemotherapeutics in hopes of identifying systems with improved tolerability in vivo and reduced susceptibility to cellular resistance mechanisms. Inspired by phenanthriplatin, a non-traditional platinum agent that contains only one labile ligand, monofunctional ruthenium polypyridyl agents have been developed, but until now, few demonstrated promising anticancer activity. Here we introduce a potent new scaffold, based on [Ru(tpy)(dip)Cl]Cl (tpy = 2,2':6',2''-terpyridine and dip = 4,7-diphenyl-1,10-phenanthroline) in pursuit of effective Ru(ii)-based monofunctional agents. Notably, the extension of the terpyridine at the 4' position with an aromatic ring resulted in a molecule that was cytotoxic in several cancer cell lines with sub-micromolar IC50 values, induced ribosome biogenesis stress, and exhibited minimal zebrafish embryo toxicity. This study demonstrates the successful design of a Ru(ii) agent that mimics many of the biological effects and phenotypes seen with phenanthriplatin, despite numerous differences in both the ligands and metal center structure.

Ionic mononuclear [Fe] and heterodinuclear [Fe,Ru] bis(diphenylphosphino)alkane complexes: Synthesis, spectroscopy, DFT structures, cytotoxicity, and biomolecular interactions

Iron(II) and Ru(II) half-sandwich compounds encompass some promising pre-clinical anticancer agents whose efficacy may be tuned by structural modification of the coordinated ligands. Here, we combine two such bioactive metal centres in cationic bis(diphenylphosphino)alkane-bridged heterodinuclear [Fe²⁺, Ru²⁺] complexes to delineate how ligand structural variations modulate compound cytotoxicity. Specifically, Fe(II) complexes of the type [(η⁵-C₅H₅)Fe(CO)₂(κ¹-PPh₂(CH₂)_nPPh₂)]{PF₆} (n = 1-5), compounds 1-5, and heterodinuclear [Fe²⁺, Ru²⁺] complexes, [(η⁵-C₅H₅)Fe(CO)₂(μ-PPh₂(CH₂)_nPPh₂))(η⁶-p-cymene)RuCl₂]{PF₆} (n = 2-5) (compounds 7-10), were synthesized and characterised. The mononuclear complexes were moderately cytotoxic against two ovarian cancer cell lines (A2780 and cisplatin resistant A2780cis) with IC₅₀ values ranging from 2.3 ± 0.5 μM to 9.0 ± 1.4 μM. For 7-10, the cytotoxicity increased with increasing Fe⋅⋅⋅Ru distance, consistent with their DNA affinity. UV-visible spectroscopy suggested the chloride ligands in heterodinuclear 8-10 undergo stepwise substitution by water on the timescale of the DNA interaction experiments, probably affording the species [RuCl(OH₂)(η⁶-p-cymene)(PRPh₂)]²⁺ and [Ru(OH)(OH₂)(η⁶-p-cymene)(PRPh₂)]²⁺ (where PRPh₂ has R = [-(CH₂)₅PPh₂-Fe(C₅H₅)(CO)₂]⁺). One interpretation of the combined DNA-interaction and kinetic data is that the mono(aqua) complex may interact with dsDNA through nucleobase coordination. Heterodinuclear 10 reacts with glutathione (GSH) to form stable mono- and bis(thiolate) adducts, 10-SG and 10-SG₂, with no evidence of metal ion reduction (k₁ = 1.07 ± 0.17 × 10^-1 min^-1 and k₂ = 6.04 ± 0.59 × 10^-3 min^-1 at 37 °C). This work highlights the synergistic effect of the Fe²⁺/Ru²⁺ centres on both the cytotoxicity and biomolecular interactions of the present heterodinuclear complexes.

Hinged Bipodal Furoylthiourea-Based Ru(II)-Arene Complexes: Effect of (ortho, meta, or para)-Substitution on Coordination and Anticancer Activity

We set out to design and synthesize bipodal ligands with the phenyl group as the spacer and varied the substitution on the spacer between ortho (L1), meta (L2), and para (L3). The respective ligands and complexes containing either p-cymene (PL1-PL3) or benzene (BL1-BL3) as the arene unit were synthesized and characterized successfully. The influence of the ligands due to substitution change on their coordination behavior was quite minimal; however, the differences were seen in the anticancer activity of the complexes. DFT studies revealed the structural variations between the three different substitutions, which was further confirmed by single-crystal X-ray diffraction studies. The anticancer activity of the complexes could be correlated with their rate of hydrolysis and their lipophilicity index as determined by UV-visible spectroscopy. The cell death mechanism of the active complexes was deduced to be apoptotic via staining assays, flow cytometry, and Western blot analysis.

Selectively inhibiting malignant melanoma migration and invasion in an engineered skin model using actin-targeting dinuclear RuII-complexes

Due to the poor prognosis of metastatic cancers, there is a clinical need for agents with anti-metastatic activity. Here we report on the anti-metastatic effect of a previously reported Ru(ii) complex [{(phen)₂Ru}₂(tpphz)]⁴⁺, 1⁴⁺, that has recently been shown to disrupt actin fiber assembly. In this study, we investigated the anti-migratory effect of ⁺1⁴⁺ and a close structural analogue⁺, 2⁴⁺, on two highly invasive, metastatic human melanoma cell lines. Laser scanning confocal imaging was used to investigate the structure of actin filament and adhesion molecule vinculin and results show disassembly of central actin filaments and focal adhesions. The effect of both compounds on actin filaments was also found to be reversible. As these results revealed that the complexes were cytostatic and produced a significant inhibitory effect on the migration of both melanoma cell lines but not human dermal fibroblasts their effect on 3D-spheroids and a tissue-engineered living skin model were also investigated. These experiments demonstrated that the compounds inhibited the growth and invasiveness of the melanoma-based spheroidal tumor model and both complexes were found to penetrate the epidermis of the skin tissue model and inhibit the invasion of melanoma cells. Taken together, the cytostatic and antimigratory effects of the complexes results in an antimetastatic effect that totally prevent invasion of malignant melanoma into skin tissue.

Synthesis, structure, properties, and cytotoxicity of a (quinoline)RuCp+ complex

A rare example of a structurally characterized metal quinoline complex was prepared using a non-covalent quinoline-based proteasome inhibitor (Quin1), and a related complex bearing an inactive quinoline ligand (Quin2) was also synthesized. The quinolines are prepared by a one-pot procedure involving titanium-catalyzed alkyne iminoamination and are bound to ruthenium by reaction with CpRu(NCMe)₃⁺ PF₆^- in CH₂Cl₂. The arene of the quinoline is η⁶-bonded to the ruthenium metal center. The kinetics of quinoline displacement were investigated, and reactivity with deuterated solvents follows the order acetonitrile > DMSO > water. Quinolines with more methyl groups on the arene are more kinetically stable, and RuCp(Quin1)⁺ PF₆^- (1), which has two methyl groups on the arene, is stable for days in DMSO. In contrast, a very similar complex (2) made with Quin2 having no methyl groups on the arene was readily displaced by DMSO. Both 1 and 2 are stable in 9 : 1 water/DMSO for days with no measurable displacement of the quinoline. The cytotoxicity of the quinolines, their CpRu⁺-complexes, and CpRu(DMSO)₃⁺ PF₆^- was investigated towards two multiple myeloma cell lines: MC/CAR and RPMI 8226. To determine whether the activity of the complexes was related to the nature of the quinoline ligands, two structurally similar quinoline ligands with vastly different biological properties were investigated. Quin1 is a cytotoxic proteasome inhibitor, whereas Quin2 is not a proteasome inhibitor and showed no discernable cytotoxicity. The ruthenium complexes showed poor cellular proteasome inhibition. However, both 1 and 2 showed good cytotoxicity towards RPMI 8226 and MC/CAR, with 1 being slightly more cytotoxic. For example, 1 has a CC₅₀ = 2 μM in RPMI 8226, and 2 has a CC₅₀ = 5 μM for the same cell line. In contrast, CpRu(DMSO)₃⁺ PF₆^- was quite active towards MC/CAR with CC₅₀ = 2.8 μM but showed no discernible cytotoxicity toward RPMI 8226. The mechanism of action responsible for the observed cytotoxicity is not known, but the new Ru(Cp)(Quin)⁺ PF₆^- complexes do not cross-link DNA as found for platinum-based drugs. It is concluded that the Ru(Cp)(Quin)⁺ PF₆^- complexes remain intact in the cellular assays and constitute a new class of cytotoxic metal complexes.

Synthesis, characterization and in vitro cytotoxicity of ruthenium(II) metronidazole complexes: Cell cycle arrest at G1/S transition and apoptosis induction in MCF-7 cells

Ruthenium compounds are known to be potential drug candidates since they offer the potential for reduced toxicity. Furthermore, the various oxidation states, different mechanisms of action and ligand substitution kinetics give them advantages over platinum-based complexes, making them suitable for use in biological applications. So, herein, novel ruthenium(II) complexes with metronidazole as ligand were obtained [RuCl(MTNZ)(dppb)(4,4'-Mebipy)]PF₆ (1), [RuCl(MTNZ)(dppb)(4,4'-Methoxybipy)]PF₆ (2), [RuCl(MTNZ)(dppb)(bipy)]PF₆ (3) and [RuCl(MTNZ)(dppb)(phen)]PF₆ (4) where, MTNZ = metronidazole, dppb = 1,4-bis(diphenylphosphino)butane, 4,4'-Mebipy = 4,4'-dimethyl-2,2'-bipyridine, 4,4'-Methoxybipy = 4,4'-dimethoxy-2,2'-bipyridine, bipy = 2,2'-bipyridine and phen = 1,10-phenanthroline. The complexes were characterized by elemental analysis, molar conductivity, infrared and UV-Vis spectroscopy, cyclic voltammetry, ³¹P{¹H}, ¹H, ¹³C{¹H} and Dept 135 NMR and mass spectrometry. The interaction of complexes 1-4 with DNA was evaluated, and their cytotoxicity profiles were determined on four different tumor cell lines derived from human cancers (SK-MEL-147, melanoma; HepG2, hepatocarcinoma; MCF-7, estrogen-positive breast cancer; A549, non-small cell lung cancer). We demonstrated that complexes (1) and (3) are promising antitumor agents once inhibited the proliferative behavior of MCF-7 cells and induced apoptosis.

Ru(II) CONTAINING PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY: A CRITIQUE ON REPORTING AND AN ATTEMPT TO COMPARE EFFICACY

Ruthenium(II)-based coordination complexes have emerged as photosensitizers (PSs) for photodynamic therapy (PDT) in oncology as well as antimicrobial indications and have great potential. Their modular architectures that integrate multiple ligands can be exploited to tune cellular uptake and subcellular targeting, solubility, light absorption, and other photophysical properties. A wide range of Ru(II) containing compounds have been reported as PSs for PDT or as photochemotherapy (PCT) agents. Many studies employ a common scaffold that is subject to systematic variation in one or two ligands to elucidate the impact of these modifications on the photophysical and photobiological performance. Studies that probe the excited state energies and dynamics within these molecules are of fundamental interest and are used to design next-generation systems. However, a comparison of the PDT efficacy between Ru(II) containing PSs and 1st or 2nd generation PSs, already in clinical use or preclinical/clinical studies, is rare. Even comparisons between Ru(II) containing molecular structures are difficult, given the wide range of excitation wavelengths, power densities, and cell lines utilized. Despite this gap, PDT dose metrics quantifying a PS's efficacy are available to perform qualitative comparisons. Such models are independent of excitation wavelength and are based on common outcome parameters, such as the photon density absorbed by the Ru(II) compound to cause 50% cell kill (LD50) based on the previously established threshold model. In this focused photophysical review, we identified all published studies on Ru(II) containing PSs since 2005 that reported the required photophysical, light treatment, and in vitro outcome data to permit the application of the Photodynamic Threshold Model to quantify their potential efficacy. The resulting LD50 values range from less than 1013 to above 1020 [hν cm-3], indicating a wide range in PDT efficacy and required optical energy density for ultimate clinical translation.

Metallo-Drugs in Cancer Therapy: Past, Present and Future

Cancer treatments which include conventional chemotherapy have not proven very successful in curing human malignancies. The failures of these treatment modalities include inherent resistance, systemic toxicity and severe side effects. Out of 50% patients administrated to chemotherapy, only 5% survive. For these reasons, the identification of new drug designs and therapeutic strategies that could target cancer cells while leaving normal cells unaffected still continues to be a challenge. Despite advances that have led to the development of new therapies, treatment options are still limited for many types of cancers. This review provides an overview of platinum, copper and ruthenium metal based anticancer drugs in clinical trials and in vitro/in vivo studies. Presumably, copper and ruthenium complexes have greater potential than Pt(II) complexes, showing reduced toxicity, a new mechanism of action, a different spectrum of activity and the possibility of non-cross-resistance. We focus the discussion towards past, present and future aspects.

Reactions of Ru(III)-drugs KP1019 and KP418 with guanine, 2'-deoxyguanosine and guanosine: a DFT study

Ruthenium (Ru)-based anticancer drugs are considered to be novel alternatives of platinum-based drugs. They exhibit potent cytotoxicity against the cancer cells and hence are useful for the treatment of cancer. Herein, the density functional theory calculations in the gas phase and aqueous media are carried out to study the reactions of two Ru(III)-based drugs such as KP1019 and KP418 with the N7 site of guanine (G), 2'-deoxyguanosine (dGua), and guanosine (Gua) to understand their reactivity against the DNA and RNA. All the reactions are found to be exothermic. The activation free energies and rate constants of these reactions indicate that KP1019 and KP418 would react with the dGua more readily than Gua. Hence, the binding of these drugs with the DNA would be more preferred as compared to RNA. It is further found that among these drugs, KP1019 would be more reactive than KP418 in agreement with the experimental observation. Thus, this study is expected to aid in the future development of potent anticancer drugs.

Polymeric Nanosystems Applied for Metal-Based Drugs and Photosensitizers Delivery: The State of the Art and Recent Advancements

Nanotechnology-based approaches for targeting the delivery and controlled release of metal-based therapeutic agents have revealed significant potential as tools for enhancing the therapeutic effect of metal-based agents and minimizing their systemic toxicities. In this context, a series of polymer-based nanosized systems designed to physically load or covalently conjugate metal-based therapeutic agents have been remarkably improving their bioavailability and anticancer efficacy. Initially, the polymeric nanocarriers were applied for platinum-based chemotherapeutic agents resulting in some nanoformulations currently in clinical tests and even in medical applications. At present, these nanoassemblies have been slowly expanding for nonplatinum-containing metal-based chemotherapeutic agents. Interestingly, for metal-based photosensitizers (PS) applied in photodynamic therapy (PDT), especially for cancer treatment, strategies employing polymeric nanocarriers have been investigated for almost 30 years. In this review, we address the polymeric nanocarrier-assisted metal-based therapeutics agent delivery systems with a specific focus on non-platinum systems; we explore some biological and physicochemical aspects of the polymer–metallodrug assembly. Finally, we summarize some recent advances in polymeric nanosystems coupled with metal-based compounds that present potential for successful clinical applications as chemotherapeutic or photosensitizing agents. We hope this review can provide a fertile ground for the innovative design of polymeric nanosystems for targeting the delivery and controlled release of metal-containing therapeutic agents.

Design and Anticancer Properties of New Water-Soluble Ruthenium–Cyclopentadienyl Complexes

Ruthenium complexes are emerging as one of the most promising classes of complexes for cancer therapy. However, their limited aqueous solubility may be the major limitation to their potential clinical application. In view and to contribute to the progress of this field, eight new water-soluble Ru(II) organometallic complexes of general formula [RuCp(mTPPMS)_n(L)] [CF₃SO₃], where mTPPMS = diphenylphosphane-benzene-3-sulfonate, for n = 2, L is an imidazole-based ligand (imidazole, 1-benzylimidazole, 1-butylimidazole, (1-(3-aminopropyl)imidazole), and (1-(4-methoxyphenyl)imidazole)), and for n = 1, L is a bidentate heteroaromatic ligand (2-benzoylpyridine, (di(2-pyridyl)ketone), and (1,2-(2-pyridyl)benzo-[b]thiophene)) were synthesized and characterized. The new complexes were fully characterized by NMR, FT-IR, UV–vis., ESI-HRMS, and cyclic voltammetry, which confirmed all the proposed molecular structures. The antiproliferative potential of the new Ru(II) complexes was evaluated on MDAMB231 breast adenocarcinoma, A2780 ovarian carcinoma, and HT29 colorectal adenocarcinoma cell lines, showing micromolar (MDAMB231 and HT29) and submicromolar (A2780) IC₅₀ values. The interaction of complex 6 with human serum albumin (HSA) and fatty-acid-free human serum albumin (HSA^faf) was evaluated by fluorescence spectroscopy techniques, and the results revealed that the ruthenium complex strongly quenches the intrinsic fluorescence of albumin in both cases.

CORM-3 induces DNA damage through Ru(II) binding to DNA

When the ‘CO-releasing molecule-3’, CORM-3 (Ru(CO)₃Cl(glycinate)), is dissolved in water it forms a range of ruthenium complexes. These are taken up by cells and bind to intracellular ligands, notably thiols such as cysteine and glutathione, where the Ru(II) reaches high intracellular concentrations. Here, we show that the Ru(II) ion also binds to DNA, at exposed guanosine N7 positions. It therefore has a similar cellular target to the anticancer drug cisplatin, but not identical, because Ru(II) shows no evidence of forming intramolecular crossbridges in the DNA. The reaction is slow, and with excess Ru, intermolecular DNA crossbridges are formed. The addition of CORM-3 to human colorectal cancer cells leads to strand breaks in the DNA, as assessed by the alkaline comet assay. DNA damage is inhibited by growth media containing amino acids, which bind to extracellular Ru and prevent its entry into cells. We conclude that the cytotoxicity of Ru(II) is different from that of platinum, making it a promising development target for cancer therapeutics.

Bonding in Nitrile Photo-dissociating Ruthenium Drug Candidates --A Local Vibrational Mode Study

In this work, we investigated bonding features 15 ruthenium complexes of the type [Ru(tpy)(L)-(CH3CN)]n+, containing the tridentate tpy ligand (tpy = 2,2':6',2'--terpyridine) and various bidentate ancillary ligands, 12 compounds originally synthesized by Loftus et al. (J. Phys. Chem. C 123, 10291-10299 (2019)) complemented with three additional complexes. The main focus of our work was to relate these local features to the experimental data of Loftus et al. which assess the efficiency of nitrile release in an indirect way via observed quantum yields for ruthenium water association after nitrile release. As a tool to quantitatively assess Ru-NC and Ru-L bonding we utilized the local vibrational mode analysis complemented by the topological analysis of the electron density and the natural bond orbital analysis. Interestingly, the stronger Ru-NC bonds have the greater observed quantum yields, leading to the conclusion that the observed quantum yields are a result of a complex interplay of several processes excluding a direct relationship between QY and Ru-NC or Ru-L bond strengths. We identified the ST splitting as one of the key players and not the Ru-NC bond strength, as one may have thought. In summary, this work has presented a modern computational tool set for the investigation of bonding features applied to nitrile photo-dissociating ruthenium drug candidates forming a valuable basis for future design and fine tuning of nitrile releasing ruthenium compounds, as well as for the understanding of how local properties affect overall experimental outcomes.

Bioactivity and Development of Small Non-Platinum Metal-Based Chemotherapeutics

Countless expectations converge in the multidisciplinary endeavour for the search and development of effective and safe drugs in fighting cancer. Although they still embody a minority of the pharmacological agents currently in clinical use, metal-based complexes have great yet unexplored potential, which probably hides forthcoming anticancer drugs. Following the historical success of cisplatin and congeners, but also taking advantage of conventional chemotherapy limitations that emerged with applications in the clinic, the design and development of non-platinum metal-based chemotherapeutics, either as drugs or prodrugs, represents a rapidly evolving field wherein candidate compounds can be fine-tuned to access interactions with druggable biological targets. Moving in this direction, over the last few decades platinum family metals, e.g., ruthenium and palladium, have been largely proposed. Indeed, transition metals and molecular platforms where they originate are endowed with unique chemical and biological features based on, but not limited to, redox activity and coordination geometries, as well as ligand selection (including their inherent reactivity and bioactivity). Herein, current applications and progress in metal-based chemoth are reviewed. Converging on the recent literature, new attractive chemotherapeutics based on transition metals other than platinum—and their bioactivity and mechanisms of action—are examined and discussed. A special focus is committed to anticancer agents based on ruthenium, palladium, rhodium, and iridium, but also to gold derivatives, for which more experimental data are nowadays available. Next to platinum-based agents, ruthenium-based candidate drugs were the first to reach the stage of clinical evaluation in humans, opening new scenarios for the development of alternative chemotherapeutic options to treat cancer.

Metallodrugs in cancer nanomedicine

Metal complexes are extensively used for cancer therapy. The multiple variables available for tuning (metal, ligand, and metal-ligand interaction) offer unique opportunities for drug design, and have led to a vast portfolio of metallodrugs that can display a higher diversity of functions and mechanisms of action with respect to pure organic structures. Clinically approved metallodrugs, such as cisplatin, carboplatin and oxaliplatin, are used to treat many types of cancer and play prominent roles in combination regimens, including with immunotherapy. However, metallodrugs generally suffer from poor pharmacokinetics, low levels of target site accumulation, metal-mediated off-target reactivity and development of drug resistance, which can all limit their efficacy and clinical translation. Nanomedicine has arisen as a powerful tool to help overcome these shortcomings. Several nanoformulations have already significantly improved the efficacy and reduced the toxicity of (chemo-)therapeutic drugs, including some promising metallodrug-containing nanomedicines currently in clinical trials. In this critical review, we analyse the opportunities and clinical challenges of metallodrugs, and we assess the advantages and limitations of metallodrug delivery, both from a nanocarrier and from a metal-nano interaction perspective. We describe the latest and most relevant nanomedicine formulations developed for metal complexes, and we discuss how the rational combination of coordination chemistry with nanomedicine technology can assist in promoting the clinical translation of metallodrugs.

Ruthenium(ii)-arene complexes as anti-metastatic agents, and related techniques

With the discovery of cisplatin, a vast area of applications of metallodrugs in cancer treatment was opened but due to the side effects caused by the cisplatin complexes, researchers began to look for alternatives with similar anticancer properties but fewer side effects. Ruthenium was found to be a promising candidate, considering its significant anticancer properties and low side effects. Several ruthenium complexes, viz. NAMI-A, KP1019, KP1339, and TLD1433, have entered clinical trials. Some other arene ruthenium complexes such as RM175 and RAPTA-C have also entered clinical trials but very few of them have shown anti-metastatic properties. Herein, we provide information and probable mechanistic pathways for ruthenium(ii)-arene complexes that have been studied, so far, for their anti-metastatic activities. Also, we discuss the techniques and their significance for determining the anti-metastatic effects of the complexes.

Detailed structural and spectroscopic elucidation of ferrocenium coupled N-heterocyclic carbene gold(I) complexes

Unambiguous assignment of redox sites on ferrocene coupled N-heterocyclic carbene gold(I) complexes [(Fc-NHC)2Au(I)]+ is critical to gain a greater mechanistic understanding of their activity in a cellular environment. Such information can be garnered with isolation and detailed characterization of the oxidized version of [(Fc-NHC)2Au(I)]+. Herein we disclose a study that unambiguously illustrates redox events pertaining to [(Fc-NHC)2Au(I)]+ that stem exclusively from ferrocene sites. This work also describes novel synthetic methodologies for isolating ferrocenium coupled N-heterocyclic carbene gold(I) complexes.

Syntheses, Structural and Serum Protein Protecting Activity of Ruthenium(II)-DMSO Complexes Containing Mercapto Ligand

Four new ruthenium(II) complexes [Ru(mpt)2(DMSO)2] (1), [Ru(mpt)2(bpy)] (2), [Ru(mpt)2(phen)] (3) and [Ru(mpt)2(tptz)] (4) have been synthesized and characterized by elemental analyses, IR, 1H and 13C NMR, and electronic absorption spectroscopy....

In vitro studies on the selective cytotoxic effect of luminescent Ru(ii)-p-cymene complexes of imidazo-pyridine and imidazo quinoline ligands

In recent years, Ru(ii) complexes have gained high importance in medicinal chemistry due to their significant anti-cancer activities, which are directly related to their DNA binding ability.