CZE-ICP-MS as a tool for studying the hydrolysis of ruthenium anticancer drug candidates and their reactivity towards the DNA model compound dGMP

Dichloro Ru(II)-p-cymene-1,3,5-triaza-7-phosphaadamantane (RAPTA-C): A Case Study

The use of organometallic compounds to treat various phenotypes of cancer has attracted increased interest in recent decades. Organometallic compounds, which are transitional between conventional inorganic and organic materials, have outstanding and one-of-a-kind features that offer fresh insight into the development of inorganic medicinal chemistry. The therapeutic potential of ruthenium(II)-arene RAPTA-type compounds is being thoroughly investigated, specifically owing to the excellent antimetastatic property of the initial candidate RAPTA-C. This review gives a thorough analysis of this complex and its evolution as a potential anticancer drug candidate. The numerous mechanistic investigations of RAPTA-C are discussed, and they are connected to the macroscopic biological characteristics that have been found. The "multitargeted" complex described here target enzymes, peptides, and intracellular proteins in addition to DNA that allow it to specifically target cancer cells. Understanding these may allow researchers to find specific targets and tune a new-generation organometallic complex accordingly.

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.

In-vitro anticancer profile of recent ruthenium complexes against liver cancer

Ruthenium complexes are considered as the most favorable alternatives to traditional platinum-based cancer drugs owing to their acceptable toxicity level, selectivity, variant oxidation states and ability to treat platinum-resistant cancer cells. They have similar ligand exchange kinetics as platinum drugs but can be tailored according to our desire by ligands influence. In the current study, we illustrate the in-vitro anticancer profile of some ruthenium complexes (2016–2021) against human hepatocellular carcinoma (HepG2). The anticancer activity of ruthenium complexes is determined by comparing their IC50 values with one another and positive controls. Fortunately, some ruthenium complexes including 3, 4, 6, 14, 15, 20, 42, and 48 exhibit surpassed in-vitro anticancer profile than that of positive controls promising as potential candidates against liver cancer. We also explored the structure-activity relationship (SAR) which is a key factor in the rational designing and synthesis of new ruthenium drugs. It covers the factors affecting anticancer activity including lipophilicity, planarity, area and bulkiness, the steric influence of different ligands, and electronic effects induced by ligands, stability, aqueous solubility and bioavailability to the target sites. The data reported here will provide strong support in the plausible design and synthesis of ruthenium anticancer drugs in the upcoming days.

Ruthenium(iii) complexes containing thiazole-based ligands that modulate amyloid-β aggregation

Alzheimer's Disease (AD) is a devastating neurodegenerative disorder where one of the commonly observed pathological hallmarks is extracellular deposits of the peptide amyloid-β (Aβ). These deposits contain a high concentration of metals and initially presented a promising target for therapy; however it has become increasingly evident that the soluble form of the peptide is neurotoxic, not the amyloidogenic species. Metal-based therapeutics are uniquely suited to target soluble Aβ and have shown considerable promise to prevent the aggregation and induced cytotoxicity of the peptide in vitro. Herein, we have prepared a small series of derivatives of two promising Ru(iii) complexes NAMI-A (imidazolium [trans-RuCl₄(1H-imidazole)(dimethyl sulfoxide-S)]) and PMRU20 (2-aminothiazolium [trans-RuCl₄(2-aminothiazole)₂]), to determine structure-activity relationships (SAR) for Ru(iii) therapeutics for AD. Using the three complementary methods of Thioflavin T fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM), it was determined that the symmetry around the metal center did not significantly impact the activity of the complexes, but rather the attached thiazole ligand(s) mitigated Aβ aggregation. Across both families of Ru(iii) complexes the determined SAR for the functional groups on the thiazole ligands to modulate Aβ aggregation were NH₂ > CH₃ > H. These results highlight the importance of secondary interactions between the metallotherapeutic and the Aβ peptide where hydrogen-bonding has the greatest impact on modulating Aβ aggregation.

Capillary electrophoresis-based approaches for the study of affinity interactions combined with various sensitive and nontraditional detection techniques

Nearly all processes in living organisms are controlled and regulated by the synergy of many biomolecule interactions involving proteins, peptides, nucleic acids, nucleotides, saccharides, and small molecular weight ligands. There is growing interest in understanding them, not only for the purposes of interactomics as an essential part of system biology, but also in their further elucidation in disease pathology, diagnostics, and treatment. The necessity of detailed investigation of these interactions leads to the requirement of laboratory methods characterized by high efficiency and sensitivity. As a result, many instrumental approaches differing in their fundamental principles have been developed, including those based on capillary electrophoresis. Although capillary electrophoresis offers numerous advantages for such studies, it still has one serious limitation, its poor concentration sensitivity with the most commonly used detection method-ultraviolet-visible spectrometry. However, coupling capillary electrophoresis with a more sensitive detector fulfils the above-mentioned requirement. In this review, capillary electrophoresis combined with fluorescence, mass spectrometry, and several nontraditional detection techniques in affinity interaction studies are summarized and discussed, together with the possibility of conducting these measurements in microchip format.

Albumin-Stabilized Metal-Organic Nanoparticles for Effective Delivery of Metal Complex Anticancer Drugs

Many metal-organic complexes showed potent anticancer efficacy, but their clinical applications were limited by the lack of administration route because of their poor solubility. To make metal-organic nanoparticles (MONPs) comprising metal complex drugs is a new formulation strategy for their administration. Herein, we developed a facile synthesis of an MONP composed of bovine serum albumin (BSA), Cu²⁺, and an anticancer agent, 5-nitro-8-hydroxyquinoline (NQ) with albumin as a nanoreactor. The resultant BSA/Cu/NQ nanoparticle (BSA/Cu/NQ NP) showed good stability in different physiological buffers and could target tumors through the enhanced permeability and retention effect and receptor-mediated cellular uptake. As the BSA/Cu/NQ NP could be readily and efficiently internalized by cancer cells, it showed much higher cytotoxic cancer cells than the NQ + Cu(II) complex and NQ. Therefore, the treatment with BSA/Cu/NQ NP noticeably enhanced the anticancer efficacy without causing systemic toxicity, indicating that such a facile preparation method has great potential to prepare other metal complex nanoparticles for drug delivery.

Hyphenation of capillary electrophoresis to inductively coupled plasma mass spectrometry with a modified coaxial sheath-flow interface

Capillary electrophoretic analyses benefit significantly from hyphenation to mass spectrometric techniques. While the coupling to ESI-MS is routinely performed, for example by using a coaxial sheath-flow interface, hyphenating it to inductively coupled plasma mass spectrometry is more technically challenging. We use a commercially available coaxial sheath-flow interface (CSFI) and a simple PTFE-based end-cap for easy, inexpensive CE-ICP-MS hyphenation with improved sensitivity and analytical performance compared to commercially available interfaces. We have optimized key nebulizer parameters such as capillary position, sheath liquid flow rate, and carrier gas flow rate, and compared the CSFI with a commercially available interface. In a set of proof-of-principle experiments employing the anticancer agent cisplatin it was demonstrated that the signal to noise response and sensitivity were considerably improved leading to detection limits for ¹⁹⁵Pt of 0.08 μM.

Metallomic study on the metabolism of RAPTA-C and cisplatin in cell culture medium and its impact on cell accumulation

The different extracellular speciation of cisplatin and the organoruthenium developmental anticancer agent RAPTA-C impacts the accumulation in cancer cells.

Ruthenium complex exerts antineoplastic effects that are mediated by oxidative stress without inducing toxicity in Walker-256 tumor-bearing rats

The present study evaluated the in vivo antitumor effects and toxicity of a new Ru(II) compound, cis-(Ru[phen]₂[ImH]₂)²⁺ (also called RuphenImH [RuC]), against Walker-256 carcinosarcoma in rats. After subcutaneous inoculation of Walker-256 cells in the right pelvic limb, male Wistar rats received 5 or 10mgkg^-1 RuC orally or intraperitoneally (i.p.) every 3 days for 13 days. A positive control group (2mgkg^-1 cisplatin) and negative control group (vehicle) were also used. Tumor progression was checked daily. After treatment, tumor weight, plasma biochemistry, hematology, oxidative stress, histology, and tumor cell respiration were evaluated. RuC was effective against tumors when administered i.p. but not orally. The highest i.p. dose of RuC (10mgkg^-1) significantly reduced tumor volume and weight, induced oxidative stress in tumor tissue, reduced the respiration of tumor cells, and induced necrosis but did not induce apoptosis in the tumor. No clinical signs of toxicity or death were observed in tumor-bearing or healthy rats that were treated with RuC. These results suggest that RuC has antitumor activity through the modulation of oxidative stress and impairment of oxidative phosphorylation, thus promoting Walker-256 cell death without causing systemic toxicity. These effects make RuC a promising anticancer drug for clinical evaluation.

New Class of Half-Sandwich Ruthenium(II) Arene Complexes Bearing the Water-Soluble CAP Ligand as an in Vitro Anticancer Agent

Ruthenium(II) arene complexes of 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP) were obtained. Cytotoxicity studies against cancer cell lines reveal higher activity than the corresponding PTA analogues and, in comparison to the effects on noncancerous cells, the complexes are endowed with a reasonable degree of cancer cell selectivity.

Lipophilicity-antiproliferative activity relationship study leads to the preparation of a ruthenium(II) arene complex with considerable in vitro cytotoxicity against cancer cells and a lower in vivo toxicity in zebrafish embryos than clinically approved cis-platin

Ru(II)-arene complexes are attracting increasing attention due to their considerable antitumoral activity. However, it is difficult to clearly establish a direct relationship between their structure and antiproliferative activity, as substantial structural changes might not only affect their anticancer activity but also tightly control their activation site(s) and/or their biological target(s). Herein, we describe the synthesis and characterization of four ruthenium(II) arene complexes bearing bidentate N,O-donor Schiff-base ligands ([Ru(η⁶-benzene)(N-O)Cl]) that display a significantly distinct antiproliferative activity against cancer cells, despite their close structural similarity. Furthermore, we suggest there is a link between their respective antiproliferative activity and their lipophilicity, as the latter affects their ability to accumulate into cancer cells. This lipophilicity-cytotoxicity relationship was exploited to design another structurally related ruthenium complex with a much higher antiproliferative activity (IC₅₀ > 25.0 μM) against three different human cancer cell lines. Whereas this complex shows a slightly lower activity than that of clinically approved cis-platin against the same human cancer cell lines, it displays a lower toxicity in zebrafish (Danio rerio) embryos at concentrations up to 20 μM.

Ruthenium(II) piano stool coordination compounds with aminomethylphosphanes: Synthesis, characterisation and preliminary biological study in vitro

Reaction of {[Ru(η⁶-p-cymene)Cl]₂(μ-Cl)₂} (1) with aminomethylphosphane derived from morpholine (P{CH₂N(CH₂CH₂)₂O}₃ (A), PPh₂{CH₂N(CH₂CH₂)₂O} (B)) or piperazine (P{CH₂N(CH₂CH₂)₂NCH₂CH₃}₃ (C), PPh₂{CH₂N(CH₂CH₂)₂NCH₂CH₃} (D)) results in four new piano stool ruthenium(II) coordination compounds: [Ru(η⁶-p-cymene)Cl₂(A)] (2A), [Ru(η⁶-p-cymene)Cl₂(B)] (2B), [Ru(η⁶-p-cymene)Cl₂(C)] (2C) and [Ru(η⁶-p-cymene)Cl₂(D)] (2D). Every complex was fully characterized using spectroscopic methods (¹H, ¹³C{¹H}, ³¹P{¹H} NMR and ESI-MS), elemental analysis, X-ray single crystal diffraction and DFT calculations. Preliminary studies of in vitro cytotoxicity on the A549 (human lung adenocarcinoma) and MCF7 (human breast adenocarcinoma) cell lines revealed 2A-2D activity in the same order of magnitude as in the case of cisplatin. Additionally, the study confirmed the ability of 2A-2D to interact with DNA helix and transferrin.

Combination of ICP-MS, capillary electrophoresis, and their hyphenation for probing Ru(III) metallodrug-DNA interactions

Determination of the DNA-binding reactivity and affinity is an important part of a successful program for the selection of metallodrug candidates. For such assaying, a range of complementary analytical techniques was proposed and tested here using one of few anticancer metal-based drugs that are currently in clinical trials, indazolium trans-[tetrachloridobis(1H-indazole)ruthenate(III), and a DNA oligonucleotide. A high reactivity of the Ru drug was confirmed in affinity capillary electrophoresis (CE) mode, where adduct formation takes place in situ (i.e., in the capillary filled with an oligonucleotide-containing electrolyte). To further characterize the binding kinetics, a drug–oligonucleotide mixture was incubated for a different period of time, followed by ultrafiltration separation into two different in molecular weight fractions (>3 and <3 kDa). The time-dependent distribution profiles of the Ru drug were then assessed by CE-inductively coupled plasma mass spectrometry (ICP-MS), revealing that at least two DNA adducts exist at equilibrium conditions. Using standalone ICP-MS, dominant equilibrium amount of the bound ruthenium was found to occur in a fraction of 5–10 kDa, which includes the oligonucleotide (ca. 6 kDa). Importantly, in all three assays, the drug was used for the first time in in-vitro studies, not in the intact form but as its active species released from the transferrin adduct at simulated cancer cytosolic conditions. This circumstance makes the established analytical platform promising to provide a detailed view on metallodrug targeting, including other possible biomolecules and ex vivo samples.

Hydrolytic behaviour of mono- and dithiolato-bridged dinuclear arene ruthenium complexes and their interactions with biological ligands

Compared to the inert and highly cytotoxic dinuclear p-cymene ruthenium trithiolato complexes, the less cytotoxic mono- and dithiolato complexes readily hydrolyse in aqueous solution and form adducts with cysteine, but do not interact with DNA.

Development of ruthenium-based complexes as anticancer agents: toward a rational design of alternative receptor targets

In the search for novel anticancer agents, the development of metal-based complexes that could serve as alternatives to cisplatin and its derivatives has received considerable attention in recent years. This becomes necessary because, at present, cisplatin and its derivatives are the only coordination complexes being used as anticancer agents in spite of inherent serious side effects and their limitation against metastasized platinum-resistant cancer cells. Although many metal ions have been considered as possible alternatives to cisplatin, the most promising are ruthenium (Ru) complexes and two Ru compounds, KP1019 and NAMI-A, which are currently in phase II clinical trials. The major obstacle against the rational design of these compounds is the fact that their mode of action in relation to their therapeutic activities and selectivity is not fully understood. There is an urgent need to develop novel metal-based anticancer agents, especially Ru-based compounds, with known mechanism of actions, probable targets, and pharmacodynamic activity. In this paper, we review the current efforts in developing metal-based anticancer agents based on promising Ru complexes and the development of compounds targeting receptors and then examine the future prospects.

Capillary electrophoresis in metallodrug development

Capillary electrophoresis (CE) is a separation method based on differential migration of analytes in electric fields. The compatibility with purely aqueous separation media makes it a versatile tool in metallodrug research. Many metallodrugs undergo ligand exchange reactions that can easily be followed with this method and the information gained can even be improved by coupling the CE to advanced detectors, such as mass spectrometers. This gives the method high potential to facilitate the development of metallodrugs, especially when combined with innovative method development and experimental design.

Polymeric Micelle-Mediated Delivery of DNA-Targeting Organometallic Complexes for Resistant Ovarian Cancer Treatment

Three half-sandwich iridium and ruthenium organometallic complexes with high cytotoxicity are synthesized, and their anticancer mechanisms are elucidated. The organometallic complexes can interact with DNA through coordination or intercalation, thereby inducing apoptosis and inhibiting proliferation of resistant cancer cells. The organometallic complexes are then incorporated into polymeric micelles through the polymer-metal coordination between poly(ethylene glycol)-b-poly(glutamic acid) [PEG-b-P(Glu)] and organometallic complexes to further enhance their anticancer effects as a result of the enhanced permeability and retention effect. The micelles with particle sizes of ≈60 nm are more efficiently internalized by cancer cells than the corresponding complexes, and selectively dissociate and release organometallic anticancer agents within late endosomes and lysosomes, thereby enhancing drug delivery to the nuclei of cancer cells and facilitating their interactions with DNA. Thus, the micelles display higher antitumor activity than the organometallic complexes alone with a lack of the systemic toxicity in a mouse xenograft model of cisplatin-resistant human ovarian cancer. These results suggest that the polymeric micelles carrying anticancer organometallic complexes provide a promising platform for the treatment of resistant ovarian cancer and other hard-to-treat solid tumors.

Albumin binding and ligand-exchange processes of the Ru(III) anticancer agent NAMI-A and its bis-DMSO analogue determined by ENDOR spectroscopy

The ruthenium anticancer compound NAMI-A, imidazolium [trans-RuCl4(1H-imidazole)(DMSO-S)], is currently undergoing advanced clinical evaluation. As with other Ru(iii) chemotherapeutic candidates, interactions with human serum albumin (HSA) have been identified as a key component of the speciation of NAMI-A following intravenous administration. To characterize coordination to HSA, we have performed electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopic analysis of deuterium-labelled isotopologues of both NAMI-A and its bis-DMSO analogue, [(DMSO)2H][trans-RuCl4(DMSO-S)2] (Ru-bis-DMSO). Samples were prepared using phosphate buffered saline, in the presence of HSA, and with the individual amino acids histidine, cysteine, and alanine. Analysis of (1)H ENDOR spectra shows characteristic hyperfine interactions from DMSO, water, and imidazole ligands. Furthermore, coordination of imidazole ligands was confirmed from diagnostic (14)N ENDOR signals. Combined with the EPR data from the complexes following incubation in the presence of histidine, the ENDOR data demonstrate that both complexes bind to HSA via histidine imidazoles. Furthermore, the protein-bound species are shown to have water ligands and, in the case of Ru-bis-DMSO, one species has a remaining coordinated DMSO.

Target profiling of an antimetastatic RAPTA agent by chemical proteomics: relevance to the mode of action

The RAPTA pharmacophore was linked to beads to identify its biomolecular targets in cancer cells.

The clinical development of anticancer metallodrugs is often hindered by the elusive nature of their molecular targets. To identify the molecular targets of an antimetastatic ruthenium organometallic complex based on 1,3,5-triaza-7-phosphaadamantane (RAPTA), we employed a chemical proteomic approach. The approach combines the design of an affinity probe featuring the pharmacophore with mass-spectrometry-based analysis of interacting proteins found in cancer cell lysates. The comparison of data sets obtained for cell lysates from cancer cells before and after treatment with a competitive binder suggests that RAPTA interacts with a number of cancer-related proteins, which may be responsible for the antiangiogenic and antimetastatic activity of RAPTA complexes. Notably, the proteins identified include the cytokines midkine, pleiotrophin and fibroblast growth factor-binding protein 3. We also detected guanine nucleotide-binding protein-like 3 and FAM32A, which is in line with the hypothesis that the antiproliferative activity of RAPTA compounds is due to induction of a G₂/M arrest and histone proteins identified earlier as potential targets.

An investigation on new ruthenium(II) hydrazone complexes as anticancer agents and their interaction with biomolecules

A new set of ruthenium(II) hydrazone complexes [Ru(H)(CO)(PPh3)2(L)] (1) and [RuCl2(DMSO)2(HL)] (2), with triphenyl phosphine or DMSO as co-ligands was synthesized by reacting benzoyl pyridine furoic acid hydrazone (HL) with [Ru(H)(Cl)(CO)(PPh3)3] and [RuCl2(DMSO)4]. The single crystal X-ray data of complexes 1 and 2 revealed an octahedral geometry around the ruthenium ion in which the hydrazone is coordinated through ON and NN atoms in complexes 1 and 2 respectively. The interaction of the compounds with calf thymus DNA (CT-DNA) has been estimated by absorption and emission titration methods which indicated that the ligand and the complexes interacted with CT-DNA through intercalation. In addition, the DNA cleavage ability of these newly synthesized ruthenium complexes assessed by an agarose gel electrophoresis method demonstrated that complex 2 has a higher DNA cleavage activity than that of complex 1. The binding properties of the free ligand and its complexes with bovine serum albumin (BSA) protein have been investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods which indicated the stronger binding nature of the ruthenium complexes to BSA than the free hydrazone ligand. Furthermore, the cytotoxicity of the compounds examined in vitro on a human cervical cancer cell line (HeLa) and a normal mouse embryonic fibroblasts cell line (NIH 3T3) revealed that complex 2 exhibited a superior cytotoxicity than complex 1 to the cancer cells but was less toxic to the normal mouse embryonic fibroblasts under identical conditions.

Luminescent ruthenium complexes for theranostic applications

The water-soluble and visible luminescent complexes cis-[Ru(L-L)2(L)2](2+) where L-L = 2,2-bipyridine and 1,10-phenanthroline and L= imidazole, 1-methylimidazole, and histamine have been synthesized and characterized by spectroscopic techniques. Spectroscopic (circular dichroism, saturation transfer difference NMR, and diffusion ordered spectroscopy NMR) and isothermal titration calorimetry studies indicate binding of cis-[Ru(phen)2(ImH)2](2+) and human serum albumin occurs via noncovalent interactions with K(b) = 9.8 × 10(4) mol(-1) L, ΔH = -11.5 ± 0.1 kcal mol(-1), and TΔS = -4.46 ± 0.3 kcal mol(-1). High uptake of the complex into HCT116 cells was detected by luminescent confocal microscopy. Cytotoxicity of cis-[Ru(phen)2(ImH)2](2+) against proliferation of HCT116p53(+/+) and HCT116p53(-/-) shows IC50 values of 0.1 and 0.7 μmol L(-1). Flow cytometry and western blot indicate RuphenImH mediates cell cycle arrest in the G1 phase in both cells and is more prominent in p53(+/+). The complex activates proapoptotic PARP in p53(-/-), but not in p53(+/+). A cytostatic mechanism based on quantification of the number of cells during the time period of incubation is suggested.

Novel ruthenium complexes ligated with 4-anilinoquinazoline derivatives: synthesis, characterisation and preliminary evaluation of biological activity

The ruthenium DMSO complexes cis-Ru(II)C12(DMSO)4 and [(DMSO)2H][trans-Ru(III)Cl4(DMSO)2] reacted with 4-(3'-chloro-4'-fluoroanilino)-6-(2-(2-aminoethyl)aminoethoxy)-7-methoxyquinazoline (L1), 4-(3'-chloro-4'-fluoroanilino)-6-(2-(1H-imidazol-1-yl)ethoxy)-7-methoxy quinazoline (L2), N-(benzo[d]imidazol-4-yl)-6,7-dimethoxyquinazolin-4-amine hydrochloride (L3), 5-(6,7-dimethoxyquinazolin-4-ylamino)quinolin-8-ol hydrochloride (L4), respectively, to afford [Ru(II)Cl2(DMSO)2(L1)] (1), [Ru(III)Cl3(DMSO)(L1)] (2), [Ru(III)Cl4(DMSO)(H-L2)] (3), [Ru(III)Cl4(DMSO)(H-L3)] (4), and [Ru(III)Cl3(DMSO)(H-L4)] (5), which were characterised by mass spectrometry, NMR, elementary analysis and single crystal X-ray diffraction (complex 1). Experimental screening (ELISA) showed that complexes 1, 2 and 3 are remarkably inhibitory towards epidermal growth factor receptor (EGFR) with IC50 values at submicromolar or nanomolar level. Docking studies indicated that complexation with ruthenium has little interference with the formation of the two essential H-bonds between the N3 of the quinazoline ring in L1 and L2 and O-H of Thr766 through a water molecule, and the N1 of the quinazoline ring and N-H of Met769 in EGFR. Moreover, complex 2 was shown to be more active against the EGF-stimulated proliferation of human breast cancer cell line MCF-7 than the better EGFR inhibitor 4-(3'-chloro-4'-fluoroanilino)-6,7-dimethoxyquinazoline, being more potential to induce early-stage apoptosis than gefitinib. These imply that apart from inhibiting EGFR, complex 2 may involve in regulating other biological events related to the proliferation of MCF-7, implicating a novel type of multi-targeting metal-based anticancer agents.

Interactions of the aquated forms of ruthenium(iii) anticancer drugs with protein: a detailed molecular docking and QM/MM investigation

The interaction of monoaqua and diaqua ruthenium complexes which are formed after intracellular aquation of their respective complexes with human serum albumin (HSA) has been computationally investigated by molecular docking and two layer QM/MM hybrid methods.

Anticancer metallodrugs of glutamic acid sulphonamides: in silico, DNA binding, hemolysis and anticancer studies

In response to an increased demand for effective anticancer drugs, a series of disodium sulphonamides ofl-glutamic acid (L1–L3) was synthesized. Sulphonamides were complexed with copper(ii), nickel(ii) and ruthenium(iii) ions, separately and respectively.

Synthesis, DNA binding, hemolysis assays and anticancer studies of copper(II), nickel(II) and iron(III) complexes of a pyrazoline-based ligand

Background: Over the last few decades, metal-based drugs, particularly cisplatin and its analogs have been used for the treatment of various cancers. Currently, scientists are developing other metal complexes as anticancer agents to eliminate the toxicity associated with platinum drugs. Results: Claisen-Schmidt condensation was used to synthesize the pyrazoline-based ligand; (5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide), followed by the synthesis of its complexes with copper(II), nickel(II) and iron(III) metal ions. DNA binding and in silico studies indicated quite good binding with DNA; requirements for good anticancer drugs. Conclusion: DNA binding constants for ligand, copper, nickel and iron complexes were 1.42 × 104, 3.16 × 104, 5.82 × 105 and 6.72 × 105 M-1, respectively, indicating strong binding with DNA. All the reported compounds were slightly hemolytic towards rabbit red blood corpuscles and exhibited moderate activities against MCF-7 cancer cell lines.

X-ray absorption near edge structure spectroscopy to resolve the in vivo chemistry of the redox-active indazolium trans-[Tetrachlorobis(1H-indazole)ruthenate(III)] (KP1019)

Indazolium trans-[tetrachlorobis(1H-indazole)ruthenate(III)] (1, KP1019) and its analogue sodium trans-[tetrachlorobis(1H-indazole)ruthenate(III)] (2, KP1339) are promising redox-active anticancer drug candidates that were investigated with X-ray absorption near edge structure spectroscopy. The analysis was based on the concept of the coordination charge and ruthenium model compounds representing possible coordinations and oxidation states in vivo. 1 was investigated in citrate saline buffer (pH 3.5) and in carbonate buffer (pH 7.4) at 37 °C for different time intervals. Interaction studies on 1 with glutathione in saline buffer and apo-transferrin in carbonate buffer were undertaken, and the coordination of 1 and 2 in tumor tissues was studied too. The most likely coordinations and oxidation states of the compound under the above mentioned conditions were assigned. Microprobe X-ray fluorescence of tumor thin sections showed the strong penetration of ruthenium into the tumor tissue, with the highest concentrations near blood vessels and in the edge regions of the tissue samples.

Inductively coupled plasma-MS in drug development: bioanalytical aspects and applications

The vast majority of today's modern bioanalytical methods for pharmacokinetic, pharmacodynamic and immunogenicity purposes are based on LC-MS/MS and immunoanalytical approaches. Indeed, these methodologies are suitable for a wide range of molecules from small to large. For a smaller but not insignificant group of compounds, LC-MS/MS is not suitable - or in some cases much less suitable - as a reliable bioanalytical methodology, and inductively coupled plasma (ICP)-MS is a more appropriate methodology. ICP-MS is one of these less widely used techniques in drug development. This methodology is predominantly used for elemental bioanalysis for pharmacokinetics, for imaging purposes, for mass-balance, food-effect and biomarker studies. In addition, in the last couple of years an increasing number of applications has been published, where ICP-MS and its various hyphenations (LC-ICP-MS, CE-ICP-MS) have been used for speciation/metabolism and proteomics studies. Here, the analytical potential, the quantitative bioanalytical aspects, the various modes of operation and the challenges of the application of ICP-MS in life sciences applications are given. This includes an overview of recent applications in this area in scientific literature, the various hyphenation possibilities and their application areas and the analysis of the various sample matrices applicable to these fields. It also provides a brief outlook of where the potential of this technique lies in the future of regulated bioanalysis and drug development.

Structure-activity relationships of targeted RuII(η6-p-cymene) anticancer complexes with flavonol-derived ligands

RuII(arene) complexes have been shown to be promising anticancer agents, capable of overcoming major drawbacks of currently used chemotherapeutics. We have synthesized RuII(η6-arene) compounds carrying bioactive flavonol ligands with the aim to obtain multitargeted anticancer agents. To validate this concept, studies on the mode of action of the complexes were conducted which indicated that they form covalent bonds to DNA, have only minor impact on the cell cycle, but inhibit CDK2 and topoisomerase IIα in vitro. The cytotoxic activity was determined in human cancer cell lines, resulting in very low IC50 values as compared to other RuII(arene) complexes and showing a structure-activity relationship dependent on the substitution pattern of the flavonol ligand. Furthermore, the inhibition of cell growth correlates well with the topoisomerase inhibitory activity. Compared to the flavonol ligands, the RuII(η6-p-cymene) complexes are more potent antiproliferative agents, which can be explained by potential multitargeted properties.

Anticancer metallodrug research analytically painting the "omics" picture--current developments and future trends

Anticancer metallodrug development has for a long time been characterised by the similarity of new drug candidates to cisplatin and DNA as the primary target. Recent advances in bioanalytical techniques with high sensitivity and selectivity have revealed that metal-based drugs can undergo a wide range of biomolecular interactions beyond DNA and have generated interest in proteins as possible targets for metallodrugs. In fact, implementation of metallomics approaches that are able to reveal the fate of the compounds in biological systems can help to move drug development towards more targeted and rational design of novel metallodrugs. Additionally, proteomic screening and gene expression analysis can provide insight into physiological response to drug treatment and identify the reasons for drug resistance. Herein, we review selected applications which led to a better understanding of the mode of action of clinically established metal-based anticancer agents and novel metallodrug candidates.

Altered DNA binding and amplification of human breast cancer suppressor gene BRCA1 induced by a novel antitumor compound, [Ru(η(6)-p-phenylethacrynate)Cl(2)(pta)]

The ruthenium-based complex [Ru(η(6)-p-phenylethacrynate)Cl(2)(pta)] (pta = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decane), termed ethaRAPTA, is an interesting antitumor compound. The elucidation of the molecular mechanism of drug activity is central to the drug development program. To this end, we have characterized the ethaRAPTA interaction with DNA, including probing the sequence specific modified DNA structural stability and DNA amplification using the breast cancer suppressor gene 1 (BRCA1) of human breast and colon adenocarcinoma cell lines as models. The preference of ethaRAPTA base binding is in the order A > G > T > C. Once modified, the ethaRAPTA-induced BRCA1 structure has higher thermal stability than the modified equivalents of its related compound, RAPTA-C. EthaRAPTA exhibits a higher efficiency than RAPTA-C in inhibiting BRCA1 amplification. With respect to both compounds, the inhibition of BRCA1 amplification is more effective in an isolated system than in cell lines. These data provide evidence that will help to understand the process of elucidating the pathways involved in the response induced by ethaRAPTA.

Capillary electrophoretic methods in the development of metal-based therapeutics and diagnostics: new methodology and applications

In recent years, capillary electrophoresis (CE) has matured to a standard method in medicinal inorganic chemistry. More and more steps of the drug discovery process are followed by CE. However, not only the number of applications has steadily increased but also the variety of used methodology has significantly broadened and, as compared to a few years ago, a wider scope of separation modes and hyphenated systems has been used. Herein, a summary of the newly utilized CE methods and their applications in metallodrug research in the timeframe 2006-2011 is presented, following related reviews from 2003 and 2007 (Electrophoresis, 2003, 24, 2023-2037; Electrophoresis 2007, 28, 3436-3446). Areas covered include impurity profiling, quality control of pharmaceutical formulations, lipophilicity estimation, interactions between metallodrugs and proteins or nucleotides, and characterization and also quantification of metabolites in biological matrices and real-world samples.