Organometallic anticancer compounds

Well designed iridium-phosphinite complexes: Biological assays, electrochemical behavior and density functional theory calculations

Mononuclear phosphinite Iridium complexes based on ferrocene group have been prepared and characterized by various spectroscopic techniques. The complexes were subjected to cyclic voltammetry studies in order to determine the energies of HOMO and LUMO levels and to estimate their electrochemical and some electronic properties. Organic complex-based memory substrates were immobilized using TiO2-modified ITO electrodes, and the memory functions of phosphinite-based organic complexes were verified by chronoamperometry (CA) and open-circuit potential amperometry (OCPA). Extensive theoretical and experimental investigations were directed to gain a more profound understanding of the chemical descriptors and the diverse electronic transitions taking place within the iridium complexes, as well as their electrochemical characteristics. The quantum chemical calculations were carried out for the iridium complexes at the DFT/CAM-B3LYP level of theory in the gas phase. Furthermore, the antioxidant, antimicrobial, DNA binding, and DNA cleavage activities of the complexes were tested. Complex 2 exhibited the highest radical scavenging activity (67.5 ± 2.24 %) at 200.0 mg/L concentration. It was observed that the complexes formed an inhibition zone in the range of 8-15 mm against Gram + bacteria and in the range of 0-13 mm against Gram - bacteria. The agarose gel electrophoresis method was used to determine the DNA binding and DNA cleavage activities of the complexes. All of the tested complexes had DNA binding activity; however, complexes 1, 2, and 8 showed better binding activity than the others.

Exploring the effect of the axial ligands on the anticancer activity of [C,N,N'] Pt(IV) cyclometallated compounds

The synthesis of three novel [C,N,N'] Pt(IV) cyclometallated compounds containing hydroxo, dichloroacetato or trifluoroacetato axial ligands is reported. Compound [PtCl(OH)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (3) was prepared by the oxidative addition of hydrogen peroxide to [C,N,N'] Pt(II) cyclometallated compound [PtCl{(CH3)2N(CH2)2NCH(4-FC6H3)}] (1) and further the reaction of compound 3 with dichloroacetate or trifluoroacetate anhydrides led to the formation of the corresponding compounds [PtCl(CHCl2COO)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (4) and [PtCl(CF3COO)2{(CH3)2N(CH2)2NCH(4-FC6H3)}] (5). The properties of the new compounds along with those of the compound [PtCl3{(CH3)2N(CH2)2NCH(4-FC6H3)}] (2), including stability in aqueous media, reduction potential using cyclic voltammetry, cytotoxic activity against the HCT116 CRC cell line, DNA interaction, topoisomerase I and cathepsin inhibition, and computational studies involving reduction of the Pt(IV) compounds and molecular docking studies, are presented. Interestingly, the antiproliferative activity of these compounds against the HCT116 CRC cell line, which is in all cases higher than that of cisplatin, follows the same trend as the reduction potentials so that the most easily reduced compound 2 is the most potent. In contrast, according to the electrophoretic mobility and molecular docking studies, the efficacy of these compounds in binding to DNA is not related to their cytotoxicity. The most active compound 2 does not modify the DNA electrophoretic mobility while the less potent compound 3 is the most efficient in binding to DNA. Although compounds 2 and 3 have only a slight effect on cell cycle distribution and apoptosis induction, generation of ROS to a higher extent for the most easily reduced compound 2 was observed.

A Self-Catalytic NO/O2 Gas-Releasing Nanozyme for Radiotherapy Sensitization through Vascular Normalization and Hypoxia Relief

Radiotherapy (RT), essential for treating various cancers, faces challenges from tumor hypoxia, which induces radioresistance. A tumor-targeted "prosthetic-Arginine" coassembled nanozyme system, engineered to catalytically generate nitric oxide (NO) and oxygen (O2) in the tumor microenvironment (TME), overcoming hypoxia and enhancing radiosensitivity is presented. This system integrates the prosthetic heme of nitric oxide synthase (NOS) and catalase (CAT) with NO-donating Fmoc-protected Arginine and Ru3+ ions, creating HRRu nanozymes that merge NOS and CAT functionalities. Surface modification with human heavy chain ferritin (HFn) improves the targeting ability of nanozymes (HRRu-HFn) to tumor tissues. In the TME, strategic arginine incorporation within the nanozyme allows autonomous O2 and NO release, triggered by endogenous hydrogen peroxide, elevating NO and O2 levels to normalize vasculature and improve blood perfusion, thus mitigating hypoxia. Employing the intrinsic O2-transporting ability of heme, HRRu-HFn nanozymes also deliver O2 directly to the tumor site. Utilizing esophageal squamous cell carcinoma as a tumor model, the studies reveal that the synergistic functions of NO and O2 production, alongside targeted delivery, enable the HRRu-HFn nanozymes to combat tumor hypoxia and potentiate radiotherapy. This HRRu-HFn nanozyme based approach holds the potential to reduce the radiation dose required and minimize side effects associated with conventional radiotherapy.

Anticancer potential of NSAID-derived tris(pyrazolyl)methane ligands in iron(II) sandwich complexes

Tris(pyrazolyl)methane (tpm), 2,2,2-tris(pyrazolyl)ethanol (tpmOH) and its esterification derivatives with ibuprofen and flurbiprofen (tpmIBU and tpmFLU) were used as ligands to obtain complexes of the type [Fe(tpmX)2]Cl2 (1-4). The tpmIBU and tpmFLU ligands and corresponding complexes 3 and 4 were characterized by IR and multinuclear NMR spectroscopy, and the structure of tpmIBU was elucidated by single crystal X-ray diffraction. Complexes 1-4 were also assessed for their behaviour in aqueous media (solubility in D2O, octanol/water partition coefficient, stability in physiological-like conditions). The antiproliferative activity of ligands and complexes was determined on A2780, A2780cis and A549 cancer cell lines and the non-cancerous HEK 293T and BJ cell lines. The ligands and complexes were investigated for their ability to inhibit COX-2 (cyclooxygenase) and HNE (4-hydroxynonenal) enzymes. Complexes 3 and 4 exhibited cytotoxicity that may be attributed predominantly to their bioactive fragments, while DNA binding and enhancement of ROS production do not appear to play any significant role.

Host-Guest Interactions of Ruthenium(II) Arene Complexes with Cucurbit[7/8]uril

Cucurbit[n]urils (CB[n]s) have been recognized for their chemical and thermal stability, and their ability to bind many neutral and cationic guest molecules makes them excellent hosts in a range of supramolecular applications. In drug delivery, CB[n]s can enhance drug solubility, improve chemical and physical drug stability, and allow for triggered and controlled release. This study aimed to investigate the ability of CB[7] and CB[8] as molecular hosts to bind ruthenium(II) arene complexes that are current anticancer lead structures in the area of metallodrugs. Both, experimental and computational methods, led to insights into the binding preferences and geometries of [RuII(cym)Cl2]2 (1; cym = η6-p-cymene), [RuII(cym)(dmb)Cl2]) (2; cym = η6-p-cymene; dmb = 1,3-dimethylbenzimidazol-2-ylidene), and [RuII(cym)(pta)Cl2] (3, RAPTA-C; cym = η6-p-cymene; pta = 1,3,5-triaza-7-phospha-adamantane) with CB[7] and CB[8]. Competition experiments by mass spectrometry revealed clear preferences of 2 for CB[8] and 3 for CB[7]. Based on a comparison of the associated interaction energies from quantum chemical calculations as well as experimental data, 3@CB[7] clearly prefers a binding mode, where the pta ligand is located inside the cavity of the host, and the metal ion interacts with two of the carbonyl groups on the rim of CB[7]. In contrast, complex 2 binds in two different orientations with interaction energies similar to those of both CB[n]s, with the cym ligand being either inside or outside of the cavity. These findings suggest that ruthenium(II) arene complexes are able to form stable host-guest interactions with CB[n]s, which can be exploited as drug delivery vehicles in further metallodrug development to improve their chemical stability.

Analysis of antiproliferative activity of new half-sandwich arene Ru(II) thiophene based aroylhydrazone complexes

Efforts in researching the efficient anti-tumor properties of three novel arene ruthenium(II) complexes incorporating thiophene-based aroylhydrazone ligands have been undertaken. The complexes' elemental composition was [(η6-p-cymene)Ru(L)Cl]. They were comprehensively characterized through elemental and spectroscopic analyses (FT-IR, UV-vis, NMR, and HR-MS). Single crystal X-ray diffraction studies revealed a pseudo-octahedral geometry with bidentate coordination of the ligands in a representative complex. The in vitro assessment of the complexes' cancer cell growth inhibition was conducted using the MTT assay against A549 (human lung carcinoma), HeLa (human cervical carcinoma), HuH-7 (hepatocellular carcinoma), and NIH-3T3 (mouse fibroblast non-cancerous cell line). Results indicated significant cytotoxicity across all cancer cell lines, with IC50 concentrations of complex 2 being 6.8 μM for A549, 11.6 μM for HeLa, and 9.4 μM for HuH-7, compared to cisplatin with IC50 values of 18.9 μM, 17.68 μM, and 24 μM respectively. Notably, complex 2 demonstrated particularly promising cytotoxicity against all tested cancerous cell lines. Fluorescent staining analysis such as acridine orange/ethidium bromide (AO-EB) and HOECHST 33342 revealed cell death mechanisms involving membrane disintegration and nuclear condensation following treatment with complex 2. Further studies were conducted to measure reactive oxygen species (ROS) levels using the dichlorodihydrofluorescein diacetate (DCFH-DA) assay, and mitochondrial membrane potential (MMP) was assessed using the JC-1 dye assay. These studies demonstrated that complex 2 increased ROS levels, decreased membrane potential, and promoted mitochondrial dysfunction-mediated cell death pathways. Additionally, flow cytometry analysis, utilizing dual staining of Annexin V-FITC and propidium iodide (PI), was employed to quantitatively study apoptosis induction.

Programmable Release of Chemotherapeutics from Ferrocene-Based Injectable Hydrogels Slows Melanoma Growth

Hydrogel-based injectable drug delivery systems provide temporally and spatially controlled drug release with reduced adverse effects on healthy tissues. Therefore, they represent a promising therapeutic option for unresectable solid tumor entities. In this study, a peptide-starPEG/hyaluronic acid-based physical hydrogel is modified with ferrocene to provide a programmable drug release orchestrated by matrix-drug interaction and local reactive oxygen species (ROS). The injectable ROS-responsive hydrogel (hiROSponse) exhibits adequate biocompatibility and biodegradability, which are important for clinical applications. HiROSponse is loaded with the two cytostatic drugs (hiROSponsedox/ptx) doxorubicin (dox) and paclitaxel (ptx). Dox is a hydrophilic compound and its release is mainly controlled by Fickian diffusion, while the hydrophobic interactions between ptx and ferrocene can control its release and thus be regulated by the oxidation of ferrocene to the more hydrophilic state of ferrocenium. In a syngeneic malignant melanoma-bearing mouse model, hiROSponsedox/ptx slows tumor growth without causing adverse side effects and doubles the relative survival probability. Programmable release is further demonstrated in a tumor model with a low physiological ROS level, where dox release, low dose local irradiation, and the resulting ROS-triggered ptx release lead to tumor growth inhibition and increased survival.

Selective COX-2 inhibitors as anticancer agents: a patent review (2018-2023)

INTRODUCTION

COX-2 is a crucial enzyme in the manufacture of prostaglandins. The enzyme's metabolites might have an important function as regulators of the inflammatory response and other medical conditions such as cancer. Selective COX-2 inhibitors are believed to enhance or reverse the response of cancer chemotherapeutics.

AREAS COVERED

This study addresses the chemical structures as well as the antitumor activity of new COX-2 inhibitors produced in the recent five years, aiming to provide an insight into the mechanism of COX-2 induced PGE2 powerful signal in cancer development.

EXPERT OPINION

The significance of selective COX-2 inhibitors as an efficient superfamily of compounds with anti-inflammatory, anti-Alzheimer's, anti-Parkinson's disease, and anticancer properties has piqued the passion of academics in the field of drug development. Long-term usage of selective COX-2 inhibitors, such as celecoxib has been proven in clinical trials to lower the incidence of several human malignancies. Furthermore, celecoxib has the potential to greatly increase the effectiveness of chemotherapy. Our extensive understanding of selective COX-2 inhibitor SAR may aid in the development of safer and more effective selective COX-2 inhibitors as cancer chemopreventive agents. This review focuses on the different structural classes of selective COX-2 inhibitors, with a particular emphasis on their SAR.

Ferrocenyl Azoles: Versatile N-Containing Heterocycles and their Anticancer Activities

The medicinal chemistry of ferrocene has gained its momentum after the discovery of biological activities of ferrocifen and ferroquine. These ferrocenyl drugs have been designed by replacing the aromatic moiety of the organic drugs, tamoxifen and chloroquine respectively, with a ferrocenyl unit. The promising biological activities of these ferrocenyl drugs have paved a path to explore the medicinal applications of several ferrocenyl conjugates. In these conjugates, the ferrocenyl moiety has played a vital role in enhancing or imparting the anticancer activity to the molecule. The ferrocenyl conjugates induce the cytotoxicity by generating reactive oxygen species and thereby damaging the DNA. In medicinal chemistry, the five membered nitrogen heterocycles (azoles) play a significant role due to their rigid ring structure and hydrogen bonding ability with the biomolecules. Several potent drug candidates with azole groups have been in use as chemotherapeutics. Considering the importance of ferrocenyl moiety and azole groups, several ferrocenyl azole conjugates have been synthesized and screened for their biological activities. Hence, in the view of a wide scope in the development of potent drugs based on ferrocenyl azole conjugates, herein we present the details of synthesis and the anticancer activities of ferrocenyl compounds bearing azole groups such as imidazole, triazoles, thiazole and isoxazoles.

Metal complexes bearing EGFR-inhibiting ligands as promising anticancer agents

Overexpression of the epidermal growth factor receptor (EGFR, erbB1) has been observed in a wide range of solid tumors and has frequently been associated with poor prognosis. As a result, EGFR inhibition has become an attractive anticancer drug design strategy, and a large number of small molecular inhibitors have been developed. Despite the widespread clinical use of EGFR tyrosine kinase inhibitors (TKIs), their drug resistance, inadequate accumulation in tumors, and severe side effects have spurred the search for better antitumor drugs. Metal complexes have attracted much attention because of their different mechanisms compared with EGFR-TKIs. Therefore, the combination of metals and inhibitors is a promising anticancer strategy. For example, Ru and Pt centers are introduced to design complexes with double or multiple targets, while Au complexes are combined with inhibitors to overcome drug resistance. Co complexes are designed as prodrugs with weak side effects and enhanced targeting by the hypoxia activation strategy, and other metals such as Rh and Fe enhance the anticancer effect of the complexes. In addition, the introduction of Ga center is beneficial to the development of nuclear imaging tracers. In this paper, metal EGFR-TKI complexes in the last 15 years are reviewed, their mechanisms are briefly introduced, and their advantages are summarized.

Beyond transition block metals: exploring the reactivity of phosphine PTA and its oxide [PTA(O)] towards gallium(iii)

The water-soluble cage-like phosphine PTA (1,3,5-triaza-7-phosphaadamantane) and its phosphine oxide derivative [PTA(O)] (1,3,5-triaza-7-phosphaadamantane-7-oxide) were used to explore their reactivity towards two gallium(iii)-halide precursors, namely GaCl3 and GaI3, for the first time. By using various reaction conditions, a series of N-mono-protonated phosphine salts with [GaCl4]- or [I]- as counterions were obtained in all cases, while the formation of coordinated Ga-PTA and Ga-[PTA(O)] complexes was not observed. All compounds were characterized in solution using multinuclear NMR spectroscopy (1H, 13C{1H}, 31P{1H} and 71Ga) and in the solid state using FT-IR spectroscopy and X-ray crystal diffraction. The new Ga-phosphine salts resulted stable and highly soluble in aqueous solution at room temperature. Density functional theory (DFT) calculations were also performed to further rationalize the coordination features of PTA with Ga3+ metal ion, highlighting that the phosphorus-gallium bond is about twice weaker than the phosphorus-metal bond commonly established by PTA with transition metals such as gold. Furthermore, the mono-protonation of PTA (or [PTA(O)]) makes the formation of ionic gallium-PTA coordination complexes thermodynamically unstable, as confirmed experimentally by the formation of Ga-phosphine salts reported herein.

Metallacarboranes in Medicinal Chemistry: Current Advances and Future Perspectives

Metallacarboranes, exemplified by cobalt bis(dicarbollide) ([COSAN]-), have excelled their historical metallocene analogue label to become promising in drug design, medical studies, and fundamental biological research. Serving as a unique platform for conjugation with biomolecules, they also constitute an auspicious building block for biologically active derivatives and a carrier for cellular transport of membrane-impermeable cargos. Modified [COSAN]- exhibits specific antimicrobial, antiviral, and anticancer actions showing promise for preclinical trials. Contributing to the ongoing development in medicinal chemistry, metallacarboranes offer desirable physicochemical properties and low acute toxicity. This article presents a critical look at metallacarboranes in the context of their application in medicinal chemistry, emphasizing [COSAN]- as a potential game-changer in drug design and biomedical sciences. As medicinal chemistry seeks innovative building blocks, metallacarboranes emerge as an important novelty with versatile solutions and promising implications.

Coumarin-modified ruthenium complexes: Synthesis, characterization, and antiproliferative activity against human cancer cells

Among ruthenium complexes studied as anticancer metallodrugs, NKP-1339, NAMI-A, RM175, and RAPTA-C have already entered clinical trials due to their potent antitumor activity demonstrated in preclinical studies and reduced toxicity in comparison with platinum drugs. Considering the advantages of ruthenium-based anticancer drugs and the cytostatic activity of organometallic complexes with triazole- and coumarin-derived ligands, we set out to synthesize Ru(II) complexes of coumarin-1,2,3,-triazole hybrids (L) with the general formula [Ru(L)(p-cymene)(Cl)]ClO4. The molecular structure of the complex [Ru(2a)(p-cymene)(Cl)]ClO4 (2aRu) was determined by single-crystal X-ray diffraction, which confirmed the coordination of the ligand to the central ruthenium(II) cation by bidentate mode of coordination. Coordination with Ru(II) resulted in the enhancement of cytostatic activity in HepG2 hepatocellular carcinoma cells and PANC-1 pancreatic cancer cells. Coumarin derivative 2a positively regulated the expression and activity of c-Myc and NPM1 in RKO colon carcinoma cells, while the Ru(II) half-sandwich complex 2cRu induced downregulation of AKT and ERK signaling in PANC-1 cells concomitant with reduced intracellular levels of reactive oxygen species. Altogether, our findings indicated that coumarin-modified half-sandwich Ru(II) complexes held potential as anticancer agents against gastrointestinal malignancies.

Visible and Red Light-Triggered Anticancer Profile of a Ferrocene-Re(I)-Tricarbonyl Conjugate: Experimental and Theoretical Studies

We have red-shifted the light absorbance property of a Re(I)-tricarbonyl complex via distant conjugation of a ferrocene moiety and developed a novel complex ReFctp, [Re(Fctp)(CO)3Cl], where Fctp = 4'-ferrocenyl-2,2':6',2″-terpyridine. ReFctp showed green to red light absorption ability and blue emission, indicating its potential for photodynamic therapy (PDT) application. The conjugation of ferrocene introduced ferrocene-based transitions, which lie at a higher wavelength within the PDT therapeutic window. The time-dependent density functional theory and excited state calculations revealed an efficient intersystem crossing for ReFctp, which is helpful for PDT. ReFctp elicited both PDT type I and type II pathways for reactive oxygen species (ROS) generation and facilitated NADH (1,4-dihydro-nicotinamide adenine dinucleotide) oxidation upon exposure to visible light. Importantly, ReFctp showed effective penetration through the layers of clinically relevant 3D multicellular tumor spheroids and localized primarily in mitochondria (Pearson's correlation coefficient, PCC = 0.65) of A549 cancer cells. ReFctp produced more than 20 times higher phototoxicity (IC50 ∼1.5 μM) by inducing ROS generation and altering mitochondrial membrane potential in A549 cancer cells than the nonferrocene analogue Retp, [Re(CO)3(tp)Cl], where tp = 2,2':6',2″-terpyridine. ReFctp induced apoptotic mode of cell death with a notable photocytotoxicity index (PI, PI = IC50dark/IC50light) and selectivity index (SI, SI = normal cell's IC50dark/cancer cell's IC50light) in the range of 25-33.

Novel antimony-based antimicrobial drug targets membranes of Gram-positive and Gram-negative bacterial pathogens

Antimicrobial resistance (AMR) poses a significant worldwide public health crisis that continues to threaten our ability to successfully treat bacterial infections. With the decline in effectiveness of conventional antimicrobial therapies and the lack of new antibiotic pipelines, there is a renewed interest in exploring the potential of metal-based antimicrobial compounds. Antimony-based compounds with a long history of use in medicine have re-emerged as potential antimicrobial agents. We previously synthesized a series of novel organoantimony(V) compounds complexed with cyanoximates with a strong potential of antimicrobial activity against several AMR bacterial and fungal pathogens. Here, five selected compounds were studied for their antibacterial efficacy against three important bacterial pathogens: Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. Among five tested compounds, SbPh4ACO showed antimicrobial activity against all three bacterial strains with the MIC of 50-100 µg/mL. The minimum bactericidal concentration/MIC values were less than or equal to 4 indicating that the effects of SbPh4ACO are bactericidal. Moreover, ultra-thin electron microscopy revealed that SbPh4ACO treatment caused membrane disruption in all three strains, which was further validated by increased membrane permeability. We also showed that SbPh4ACO acted synergistically with the antibiotics, polymyxin B and cefoxitin used to treat AMR strains of P. aeruginosa and S. aureus, respectively, and that at synergistic MIC concentration 12.5 µg/mL, its cytotoxicity against the cell lines, Hela, McCoy, and A549 dropped below the threshold. Overall, the results highlight the antimicrobial potential of novel antimony-based compound, SbPh4ACO, and its use as a potentiator of other antibiotics against both Gram-positive and Gram-negative bacterial pathogens.

IMPORTANCE

Antibiotic resistance presents a critical global public health crisis that threatens our ability to combat bacterial infections. In light of the declining efficacy of traditional antibiotics, the use of alternative solutions, such as metal-based antimicrobial compounds, has gained renewed interest. Based on the previously synthesized innovative organoantimony(V) compounds, we selected and further characterized the antibacterial efficacy of five of them against three important Gram-positive and Gram-negative bacterial pathogens. Among these compounds, SbPh4ACO showed broad-spectrum bactericidal activity, with membrane-disrupting effects against all three pathogens. Furthermore, we revealed the synergistic potential of SbPh4ACO when combined with antibiotics, such as cefoxitin, at concentrations that exert no cytotoxic effects tested on three mammalian cell lines. This study offers the first report on the mechanisms of action of novel antimony-based antimicrobial and presents the therapeutic potential of SbPh4ACO in combating both Gram-positive and Gram-negative bacterial pathogens while enhancing the efficacy of existing antibiotics.

Advancements in steroidal Pt(II) & Pt(IV) derivatives for targeted chemotherapy (2000-2023)

One of the key strategies in chemotherapy involves crosslinking the DNA strands of cancer cells to impede their replication, with platinum (Pt) coordination compounds being a prominent class and cisplatin being its major representative. Steroidal ligands tethered to DNA interactive Pt core act as drug carriers for targeted therapy. While crosslinking of nuclear or mitochondrial DNA strands using coordination complexes has been studied for years, there remains a lack of comprehensive reviews addressing the advancements made in steroidal-Pt derivatives. This review specifically focuses on advancements made in steroid-tethered structural derivatives of Pt(II) or prodrug Pt(IV) for targeted chemotherapy, synthesized between 2000 and 2023. This period was deliberately chosen due to the widespread use of computational techniques for more accurate structure-based drug-design in last two decades. This review discusses the strategy behind tethering steroidal ligands such as testosterone, estrogen, bile acids, and cholesterol to the central DNA interactive Pt core through specific linker groups. The steroidal ligands function as drug delivery vehicles of DNA interactive Pt core and bind with their respective target receptors or proteins that are often overexpressed in cancer cells, thus enabling targeted delivery of Pt moiety to interact with DNA. We discussed structural features such as the location of the linker group on the steroid, the mono, bi, and tridentate configuration of the chelating arm in coordination with Pt, and the rigidity and flexibility of the linker group. The comparative in vitro, in vivo activities, and relative binding affinities of the designed compounds against standard Pt drugs are also discussed. We also provided a critique of observed trends and shortcomings. Our review will provide insights into future molecular designing of targeted DNA crosslinkers and their structural optimization to achieve desired drug properties. From this analysis, we proposed further research directions leading to the future of targeted chemotherapy.

Synthesis and Characterization of Piano-Stool Ruthenium(II)-Arene Complexes of Isatin Schiff Bases: Cytotoxicity and DNA Intercalation

A series of aryl-isatin Schiff base derivatives (3a-d) and their piano-stool ruthenium complexes (4a-d) were synthesized and characterized via 1H and 13C NMR and Fourier transform infrared (FTIR) spectroscopy. In addition, the purity of all of the compounds (3a-c and 4a-d) was determined via elemental analysis. Complex 4d was analyzed using X-ray crystallography. An in vitro antiproliferative study of the compounds (3a-c and 4a-d) against human hepatocellular carcinoma (HEPG2), human breast cancer (MCF-7), human prostate cancer (PC-3), and human embryonic kidney (HEK-293) cells exhibited their considerable antiproliferative activity. 4d exhibited effective cytotoxicity against HEPG2 and MCF-7. It displayed higher cytotoxicity than the reference metallo-drug cisplatin. Moreover, the stability of 4d was studied via 1H NMR spectroscopy, and the binding model between 4d and DNA was investigated via ultraviolet-visible spectroscopy. The lipophilicity of the synthesized complexes was determined using an extraction method.

In vitro and in vivo activities of a trithiolato-diRuthenium complex conjugated with sulfadoxine against the apicomplexan parasite Toxoplasma gondii

Organometallic compounds, including Ruthenium complexes, have been widely developed as anti-cancer chemotherapeutics, but have also attracted much interest as potential anti-parasitic drugs. Recently hybrid drugs composed of organometallic Ruthenium moieties that were complexed to different antimicrobial agents were synthesized. One of these compounds, a trithiolato-diRuthenium complex (RU) conjugated to sulfadoxine (SDX), inhibited proliferation of Toxoplasma gondii tachyzoites grown in human foreskin fibroblast (HFF) monolayers with an IC50 < 150 nM, while SDX and the non-modified RU complex applied either individually or as an equimolar mixture were much less potent. In addition, conjugation of SDX to RU lead to decreased HFF cytotoxicity. RU-SDX did not impair the in vitro proliferation of murine splenocytes at concentrations ranging from 0.1 to 0.5 μM but had an impact at 2 μM, and induced zebrafish embryotoxicity at 20 μM, but not at 2 or 0.2 μM. RU-SDX acted parasitostatic but not parasiticidal, and induced transient ultrastructural changes in the mitochondrial matrix of tachyzoites early during treatment. While other compounds that target the mitochondrion such as the uncouplers FCCP and CCCP and another trithiolato-Ruthenium complex conjugated to adenine affected the mitochondrial membrane potential, no such effect was detected for RU-SDX. Evaluation of the in vivo efficacy of RU-SDX in a murine T. gondii oocyst infection model comprised of non-pregnant outbred CD1 mice showed no effects on the cerebral parasite burden, but reduced parasite load in the eyes and in heart tissue.

A promising future of metal-N-heterocyclic carbene complexes in medicinal chemistry: The emerging bioorganometallic antitumor agents

Metal complexes based on N-heterocyclic carbene (NHC) ligands have emerged as promising broad-spectrum antitumor agents in bioorganometallic medicinal chemistry. In recent decades, studies on cytotoxic metal-NHC complexes have yielded numerous compounds exhibiting superior cytotoxicity compared to cisplatin. Although the molecular mechanisms of these anticancer complexes are not fully understood, some potential targets and modes of action have been identified. However, a comprehensive review of their biological mechanisms is currently absent. In general, apoptosis caused by metal-NHCs is common in tumor cells. They can cause a series of changes after entering cells, such as mitochondrial membrane potential (MMP) variation, reactive oxygen species (ROS) generation, cytochrome c (cyt c) release, endoplasmic reticulum (ER) stress, lysosome damage, and caspase activation, ultimately leading to apoptosis. Therefore, a detailed understanding of the influence of metal-NHCs on cancer cell apoptosis is crucial. In this review, we provide a comprehensive summary of recent advances in metal-NHC complexes that trigger apoptotic cell death via different apoptosis-related targets or signaling pathways, including B-cell lymphoma 2 (Bcl-2 family), p53, cyt c, ER stress, lysosome damage, thioredoxin reductase (TrxR) inhibition, and so forth. We also discuss the challenges, limitations, and future directions of metal-NHC complexes to elucidate their emerging application in medicinal chemistry.

Strategies for the Nuclear Delivery of Metal Complexes to Cancer Cells

The nucleus is an essential organelle for the function of cells. It holds most of the genetic material and plays a crucial role in the regulation of cell growth and proliferation. Since many antitumoral therapies target nucleic acids to induce cell death, tumor-specific nuclear drug delivery could potentiate therapeutic effects and prevent potential off-target side effects on healthy tissue. Due to their great structural variety, good biocompatibility, and unique physico-chemical properties, organometallic complexes and other metal-based compounds have sparked great interest as promising anticancer agents. In this review, strategies for specific nuclear delivery of metal complexes are summarized and discussed to highlight crucial parameters to consider for the design of new metal complexes as anticancer drug candidates. Moreover, the existing opportunities and challenges of tumor-specific, nucleus-targeting metal complexes are emphasized to outline some new perspectives and help in the design of new cancer treatments.

Follow-Up Study of Trans-C to Cis-C Thermally or Photochemically Induced Isomerization of Terpyridine Adducts of Cycloruthenated 2-Aryl-2'-pyridine Compounds

The mechanism of isomerization of the known 2-phenyl,pyridine (phpy) derivatives [Ru(phpy-κC,N) (MeCN-trans-N)(terpy)]PF6, 2, to [Ru(phpy-κC,N)(MeCN-trans-C)(terpy)]PF6 (terpy = 2,2';6',2″-terpyridine), 3, at temperatures >50 °C has been investigated both by 1H NMR spectroscopy and by DFT calculations. The photoisomerization of 2 to 3 by UV light occurred also quantitatively in MeCN after 20 h at room temperature. A similar behavior to that of 2 could be established for the related compound [Ru(3-acridine-2'-C5H4N-κC,N)(MeCN-trans-N)(2,2';6',2″-terpyridine)]PF6, 6 (acridine = dibenzo[b,e]pyridine or 2,3-benzoquinoline), that was obtained from the reaction between [Ru(3-acridine-2'-C5H4N-κC,N) (MeCN)4]PF6, 4, and terpy in MeOH/MeCN at 60 °C for 24 h. Similar to 2, the isomerization of 6 to [Ru(3-acridine-2'-C5H4N-κC,N)(MeCN-trans-C) (terpy)]PF6, 7, could be induced thermally (48 h at 60 °C in pure MeOH) or photochemically under UV radiation in MeCN at room temperature. A compound closely related to 7 but in which MeCN was replaced by H2O was described earlier (Tanaka et al. Inorg. Chem. 2012, 51, 5386-539). The presence of water on this compound had a dramatic effect as far as the coordination of terpy was concerned as its isomerization to a compound related to 6 (in which H2O instead of MeCN is coordinated to Ru) occurred indeed photochemically via irradiation with visible light.

Organometallic Ru(II), Rh(III) and Re(I) complexes of sterane-based bidentate ligands: synthesis, solution speciation, interaction with biomolecules and anticancer activity

In this study, we present the synthesis, characterization and in vitro cytotoxicity of six organometallic [Ru(II)(η6-p-cymene)(N,N)Cl]Cl, [Rh(III)(η5-C5Me5)(N,N)Cl]Cl and [Re(I)(CO)3(N,N)Cl] complexes, in which the (N,N) ligands are sterane-based 2,2'-bipyridine derivatives (4-Me-bpy-St-OH, 4-Ph-bpy-St-OH). The solution chemical behavior of the ligands and the complexes was explored by UV-visible spectrophotometry and 1H NMR spectroscopy. The ligands and their Re(I) complexes are neutral at pH = 7.40; this contributes to their highly lipophilic character (log D7.40 > +3). The Ru(II) and Rh(III) half-sandwich complexes are much more hydrophilic, and this property is greatly affected by the actual chloride ion content of the medium. The half-sandwich Ru and Rh complexes are highly stable in 30% (v/v) DMSO/water (<5% dissociation at pH = 7.40); this is further increased in water. The Rh(III)(η5-C5Me5) complexes were characterized by higher water/chloride exchange and pKa constants compared to their Ru(II)(η6-p-cymene) counterparts. The Re(I)(CO)3 complexes are also stable in solution over a wide pH range (2-12) without the release of the bidentate ligand; only the chlorido co-ligand can be replaced with OH- at higher pH values. A comprehensive discussion of the binding affinity of the half-sandwich Ru(II) and Rh(III) complexes toward human serum albumin and calf-thymus DNA is also provided. The Ru(II)(η6-p-cymene) complexes interact with human serum albumin via intermolecular forces, while for the Rh(III)(η5-C5Me5) complexes the coordinative binding mode is suggested as well. They are also able to interact with calf-thymus DNA, most likely via the coordination of the guanine nitrogen. The Ru(II)(η6-p-cymene) complexes were found to be the most promising among the tested compounds as they exhibited moderate-to-strong cytotoxic activity (IC50 = 3-11 μM) in LNCaP as well as in PC3 prostate cells in an androgen receptor-independent manner. They were also significantly cytotoxic in breast and colon adenocarcinoma cancer cell lines and showed good selectivity for cancer cells.

Antifungal and Antiparasitic Activities of Metallocene-Containing Fluconazole Derivatives

The search for new anti-infectives based on metal complexes is gaining momentum. Among the different options taken by researchers, the one involving the use of organometallic complexes is probably the most successful one with a compound, namely, ferroquine, already in clinical trials against malaria. In this study, we describe the preparation and in-depth characterization of 10 new (organometallic) derivatives of the approved antifungal drug fluconazole. Our rationale is that the sterol 14α-demethylase is an enzyme part of the ergosterol biosynthesis route in Trypanosoma and is similar to the one in pathogenic fungi. To demonstrate our postulate, docking experiments to assess the binding of our compounds with the enzyme were also performed. Our compounds were then tested on a range of fungal strains and parasitic organisms, including the protozoan parasite Trypanosoma cruzi (T. cruzi) responsible for Chagas disease, an endemic disease in Latin America that ranks among some of the most prevalent parasitic diseases worldwide. Of high interest, the two most potent compounds of the study on T. cruzi that contain a ferrocene or cobaltocenium were found to be harmless for an invertebrate animal model, namely, Caenorhabditis elegans (C. elegans), without affecting motility, viability, or development.

DNA structural changes (photo)induced by tricarbonyl (pterin)rhenium(I) complex

We report on interactions of different types of DNA molecules including double-stranded and plasmid DNA as well as polynucleotides (poly[dGdC]2 and poly[dAdT]2) with fac-[ReI(CO)3(pterin)(H2O)] (or Reptr) complex. The interaction was characterized spectroscopically and changes in the plasmid structure were verified by both electrophoresis and AFM microscopy. For comparative reasons, two others related tricarbonyl rhenium(I) complexes, fac-[(4,4'-bpy)ReI(CO)3(dppz)]+ (or Redppz) and fac-[(CF3SO3)ReI(CO)3(2,2'-bpy)] (or Rebpy) were also studied to further explore the influence of the different co-ligands on the interaction and DNA (photo)damage. Data reported herein suggests that DNA molecules can be structurally modified either by direct interaction with Re(I) complexes in their ground states inducing DNA relaxation, and/or through photoinduced cross-linking processes. The chemical nature of the co-ligands modulates the extent of the damage observed.

Crystal structure and Hirshfeld surface analysis of (Z)-N-{chloro-[(4-ferrocenylphen-yl)imino]-meth-yl}-4-ferrocenylaniline N,N-di-methyl-formamide monosolvate

The title mol-ecule, [Fe2(C5H5)2(C23H17ClN2)]·C3H7NO, is twisted end to end and the central N/C/N unit is disordered. In the crystal, several C-H⋯π(ring) inter-actions lead to the formation of layers, which are connected by further C-H⋯π(ring) inter-actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (60.2%) and H⋯C/C⋯H (27.0%) inter-actions. Hydrogen bonding, C-H⋯π(ring) inter-actions and van der Waals inter-actions dominate the crystal packing.

Aminoquinoline-based Re(I) tricarbonyl complexes: Insights into their antiproliferative activity and mechanisms of action

In an effort to develop new potent anticancer agents, two Schiff base rhenium(I) tricarbonyl complexes, containing the ubiquitous aminoquinoline scaffold, were synthesized. Both aminoquinoline ligands and Re(I) complexes showed adequate stability over a 48-h incubation period. Furthermore, the cytotoxic activity of the precursor ligands and rhenium(I) complexes were evaluated against the hormone-dependent MCF-7 and hormone-independent triple negative MDA-MB-231 breast cancer cell lines. Inclusion of the [Re(CO)3Cl]+ entity significantly enhanced the cytotoxicity of the aminoquinoline Schiff base ligands against the tested cancer cell lines. Remarkably, the incorporation of the Schiff-base iminoquinolyl entity notably enhanced the cytotoxic activity of the Re(I) complexes, in comparison with the iminopyridyl entity. Notably, the quinolyl-substituted complex showed up to three-fold higher activity than cisplatin against breast cancer cell lines, underpinning the significance of the quinoline pharmacophore in rational drug design. In addition, the most active Re(I) complex showed better selectivity towards the breast cancer cells over non-tumorigenic FG-0 cells. Western blotting revealed that the complexes increased levels of γH2AX, a key DNA damage response protein. Moreover, apoptosis was confirmed in both cell lines due to the detection of cleaved PARP. The complexes show favourable binding affinities towards both calf thymus DNA (CT-DNA), and bovine serum albumin (BSA), and the order of their interactions align with their cytotoxic effects. The in silico molecular simulations of the complexes were also performed with CT-DNA and BSA targets.

The cytotoxic and antiproliferative properties of ruthenium nitrosyl complexes and their modulation effect on cytochrome P450 in the HepG2 cell line

Ruthenium nitrosyl complexes are actively investigated as antitumor agents. Evaluation of potential interactions between cytochromes P450 (CYPs) with new compounds is carried out regularly during early drug development. In this study we have investigated the cytotoxic and antiproliferative activities of ruthenium nitrosyl complexes with methyl/ethyl esters of nicotinic and isonicotinic acids and γ-picoline against 2D and 3D cultures of human hepatocellular carcinoma HepG2 and non-cancer human lung fibroblasts MRC-5, assessed their photoinduced activity at λrad = 445 nm, and also evaluated their modulating effect on CYP3A4, CYP2C9, and CYP2C19. The study of cytotoxic and antiproliferative activities against 2D and 3D cell models was performed using phenotypic-based high content screening (HCS). The expression of CYP3A4, CYP2C9, and CYP2C19 mRNAs and CYP3A4 protein was examined using target-based HCS. The results of CYP3A4 mRNA expression were confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR). The ruthenium nitrosyl complexes exhibited a dose-dependent cytotoxic effect against HepG2 and MRC-5 cells. The cytotoxic activity of complexes with ethyl isonicotinate (1) and nicotinate (3, 4) was significantly lower for MRC-5 than for HepG2, for a complex with methyl isonicotinate (2) it was higher for MRC-5 than for HepG2, for a complex with γ-picoline (5) it was comparable for both lines. The antiproliferative effect of complexes 2 and 5 was one order of magnitude higher for MRC-5; for complexes 1, 3, and 4 it was comparable for both lines. The cytotoxic activity of all compounds for 3D HepG2 was lower than for 2D HepG2, with the exception of 4. Photoactivation affected the activity of complex 1 only. Its cytotoxic activity decreased, while the antiproliferative activity increased. The ruthenium nitrosyl complexes 1-4 acted as inducers of CYP3A4 and CYP2C19, while the complex with γ-picoline (5) induced of CYP3A4. Among the studied ruthenium nitrosyl complexes, the most promising potential antitumor compound is the ruthenium compound with methyl nicotinate (4).

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

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

Anticancer Study on IrIII and RhIII Half-Sandwich Complexes with the Bipyridylsulfonamide Ligand

Organometallic half-sandwich complexes [(η5-Cp)IrCl(L)]PF6 (1) and [(η5-Cp)RhCl(L)]PF6 (2) were prepared using pentamethylcyclopentadienyl chloride dimers of iridium(III) or rhodium(III) with the 4-amino-N-(2,2'-bipyridin-5-yl)benzenesulfonamide ligand (L) and ammonium hexafluorophosphate. The crystal structures of L, 1, and 2 were analyzed in detail. The coordination reactions of the ligand with the central ions were confirmed using various spectroscopic techniques. Additionally, the interactions between sulfaligand, Ir(III), and Rh(III) complexes with carbonic anhydrase (CA), human serum albumin (HSA), and CT-DNA were investigated. The iridium(III) complex (1) did not show any antiproliferative properties against four different cancer cell lines, i.e., nonsmall cell lung cancer A549, colon cancer HCT-116, breast cancer MCF7, lymphoblastic leukemia Nalm-6, and a nonmalignant human embryonic kidney cell line HEK293, due to high binding affinity to GSH. The sulfonamide ligand (L) and rhodium(III) complex (2) were further studied. L showed competitive inhibition toward CA, while complexes 1 and 2, uncompetitive. All compounds interacted with HSA, causing a conformational change in the protein's α-helical structure, suggesting the induction of a more open conformation in HSA, reducing its biological activity. Both L and 2 were found to induce cell death through a caspase-dependent pathway. These findings position L and 2 as potential starting compounds for pharmaceutical, therapeutic, or medicinal research.

Cyclometalated ruthenium complexes overcome cisplatin resistance through PI3K/mTOR/Nrf2 signaling pathway

Currently, cisplatin resistance remains a primary clinical obstacle in the successful treatment of non-small cell lung cancer. Here, we designed, synthesized, and characterized two novel cyclometalated Ru(II) complexes, [Ru(bpy)2(1-Ph-7-OCH3-IQ)] (PF6) (bpy = 2,2'-bipyridine, IQ = isoquinoline, RuIQ7)and [Ru(bpy)2(1-Ph-6,7-(OCH3)2-IQ)] (PF6) (RuIQ8). As experimental controls, we prepared complex [Ru(bpy)2(1-Ph-IQ)](PF6) (RuIQ6) lacking a methoxy group in the main ligand. Significantly, complexes RuIQ6-8 displayed higher in vitro cytotoxicity when compared to ligands, precursor cis-[Ru(bpy)2Cl2], and clinical cisplatin. Mechanistic investigations revealed that RuIQ6-8 could inhibit cell proliferation by downregulating the phosphorylation levels of Akt and mTOR proteins, consequently affecting the rapid growth of human lung adenocarcinoma cisplatin-resistant cells A549/DDP. Moreover, the results from qRT-PCR demonstrated that these complexes could directly suppress the transcription of the NF-E2-related factor 2 gene, leading to the inhibition of downstream multidrug resistance-associated protein 1 expression and effectively overcoming cisplatin resistance. Furthermore, the relationship between the chemical structures of these three complexes and their anticancer activity, ability to induce cell apoptosis, and their efficacy in overcoming cisplatin resistance has been thoroughly examined and discussed. Notably, the toxicity test conducted on zebrafish embryos indicated that the three Ru-IQ complexes displayed favorable safety profiles. Consequently, the potential of these developed compounds as innovative therapeutic agents for the efficient and low-toxic treatment of NSCLC appears highly promising.

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

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

Research Progress of Metal Anticancer Drugs

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

A new ferrocene derivative blocks K-Ras localization and function by oxidative modification at His95

Ras proteins are membrane-bound GTPases that regulate essential cellular processes at the plasma membrane (PM). Constitutively active mutations of K-Ras, one of the three Ras isoforms in mammalian cells, are frequently found in human cancers. Ferrocene derivatives, which elevate cellular reactive oxygen species (ROS), have shown to block the growth of non-small cell lung cancers harboring oncogenic mutant K-Ras. Here, we tested a novel ferrocene derivative on the growth of pancreatic ductal adenocarcinoma and non-small cell lung cancer. Our compound, which elevated cellular ROS levels, inhibited the growth of K-Ras-driven cancers, and abrogated the PM binding and signaling of K-Ras in an isoform-specific manner. These effects were reversed upon antioxidant supplementation, suggesting a ROS-mediated mechanism. We further identified that K-Ras His95 residue plays an important role in this process, and it is putatively oxidized by cellular ROS. Together, our study demonstrates that the redox system directly regulates K-Ras/PM binding and signaling via oxidative modification at the His95, and proposes a role of oncogenic mutant K-Ras in the recently described antioxidant-induced growth and metastasis of K-Ras-driven cancers.

Organotin(IV)-Decorated Graphene Quantum Dots as Dual Platform for Molecular Imaging and Treatment of Triple Negative Breast Cancer

The pharmacological activity of organotin(IV) complexes in cancer therapy is well recognized but their large applicability is hampered by their poor water solubility. Hence, carbon dots, in particular nitrogen-doped graphene quantum dots (NGQDs), may be a promising alternative for the efficient delivery of organotin(IV) compounds as they have a substantial aqueous solubility, a good chemical stability, and non-toxicity as well as a bright photoluminescence that make them ideal for theranostic applications against cancer. Two different multifunctional nanosystems have been synthesized and fully characterized based on two fragments of organotin-based cytotoxic compounds and 4-formylbenzoic acid (FBA), covalently grafted onto the NGQDs surface. Subsequently, an in vitro determination of the therapeutic and theranostic potential of the achieved multifunctional systems was carried out. The results showed a high cytotoxic potential of the NGQDs-FBA-Sn materials against breast cancer cell line (MDA-MB-231) and a lower effect on a non-cancer cell line (kidney cells, HEK293T). Besides, thanks to their optical properties, the dots enabled their fluorescence molecular imaging in the cytoplasmatic region of the cells pointing towards a successful cellular uptake and a release of the metallodrug inside cancer cells (NGQDs-FBA-Sn).

Engineered Bacteria Labeled with Iridium(III) Photosensitizers for Enhanced Photodynamic Immunotherapy of Solid Tumors

Despite metal-based photosensitizers showing great potential in photodynamic therapy for tumor treatment, the application of the photosensitizers is intrinsically limited by their poor cancer-targeting properties. Herein, we reported a metal-based photosensitizer-bacteria hybrid, Ir-HEcN, via covalent labeling of an iridium(III) photosensitizer to the surface of genetically engineered bacteria. Due to its intrinsic self-propelled motility and hypoxia tropism, Ir-HEcN selectively targets and penetrates deeply into tumor tissues. Importantly, Ir-HEcN is capable of inducing pyroptosis and immunogenic cell death of tumor cells under irradiation, thereby remarkably evoking anti-tumor innate and adaptive immune responses in vivo and leading to the regression of solid tumors via combinational photodynamic therapy and immunotherapy. To the best of our knowledge, Ir-HEcN is the first metal complex decorated bacteria for enhanced photodynamic immunotherapy.

Beneficial Effects of Resveratrol and γ-Cyclodextrin on the Hematological and Biochemical Parameters of Healthy Wistar Rats Treated with Cisplatin: A PCA Approach

It is well known that platinum-based antineoplastic agents, including cisplatin (CP), have side effects that limit their use. Nefrotoxicity, neurotoxicity, and hemolytic anemia are the most common side effects. There are few studies on the reduction in these effects that involves nanoencapsulation; however, almost none involve cyclodextrins (CDs). Changes in the hematological and biochemical parameters of healthy Wistar rats treated with solutions of γ-cyclodextrin/resveratrol/cisplatin (γ-CD/Rv/CP) ternary complexes are investigated for the first time. They are intraperitoneally injected with γ-CD/Rv/CP solutions containing 5 mg CP/kg.b.w. Single shots were administered to six groups of Wistar rats (six individuals for every group) using γ-CD/Rv/CP, γ-CD/CP, γ-CD/Rv complexes, as well as positive- and negative-control groups, respectively. Thirty-two hematological and biochemical parameters were evaluated from blood samples and used as input variables for the principal component analysis (PCA) discrimination of the groups. The best protection was obtained for the γ-CD/Rv/CP ternary complex, which determined closer biochemical values to the control group. These values significantly differ from those of the γ-CD/CP treated group, especially for the IP, UA, and T-Pro kidney-related biochemical parameters. This finding proves the beneficial influence of Rv during CP administration through CD-based carriers.

Steroids Bearing Heteroatom as Potential Drugs for Medicine

Heteroatom steroids, a diverse class of organic compounds, have attracted significant attention in the field of medicinal chemistry and drug discovery. The biological profiles of heteroatom steroids are of considerable interest to chemists, biologists, pharmacologists, and the pharmaceutical industry. These compounds have shown promise as potential therapeutic agents in the treatment of various diseases, such as cancer, infectious diseases, cardiovascular disorders, and neurodegenerative conditions. Moreover, the incorporation of heteroatoms has led to the development of targeted drug delivery systems, prodrugs, and other innovative pharmaceutical approaches. Heteroatom steroids represent a fascinating area of research, bridging the fields of organic chemistry, medicinal chemistry, and pharmacology. The exploration of their chemical diversity and biological activities holds promise for the discovery of novel drug candidates and the development of more effective and targeted treatments.

Impact of the central atom and halido ligand on the structure, antiproliferative activity and selectivity of half-sandwich Ru(II) and Ir(III) complexes with a 1,3,4-thiadiazole-based ligand

Half-sandwich complexes [Ru(η6-pcym)(L1)X]PF6 (1, 3) and [Ir(η5-Cp*)(L1)X]PF6 (2, 4) featuring a thiadiazole-based ligand L1 (2-(furan-2-yl)-5-(pyridin-2-yl)-1,3,4-thiadiazole) were synthesized and characterized by varied analytical methods, including single-crystal X-ray diffraction (X = Cl or I, pcym = p-cymene, Cp* = pentamethylcyclopentadienyl). The structures of the molecules were analysed and interpreted using computational methods such as Density Functional Theory (DFT) and Quantum Theory of Atoms in Molecules (QT-AIM). A 1H NMR spectroscopy study showed that complexes 1-3 exhibited hydrolytic stability while 4 underwent partial iodido/chlorido ligand exchange in phosphate-buffered saline. Moreover, 1-4 demonstrated the ability to oxidize NADH (reduced nicotinamide adenine dinucleotide) to NAD+ with Ir(III) complexes 2 and 4 displaying higher catalytic activity compared to their Ru(II) analogues. None of the complexes interacted with reduced glutathione (GSH). Additionally, 1-4 exhibited greater lipophilicity than cisplatin. In vitro biological analyses were performed in healthy cell lines (CCD-18Co colon and CCD-1072Sk foreskin fibroblasts) as well as in cisplatin-sensitive (A2780) and -resistant (A2780cis) ovarian cancer cell lines. The results indicated that Ir(III) complexes 2 and 4 had no effect on human fibroblasts, demonstrating their selectivity. In contrast, complexes 1 and 4 exhibited moderate inhibitory effects on the metabolic and proliferation activities of the cancer cells tested (selectivity index SI > 3.4 for 4 and 2.6 for cisplatin; SI = IC50(A2780)/IC50(CCD-18Co)), including the cisplatin-resistant cancer cell line. Based on these findings, it is possible to emphasize that mainly complex 4 could represent a further step in the development of selective and highly effective anticancer agents, particularly against resistant tumour types.

Half-Sandwich Iridium(III), Rhodium(III), and Ruthenium(II) Complexes Chelating Hybrid sp2-N/sp3-N Donor Ligands to Achieve Improved Anticancer Selectivity

The biological efficacy of half-sandwich platinum group organometallic complexes of the formula [(η5-Cpx)/(η6-arene)M(XY)Cl]0/+ (XY = bidentate ligands; Cpx = functionalized cyclopentadienyl; M = Ir, Rh, Ru, Os) has received considerable attention due to the significance of the metal center, chelating ligand, and Cpx/arene moieties in defining their anticancer potency and selectivity. With a facile access to the BIAN-derived imine-amine ligands using alkylaluminum as the reductant, we herein described the preparation and characterization of 16 half-sandwich Ir(III), Rh(III), and Ru(II) complexes chelating the hybrid sp2-N/sp3-N donor ligand. A nonplanar five-member metallacycle was confirmed by X-ray single-crystal structures of Ir1-Ir3, Ir7, Rh1, Ru1, and Ru4. The attempt to prepare imine-amido complexes using a base as the deprotonating agent led to the mixture of imine-amine complexes, within which the leaving group Cl- was displaced, and 16-electron imine-amido complexes without Cl-. The half-sandwich imine-amine complexes in this system underwent rapid hydrolysis in aqueous solution, exhibited weak photoluminescence, and showed the ability of binding to CT-DNA and BSA. The cytotoxicity of all imine-amine complexes against A549 lung cancer cell lines, HeLa cervical cancer cell lines, and 4T1 mouse breast cancer cells was determined by an MTT assay. The IC50 values of these complexes were in a range of 5.71-67.28 μM. Notably, most of these complexes displayed improved selectivity toward A549 cancer cells versus noncancerous BEAS-2B cells in comparison with the corresponding α-diimine complexes chelating the sp2-N/sp2-N donor ligand, which have been shown no selectivity in our previous report. The anticancer selectivity of these complexes appeared to be related to the redox-based mechanism including the catalytic oxidation of NADH to NAD+, reactive oxygen species (ROS) generation, and depolarization of the mitochondrial membrane. Further, inducing apoptosis of these complexes in A549 cancer cells and BEAS-2B normal cells also correlated with their anticancer selectivity, indicating the apoptosis mode of cell death in this system. In addition, these complexes could enter A549 cells via energy-dependent pathway and were able to impede the in vitro migration of A549 cells.

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.

Hydrazylpyridine salicylaldehyde-copper(II)-1,10-phenanthroline complexes as potential anticancer agents: synthesis, characterization and anticancer evaluation

We synthesized and analyzed nine unique copper(II) hydrazylpyridine salicylaldehyde and 1,10-phenanthroline complexes, [Cu(L1a)(phen)] (Cugdupt1), [Cu(L2a)(phen)]·(CH3CN) (Cugdupt2), [Cu(L3a)(phen)] (Cugdupt3), [Cu(L4a)(phen)]·(CH3CN) (Cugdupt4), [Cu(L5a)(phen)] (Cugdupt5), [Cu(L6a)(phen)] (Cugdupt6), [Cu(L7a)(phen)] (Cugdupt7) [Cu(L8a)(phen)] (Cugdupt8) and [Cu(L9a)(phen)]·0.5(H2O) (Cugdupt9). We were motivated by the intriguing properties of the coupled ligands of hydrazylpyridine, salicylaldehyde, and 1,10-phenanthroline. The MTT assay demonstrated that Cugdupt1-Cugdupt9 have higher anticancer activity than L1H2-L9H2, phen and cisplatin on A549/DDP cancer cells (A549cis). Cugdupt1-Cugdupt9 were superior to cisplatin with IC50 values of 1.6-100.0 fold on A549cis cells (IC50(Cugdupt1-Cugdupt9) = 0.5-30.5 μM, IC50(cisplatin) = 61.5 ± 1.0 μM). However, Cugdupt1-Cugdupt9 had lower cytotoxicity toward the HL-7702 normal cells. Cugdupt1 and Cugdupt8 can induce reduction of mitochondrial respiratory chain complexes I/IV (MRCC-I/IV), mitophagy pathways, and eventually protein regulation and adenosine triphosphate (ATP) depletion in A549cis cells. The findings indicated that Cugdupt1 and Cugdupt8 caused cell death via both ATP diminution and mitophagy pathways. Finally, Cugdupt8 demonstrated high efficacy and no obvious cytotoxicity in A549 tumor-bearing mice. This study thus helps evaluate the potential of the hydrazylpyridine salicylaldehyde-copper(II)-1,10-phenanthroline compounds for cisplatin-resistant tumor therapy.

Thioredoxin Reductase and Organometallic Complexes: A Pivotal System to Tackle Multidrug Resistant Tumors?

Cancers classified as multidrug-resistant (MDR) are a family of diseases with poor prognosis despite access to increasingly sophisticated treatments. Several mechanisms explain these resistances involving both tumor cells and their microenvironment. It is now recognized that a multi-targeting approach offers a promising strategy to treat these MDR tumors. Inhibition of thioredoxin reductase (TrxR), a key enzyme in maintaining redox balance in cells, is a well-identified target for this approach. Auranofin was the first inorganic gold complex to be described as a powerful inhibitor of TrxR. In this review, we will first recall the main results obtained with this metallodrug. Then, we will focus on organometallic complexes reported as TrxR inhibitors. These include gold(I), gold(III) complexes and metallocifens, i.e., organometallic complexes of Fe and Os derived from tamoxifen. In these families of complexes, similarities and differences in the molecular mechanisms of TrxR inhibition will be highlighted. Finally, the possible relationship between TrxR inhibition and cytotoxicity will be discussed and put into perspective with their mode of action.

Effects of Ferrocene and Ferrocenium on MCF-7 Breast Cancer Cells and Interconnection with Regulated Cell Death Pathways

The effects of ferrocene (Fc) and ferrocenium (Fc+) induced in triple negative human breast cancer MCF-7 cells were explored by immunofluorescence, flow cytometry, and transmission electron microscopy analysis. The different abilities of Fc and Fc+ to produce reactive oxygen species and induce oxidative stress were clearly observed by activating apoptosis and morphological changes after treatment, but also after tests performed on the model organism D. discoideum, particularly in the case of Fc+. The induction of ferroptosis, an iron-dependent form of regulated cell death driven by an overload of lipid peroxides in cellular membranes, occurred after 2 h of treatment with Fc+ but not Fc. However, the more stable Fc showed its effects by activating necroptosis after a longer-lasting treatment. The differences observed in terms of cell death mechanisms and timing may be due to rapid interconversion between the two oxidative forms of internalized iron species (from Fe2+ to Fe3+ and vice versa). Potential limitations include the fact that iron metabolism and mitophagy have not been investigated. However, the ability of both Fc and Fc+ to trigger different and interregulated types of cell death makes them suitable to potentially overcome the shortcomings of traditional apoptosis-mediated anticancer therapies.

A binuclear Cu(I)-phosphine complex as a specific HSA site I binder: synthesis, X-ray structure determination, and a comprehensive HSA interaction analysis

In this research, we present a method for synthesis and a detailed description of geometry characterization of a novel binuclear Cu(I) phosphine complex, along with analysis of its interaction with HSA using spectroscopic and simulation methods. The Cu atoms are coordinated in a tetrahedral geometry, which results in coordination by two nitrogen atoms from the N,N'-(ethane-1,2-diyl)bis(1-(pyridin-2-yl)methanimine ligand (L), a chloride, and a PPh3. The complex binding constant to HSA in a biochemical environment was determined to be ∼106, which is indicative of a strong interaction. The fluorescence of HSA is significantly quenched by binding to the complex via a static mechanism, whereas the microenvironment of the tryptophan residue remains unchanged. A spontaneous binding process was indicated by a negative value for ΔG. Thermodynamic signatures reflect the dominance of hydrophobic forces during the interaction. The site marker competitive experiment combined with docking simulation analysis revealed the closeness position of the complex binding site to warfarin location in specific ligand site I of HSA. The information generated in the present study would be valuable to understand the interaction mechanistic and pharmacological behavior of Cu(I) complexes.Communicated by Ramaswamy H. Sarma.

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

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

Rhenium(I) Tricarbonyl Complexes of 1,10-Phenanthroline Derivatives with Unexpectedly High Cytotoxicity

Eight rhenium(I) tricarbonyl aqua complexes with the general formula fac-[Re(CO)3(N,N'-bid)(H2O)][NO3] (1-8), where N,N'-bid is (2,6-dimethoxypyridyl)imidazo[4,5-f]1,10-phenanthroline (L1), (indole)imidazo[4,5-f]1,10-phenanthroline (L2), (5-methoxyindole)-imidazo[4,5-f]1,10-phenanthroline (L3), (biphenyl)imidazo[4,5-f]1,10-phenanthroline (L4), (fluorene)imidazo[4,5-f]1,10-phenanthroline (L5), (benzo[b]thiophene)imidazo[4,5-f]1,10-phenanthroline (L6), (5-bromothiazole)imidazo[4,5-f]1,10-phenanthroline (L7), and (4,5-dimethylthiophene)imidazo[4,5-f]1,10-phenanthroline (L8), were synthesized and characterized using 1H and 13C{1H} NMR, FT-IR, UV/Vis absorption spectroscopy, and ESI-mass spectrometry, and their purity was confirmed by elemental analysis. The stability of the complexes in aqueous buffer solution (pH 7.4) was confirmed by UV/Vis spectroscopy. The cytotoxicity of the complexes (1-8) was then evaluated on prostate cancer cells (PC3), showing a low nanomolar to low micromolar in vitro cytotoxicity. Worthy of note, three of the Re(I) tricarbonyl complexes showed very low (IC50 = 30-50 nM) cytotoxic activity against PC3 cells and up to 26-fold selectivity over normal human retinal pigment epithelial-1 (RPE-1) cells. The cytotoxicity of both complexes 3 and 6 was lowered under hypoxic conditions in PC3 cells. However, the compounds were still 10 times more active than cisplatin in these conditions. Additional biological experiments were then performed on the most selective complexes (complexes 3 and 6). Cell fractioning experiments followed by ICP-MS studies revealed that 3 and 6 accumulate mostly in the mitochondria and nucleus, respectively. Despite the respective mitochondrial and nuclear localization of 3 and 6, 3 did not trigger the apoptosis pathways for cell killing, whereas 6 can trigger apoptosis but not as a major pathway. Complex 3 induced a paraptosis pathway for cell killing while 6 did not induce any of our other tested pathways, namely, necrosis, paraptosis, and autophagy. Both complexes 3 and 6 were found to be involved in mitochondrial dysfunction and downregulated the ATP production of PC3 cells. To the best of our knowledge, this report presents some of the most cytotoxic Re(I) carbonyl complexes with exceptionally low nanomolar cytotoxic activity toward prostate cancer cells, demonstrating further the future viability of utilizing rhenium in the fight against cancer.

Evaluating the inhibitory activity of ferrocenyl Schiff bases derivatives on 5-lipoxygenase: Computational and biological studies

In the search for new 5-LOX inhibitors, two ferrocenyl Schiff base complexes functionalized with catechol ((ƞ5-(E)-C5H4-NCH-3,4-benzodiol)Fe(ƞ5-C5H5) (3a)) and vanillin ((ƞ5-(E)-C5H4-NCH-3-methoxy-4-phenol)Fe(ƞ5-C5H5) (3b)) were obtained. Complexes 3a and 3b were biologically evaluated as 5-LOX inhibitors showed potent inhibition compared to their organic analogs (2a and 2b) and known commercial inhibitors, with IC50 = 0.17 ± 0.05 μM for (3a) and 0.73 ± 0.06 μM for (3b) demonstrated a highly inhibitory and potent effect against 5-LOX due to the incorporation of the ferrocenyl fragment. Molecular dynamic studies showed a preferential orientation of the ferrocenyl fragment toward the non-heme iron of 5-LOX, which, together with electrochemical and in-vitro studies, allowed us to propose a competitive redox deactivation mechanism mediated by water, where Fe(III)-enzyme can be reduced by the ferrocenyl fragment. An Epa/IC50 relationship was observed, and the stability of the Schiff bases was evaluated by SWV in the biological medium, observing that the hydrolysis does not affect the high potency of the complexes, making them interesting alternatives for pharmacological applications.

Silver N-heterocyclic carbene complexes are potent uncompetitive inhibitors of the papain-like protease with antiviral activity against SARS-CoV-2

The ongoing SARS-CoV-2 pandemic has caused a high demand for novel innovative antiviral drug candidates. Despite promising results, metal complexes have been relatively unexplored as antiviral agents in general and in particular against SARS-CoV-2. Here we report on silver NHC complexes with chloride or iodide counter ligands that are potent inhibitors of the SARS-CoV-2 papain-like protease (PL^pro) but inactive against 3C-like protease (3CL^pro) as another SARS-CoV-2 protease. Mechanistic studies on a selected complex confirmed zinc removal from a zinc binding domain of PL^pro as relevant factor of their activity. In addition, enzyme kinetic experiments revealed that the complex is an uncompetitive inhibitor and with this rare type of inhibition it offers great pharmacological advantages in terms selectivity. The silver NHC complexes with iodide ligands showed very low or absent host cell toxicity and triggered strong effects on viral replication in cells infected with SARS-CoV-2, making them promising future antiviral drug candidates.

Silver complexes with substituted terpyridines as promising anticancer metallodrugs and their crystal structure, photoluminescence, and DNA interactions

Six silver hexafluoroantimonate complexes (1-6) with 4'-(4'-substituted-phenyl)-2,2':6',2''-terpyridine compounds bearing hydrogen (L1), methyl (L2), methylsulfonyl (L3), chloro (L4), bromo (L5) and iodo (L6) were prepared and characterized by 1H NMR, 13C NMR, IR, elemental analysis and single crystal X-ray diffraction. All the compounds exhibit interesting photoluminescence properties in the solid state and solution. In vitro data demonstrate that all of them show higher antiproliferative activities than cisplatin against three human carcinoma cell lines, A549, Eca-109 and MCF-7. Compound 3 exhibits the lowest IC50 value (2.298 μM) against A549 cell lines, which is 2.963 μM for 4 against Eca-109 and 1.830 μM for 1 against MCF-7. For silver halogen-substituted terpyridine compounds, their anticancer activities decrease following the sequence of -Cl, -Br, and -I substituents. The comparison results show that their anticancer activity is significantly higher than that of their free ligands. The DNA interaction was studied by fluorescence titration, circular dichroism spectroscopy and molecular modeling methods. Spectrophotometric results reveal that the compounds have strong affinity binding with DNA as intercalators and molecular docking studies indicate that the binding is contributed by the π-π stacking and hydrogen bonds. The DNA binding ability of the complexes has been correlated with their anticancer activities, which could potentially provide a new rationale for the future design of terpyridine-based metal complexes with antitumor potential.

Anticancer Tungstenocenes with a Diverse Set of (O,O-), (O,S-) and (O,N-) Chelates-A Detailed Biological Study Using an Improved Evaluation via 3D Spheroid Models

The synthesis, characterization and biological activity of tungstenocenes with varying biologically active (O,O-), (S,O-) and (N,O-) chelates are described. Complexes were characterized by ¹H and ¹³C NMR, elemental analysis, ESI-mass spectrometry, FT-IR spectroscopy and X-ray diffraction analysis. The aqueous stability was studied by UV/Vis spectroscopy and the W^IV to W^V process by cyclic voltammetry. The cytotoxicity was determined by the MTT assay in A549, CH1/PA-1 and SW480 cancer cells as well as in IMR-90 human fibroblasts. Extensive biological evaluation was performed in three other human cancer cell lines (HCT116, HT29 and MCF-7) in monolayer and multicellular tumor spheroid cultures to better understand the mode of action. Lead compounds showed promising in vitro anticancer activity in all cancer cell lines. Further studies yielded important insights into apoptosis induction, ROS generation, different patterns in metal distribution (detected by LA-ICP-TOF-MS), changes in KI67 (proliferation marker) expression and DNA interactions. The results based on qualitative and quantitative research designs show that complexes containing (S,O-) chelates are more active than their (O,O-) and (N,O-) counterparts. The most striking results in spheroid models are the high antiproliferative capacity and the different distribution pattern of two complexes differing only in a W-S or W-O bond.