Ferrocenyl and dicobalt hexacarbonyl chromones – New organometallics inducing oxidative stress and arresting human cancer cells in G2/M phase

Experimental and molecular modelling demonstration of effective DNA and protein binding as well as anticancer potential of two mononuclear Cu(II) and Co(II) complexes with isothiocyanate and azide as anionic residues

In the present study, one mononuclear Cu(II) [CuL(SCN)] (1) and one mononuclear Co(II) [CoLN3] (2) complexes, with a Schiff base ligand (HL) formed by condensation of 2-picolylamine and salicylaldehyde, have been successfully developed and structurally characterized. The square planer geometry of both complexes is fulfilled by the coordination of one deprotonated ligand and one ancillary ligand SCN-(1) or N3-(2) to the metal centre. Binding affinities of both complexes with deoxyribonucleic acid (DNA) and human serum albumin (HSA) are investigated using several biophysical and spectroscopic techniques. High values of the macromolecule-complex binding constants and other results confirm the effectiveness of both complexes towards binding with DNA and HSA. The determined values of the thermodynamic parameters support spontaneous interactions of both complexes with HSA, while fluorescence displacement and DNA melting studies establish groove-binding interactions with DNA for both complexes 1 and 2. The molecular modelling study validates the experimental findings. Both complexes are subjected to an MTT test establishing the anticancer property of complex 1 with lower risk to normal cells, confirmed by the IC50 values of the complex for HeLa cancer cells and HEK normal cells. Finally, a nuclear staining analysis reveals that the complexes have caused apoptotic cell death.

Ferrocene-Based Drugs, Delivery Nanomaterials and Fenton Mechanism: State of the Art, Recent Developments and Prospects

Ferrocene has been the most used organometallic moiety introduced in organic and bioinorganic drugs to cure cancers and various other diseases. Following several pioneering studies, two real breakthroughs occurred in 1996 and 1997. In 1996, Jaouen et al. reported ferrocifens, ferrocene analogs of tamoxifen, the chemotherapeutic for hormone-dependent breast cancer. Several ferrocifens are now in preclinical evaluation. Independently, in 1997, ferroquine, an analog of the antimalarial drug chloroquine upon the introduction of a ferrocenyl substituent in the carbon chain, was reported by the Biot-Brocard group and found to be active against both chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum. Ferroquine, in combination with artefenomel, completed phase IIb clinical evaluation in 2019. More than 1000 studies have been published on ferrocenyl-containing pharmacophores against infectious diseases, including parasitic, bacterial, fungal, and viral infections, but the relationship between structure and biological activity has been scarcely demonstrated, unlike for ferrocifens and ferroquines. In a majority of ferrocene-containing drugs, however, the production of reactive oxygen species (ROS), in particular the OH. radical, produced by Fenton catalysis, plays a key role and is scrutinized in this mini-review, together with the supramolecular approach utilizing drug delivery nanosystems, such as micelles, metal-organic frameworks (MOFs), polymers, and dendrimers.

Click ferrocenyl-erlotinib conjugates active against erlotinib-resistant non-small cell lung cancer cells in vitro

Thanks to development of erlotinib and other target therapy drugs the lung cancer treatment have improved a lot in recent years. However, erlotinib-resistant lung cancer remains an unsolved clinical problem which demands for new therapeutics to be developed. Herein we report the synthesis of a library of 1,4- and 1,5-triazole ferrocenyl derivatives of erlotinib together with their anticancer activity studies against erlotinib-sensitive A549 and H1395 as well as erlotinib-resistant H1650 and H1975 cells. Studies showed that extend of anticancer activity is mainly related to the length of the spacer between the triazole and the ferrocenyl entity. Among the series of investigated compounds two isomers commonly bearing C(O)CH₂CH₂ spacer have shown superior to erlotinib activity against erlotinib-resistant H1650 and H1975 cells whereas compound with short methylene spacer devoid of any activity. In-depth biological studies for the most active compound showed differences in its mechanism of action in compare to erlotinib. The latter is known EGFR inhibitor whereas their ferrocenyl congener exerts anticancer activity mainly as ROS-inducer which activates mitochondrial pathway of apoptosis in cancer cells. However, docking studies suggested that the most active compound can also binds to the active site of EGFR TK in a similar way as erlotinib.

Novel Ferrocene Derivatives Induce Apoptosis through Mitochondria-Dependent and Cell Cycle Arrest via PI3K/Akt/mTOR Signaling Pathway in T Cell Acute Lymphoblastic Leukemia

Simple Summary

T cell acute lymphoblastic leukemia (T-ALL) is a malignant hematologic disease that urgently requires efficient therapeutic agents. The aim of this study is to explore the anti-T-ALL activity of novel ferrocene derivatives. It was found that ferrocene derivatives F1–F7 synthesized by our group inhibited the proliferation of several cancer cell lines in vitro. Among them, F1 and F3 displayed potent cytotoxicity against T-ALL cell lines, especially Jurkat cells, with low cytotoxicity for normal cells. Mechanistically, F1 and F3 could induce apoptosis through mitochondria-dependent pathway mediated by ROS, and cell cycle arrest at G0/G1 phase via the PI3K/Akt/mTOR signaling pathway in Jurkat cells. These results suggested that F1 and F3 could be potential candidates for future T-ALL therapy.

Abstract

T cell acute lymphoblastic leukemia (T-ALL) is one of the most common causes of death in pediatric malignancies. However, the clinical chemotherapy for T-ALL has been limited by numerous side effects, emphasizing that novel anti-T-ALL drugs are urgently needed. Herein, a series of 2-acyl-1-dimethylaminomethyl-ferrocenes for cancer therapy have been evaluated. Among them, F1 and F3 exhibited potent cytotoxicity against T-ALL cell lines, especially Jurkat cells, with low cytotoxicity for normal cells. Further mechanistic studies revealed that F1 and F3 could induce apoptosis in Jurkat cells by destructing mitochondrial membrane, enhancing reactive oxygen species (ROS) generation, decreasing the Bcl-2/Bax ratio, releasing Cytochrome c, and increasing the expression of Cleaved Caspase-9/-3 and Cleaved PARP. Additionally, F1 and F3 could suppress cell proliferation and arrest the cell cycle at G0/G1 phase through the PI3K/Akt/mTOR signaling pathway by down-regulating the expression of CDK6, Cyclin D1, p-Akt, p-GSK-3β, p-mTOR, p-p70 S6K, and up-regulating the expression of P21 and P27, which would also be a possible mechanism. Consequently, ferrocene derivatives F1 and F3 could induce apoptosis through a mitochondria-dependent pathway mediated by ROS, and cell cycle arrest at G0/G1 phase via the PI3K/Akt/mTOR signaling pathway in Jurkat cells. The present study provided fundamental insights into the clinical application of F1 and F3 for the treatment of T-ALL.

Chromones: Privileged scaffold in anticancer drug discovery

In the design and discovery of anticancer drugs, various natural heterocyclic scaffolds have attracted considerable interest as privileged structures. For rational drug design, some of the natural scaffolds such as chromones have exhibited wide acceptability due to their drug-like properties. Among the approved anticancer drugs, the scaffolds with high selectivity for a small group of closely related targets are of importance. In the development of selective anticancer agents, the natural, as well as synthetic, can generate highly selective compounds toward cancer targets. The present manuscript includes more particularly the development of cancer inhibitors incorporating the chromone scaffold, with a strong emphasis on their molecular interactions in the anticancer mechanism. It also includes the structure-activity relationship studies and related examples of lead optimization.

Preparation and the anticancer mechanism of configuration-controlled Fe(II)-Ir(III) heteronuclear metal complexes

A series of configuration-controlled Fe(ii)-Ir(iii) heteronuclear metal complexes, including ferrocene and half-sandwich like iridium(iii) complex units, have been designed and prepared. These complexes show better anticancer activity than cisplatin under the same conditions, especially cis-configurational ones. Laser confocal microscopy analysis confirms that the complexes follow a non-energy-dependent cellular uptake mechanism, accumulate in lysosomes (pearson co-localization coefficient: ∼0.7), lead to lysosomal damage, and eventually induce apoptosis. These complexes can reduce the mitochondrial membrane potential, disturb the cell circle, catalyze the oxidation of nicotinamide-adenine dinucleotide (NADH) and increase the levels of intracellular reactive oxygen species (ROS), following an anticancer mechanism of oxidation. In addition, the complexes could bind to serum protein, and transport through it. Above all, the Fe(ii)-Ir(iii) heteronuclear metal complexes hold promise as potential anticancer agents for further study.

Recent advances in iron-complexes as drug candidates for cancer therapy: reactivity, mechanism of action and metabolites

In this perspective, we discuss iron-complexes as drug candidates that are promising alternatives to conventional platinum-based chemotherapies owing to their broad range of reactivities and to the targeting of different biological systems. Breakthroughs in the comprehension of iron complexes' structure-activity relationship contributed to the clarification of their metabolization pathways, sub-cellular localization and influence on iron homeostasis, while enlightening the primary molecular targets of theses likely multi-target metallodrugs. Both the antiproliferative activity and elevated safety index observed among the family of iron complexes showed encouraging results as per their therapeutic potential and selectivity also with the aim of reducing chemotherapy side-effects, and facilitated more pre-clinical investigations. The purpose of this perspective is to summarize the recent advances that contributed in unveiling the intricate relationships between the structural modifications on iron-complexes and their reactivity, cellular trafficking and global mechanisms of action to broaden their use as anticancer drugs and advance to clinical evaluation.

Ferrocene-containing hybrids as potential anticancer agents: Current developments, mechanisms of action and structure-activity relationships

Cancer is one of the most fatal threatens to human health throughout the world. The major challenges in the control and eradication of cancers are the continuous emergency of drug-resistant cancer and the low specificity of anticancer agents, creating an urgent need to develop novel anticancer agents. Organometallic compounds especially ferrocene derivatives possess remarkable structural and mechanistic diversity, inherent stability towards air, heat and light, low toxicity, low cost, reversible redox, ligand exchange, and catalytic properties, making them promising drug candidates for cancer therapy. Ferrocifen, a ferrocene-phenol hybrid, has demonstrated promising anticancer properties on drug-resistant cancers. Currently, Ferrocifen is in pre-clinical trial against cancers. Obviously, ferrocene moiety is a useful template for the development of novel anticancer agents. This review will provide an overview of ferrocene-containing hybrids with potential application in the treatment of cancers covering articles published between 2010 and 2020. The mechanisms of action, the critical aspects of design and structure-activity relationships are also discussed.

Luminescent fac-[Re(CO)3(phen)] carboxylato complexes with non-steroidal anti-inflammatory drugs: synthesis and mechanistic insights into the in vitro anticancer activity of fac-[Re(CO)3(phen)(aspirin)]

Luminescent fac-[Re(CO)₃(phen)(aspirin)]: insights into in vitro anticancer activity and confocal microscopy imaging in HeLa cells.

Design, synthesis and biological evaluation of novel ferrocene-pyrazole derivatives containing nitric oxide donors as COX-2 inhibitors for cancer therapy

A series of novel ferrocene-pyrazole derivatives containing nitric oxide donors as COX-2 inhibitors for cancer therapy were designed, synthesized and biologically evaluated. Among them, compound 7l displayed the most potent inhibitory against COX-2 (IC₅₀ = 0.82 μM) and antiproliferative activities against Hela cells (IC₅₀ = 0.34 μM) compared with Celecoxib (IC₅₀ = 0.38 and 7.91 μM). The further mechanistic studies revealed that 7l could induce apoptosis of Hela cells by mitochondrial depolarization and the antiproliferative activities of 7l were positively correlated with the levels of intracellular NO release in Hela cells. Most notably, 7l could dramatically suppress tumor growth in Hela cells xenografted mouse model. In summary, compound 7l may be promising candidates for cancer therapy.

Chromone as a Privileged Scaffold in Drug Discovery: Recent Advances

The use of privileged structures in drug discovery has proven to be an effective strategy, allowing the generation of innovative hits/leads and successful optimization processes. Chromone is recognized as a privileged structure and a useful template for the design of novel compounds with potential pharmacological interest, particularly in the field of neurodegenerative, inflammatory, and infectious diseases as well as diabetes and cancer. This perspective provides the reader with an update of an earlier article entitled "Chromone: A Valid Scaffold in Medicinal Chemistry" ( Chem. Rev. 2014 , 114 , 4960 - 4992 ) and is mainly focused on chromones of biological interest, including those isolated from natural sources. Moreover, as drug repurposing is becoming an attractive drug discovery approach, recent repurposing studies of chromone-based drugs are also reported.

Synthesis of ferrocenylmethylidene and arylidene substituted camphane based compounds as potential anticancer agents

A series of new compounds with a camphane moiety was synthesized, and some of the ferrocene-containing compounds showed promising anticancer activity and selectivity.

(Chalcogen)semicarbazones and their cobalt complexes differentiate HL-60 myeloid leukaemia cells and are cytotoxic towards tumor cell lines

Cobalt complexes with semi- and thiosemicarbazones of 8-quinolinecarboxaldehyde have been synthesized and characterized by X-ray diffraction analysis. These novel complexes and a previously synthesized cobalt complex with a selenium-based selenosemicarbazone ligand showed myeloid differentiation activity on all trans retinoic acid resistant HL-60 acute myeloid leukaemia cells. They also showed varying levels of cytotoxicity on five human tumor cell lines: cervix carcinoma cells (HeLa), lung adenocarcinoma cells (A549), colorectal adenocarcinoma cells (LS-174), breast carcinoma cells (MDA-MB-361), and chronic myeloid leukaemia (K562) as well as one normal human cell line: fetal lung fibroblast cells (MRC-5). Leukaemia differentiation was most strongly induced by a metal-free oxygen ligand and the selenium ligand, whilst the latter and the cobalt(ii) complex with an oxygen ligand showed the strongest dose-dependent cytotoxic activity. In four out of five investigated tumor cell lines, it was of the same order of magnitude as cisplatin. These best compounds, however, had lower toxicity on non-transformed MRC-5 cells than cisplatin.

Advances in cobalt complexes as anticancer agents

The evolution of resistance to traditional platinum-based anticancer drugs has compelled researchers to investigate the cytostatic properties of alternative transition metal-based compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. This perspective catalogues the development of antiproliferative cobalt complexes, and provides an in depth analysis of their mode of action. Early studies on simple cobalt coordination complexes, Schiff base complexes, and cobalt-carbonyl clusters will be documented. The physiologically relevant redox properties of cobalt will be highlighted and the role this plays in the preparation of hypoxia selective prodrugs and imaging agents will be discussed. The use of cobalt-containing cobalamin as a cancer specific delivery agent for cytotoxins will also be described. The work summarised in this perspective shows that the biochemical and biophysical properties of cobalt-containing compounds can be fine-tuned to produce new generations of anticancer agents with clinically relevant efficacies.

A novel 4-fluorobenzenetelluronic trimethyltin ester: synthesis, characterization and in vitro cytotoxicity assessment

A novel 4-fluorobenzenetelluronic trimethyltin ester (Me₃Sn)₄[p-F-PhTe(μ-O)(OH)O₂]₂ (1) has been prepared and structurally characterized, and apoptotic cytotoxicity assessments for A549 cells are made.

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.