Metal complex SERMs (selective oestrogen receptor modulators). The influence of different metal units on breast cancer cell antiproliferative effects

Recent Advances in the Development of Hybrid Drugs

In the search for innovative, selective, effective, and safer treatment strategies, hybrid drugs have gained worldwide momentum [...].

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.

Half-Sandwich Ruthenium Arene Complexes Bearing Clinically Approved Drugs as Ligands: The Importance of Metal-Drug Synergism in Metallodrug Design

A novel strategy in metallodrug discovery today is incorporating clinically approved drugs into metal complexes as coordinating ligands. Using this strategy, various drugs have been repurposed to prepare organometallic complexes to overcome the resistance of drugs and to design promising alternatives to currently available metal-based drugs. Notably, the combination of organoruthenium moiety and clinical drug in a single molecule has been shown, in some instances, to enhance pharmacological activity and reduce toxicity in comparison to the parent drug. Thus, for the past two decades, there has been increasing interest in exploiting metal-drug synergism to develop multifunctional organoruthenium drug candidates. Herein, we summarized the recent reports of rationally designed half-sandwich Ru(arene) complexes containing different FDA-approved drugs. This review also focuses on the mode of coordination of drugs, ligand-exchange kinetics, mechanism of action, and structure-activity relationship of organoruthenated complexes containing drugs. We hope this discussion may serve to shed light on future developments in ruthenium-based metallopharmaceuticals.

Research Progress on Bioactive Metal Complexes against ER-Positive Advanced Breast Cancer

Breast cancer is the most prevalent cancer in women and represents a serious disease that is harmful to life and health. In 1977, with the approval of tamoxifen, endocrine therapy has become the main clinical treatment for ER-positive (ER+) breast cancer. Although patients initially respond well to endocrine therapies, drug resistance often emerges and side effects can be challenging. To overcome drug resistance, the exploration for new drugs is a priority. Metal complexes have demonstrated significant antitumor activities, and platinum complexes are widely used in the clinic against various cancers, including breast cancer. In this Perspective, the first section describes the classification and mechanism of endocrine therapy drugs for ER+ breast cancer, and the second section summarizes research since 2000 into metal complexes with activity toward ER+ breast cancer. Finally, we discuss the opportunities, challenges, and future directions for metal complexes in the treatment of ER+ breast cancer.

Metallodrugs against Breast Cancer: Combining the Tamoxifen Vector with Platinum(II) and Palladium(II) Complexes

The luminal A-subtype of breast cancer, where the oestrogen receptor α (ERα) is overexpressed, is the most frequent one. The prodrug tamoxifen (1) is the clinically used agent, inhibiting the ERα activity via the formation of several active metabolites, such as 4-hydroxytamoxifen (2) or 4,4'-dihydroxytamoxifen (3). In this study, we present the tamoxifen derivative 4-[1,1-bis(4-methoxyphenyl)but-1-en-2-yl]-2,2'-bipyridine (4), which was combined with platinum or palladium dichloride, the former a well-known scaffold in anticancer treatment, to give [PtCl₂(4-κ²N,N')] (5) or [PdCl₂(4-κ²N,N'] (6). To prevent fast exchange of weakly coordinating chlorido ligands in aqueous solution, a bulky, highly stable and hydrophobic nido-carborate(-2) ([C₂B₉H₁₁]^2-) was incorporated. The resulting complexes [3-(4-κ²N,N')-3,1,2-PtC₂B₉H₁₁] (7) and [3-(4-κ²N,N')-3,1,2-PdC₂B₉H₁₁] (8) exhibit a dramatic change in electronic and biological properties compared to 5 and 6. Thus, 8 is highly selective for triple-negative MDA-MB-231 cells (IC₅₀ = 3.7 μM, MTT test), while 7 is completely inactive against this cell line. The observed cytotoxicity of compounds 4-6 and 8 against this triple-negative cell line suggests off-target mechanisms rather than only ERα inhibition, for which these compounds were originally designed. Spectroscopic properties and electronic structures of the metal complexes were investigated for possible explanations of the biological activities.

Novel Set of Diarylmethanes to Target Colorectal Cancer: Synthesis, In Vitro and In Silico Studies

Distinctive structural, chemical, and physical properties make the diarylmethane scaffold an essential constituent of many active biomolecules nowadays used in pharmaceutical, agrochemical, and material sciences. In this work, 33 novel diarylmethane molecules aiming to target colorectal cancer were designed. Two series of functionalized olefinic and aryloxy diarylmethanes were synthesized and chemically characterized. The synthetic strategy of olefinic diarylmethanes involved a McMurry cross-coupling reaction as key step and the synthesis of aryloxy diarylmethanes included an O-arylation step. A preliminarily screening in human colorectal cancer cells (HT-29 and HCT116) and murine primary fibroblasts (L929) allowed the selection, for more detailed analyses, of the three best candidates (10a, 10b and 12a) based on their high inhibition of cancer cell proliferation and non-toxic effects on murine fibroblasts (<100 µM). The anticancer potential of these diarylmethane compounds was then assessed using apoptotic (phospho-p38) and anti-apoptotic (phospho-ERK, phospho-Akt) cell survival signaling pathways, by analyzing the DNA fragmentation capacity, and through the caspase-3 and PARP cleavage pro-apoptotic markers. Compound 12a (2-(1-(4-methoxyphenyl)-2-(4-(trifluoromethyl)phenyl) vinyl) pyridine, Z isomer) was found to be the most active molecule. The binding mode to five biological targets (i.e., AKT, ERK-1 and ERK-2, PARP, and caspase-3) was explored using molecular modeling, and AKT was identified as the most interesting target. Finally, compounds 10a, 10b and 12a were predicted to have appropriate drug-likeness and good Absorption, Distribution, Metabolism and Excretion (ADME) profiles.

Modern Trends in Bio-Organometallic Ferrocene Chemistry

Organometallic sandwich compounds, especially ferrocenes, possess a wide variety of pharmacological activities and therefore are attracting more and more attention from chemists, biologists, biochemists, etc. Excellent reviews concerning biological aspects and design of ferrocene-modified compounds appear regularly in scientific journals. This brief overview highlights recent achievements in the field of bio-organometallic ferrocene chemistry from 2017 to 2022. During this period, new ferrocene-modified analogues of various bio-structures were synthesized, namely, betulin, artemisinin, steroids, and alkaloids. In addition, studies of the biological potential of ferrocenes have been expanded. Since ferrocene is 70 years old this year, a brief historical background is also given. It seemed to me useful to sketch the ‘ferrocene picture’ in broad strokes.

Nanoencapsulation of Ru(p-cymene) Complex Bearing Ginger-based Natural Product into Liposomal Nanoformulation to Improve Its Cellular Uptake and Antiproliferative Activity

The organometallic compounds are prospective candidates in the row of developing metallochemotherapeutics with the aim of overcoming the limitations of platinum drugs. In order to explore the anticancer properties of organometallic compounds with the natural medicines, two Ru(II)-p-cymene complexes containing the natural products, viz., 6-gingerol (6G) and benzylated-6-gingerdione (B-6GD) have been synthesized and characterized well. The phenolic group of the Ru(6G) complex facilitates its higher cell-free antioxidant activity than its analogue complex. Also, the same complex shows higher cytotoxicity toward A549 lung and HeLa-S3 cervical cancer cells than the Ru(B-6GD) complex but lower cytotoxicity toward A2058 metastatic melanoma cancer cells. Both complexes are shown to easily accumulate in melanoma cancer cells, and their degree of cytotoxicity in the same cells is found to be positively correlated with cell uptake. The cytotoxicity of complexes arises from their intracellular activity, mainly due to the induction of singlet oxygen production in cancer cells. The subcellular fractionation study shows that mitochondria and ER-Golgi membranes might be their predominant targets. Also, the mechanistic investigation revealed that Ru(B-6GD) induces caspase-dependent non-apoptotic cell death whereas Ru(6G) can induce caspase-independent non-apoptotic cell death. Furthermore, both complexes are found to moderately alter the adhesion properties of cancer cells, which is beneficial for antimetastatic treatment. Despite the potential pharmacological activity, Ru(6G) is encapsulated into polymer-supported liposomes to reduce its toxicity and further improve its anticancer potency. The π-conjugated yne-ene chain of polydiacetylene aids in the development of a stable nanoformulation, which achieved a slow release of the complex. Most importantly, the cancer cell uptake of the liposome-encapsulated Ru(6G) complex is 20 times enhanced and the total ROS formation in cancer cells is significantly increased compared to the non-encapsulated complex. However, the nanoformulation does not alter the antimetastatic potency of the encapsulated complex.

Ferrocifen Loaded Lipid Nanocapsules: A Promising Anticancer Medication against Multidrug Resistant Tumors

Resistance of cancer cells to current chemotherapeutic drugs has obliged the scientific community to seek innovative compounds. Ferrocifens, lipophilic organometallic compounds composed of a tamoxifen scaffold covalently bound to a ferrocene moiety, have shown very interesting antiproliferative, cytotoxic and immunologic effects. The formation of ferrocenyl quinone methide plays a crucial role in the multifaceted activity of ferrocifens. Lipid nanocapsules (LNCs), meanwhile, are nanoparticles obtained by a free organic solvent process. LNCs consist of an oily core surrounded by amphiphilic surfactants and are perfectly adapted to encapsulate these hydrophobic compounds. The different in vitro and in vivo experiments performed with this ferrocifen-loaded nanocarrier have revealed promising results in several multidrug-resistant cancer cell lines such as glioblastoma, breast cancer and metastatic melanoma, alone or in combination with other therapies. This review provides an exhaustive summary of the use of ferrocifen-loaded LNCs as a promising nanomedicine, outlining the ferrocifen mechanisms of action on cancer cells, the nanocarrier formulation process and the in vivo results obtained over the last two decades.

Replacing the Z-phenyl Ring in Tamoxifen® with a para-Connected NCN Pincer-Pt-Cl Grouping by Post-Modification †

Post-modification of a series of NCN-pincer platinum(II) complexes [PtX(NCN-R-4)] (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]^–, R = C(O)H, C(O)Me and C(O)Et), X = Cl^– or Br^–) at the para-position using the McMurry reaction was studied. The synthetic route towards two new [PtCl(NCN-R-4)] (R = C(O)Me and C(O)Et) complexes used above is likewise described. The utility and limitations of the McMurry reaction involving these pincer complexes was systematically evaluated. The predicted “homo-coupling” reaction of [PtBr(NCN-C(O)H-4)] led to the unexpected formation of 3,3′,5,5′-tetra[(dimethylamino)methyl]-4,4′-bis(platinum halide)-benzophenone (halide = Br or Cl), referred to hereafter as the bispincer-benzophenone complex 13. This material was further characterized using X-ray crystal structure determination. The applicability of the pincer complexes in the McMurry reaction is shown to open a route towards the synthesis of tamoxifen-type derivatives of which one phenyl ring of Tamoxifen^® itself is replaced by an NCN arylplatinum pincer fragment. The newly synthesized derivatives can be used as potential candidates in anti-cancer drug screening protocols. Two NCN-arylpincer platinum tamoxifen type derivatives, 5 and 6, were successfully synthesized and of 5 the separation of the diastereomeric E-/Z-forms was achieved. Compound 6, which is the pivaloyl protected NCN pincer platinum hydroxy-Tamoxifen^® derivative, was obtained as a mixture of E-/Z-isomers. The new derivatives were further analyzed and characterized with ¹H-, ¹³C{¹H}- and ¹⁹⁵Pt{¹H}-NMR, IR, exact mass MS and elemental analysis.

Organometallic nucleoside analogues: effect of the metallocene metal atom on cancer cell line toxicity

A new chiral organometallic nucleoside analogue containing ruthenocene is reported, in which alkylthymine and alkylhydroxyl groups are attached in adjacent positions on one cyclopentadienyl ring. The synthetic procedures for this metallocene derivative and two control compounds are described, along with their characterisation by cyclic voltammetry and X-ray crystallography. Their biological activities in a human pancreatic cancer cell line (MIA-Pa-Ca-2) were significantly lower than those of three previously reported analogous ferrocene compounds, indicating that the choice of metallocene metal atom (Fe or Ru) plays a pivotal role in determining the anticancer properties of these nucleoside analogues, which in turn suggests a different mode of action from that of a conventional nucleoside analogue.

Effects of Ferrocenyl 4-(Imino)-1,4-Dihydro-quinolines on Xenopus laevis Prophase I - Arrested Oocytes: Survival and Hormonal-Induced M-Phase Entry

Xenopus oocytes were used as cellular and molecular sentinels to assess the effects of a new class of organometallic compounds called ferrocenyl dihydroquinolines that have been developed as potential anti-cancer agents. One ferrocenyl dihydroquinoline compound exerted deleterious effects on oocyte survival after 48 h of incubation at 100 μM. Two ferrocenyl dihydroquinoline compounds had an inhibitory effect on the resumption of progesterone induced oocyte meiosis, compared to controls without ferrocenyl groups. In these inhibited oocytes, no MPF (Cdk1/cyclin B) activity was detected by western blot analysis as shown by the lack of phosphorylation of histone H3. The dephosphorylation of the inhibitory Y15 residue of Cdk1 occurred but cyclin B was degraded. Moreover, two apoptotic death markers, the active caspase 3 and the phosphorylated histone H2, were detected. Only 7-chloro-1-ferrocenylmethyl-4-(phenylylimino)-1,4-dihydroquinoline (8) did not show any toxicity and allowed the assembly of a histologically normal metaphase II meiotic spindle while inhibiting the proliferation of cancer cell lines with a low IC₅₀, suggesting that this compound appears suitable as an antimitotic agent.

Rationally Designed Ruthenium Complexes for Breast Cancer Therapy

Since the discovery of the anticancer potential of ruthenium-based complexes, several species were reported as promising candidates for the treatment of breast cancer, which accounts for the greatest number of new cases in women every year worldwide. Among these ruthenium complexes, species containing bioactive ligand(s) have attracted increasing attention due to their potential multitargeting properties, leading to anticancer drug candidates with a broader range of cellular targets/modes of action. This review of the literature aims at providing an overview of the rationally designed ruthenium-based complexes that have been reported to date for which ligands were carefully selected for the treatment of hormone receptor positive breast cancers (estrogen receptor (ER+) or progesterone receptor (PR+)). In addition, this brief survey highlights some of the most successful examples of ruthenium complexes reported for the treatment of triple negative breast cancer (TNBC), a highly aggressive type of cancer, regardless of if their ligands are known to have the ability to achieve a specific biological function.

Encapsulation of a Ru(η6-p-cymene) complex of the antibacterial drug trimethoprim into a polydiacetylene-phospholipid assembly to enhance its in vitro anticancer and antibacterial activities

The first report of a Ru(arene)–liposome nanoaggregate to enhance the in vitro anticancer activity of a Ru–arene complex in liver cancer cells.

2,2'-Bipyridine-Modified Tamoxifen: A Versatile Vector for Molybdacarboranes

Investigations on the antitumor activity of metallacarboranes are sparse in the literature and limited to a handful of ruthena- and molybdacarboranes. In this study, the molybdacarborane fragment [3-(CO)2 -closo-3,1,2-MoC2 B9 H11 ] was combined with a vector molecule, inspired by the well-known drug tamoxifen or 4,4'-dihydroxytamoxifen (TAM-diOH). The molybdacarborane derivative [3,3-{4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2'-bipyridine-κ2 N,N'}-3-(CO)2 -closo-3,1,2-MoC2 B9 H11 ] (10), as well as the ligand itself 4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2'-bipyridine (6) showed cytotoxic activities in the low micromolar range against breast adenocarcinoma (MDA-MB-231, MDA-MB-361 and MCF-7), human glioblastoma (LN-229) and human glioma (U-251) cell lines. In addition, compounds 6 and 10 were found to induce senescence and cytodestructive autophagy, lower ROS/RNS levels, but only the molybdacarborane 10 induced a strong increase of nitric oxide (NO) concentration in the MCF-7 cells.

A brief overview of metal complexes as nuclear imaging agents

Metallic radionuclides have been instrumental in the field of nuclear imaging for over half a century. While recent years have played witness to a dramatic rise in the use of radiometals as labels for chelator-bearing biomolecules, imaging agents based solely on coordination compounds of radiometals have long played a critical role in the discipline as well. In this work, we seek to provide a brief overview of metal complex-based radiopharmaceuticals for positron emission tomography (PET) and single photon emission computed tomography (SPECT). More specifically, we have focused on imaging agents in which the metal complex itself rather than a pendant biomolecule or targeting moiety is responsible for the in vivo behavior of the tracer. This family of compounds contains metal complexes based on an array of different nuclides as well as probes that have been used for the imaging of a variety of pathologies, including infection, inflammation, cancer, and heart disease. Indeed, two of the defining traits of transition metal complexes-modularity and redox chemistry-have both been creatively leveraged in the development of imaging agents. In light of our audience, particular attention is paid to structure and mechanism, though clinical data is addressed as well. Ultimately, it is our hope that this review will not only educate readers about some of the seminal work performed in this space over the last 30 years but also spur renewed interest in the creation of radiopharmaceuticals based on small metal complexes.

Synthesis, characterization and DNA interaction studies of new copper complex containing pseudoephedrine hydrochloride drug

A new copper(II) complex, [Cu(pse)(phen)Cl₂]; in which phen = 1,10-phenanthroline and pse = pseudoephedrine hydrochloride drug; was synthesized and characterized by FT-IR, Mass and UV-Vis spectroscopy in combination with computational methods. Binding interaction of this complex with calf thymus DNA (ct-DNA) has been investigated by absorption, emission, circular dichroism, molecular docking and viscosity measurements. The complex displays significant binding properties of ct-DNA. The results of fluorescence and UV-Vis absorption spectroscopy indicated that, this complex interacted with ct-DNA in a groove-binding mode, and the binding constant was 8 × 10⁴ L mol^-1. Competitive fluorimetric studies with Hoechst 33258 have shown that Cu(II) complex exhibit the ability to displace the DNA-bound Hoechst 33258 indicating that it binds to DNA in strong competition with Hoechst 33258 for the groove binding. Furthermore, the complex induces detectable changes in the CD spectrum of ct-DNA and does not induce any changes in DNA viscosity which verified the groove-binding mode. The molecular modeling results illustrated that the complex strongly binds to groove of DNA by relative binding energy of docked structure (-27.61 kJ mol^-1).

Organoruthenium(II) Complexes Bearing an Aromatase Inhibitor: Synthesis, Characterization, in Vitro Biological Activity and in Vivo Toxicity in Zebrafish Embryos

Third-generation aromatase inhibitors such as anastrozole (ATZ) and letrozole (LTZ) are widely used to treat estrogen receptor-positive ER+ breast cancers in postmenopausal women. Investigating their ability to coordinate metals could lead to the emergence of a new category of anticancer drug candidates with a broader spectrum of pharmacological activities. In this study, a series of ruthenium (II) arene complexes bearing the aromatase inhibitor anastrozole was synthesized and characterized. Among these complexes, [Ru(η ⁶ -C₆H₆)(PPh₃)(η ¹ -ATZ)Cl]BPh₄ (3) was found to be the most stable in cell culture media, to lead to the highest cellular uptake and in vitro cytotoxicity in two ER+ human breast cancer cell lines (MCF7 and T47D), and to induce a decrease in aromatase activity in H295R cells. Exposure of zebrafish embryos to complex 3 (12.5 μM) did not lead to noticeable signs of toxicity over 96 h, making it a suitable candidate for further in vivo investigations.

Scope of organometallic compounds based on transition metal-arene systems as anticancer agents: starting from the classical paradigm to targeting multiple strategies

The advent of the clinically approved drug cisplatin started a new era in the design of metallodrugs for cancer chemotherapy. However, to date, there has not been much success in this field due to the persistence of some side effects and multi-drug resistance of cancer cells. In recent years, there has been increasing interest in the design of metal chemotherapeutics using organometallic complexes due to their good stability and unique properties in comparison to normal coordination complexes. Their intermediate properties between that of traditional inorganic and organic materials provide researchers with a new platform for the development of more promising cancer therapeutics. Classical metal-based drugs exert their therapeutic potential by targeting only DNA, but in the case of organometallic complexes, their molecular target is quite distinct to avoid drug resistance by cancer cells. Some organometallic drugs act by targeting a protein or inhibition of enzymes such as thioredoxin reductase (TrRx), while some target mitochondria and endoplasmic reticulum. In this review, we mainly discuss organometallic complexes of Ru, Ti, Au, Fe and Os and their mechanisms of action and how new approaches improve their therapeutic potential towards various cancer phenotypes. Herein, we discuss the role of structure-reactivity relationships in enhancing the anticancer potential of drugs for the benefit of humans both in vitro and in vivo. Besides, we also include in vivo tumor models that mimic human physiology to accelerate the development of more efficient clinical organometallic chemotherapeutics.

Tracking antitumor metallodrugs: promising agents with the Ru(II)- and Fe(II)-cyclopentadienyl scaffolds

Research on the field of metal complexes for the treatment of cancer diseases has attracted increasing interest due to the urgency in finding more efficient and selective treatments. Owing to their wide structural diversity, organometallic complexes appear as potential alternatives to the design of new anticancer candidates. Herein, we review recent progress in our work toward the development of new drugs based on Ru(II)- and Fe(II)-cyclopentadienyl scaffolds. Their design and chemical properties are reviewed and correlated with their biological effects, in particular the key role that coligands play in the overall behavior of the complex.

Regulating the anticancer properties of organometallic dendrimers using pyridylferrocene entities: synthesis, cytotoxicity and DNA binding studies

Eight new heterometallic ferrocenyl-derived metal–arene metallodendrimers have been prepared and evaluated for anti-tumor activity.

Anticancer and Antibacterial Activity Studies of Gold(I)-Alkynyl Chromones

Three gold(I) complexes of alkynyl chromones were synthesized and characterized. The single-crystal X-ray structure analysis of a dinuclear compound and of a flavone derivative exhibit a typical d10 gold(I)-alkynyl linear arrangement. All complexes were evaluated as anticancer and antibacterial agents against four human cancer cell lines and four pathogenic bacterial strains. All compounds show antiproliferative activity at lower micromolar range concentrations. Complex 4 showed a broad activity profile, being more active than the reference drug auranofin against HepG2, MCF-7 and CCRF-CEM cancer cells. The cellular uptake into MCF-7 cells of the investigated complexes was measured by atomic absorption spectroscopy (AAS). These measurements showed a positive correlation between an increased cellular gold content and the incubation time of the complexes. Unexpectedly an opposite effect was observed for the most active compound. Biological assays revealed various molecular mechanisms for these compounds, comprising: (i) thioredoxin reductase (TrxR) inhibition, (ii) caspases-9 and -3 activation; (iii) DNA damaging activity and (iv) cell cycle disturbance. The gold(I) complexes were also bactericidal against Gram-positive methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) bacterial strains, while showing no activity against the Gram-negative Escherichia coli bacterial strain.

Cyclopentadienyl-ruthenium(II) and iron(II) organometallic compounds with carbohydrate derivative ligands as good colorectal anticancer agents

New ruthenium(II) and iron(II) organometallic compounds of general formula [(η(5)-C5H5)M(PP)Lc][PF6], bearing carbohydrate derivative ligands (Lc), were prepared and fully characterized and the crystal structures of five of those compounds were determined by X-ray diffraction studies. Cell viability of colon cancer HCT116 cell line was determined for a total of 23 organometallic compounds and SAR's data analysis within this library showed an interesting dependency of the cytotoxic activity on the carbohydrate moiety, linker, phosphane coligands, and metal center. More importantly, two compounds, 14Ru and 18Ru, matched oxaliplatin IC50 (0.45 μM), the standard metallodrug used in CC chemotherapeutics, and our leading compound 14Ru was shown to be significantly more cytotoxic than oxaliplatin to HCT116 cells, triggering higher levels of caspase-3 and -7 activity and apoptosis in a dose-dependent manner.

Crystal structure of bis-[4-(1H-pyrrol-1-yl)phen-yl] ferrocene-1,1'-di-carboxyl-ate: a potential chemotherapeutic drug

The title iron(II) complex, [Fe(C16H12NO2)2], crystallizes in the ortho-rhom-bic space group Pbca with the Fe(2+) cation positioned on an inversion center. The cyclo-penta-dienyl (Cp) rings adopt an anti conformation in contrast with other substituted ferrocenes in which the Cp rings appear in a nearly eclipsed conformation. The Cp and the aromatic rings are positioned out of the plane, with a twist angle of 70.20 (12)°, and the C(Cp)-C(CO) bond length is shorter than a typical C-C single bond, which suggests a partial double-bond character and delocalization with the Cp π system. The structure of the complex is compared to other functionalized ferrocenes synthesized in our laboratory.

Transition metal complexes with bioactive ligands: mechanisms for selective ligand release and applications for drug delivery

The unique properties of transition metal complexes, such as environment-responsive ligand exchange kinetics, diverse photochemical and photophysical properties, and the ability to form specific interactions with biomolecules, make them interesting platforms for selective drug delivery. This minireview will focus on recent examples of rationally designed complexes with bioactive ligands, exploring the different roles of the metal, and mechanisms of ligand release. Developments in the techniques used to study the mechanisms of action of metal-drug complexes will also be discussed, including X-ray protein crystallography, fluorescence lifetime imaging, and X-ray absorption spectroscopy.