Anti-cancer property and DNA binding interaction of first row transition metal complexes: A decade update

Metal ions carry out a wide variety of functions, including acid-base/redox catalysis, structural functions, signaling, and electron transport. Understanding the interactions of transition metal complexes with biomacromolecules is essential for biology, medicinal chemistry, and the production of synthetic metalloenzymes. After the coincidental discovery of cisplatin, importance of the metal complexes in biochemistry became a top priority for inquiry. In this review, a decade update on various synthetic strategies to first row transition metal complex and their interaction with DNA through non-covalent binding are explored. Moreover, this effort provides an excellent analysis on the efficacy of theoretical and practical approaches to the systematic generation of new non-platinum based metallodrugs for anti-cancer therapeutics.

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.

Dissimilar effect of organometallic ruthenium complexes on the viability of MDR and non-MDR experimental models

Ruthenium complexes containing triphenylphosphine diamide ligands were prepared, characterized, and tested for their biological activity against various cancer cell lines and the malaria parasite, Plasmodium falciparum. The effect of M (mono-substituted) and B (bis-substituted) complexes on the human cervical carcinoma (HeLa) cell line was investigated using the MTT assay. Five (B2, B3, B5, B6, and B13) of the 24 synthesized ruthenium complexes showed significant effects with IC50 values ranging between 0.3 and 2.3 μM. Evaluation of the potential biomolecular targets of B2 and B13 by fluorescence spectroscopy revealed relevant interactions with BSA and only a weak affinity for ctDNA. Complexes M2, B2, M13 and B13 were selected for further biological characterization. Their effect on the viability of two ovarian cancer cell lines was compared to normal cell lines, denoting their selectivity. Upon treatment of four different drug-resistant gynaecological cancer cell lines, differing in their multidrug-resistant phenotypes, the efficacy of the bis-substituted complexes was shown to be greater than their mono-substituted counterparts. The non-MDR cells are sensitive to all the tested complexes, compared to MDR cells which are less sensitive. Upon investigation of complexes M2, M13, B2, and B13 against sensitive and multidrug-resistant parasite strains of P. falciparum, the bis-substituted complexes were again shown to be the most potent, with submicromolar activity against both strains. Furthermore, the resistance indexes for the complexes were approximately equal to 1, which is at least 5-fold lower than chloroquine diphosphate, suggesting the ability of these complexes to retain their activity in resistant forms of the parasite.

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Exploring the coordination chemistry of ruthenium complexes with lysozymes: structural and in-solution studies

This study presents a comprehensive structural analysis of the adducts formed upon the reaction of two Ru(III) complexes [HIsq][trans-RuIIICl4(dmso)(Isq)] (1) and [H2Ind][trans-RuIIICl4(dmso)(HInd)] (2) (where HInd-indazole, Isq-isoquinoline, analogs of NAMI-A) and two Ru(II) complexes, cis-[RuCl2(dmso)4] (c) and trans-[RuCl2(dmso)4] (t), with hen-egg white lysozyme (HEWL). Additionally, the crystal structure of an adduct of human lysozyme (HL) with ruthenium complex, [H2Ind][trans-RuCl4(dmso)(HInd)] was solved. X-ray crystallographic data analysis revealed that all studied Ru complexes, regardless of coordination surroundings and metal center charge, coordinate to the same amino acids (His15, Arg14, and Asp101) of HEWL, losing most of their original ligands. In the case of the 2-HL adduct, two distinct metalation sites: (i) Arg107, Arg113 and (ii) Gln127, Gln129, were identified. Crystallographic data were supported by studies of the interaction of 1 and 2 with HEWL in an aqueous solution. Hydrolytic stability studies revealed that both complexes 1 and 2 liberate the N-heterocyclic ligand under crystallization-like conditions (pH 4.5) as well as under physiological pH conditions, and this process is not significantly affected by the presence of HEWL. A comparative examination of nine crystal structures of Ru complexes with lysozyme, obtained through soaking and co-crystallization experiments, together with in-solution studies of the interaction between 1 and 2 with HEWL, indicates that the hydrolytic release of the N-heterocyclic ligand is one of the critical factors in the interaction between Ru complexes and lysozyme. This understanding is crucial in shedding light on the tendency of Ru complexes to target diverse metalation sites during the formation and in the final forms of the adducts with proteins.

Assessment of Mononuclear/Dinuclear copper acylhydrazone complexes for lung cancer treatment

Non-platinum metal-based complexes have good potential for cancer treatment. Here, we designed and synthesized five hydrazone copper(II) complexes, [Cu2(HL)2Cl2] 1A, [Cu2(HL)2(NO3)H2O]·NO3 2A, [Cu2(HL)2Br2] 3A, [Cu(L)pyridine] 1B and [Cu(HL)(pyridine)Br] 3B, and evaluated their anti-lung cancer activities. MTT experiments revealed that these copper(II) complexes exhibit higher anticancer activity than cisplatin. Mechanism studies revealed that complex 3A induced G1 phase cell cycle arrest, and induced cell apoptosis via reactive oxygen species (ROS)-mediated mitochondrial dysfunction. Scratch wound healing assay was also performed, revealing that complex 3A have good anti-cell migration activity. Hemolysis assays showed good blood biocompatibility of complex 3A. Furthermore, complex 3A can significantly inhibit the proliferation of A549 3D tumor spheroid. An in vivo anticancer study showed that complex 3A could delays the growth of A549 tumor xenografts with lower systemic toxicity. These results highlight the great possibility of developing highly active copper complexes as anti-lung cancer agents.

Catalytic, Antifungal, and Antiproliferative Activity Studies of a New Family of Mononuclear [VIVO]/[VVO2] Complexes

Ligands derived from 2-(1-phenylhydrazinyl)pyridine and salicylaldehyde (HL1), 3-methoxysalicylaldehyde (HL2), 5-bromosalicylaldehyde (HL3), and 3,5-di-tert-butylsalicylaldehyde (HL4) react with [VIVO(acac)2] in MeOH followed by aerial oxidation to give [VVO2(L1)] (1), [VVO2(L2)] (2), [VVO2(L3)] (3), and [VVO2(L4)] (4). Complex [VIVO(acac)(L1)] (5) is also isolable from [VIVO(acac)2] and HL1 in dry MeOH. Structures of all complexes were confirmed by single-crystal X-ray and spectroscopic studies. They efficiently catalyze benzyl alcohol and its derivatives' oxidation in the presence of H2O2 to their corresponding aldehydes. Under optimized reaction conditions using 1 as a catalyst precursor, conversion of benzyl alcohol follows the order: 4 (93%) > 2 (90%) > 1 (86%) > 3 (84%) ≈ 5 (84%). These complexes were also evaluated for antifungal and antiproliferative activities. Complex 3 with MIC50 = 16 μg/mL, 4 with MIC50 = 12 μg/mL, and 5 with MIC50 = 16 μg/mL are efficient toward planktonic cells of Candida albicans and Candida tropicalis. On Michigan cancer foundation-7 (MCF-7) cells, they show comparable cytotoxic effects and exhibit IC50 in the 27.3-33.5 μg/mL range, and among these, 4 exhibits the highest cytotoxicity. A similar study on human embryonic kidney cells (HEK293) confirms their less toxicity at lower concentrations (4 to 16 μg/mL) compared to MCF-7.

Density Functional Theory-Guided Photo-Triggered Anticancer Activity of Curcumin-Based Zinc(II) Complexes

Photodynamic therapy (PDT) has evolved as a new therapeutic modality for cancer treatment with fewer side effects and drug resistance. Curcumin exhibits PDT activity, but its low bioavailability restricts its clinical application. Here, the bioavailability of curcumin was increased by its complex formation with the Zn(II) center. For a structure-activity relationship study, Zn(II)-based complexes (1-3) comprising N^N-based ligands (2,2'-bipyridine in 1 and 2 or 1,10-phenanthroline in 3) and O^O-based ligands (acetylacetone in 1, monoanionic curcumin in 2 and 3) were synthesized and thoroughly characterized. The X-ray structure of the control complex, 1, indicated a square pyramidal shape of the molecules. Photophysical and TD-DFT studies indicated the potential of 2 and 3 as good visible light type-II photosensitizers for PDT. Guided by the TD-DFT studies, the low-energy visible light-triggered singlet oxygen (1O2) generation efficacy of 2 and 3 was explored in solution and in cancer cells. As predicted by the TD-DFT calculations, these complexes produced 1O2 efficiently in the cytosol of MCF-7 cancer cells and ultimately displayed excellent apoptotic anticancer activity in the presence of light. Moreover, the molecular docking investigation showed that complexes 2 and 3 have very good binding affinities with caspase-9 and p-53 proteins and could activate them for cellular apoptosis. Further molecular dynamics simulations confirmed the stability of 3 in the caspase-9 protein binding site.

New Copper-Based Metallodrugs with Anti-Invasive Capacity

While metal-based complexes are deeply investigated as anticancer chemotherapeutic drugs, fewer studies are devoted to their anti-invasive activity. Herein, two copper (Cu)(II) tropolone derivatives, [Cu(Trop)Cl] and [Cu(Trop)Sac], both containing the N,N-chelated 4,4'-bishydroxymethyl-2,2'-bipyridne ligand, were evaluated for their anticancer and anti-invasive properties. RKO (RKO-ctr) colon cancer cells and their derivatives undergoing stable small interference (si) RNA for HIPK2 protein (RKO-siHIPK2) with acquisition of pro-invasive capacity were used. The results demonstrate that while [Cu(Trop)Sac] did not show cytotoxic activity, [Cu(Trop)Cl] induced cell death in both RKO-ctr and RKO-siHIPK2 cells, indicating that structural changes on substituting the coordinated chloride ligand with saccharine (Sac) could be a key factor in suppressing mechanisms of cellular death. On the other hand, both [Cu(Trop)Sac] and [Cu(Trop)Cl] complexes counteracted RKO-siHIPK2 cell migration in the wound healing assay. The synergic effect exerted by the concomitant presence of both tropolone and saccharin ligands in [Cu(Trop)Sac] was also supported by its significant inhibition of RKO-siHIPK2 cell migration compared to the free Sac ligand. These data suggest that the two Cu(II) tropolone derivatives are also interesting candidates to be further tested in in vivo models as an anti-invasive tumor strategy.

Study on antitumor activity of three ruthenium arene complexes in vitro

Three ruthenium arene complexes, namely {[(η6-p-cymene)Ru(Cl)]2(dpb)}(PF6)2 (1), [(η6-p-cymene)Ru(dpb)Cl](PF6) (2) and [(η6-p-cymene) Ru(dpb)py](PF6) (3) (dpb = 2,3-bis(2-pyridyl)benzo-quinoxaline, py = pyridine), were synthesized and their antitumor properties were introduced. Complexes 1-3 were characterized by 1H NMR, MS, and elemental analysis. As a binuclear ruthenium structure, the absorption of metal ligand electron transfer (MLCT) of 1 extended to 700 nm. Complex 1 was significantly hydrolyzed under dark conditions. The cytotoxicity in vitro study showed that complexes 1 and 2 are more toxic to human lung cancer cells (A549) and human cervial cancer cells (Hela) than cisplatin. Moreover, there was almost no cross-resistance between complex 1-2 and cisplatin. Under the irradiation at 478 nm, complexes 1-3 all produced singlet oxygen (1O2), and the 1O2 quantum yield of complex 1 in PBS is the highest among complexes 1-3. Complex 1 also produced 1O2 under 600 nm light irradiation. DNA gel electrophoresis showed that 1 caused the photocleavage of plasmid DNA. The hydrolysis rate of complex 1 was accelerated under light (λ > 600 nm). And the phototoxicity of complex 1 to Hela cells under light (λ > 600 nm) was much greater than its dark toxicity, which may be due to its generation of 1O2 and the promotion of its hydrolysis under long-wave light irradiation.

Carbohydrate effect of novel arene Ru(II) phenanthroline-glycoconjugates on metastatic biological processes

Novel water-soluble half-sandwich ruthenium(II) polypyridyl-glycoconjugates [Ru(p-cymene)Cl{N-(1,10-phenanthroline-5-yl)-β-glycopyranosylamine}][Cl] (glycopyranosyl = d-glucopyranosyl (1), D-mannopyranosyl (2), L-rhamnopyranosyl (3) and l-xylopyranosyl (4)) have been synthesized and fully characterized. Their behaviour in water under physiological conditions has been studied by nuclear magnetic resonance spectroscopy, revealing their hydrolytic stability. Interactions of the novel compounds with duplex-deoxiribonucleic acid (dsDNA) were investigated by different techniques and the results indicate that, under physiological pH and saline conditions, the metal glycoconjugates bind DNA in the minor groove and/or through external, electrostatic interactions, and by a non-classical, partial intercalation mechanism in non-saline phosphate buffered solution. Effects of compounds 1-4 on cell viability have been assessed in vitro against two human cell lines (androgen-independent prostate cancer PC-3 and non-tumorigenic prostate RWPE-1), showing moderate cytotoxicities, with IC50 values higher than those found for free ligands [N-(1,10-phenanthroline-5-yl)-β-glycopyranosylamine] (glycopyranosyl = d-glucopyranosyl (a), D-mannopyranosyl (b), L-rhamnopyranosyl (c) and l-xylopyranosyl (d)) or corresponding metal-aglycone. Cell viability was assayed in the presence and absence of the glucose transporters (GLUTs) inhibitor [N4-{1-(4-cyanobenzyl)-5-methyl-3-(trifluoromethyl)-1H-pyrazol-4-yl}-7-fluoroquinoline-2,4-dicarboxamide] (BAY-876), and the results point to a negligible impact of the inhibition of GLUTs on the cytotoxicity caused by Ru(II) compounds 1-4. Remarkably, glycoconjugates 1-4 potently affect the migration pattern of PC-3 cells, and the wound healing assay evidence that the presence of the carbohydrate and the Ru(II) center is a requisite for the anti-migratory activity observed in these novel derivatives. In addition, derivatives 1-4 strongly affect the matrix metalloproteinase MMP-9 activities of PC-3 cells, while proMMP-2 and especially proMMP-9 were influenced to a much lesser extent.

Ruthenium(II) polypyridyl complexes with visible light-enhanced anticancer activity and multimodal cell imaging

Ruthenium(II) polypyridyl complexes have drawn growing attention due to their photophysical properties and anticancer activity. Herein we report four ruthenium(II) polypyridyl complexes [(N^N)2RuII(L)]2+ (1-4, L = 4-anilinoquinazoline derivatives, N^N = bidentate ligands with bis-nitrogen donors) as multi-functional anticancer agents. The epidermal growth factor receptor (EGFR) is overexpressed in a broad range of cancer cells and related to many kinds of malignance. EGFR inhibitors, such as gefitinib and erlotinib, have been approved as clinical anticancer drugs. The EGFR-inhibiting 4-anilinoquinazoline ligands greatly enhanced the in vitro anticancer activity of these ruthenium(II) polypyridyl complexes against a series of human cancer cell lines compared to [Ru(bpy)2(phen)], but interestingly, these complexes were actually not potent EGFR inhibitors. Further mechanism studies revealed that upon irradiation with visible light, complexes 3 and 4 generated a high level of singlet oxygen (1O2), and their in vitro anticancer activities against human non-small-cell lung (A549), cervical (HeLa) and squamous (A431) cancer cells were significantly improved. Specifically, complex 3 displayed potent phototoxicity upon irradiation with blue light, of which the photo-toxicity indexes (PIs) against HeLa and A431 cells were 11 and 8.3, respectively. These complexes exhibited strong fluorescence emission at ca. 600 nm upon excitation at about 450 nm. A subcellular distribution study by fluorescence microscopy imaging and secondary ion mass spectrometry imaging (ToF-SIMS) demonstrated that complex 3 mainly localized at the cytoplasm and complex 4 mainly localized in the nuclei of cells. Competitive binding with ctDNA showed that complex 4 was more favorable to bind to the DNA minor groove than complex 3. These differences support that complex 3 possibly exerts its anticancer activities majorly by photo-induced 1O2 generation and complex 4 by binding to DNA.

A novel water-soluble Cu(II) gluconate complex inhibits cancer cell growth by triggering apoptosis and ferroptosis related mechanisms

Metal copper complexes have attracted extensive attention as potential alternatives to platinum-based anticancer drugs due to their possible different modes of action. Herein, a new copper(II) gluconate complex, namely [Cu(DPQ)(Gluc)]·2H₂O (CuGluc, DPQ = pyrazino[2,3-f][1,10]phenanthroline), with good water-solubility and high anticancer activity was synthesized by using D-gluconic acid (Gluc-2H) as an auxiliary ligand. The complex was well characterized by single-crystal X-ray diffraction analysis, elemental analysis, molar conductivity, and Fourier transform infrared spectroscopy (FTIR). The DNA-binding experiments revealed that CuGluc was bound to DNA by intercalation with end-stacking binding. CuGluc could oxidatively cleave DNA, in which ¹O₂ and H₂O₂ were involved. In addition, CuGluc was bound to the IIA subdomain of human serum albumin (HSA) through hydrophobic interaction and hydrogen bonding, showing a good affinity for HSA. The complex showed superior anticancer activity toward several cancer cells than cisplatin in vitro. Further studies indicated that CuGluc caused apoptotic cell death in human liver cancer (HepG2) cells through elevated intracellular reactive oxygen species (ROS) levels, mitochondrial dysfunction, cell cycle arrest, and caspase activation. Interestingly, CuGluc also triggered the ferroptosis mechanism through lipid peroxide accumulation and inhibition of glutathione peroxidase 4 (GPX4) activity. More importantly, CuGluc significantly inhibited tumor growth in vivo, which may benefit from the combined effects of apoptosis and ferroptosis. This work provides a promising strategy to develop highly effective antitumor copper complexes by coordinating with the glucose metabolite D-gluconic acid and exploiting the synergistic effects of apoptosis and ferroptosis mechanisms.

Immunostimulation with chemotherapy of a ruthenium-arene complex via blockading CD47 signal in chronic myelogenous leukemia cells

Combination of novel immunomodulation and traditional chemotherapy has become a new tendency in cancer treatment. Increasing evidence suggests that blocking the "don't eat me" signal transmitted by the CD47 can promote the phagocytic ability of macrophages to cancer cells, which might be promising for improved cancer chemoimmunotherapy. In this work, we conjugated CPI-alkyne modified by Devimistat (CPI-613) with ruthenium-arene azide precursor Ru-N₃ by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to construct Ru complex CPI-Ru. CPI-Ru exhibited satisfactory cytotoxicity towards the K562 cells while nearly non-toxic towards the normal HLF cells. CPI-Ru has been demonstrated to cause severe damage to mitochondria and DNA, ultimately inducing cancer cell death through the autophagic pathway. Moreover, CPI-Ru could significantly downregulate the expression of CD47 on the surface of K562 accompanied by the enhanced immune response by targeting the blockade of CD47. This work provides a new strategy for utilizing metal-based anticancer agents to block CD47 signal to achieve chemoimmunotherapy in chronic myeloid leukemia treatment.

Cyclometalated Ru(II)-NHC complexes with phenanthroline ligands induce apoptosis mediated by mitochondria and endoplasmic reticulum stress in cancer cells

The exploration of ruthenium complexes as anticancer drugs has been the focus of intense investigation. In this study, we synthesized and characterized four C,N-cyclometalated ruthenium(II) complexes (Ru1-Ru4) coordinated with pyridine-functionalized N-heterocyclic carbene (NHC) and auxiliary ligands (e.g., acetonitrile, 1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline). X-ray diffraction analysis showed that all of the four cycloruthenated complexes are hexa-coordinated in a typical octahedral geometry. In vitro cytotoxic studies revealed that cyclometalated Ru-NHC complexes Ru3 and Ru4 had stronger anticancer activity than their corresponding Ru-NHC precursor Ru1 and the clinically used cisplatin. For HeLa cells, Ru3 and Ru4 exhibited potent cytotoxicity with the IC₅₀ value of 4.31 ± 0.42 μM and 3.14 ± 0.23 μM, respectively, which was approximately three times lower than that of cisplatin. More interestingly, Ru3 and Ru4 not only effectively inhibited the proliferation of HeLa cells, but also exhibited potential anti-migration activity. In the scratch wound healing assay, Ru3 and Ru4 treatment significantly reduced the wound healing rate of HUVEC cells. Mechanistic studies showed that Ru3 and Ru4 caused a dual action mode of mitochondrial membrane depolarization and endoplasmic reticulum stress and finally induced apoptosis of HeLa cells.

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.

Dual drug delivery system of RAPTA-C and paclitaxel based on fructose coated nanoparticles for metastatic cancer treatment

Ruthenium complexes have been widely studied as potential alternatives to platinum-type anticancer drugs due to their unique medical properties such as high selectivity, strong ability to inhibit solid tumour metastasis. However, non-specific biodistribution, and weak lethality of ruthenium to cancer cells limit its use in medical application. Drug delivery systems offer the ability to integrate multiple drugs in one system, which is particularly important to enhance the chemotherapeutic efficacy and to potentially achieve a synergistic effect of both drugs. Here, we report a dual drug nanocarrier that is based on a self-assembled biodegradable block copolymer, where the ruthenium complex (RAPTA-C) is chemically attached to the polymer chain, while another drug, paclitaxel (PTX), is entrapped in the core of the micelle. The dual drug delivery system was studied via in vitro tests using MDA-MB-231 breast cancer cells and it was observed that RAPTA-C in combination with PTX significantly enhanced anti-tumour and anti-metastasis activity.

Interaction with bioligands and in vitro cytotoxicity of a new dinuclear dioxido vanadium(V) complex

One centrosymmetric bis(μ-oxido)-bridged vanadium(V) dimer with molecular formula [(V^VO₂)₂(pedf)₂] (1) has been synthesized from the reaction of VOSO₄·5H₂O with a Schiff base ligand (abbreviated with pedf^-) obtained from 2-acetylpyridine and 2-furoic hydrazide in methanol. Complex 1 was characterized by elemental analysis, UV-visible (UV-Vis), Fourier-transform infrared spectra (FT-IR), cyclic voltammetry (CV), electron paramagnetic resonance spectroscopy (EPR) and electrospray ionization-mass spectrometry (ESI-MS) techniques along with single crystal X-ray diffraction (SCXRD). The FT-IR spectral data of 1 indicated the involvement of oxygen and azomethine nitrogen in coordination to the central metal ion. The crystallographic studies revealed a dinuclear oxovanadium(V) complex with the Schiff base coordinated via the ONN donor set with formation of two five-membered chelate rings resulting in a distorted octahedral geometry. The interaction of 1 with calf thymus DNA (CT-DNA) was investigated by spectroscopic measurements and results suggested that the complex binds to CT-DNA via moderate intercalative mode with a binding constant (K_b) around 10³ M^-1. In addition, the in vitro protein binding behavior was studied by fluorescence spectrophotometric method using both bovine serum albumin (BSA) and human serum albumin (HSA) and a static quenching mechanism was observed for the interaction of the complex with both albumins that occurs with a K_b in the range (5-6) × 10³ M^-1. In vitro cytotoxicity of complex 1 on lung cancer cells (A549) and human skin carcinoma cell line (A431) demonstrated that the complex had a broad-spectrum of anti-proliferative activity with IC₅₀ value of 64.2 μM and 56.2 μM.

Antitumor activity of copper(II) complexes with Schiff bases derived from N'-tosylbenzene-1,2-diamine

The electrochemical oxidation of anodic metal copper in a solution of the ligands N-[(5-tert-butyl-2-hydroxyphenyl)methylidine]-N'-tosylbenzene-1,2-diamine [H₂L¹] and N-[(3,5-di-tert-butyl-2-hydroxyphenyl)methylidine]-N'-tosylbenzene-1,2-diamine, [H₂L²] afforded homoleptic [CuL] compounds or solvate [CuLS] complexes. The addition to the electrochemical cell of coligands (L') such as 2,2'-bipyridine (2-bpy), 4,4'-bipyridine(4-bpy) or 1,10-phenanthroline (phen) allowed the synthesis, in one step, of heteroleptic [CuLL'] compounds, namely [CuL¹(H₂O)] (1), [CuL¹(2,2'-bpy)]⋅CH₃CN (2), [CuL¹(phen)]·H₂O (3), [Cu₂L¹₂(4,4'-bpy)] (4), [CuL²(CH₃OH)] (5), [CuL²(2,2'-bpy)] (6), [CuL²(phen)] (7) and [Cu₂L²₂(4,4'-bpy)] (8). The crystal structures of both ligands, H₂L¹, H₂L², and those of the complexes (2), (4), (5), (6) and (7) have been determined by X-ray diffraction techniques. Coordination polyhedron around metal atom is square planar for [CuL²(CH₃OH)] (5) and [Cu₂L¹₂(4,4'-bpy)] (4) and square pyramid for the other complexes with additional chelating ligands. The cytotoxic activity of this new series of copper(II) complexes against the SH-SY5Y neuroblastoma cell line and U87-MG and U373-MG glioblastoma cell lines has been investigated. Most of the test compounds showed higher activity than cisplatin in the three cell lines. Among this series, compound [CuL¹(phen)] (3) displayed the highest activity with IC₅₀ equal to 1.77 μM on SH-SY5Y whereas compound [Cu₂L¹₂(4.4'-bpy)] (4) resulted the most potent compounds on U87 MG and U373 MG glioblastoma cell lines. Studies on the cytotoxic activity of these derivatives suggest that these compounds induce cell death by a mechanism other than apoptosis.

A novel heterometallic ruthenium-silver complex as potential antitumor agent: Studies on its synthesis, in vitro assays and interactions with biomolecular targets

Certain ruthenium compounds are found to be potent growth inhibitors for cancer cells. In the current study, a novel ruthenium-triphenylphosphine (PPh₃) cation and silver-2-mercapto nicotinate acid (H₂mna) anion complex (RSC) was synthesized, and its molecular structure was determined by IR, NMR and X-ray crystallography. Biological assays revealed that RSC strongly inhibited the viability of MCF-7 and MDA-MB-231 cells with IC₅₀ values of 9.6±1.1 and 7.5±0.8 µM, respectively, and significantly blocked their migration rates. Ultraviolet spectroscopy and fluorescence emission experiments demonstrated that RSC interacted with BSA, but not DNA. Further studies on [Ag₆(Hmna)₂(mna)₄]^4- binding with BSA and DNA found the anion did not interact with these biomolecules, indicating that RSC exerted its biological functions through its ruthenium-PPh₃ complex (RTC) moiety, and molecular docking provided additional evidence supporting this result. Fluorescence resonance energy transfer showed that the number of binding sites (n) and binding constant of RTC-BSA complex were 1 and 8.60 × 10⁴ M^-1 at 310K, suggesting a strong interaction between RTC and BSA. The thermodynamic parameters ΔG⁰, ΔH⁰ and ΔS⁰ of the binding were calculated, and it was demonstrated that the binding of RTC with BSA was enthalpy-driven, and the main forces between RTC and BSA were electrostatic force and hydrogen bonding. Molecular docking showed that the binding site of BSA with RSC was located on the interface between the domains IIA and IIB of the protein. The present study sheds light on that a ruthenium mono-coordinated with PPh₃ complex could help to design and develop a new class of antitumor drugs.

Impact of Polypyridyl Ru Complexes on Angiogenesis—Contribution to Their Antimetastatic Activity

The use of polypyridyl Ru complexes to inhibit metastasis is a novel approach, and recent studies have shown promising results. We have reported recently that Ru (II) complexes gathering two 4,7-diphenyl-1,10-phenanthroline (dip) ligands and the one being 2,2′-bipyridine (bpy) or its derivative with a 4-[3-(2-nitro-1H-imidazol-1-yl)propyl (bpy-NitroIm) or 5-(4-{4′-methyl-[2,2′-bipyridine]-4-yl}but-1-yn-1-yl)pyridine-2-carbaldehyde semicarbazone (bpy-SC) moieties can alter the metastatic cascade, among others, by modulating cell adhesion properties. In this work, we show further studies of this group of complexes by evaluating their effect on HMEC-1 endothelial cells. While all the tested complexes significantly inhibited the endothelial cell migration, Ru-bpy additionally interrupted the pseudovessels formation. Functional changes in endothelial cells might arise from the impact of the studied compounds on cell elasticity and expression of proteins (vinculin and paxillin) involved in focal adhesions. Furthermore, molecular studies showed that complexes modulate the expression of cell adhesion molecules, which has been suggested to be one of the factors that mediate the activation of angiogenesis. Based on the performed studies, we can conclude that the investigated polypyridyl Ru (II) complexes can deregulate the functionality of endothelial cells which may lead to the inhibition of angiogenesis.

Sawhorse-type ruthenium complexes with triazolopyrimidine ligands - what do they represent in terms of cytotoxic and CORM compounds?

Three sawhorse-type ruthenium(I) complexes containing purine analogs such as triazolopyrimidines of the general formula [Ru₂(CO)₄(μ-OOCCH₃)₂(L)₂], where L is 1,2,4-triazolo[1,5-a]pyrimidine (tp for 1), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp for 2) and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp for 3), have been synthesized and characterized by elemental analysis, infrared analysis, multinuclear magnetic resonance spectroscopic techniques (¹H, ¹³C, ¹⁵N), and single-crystal X-ray diffraction (for 1 and 2). By assay with myoglobin, the photo-activated CO-releasing molecule (PhotoCORM) character of (1-3) has been confirmed, thus indicating the possibility of use in CO-based therapies. The importance of UV-induced modification has been investigated in the context of anticancer properties. Complexes (1) and (2) have been thoroughly screened for their in vitro cytotoxicity against various cancer cell lines: MCF-7 (breast cancer), HeLa (cervical cancer) and C32 (melanoma), as well as L929 normal fibroblasts in the dark and presence of UV-A light (365 nm). The results were compared with those for cisplatin and two reference ruthenium complexes, namely NAMI-A and KP1019. The most hydrophilic [Ru₂(CO)₄(μ-OOCCH₃)₂(tp)₂] (1) (log P = -1.12) was found to be more cytotoxic than (2), despite the lower cellular uptake measured by ICP-MS toward HeLa cells. Importantly, photo-induced stimulation of cells with (1) resulted in a lower decrease in the viability of L929 normal cells (IC₅₀ = 154.7 ± 6.5 μM) in comparison with HeLa cancer cells (IC₅₀ = 66.7 ± 3.4 μM). The photo-induced stimulation of (1) and (2) increases ROS generation, and their anticancer activity may be a partially ROS-dependent phenomenon.

Antiproliferative activity and DNA binding studies of cyclometalated complexes of platinum(II) containing 2-vinylpyridine

The cytotoxic activity of four cyclometalated platinum(II) complexes [PtMe(vpy)(L)], containing 2-vinylpyridine (vpy) and the phosphine ligands (L) PMe₂Ph (1a), PPh₃ (1b), PMePh₂ (1c), and P(c-Hex)₃ (1d), were evaluated against human breast cancer (MDA-MB-231), human lung cancer (A549), human colon cancer (SW1116), and non-tumor epithelial breast (MCF-10 A) cell lines. The highest activity was found for 1c with IC₅₀ values of 21.10 µM, 23.36 µM, and 12.96 µM, compared to cisplatin, which was 10.12 µM, 47.57 µM, and 19.50 µM against the A549, SW1116, and MDA-MB-231 cell lines, respectively. 1a-d showed a higher selectivity index (SI) than cisplatin. Docking studies confirmed interaction to the DNA minor groove for all complexes. Genotoxicity studies on 1c showed interactions with the genomic content of malignant cells. Compared with cisplatin as a positive control, a slight shift was found in the electrophoresis mobility, which was utilized further to study the direct interaction of 1c with DNA.

Study of the DNA binding mechanism and in vitro activity against cancer cells of iron(III) and aluminium(III) kojic acid derivative complexes

Metal ions have unique electrochemical and spectroscopical properties that cannot be attained by purely organic compounds. Most of the metal ions are toxic to humans, but paradoxically, metallodrugs are used in medicine as therapeutics and theranostics. Metallodrugs are eliminated in urine and faeces, and therefore release toxic metals and ligands into aquatic ecosystems, thereby raising concerns regarding environmental risks. The use of metallodrugs based on essential metal ions (i.e., iron, copper and zinc), instead of toxic ions, is a new alternative with minor hazards. Kojic acid is an Asperigillus oryzae metabolite of low toxicity used in the food and cosmetics industries. Its derivatives form stable complexes with iron(III) ions, which bind effectively to DNA and inhibit DNA polymerization. The iron(III)/S2 ligand complexes reduce in vitro colon carcinoma (Caco₂) cell viability and significantly decrease the cell number. The kojic acid derivative complexes with iron(III) presented here are an alternative to the currently used platinum complexes in cancer therapy.

Half-Sandwich Cyclometalated RhIII Complexes Bearing Thiolate Ligands: Biomolecular Interactions and In Vitro and In Vivo Evaluations

A class of cyclometalated RhIII complexes [Cp*Rh(ppy)(SR)] bearing thiolate ligands, Cp* = pentamethylcyclopentadienyl, ppy = 2-phenylpyridinate, and R = pyridyl (Spy, 2), pyrimidyl (SpyN, 3), benzimidazolyl (Sbi, 4), and benzothiazolyl (Sbt, 5), were produced and identified by means of spectroscopic methods. The in vitro cytotoxicity of the RhIII compounds in three different human mortal cancerous cell lines (ovarian, SKOV3; breast, MCF-7; lung, A549) and a normal lung (MRC-5) cell line were evaluated, indicating the selectivity of these cyclometalated RhIII complexes to cancer cells. Complex 5, selected for in vivo experiment, has shown an effective inhibition of tumor growth in SKOV3 xenograft mouse model relative to control (p-values < 0.05 and < 0.01). Importantly, the outcomes of H&E (hematoxylin and eosin) staining and hematological analysis revealed negligible toxicity of 5 compared to cisplatin on a functioning of the main organs of mouse. Molecular docking, UV-vis, and emission spectroscopies (fluorescence, 3D fluorescence, synchronous) techniques were carried out on 1-5 to peruse the mechanism of the anticancer activities of these complexes. The obtained data help to manifest the binding affinity between the rhodium compounds and calf thymus DNA (CT-DNA) through the interaction by DNA minor groove and moderate binding affinity with bovine serum albumin (BSA), particularly with the cavity in the subdomain IIA. It can be concluded that the Rh-thiolate complexes are highly promising leads for the development of novel effective DNA-targeted anticancer drugs.

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.

Palladium(ii) and platinum(ii) complexes with ONN donor pincer ligand: synthesis, characterization and in vitro cytotoxicity study

New Pd(ii) and Pt(ii) complexes with ONN donor pincer ligand are synthesized. Antiproliferative activity of the complexes is explored towards HCT116, HepG2, MCF-7 and A549 cell lines.

A MXene-Based Bionic Cascaded-Enzyme Nanoreactor for Tumor Phototherapy/Enzyme Dynamic Therapy and Hypoxia-Activated Chemotherapy

The enzyme-mediated elevation of reactive oxygen species (ROS) at the tumor sites has become an emerging strategy for regulating intracellular redox status for anticancer treatment. Herein, we proposed a camouflaged bionic cascaded-enzyme nanoreactor based on Ti₃C₂ nanosheets for combined tumor enzyme dynamic therapy (EDT), phototherapy and deoxygenation-activated chemotherapy. Briefly, glucose oxidase (GOX) and chloroperoxidase (CPO) were chemically conjugated onto Ti₃C₂ nanosheets, where the deoxygenation-activated drug tirapazamine (TPZ) was also loaded, and the Ti₃C₂-GOX-CPO/TPZ (TGCT) was embedded into nanosized cancer cell-derived membrane vesicles with high-expressed CD47 (m_eTGCT). Due to biomimetic membrane camouflage and CD47 overexpression, m_eTGCT exhibited superior immune escape and homologous targeting capacities, which could effectively enhance the tumor preferential targeting and internalization. Once internalized into tumor cells, the cascade reaction of GOX and CPO could generate HClO for efficient EDT. Simultaneously, additional laser irradiation could accelerate the enzymic-catalytic reaction rate and increase the generation of singlet oxygen (¹O₂). Furthermore, local hypoxia environment with the oxygen depletion by EDT would activate deoxygenation-sensitive prodrug for additional chemotherapy. Consequently, m_eTGCT exhibits amplified synergistic therapeutic effects of tumor phototherapy, EDT and chemotherapy for efficient tumor inhibition. This intelligent cascaded-enzyme nanoreactor provides a promising approach to achieve concurrent and significant antitumor therapy.

Moving Ru polypyridyl complexes beyond cytotoxic activity towards metastasis inhibition

In recent years, Ru polypyridyl complexes have been intensively studied for their anticancer activity. The vast majority of research focuses on assessing their cytotoxic activity, as well as targeting cancer cells with them. Since the formation of metastases poses a greater risk than primary tumors, scientists recently began evaluating these compounds as potential metastasis inhibitors. This review highlights the latest achievements in this field with particular attention to the identification of the target proteins responsible for such activity. Cell migration, invasion, and adhesion are key components of metastasis, therefore understanding how they are affected by Ru polypyridyl complexes is of great importance. KEYWORDS: Ruthenium polypyridyl complexes Antimetastatic Migration Invasion Adhesion Metalloproteinases.

Inhibition of Matrix Metalloproteinases and Cancer Cell Detachment by Ru(II) Polypyridyl Complexes Containing 4,7-Diphenyl-1,10-phenanthroline Ligands-New Candidates for Antimetastatic Agents

Primary tumor targeting is the dominant approach in drug development, while metastasis is the leading cause of cancer death. Therefore, in addition to the cytotoxic activity of a series of Ru(II) polypyridyl complexes of the type [Ru(dip)₂L]²⁺ (dip: 4,7-diphenyl-1,10-phenanthroline while L = dip; bpy: 2,2′-bipyridine; bpy-SC: bipyridine derivative bearing a semicarbazone 2-formylopyridine moiety; dpq, dpq(CH₃)₂, dpb: quinoxaline derivatives) their ability to inhibit cell detachment was investigated. In vitro studies performed on lung cancer A549 cells showed that they accumulate in cells very well and exhibit moderate cytotoxicity with IC₅₀ ranging from 4 to 13 µM. Three of the studied compounds that have dip, bpy-SC, or dpb ligands after treatment of the cells with a non-toxic dose (<¹/₂IC₅₀) enhanced their adhesion properties demonstrated by lower detachment in the trypsin resistance assay. The same complexes inhibited both MMP-2 and MMP-9 enzyme activities with IC₅₀ ranging from 2 to 12 µM; however, the MMP-9 inhibition was stronger. More detailed studies for [Ru(dip)₂(bpy-SC)]²⁺, which induced the greatest increase in cell adhesion, revealed that it is predominately accumulated in the cytoskeletal fraction of A549 cells. Moreover, cells treated with this compound showed the localization of MMP-9 to a greater extent also in the cytoskeleton. Taken together, our results indicate the possibility of a reduction of metastatic cells escaping from the primary lesion to the surrounding tissue by prevention of their detachment and by influencing the activity of MMP-2 and MMP-9.

Interaction of the potent antitumoral compounds Casiopeinas® with blood serum and cellular bioligands

Casiopeinas® are among the few Cu^II compounds patented for their antitumor activity, but their mode of action has not been fully elucidated yet. One of them, Cas II-gly, is formed by 4,7-dimethyl-1,10-phenanthroline (Me₂phen) and glycinato (Gly). In blood and cells, Cas II-gly can keep its identity or form mixed species with serum or cytosol bioligands (bL or cL) with composition Cu^II-Me₂phen-bL/cL, Cu^II-Gly-bL/cL, or Cu^II-bL/cL. In this study, the binding of Cas II-gly with low molecular mass bioligands of blood serum (citric, L-lactic acid, and L-histidine) and cytosol (reduced glutathione (GSH), reduced nicotinamide adenine dinucleotide (NADH), adenosine triphosphate (ATP), and l-ascorbic acid) was examined through the application of instrumental (ElectroSpray Ionization-Mass Spectrometry and Electron Paramagnetic Resonance) and computational (Density Functional Theory) methods. The results indicated that mixed species Cu^II-Me₂phen-bL/cL are formed, with the bioligands replacing glycinato. The formation of these adducts may participate in the copper transport toward the target organs and facilitate the cellular uptake or, in constrast, preclude it. In the systems with GSH, NADH and L-ascorbate, a redox reaction occurs with the partial oxidation of cL to the corresponding oxidized form (GSSG, NAD⁺ and dehydroascorbate) which interact with Cu^II. Formed Cu^I ion does not give complexation reactions with reduced or oxidized form of bioligands for its 'soft' character and low affinity for oxygen and nitrogen donors compared to Cu^II. However, Cu^I could promote Fenton-like reactions with production of reactive oxygen species (ROS) related to the antitumor activity of Casiopeinas®.

Electrochemical, mechanistic, and DFT studies of amine derived diphosphines containing Ru(II)-cymene complexes with potent in vitro cytotoxic activity against HeLa and triple-negative breast cancer cells MDA-MB-231

Complexes with general formula [RuCl(η6-p-cymene)(P-NR-P)]X (R = CH2Py (Py = pyridine) - [1a]+, CH2Ph (Ph = phenyl) - [1b]+, Ph - [1c] and p-tol (p-tol = p-tolyl) - [1d]+; X = PF6- or BF4-) were evaluated as cytotoxic agents against two cancer cell lines (HeLa and MDA-MB-231). All metal complexes are active in the range of concentrations tested (up to 100 μmol L-1). The IC50 (μmol L-1) values for the metal complexes are lower than that found for cisplatin. The activities are up to 6- and 15-fold higher than cisplatin for HeLa and MDA-MB-231 cancer cell lines, respectively. Studies of DNA binding and DNA cleavage were performed. DNA binding studies revealed a modest hypochromic shift in the metal complexes electronic spectra, indicating a weak interaction with Kb values in the range of 1.7 × 103-1.6 × 104. Although the cleavage tests revealed that in the dark DNA is not a biological target for these metal complexes, upon blue light irradiation they are activated causing DNA cleavage. Electrochemical studies showed the presence of two independent redox processes, one attributed to the oxidation process of Ru2+ → Ru3+ (EC process) and the other one to the reduction of Ru2+ → Ru1+, which is further reduced to Ru0 (ECE mechanism). In both processes, coupled chemical reactions were observed. DFT calculations were performed to support the electrochemical/chemical behavior of the complexes. The reactivity of complex [1b]BF4 with CH3CN was evaluated and two complexes were isolated [2b]BF4 and [3b]BF4. The complex mer-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4 ([2b]BF4) was isolated after refluxing the precursor [1b]BF4 in CH3CN. Isomerization of [2b]BF4 in CH3CN resulted in the formation of fac-[RuCl(CH3CN)3(P-NCH2Ph-P)]BF4. An attempt to isolate the fac-isomer by adding diethyl ether was unsuccessful, and the complex [3b]BF4 was observed as the major component. The complex [Ru2(μ-Cl3)(CH3CN)2(P-NCH2Ph-P)2]BF4 ([3b]BF4) proved to be very stable and can be obtained from both the mer- and the fac-isomers. The molecular structures of [1b]BF4 and [3b]BF4 were solved by single-crystal X-ray diffraction.

Phosphorescent rhenium(I) complexes conjugated with artesunate: Mitochondrial targeting and apoptosis-ferroptosis dual induction

Cell death is essential for cancer, which can be induced through multiple mechanisms. Ferroptosis, a newly emerging form of non-apoptotic cell death, involves the generation of iron-dependent reactive oxygen species (ROS). In this study, we designed and synthesized two artesunate (ART) conjugated phosphorescent rhenium(I) complexes (Re(I)-ART conjugates), [Re(N^N)(CO)₃(PyCH₂OART)](PF₆) (Re-ART-1 and Re-ART-2) (Py = pyridine, N^N = 1,10-phenanthroline (phen, in Re-ART-1) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Re-ART-2)) that can specifically locate in the mitochondria of human cervical carcinoma (HeLa). Mechanism studies show that Re-ART-1 and Re-ART-2 exhibit high cytotoxicity against cancer cells lines and can induce both apoptosis and ferroptosis in HeLa cells through mitochondrial damage, caspase cascade, glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) inactivation and lipid peroxidation accumulation. As a result, this work presents the rational design of Re(I)-ART conjugates as a promising strategy to induce both apoptosis and ferroptosis and improve therapeutic efficiency of cancer treatment.

Development of novel ruthenium(II)-arene complexes displaying potent anticancer effects in glioblastoma cells

Glioblastomas (GBs) are highly aggressive and malignant brain tumors, which are highly resistant to conventional multimodal treatments, leading to their abysmal prognosis. Herein, we designed two organometallic half-sandwich Ru(ii)-η6-p-cymene complexes containing Schiff bases derived from 3-aminoquinoline and 2-hydroxy-benzaldehyde (L1) and 2-hydroxy-naphthaldehyde (L2), namely [Ru(η6-p-cymene)(L1)Cl] (1) and [Ru(η6-p-cymene)(L2)Cl] (2), respectively, and studied their activity on GB cells. Both complexes were structurally characterized using single-crystal X-ray diffraction, which exhibited their half-sandwich three-legged piano-stool geometry. Furthermore, we studied their physicochemical behavior, solution speciation, aquation kinetics, and photo-substitution reactions using various spectroscopic methods. The complexes exhibited a moderate binding affinity with calf-thymus (CT)-DNA (Kb ∼ 105 M-1). The complexes effectively interacted with human serum albumin (HSA) (K ∼ 105 M-1) with preferential tryptophan binding, as determined via synchronous fluorescence studies. The in vitro studies showed their significant antiproliferative activity against an aggressive human GB cell line, LN-229 (IC50 = 22.8 μM), with moderate selectivity relative to normal mouse fibroblast L929 cells. Notably, [Ru(η6-p-cymene)(L1)Cl] (1) exhibited a higher selectivity index (S.I.) than [Ru(η6-p-cymene)(L2)Cl] (2) and cisplatin. We evaluated the clonogenic potential of the GB cells using a colony formation assay in the presence of complex 1. Excitingly, it showed ∼75% inhibition of the clonogenic potential of GB cells at the IC50 concentration. Complex 1 also effectively lowered the migratory potential of the GB cells, as assessed by the wound healing assay. The studied compound led to the apoptosis of GB cells, as evidenced by nuclear condensation, blebbing, and enhanced caspase 3/7 activity, and thus has anticipated utility in the treatment of GBs using photochemotherapy.

Insights into the Protein Ruthenation Mechanism by Antimetastatic Metallodrugs: High-Resolution X-ray Structures of the Adduct Formed between Hen Egg-White Lysozyme and at Various Time Points

The pharmacological profile of medicinally relevant Ru(III) coordination compounds has been ascribed to their interactions with proteins, as several studies have provided evidence that DNA is not the primary target. In this regard, numerous spectroscopic and crystallographic studies have indicated that the Ru(III) ligands play an important role in determining the metal binding site, acting as the recognition element in the early stages of the protein-complex formation. Herein, we present a series of near-atomic-resolution X-ray crystal structures of the adducts formed between the antimetastatic metallodrug imidazolium trans-[tetrachlorido(S-dimethyl sufoxide)(1H-imidazole)ruthenate(III)] (NAMI-A) and hen egg-white lysozyme (HEWL). These structures elucidate a series of binding events starting from the noncovalent interaction of intact NAMI-A ions with HEWL (1.5 h), followed by the stepwise exchange of all Ru ligands except for 1H-imidazole (26 h) to the final "ruthenated" protein comprising one aquated Ru ion coordinated to histidine-15 of HEWL (98 h). Our structural data clearly support a two-step mechanism of protein ruthenation, illustrating the ligand-mediated recognition step of the process.

A new bis-pyrazolylpyridine ruthenium(III) complex as a potential anticancer drug: in vitro and in vivo activity in murine colon cancer

We synthesized and characterized the ruthenium(iii) pincer-type complex [RuCl3(H2Lt-Bu] (H2Lt-Bu = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine, 1) by elemental analysis, IR and UV-Vis spectroscopy, and the mass spectrometry (MS) method ESI Q-TOF. For comparison reasons, we also studied ruthenium(iii) terpyridine complexes of the general formula [Ru(N-N-N)Cl3], where N-N-N = 4'-chloro-terpyridine (Cl-tpy; 2) or 4'-chlorophenyl-terpyridine (Cl-Ph-tpy; 3). A kinetic study of the substitution reactions of 1-3 with biomolecules showed that the rate constants depend on the properties of the spectator ligand and the nature of the entering nucleophile. The DNA/HSA binding study showed that in comparison to complex 1 (bis-pyrazolylpyridine), the other two (2 and 3) terpyridine complexes had a slightly better binding affinity to calf thymus DNA (CT DNA), while in the case of human serum albumin (HSA), complex 1 exhibited the strongest quenching ability. We demonstrated that 1 possesses significant in vitro cytotoxic activity against mouse colon carcinoma CT26 cells and in vivo antitumor activity in murine heterotopic colon carcinoma. Complex 1 induced G0/G1 cell cycle arrest and apoptotic death in CT26 cells. Additionally, 1 showed antiproliferative activity, as evaluated by the detection of the expression levels of the Ki67 protein. Furthermore, the in vivo results showed that 1 reduced primary tumour growth and the number and growth of lung and liver metastases, significantly prolonging the treated mice's survival rate. This study highlighted that 1 does not show hepato- and nephrotoxicity. Our data demonstrated the considerable antitumor activity of the ruthenium(iii) pincer complex against CT26 tumour cells and implicated further investigations of its role as a potential chemotherapeutic agent for colon carcinoma.

Piano-Stool Ruthenium(II) Complexes with Delayed Cytotoxic Activity: Origin of the Lag Time

We have recently reported a series of piano-stool ruthenium(II) complexes of the general formula [RuCl₂(η⁶-arene)(P(1-pyrenyl)R²R³)] showing excellent cytotoxic activities (particularly when R² = R³ = methyl). In the present study, new members of this family of compounds have been prepared with the objective to investigate the effect of the steric hindrance of a bulky phosphane ligand, namely diisopropyl(1-pyrenyl)phosphane (L), on exchange reactions involving the coordinated halides (X = Cl, I). Two η⁶-arene rings were used, i.e. η⁶-methyl benzoate (mba) and η⁶-p-cymene (p-cym), and four complexes were synthesized, namely [RuCl₂(mba)(L)] (1_Cl2^iPr), [RuI₂(mba)(L)] (1_I2^iPr), [RuCl₂(p-cym)(L)] (2_Cl2^iPr), and [RuI₂(p-cym)(L)] (2_I2^iPr). Unexpectedly, all of the complexes exhibited poor cytotoxic activities after 24 h of incubation with cells, in contrast to the related compounds previously reported. However, it was observed that aged DMSO solutions of 2_I2^iPr (from 2 to 7 days) exhibited better activities in comparison to freshly prepared solutions and that the activity improved over “aging” time. Thorough studies were therefore performed to uncover the origin of this lag time in the cytotoxicity efficiency. The data achieved clearly demonstrated that compounds 2_I2^iPr and 2_Cl2^iPr were undergoing a series of transformation reactions in DMSO (with higher rates for the iodido complex 2_I2^iPr), ultimately generating cyclometalated species through a mechanism involving DMSO as a coordinated proton abstractor. The cyclometalated complexes detected in solution were subsequently prepared; hence, pure [RuCl(p-cym)(κ²C-diisopropyl(1-pyrenyl)phosphane)] (3_Cl^iPr), [RuI(p-cym)(κ²C-diisopropyl(1-pyrenyl)phosphane)] (3_I^iPr), and [Ru(p-cym)(κS-dmso)(κ²C-diisopropyl(1-pyrenyl)phosphane)]PF₆ (3_dmso^iPr) were synthesized and fully characterized. Remarkably, 3_Cl^iPr, 3_I^iPr, and 3_dmso^iPr are all very efficient cytotoxic agents, exhibiting slightly better activities in comparison to the chlorido noncyclometalated complexes [RuCl₂(η⁶-arene)(P(1-pyrenyl)R²R³)] described in an earlier report. For comparison purposes, the iodido compounds [RuI₂(mba)(dimethyl(1-pyrenyl)phosphane)] (1_I2^Me) and [RuI₂(p-cym)(dimethyl(1-pyrenyl)phosphane)] (2_I2^Me), bearing the less hindered dimethyl(1-pyrenyl)phosphane ligand, have also been prepared. The cytotoxic and chemical behaviors of 1_I2^Me and 1_I2^Me were comparable to those of their chlorido counterparts reported previously.

DMSO gradually converts half-sandwich, 1-pyrenyl-containing ruthenium(II) complexes into cyclometalated species showing notable cytotoxic properties.

Platinum(II) N-heterocyclic carbene complexes arrest metastatic tumor growth

Vimentin is a cytoskeletal intermediate filament protein that plays pivotal roles in tumor initiation, progression, and metastasis, and its overexpression in aggressive cancers predicted poor prognosis. Herein described is a highly effective antitumor and antimetastatic metal complex [Pt^II(C^N^N)(NHC^2Bu)]PF₆ (Pt1a; HC^N^N = 6-phenyl-2,2'-bipyridine; NHC= N-heterocyclic carbene) that engages vimentin via noncovalent binding interactions with a distinct orthogonal structural scaffold. Pt1a displays vimentin-binding affinity with a dissociation constant of 1.06 µM from surface plasmon resonance measurements and fits into a pocket between the coiled coils of the rod domain of vimentin with multiple hydrophobic interactions. It engages vimentin in cellulo, disrupts vimentin cytoskeleton, reduces vimentin expression in tumors, suppresses xenograft growth and metastasis in different mouse models, and is well tolerated, attributable to biotransformation to less toxic and renal-clearable platinum(II) species. Our studies uncovered the practical therapeutic potential of platinum(II)‒NHC complexes as effective targeted chemotherapy for combating metastatic and cisplatin-resistant cancers.

Cis,cis,trans-[PtIVCl2(NH3)2(perillato)2], a dual-action prodrug with excellent cytotoxic and antimetastatic activity

Two Pt(iv) conjugates containing one or two molecules of perillic acid (4-isopropenylcyclohexene-1-carboxylic acid), an active metabolite of limonene, were synthesized both with traditional and microwave-assisted methods and characterized. Their antiproliferative activity was tested on a panel of human tumor cell lines. In particular, cis,cis,trans-[Pt^IVCl₂(NH₃)₂(perillato)₂] exhibited excellent antiproliferative and antimetastatic activity on A-549 lung tumor cells at nanomolar concentrations. A number of in vitro biological tests were performed to decipher some aspects of its mechanism of action, including transwell migration and invasion as well as wound healing assay.

Conformational Modulation of Iduronic Acid-Containing Sulfated Glycosaminoglycans by a Polynuclear Platinum Compound and Implications for Development of Antimetastatic Platinum Drugs

1 H NMR spectroscopic studies on the 1:1 adduct of the pentasaccharide Fondaparinux (FPX) and the substitution-inert polynuclear platinum complex TriplatinNC show significant modulation of geometry around the glycosidic linkages of the FPX constituent monosaccharides. FPX is a valid model for the highly sulfated cell signalling molecule heparan sulfate (HS). The conformational ratio of the 1 C4 :2 S0 forms of the FPX residue IdoA(2S) is altered from ca. 35:65 (free FPX) to ca. 75:25 in the adduct; the first demonstration of a small molecule affecting conformational changes on a HS oligosaccharide. Functional consequences of such binding are suggested to be inhibition of HS cleavage in MDA-MB-231 triple-negative breast cancer (TNBC) cells. We further describe inhibition of metastasis by TriplatinNC in the TNBC 4T1 syngeneic tumour model. Our work provides insight into a novel approach for design of platinum drugs (and coordination compounds in general) with intrinsic anti-metastatic potential.