On the medicinal chemistry of ferrocene

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.

P(III)-Directed Asymmetric C-H Arylation toward Planar Chiral Ferrocenes by Palladium Catalysis

Planar chiral ferrocenyl phosphines have been employed as highly valuable ligands in metal-catalyzed asymmetric reactions. However, their preparation remains a formidable challenge due to the requirement for intricate, multistep synthetic sequences. In addressing this issue, we have developed a groundbreaking enantioselective C-H activation strategy facilitated by P(III) directing groups, enabling the efficient construction of planar chiral ferrocenyl phosphines in a single step. Our innovative approach entails the combination of a palladium catalyst, a parent ferrocenyl phosphine, and a chiral phosphoramidite ligand, leading to exceptional reactivity and enantioselectivity. Remarkably, these novel ligands exhibit remarkable efficacy in silver-catalyzed asymmetric 1,3-dipolar cycloadditions. We carried out a combination of experimental and computational studies to obtain a more comprehensive understanding of the reaction pathway and the factors contributing to enantioselectivity.

Regio- and Stereoselective Iodoamination of Ferrocene-Containing Allenylphosphonates: Synthesis of Multifunctional Tetrasubstituted Allylic Amines and Allylic Azides

A general and practical methodology for the regio- and stereoselective synthesis of multifunctional tetrasubstituted allylic amines and azides based on iodoamination of ferrocene-containing allenylphosphonates with anilines and sodium azide is described. A tetrasubstituted olefin moiety, as well as an iodine atom, a phosphonate, and a ferrocene group, are installed to the allylic amine motif simultaneously in moderate to good yields.

Charge-compensated nido-carborane derivatives in the synthesis of iron(II) bis(dicarbollide) complexes

A series of stable iron(II) bis(dicarbollide) derivatives [8,8'-(RNHC(Et)HN)2-3,3'-Fe(1,2-C2B9H10)2] (R = Pr, R = Ph, (CH2)2OH, (CH2)3OH, (CH2)2NMe2) was prepared starting from FeCl2 or [FeCl2(dppe)] and the corresponding nido-carboranyl amidines [10-RNHC(Et)HN-7,8-C2B9H11]. In a similar way, the reactions of the oxonium derivatives of nido-carborane with FeCl2 in tetrahydrofuran in the presence of t-BuOK lead to the corresponding stable oxonium derivatives iron(II) bis(dicarbollide) [8,8'-(RR'O)2-3,3'-Fe(1,2-C2B9H10)2] (RR' = (CH2)4, (CH2)2O(CH2)2, (CH2)5; R = R' = Et), which can be alternatively prepared by the reaction of the parent iron(II) bis(dicarbollide) with tetrahydrofuran or 1,4-dioxane in the presence of Me2SO4. The cyclic voltammetry studies of the synthesized iron(II) bis(dicarbollide) derivatives revealed that the introduction of amidinium and oxonium substituents leads to a significant increase in the Fe2+/Fe3+ redox potential relative to the parent iron(II) bis(dicarbollide). The redox potentials of the oxonium derivatives are close to the redox potential of ferrocene and somewhat lower than redox potentials of sulfonium and phosphonium derivatives of iron(II) bis(dicarbollide).

Oxidation-derived anticancer potential of sumanene-ferrocene conjugates

An effective synthetic protocol towards the oxidation of sumanene-ferrocene conjugates bearing one to four ferrocene moieties has been established. The oxidation protocol was based on the transformation of FeII from ferrocene to FeIII-containing ferrocenium cations by means of the treatment of the title organometallic buckybowls with a mild oxidant. Successful isolation of these ferrocenium-tethered sumanene derivatives 5-7 gave rise to the biological evaluation of the first, buckybowl-based anticancer agents, as elucidated by in vitro assays with human breast adenocarcinoma cells (MDA-MB-231) and embryotoxicity trials in zebrafish embryos supported with in silico toxicology studies. The designed ferrocenium-tethered sumanene derivatives featured attractive properties in terms of their use in cancer treatments in humans. The tetra-ferrocenium sumanene derivative 7 featured especially beneficial biological features, elucidated by low (<40% for 10 μM) viabilities of MDA-MB-231 cancer cells together with a 1.4-1.7-fold higher viability of normal cells (human mammary fibroblasts, HMF) for respective concentrations. Compound 7 featured significant cytotoxicity against cancer cells thanks to the presence of sumanene and ferrocenium moieties; the latter motif also provided the selectivity of anticancer action. The biological properties of 7 were also improved in comparison with those of native building blocks, which suggested the effects of the presence of the sumanene skeleton towards the anticancer action of this molecule. Ferrocenium-tethered sumanene derivatives exhibited potential towards the generation of reactive oxygen species (ROS), responsible for biological damage to the cancer cells, with the most efficient generation of the tetra-ferrocenium sumanene derivative 7. Derivative 7 also did not show any embryotoxicity in zebrafish embryos at the tested concentrations, which supports its potential as an effective and cancer-specific anticancer agent. In silico computational analysis also showed no chromosomal aberrations and no mutation with AMES tests for the compound 7 tested with and without microsomal rat liver fractions, which supports its further use as a potent drug candidate in detailed anticancer studies.

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.

Magnetically Induced Binary Ferrocene with Oxidized Iron

Ferrocene is perhaps the most popular and well-studied organometallic molecule, but our understanding of its structure and electronic properties has not changed for more than 70 years. In particular, all previous attempts of chemically oxidizing pure ferrocene by binding directly to the iron center have been unsuccessful, and no significant change in structure or magnetism has been reported. Using a metal organic framework host material, we were able to fundamentally change the electronic and magnetic structure of ferrocene to take on a never-before observed physically stretched/bent high-spin Fe(II) state, which readily accepts O2 from air, chemically oxidizing the iron from Fe(II) to Fe(III). We also show that the binding of oxygen is reversible through temperature swing experiments. Our analysis is based on combining Mößbauer spectroscopy, extended X-ray absorption fine structure, in situ infrared, SQUID, thermal gravimetric analysis, and energy dispersive X-ray fluorescence spectroscopy measurements with ab initio modeling.

Contemporary Developments in Ferrocene Chemistry: Physical, Chemical, Biological and Industrial Aspects

Ferrocenyl-based compounds have many applications in diverse scientific disciplines, including in polymer chemistry as redox dynamic polymers and dendrimers, in materials science as bioreceptors, and in pharmacology, biochemistry, electrochemistry, and nonlinear optics. Considering the horizon of ferrocene chemistry, we attempted to condense the neoteric advancements in the synthesis and applications of ferrocene derivatives reported in the literature from 2016 to date. This paper presents data on the progression of the synthesis of diverse classes of organic compounds having ferrocene scaffolds and recent developments in applications of ferrocene-based organometallic compounds, with a special focus on their biological, medicinal, bio-sensing, chemosensing, asymmetric catalysis, material, and industrial applications.

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.

Impact of Coordination Mode and Ferrocene Functionalization on the Anticancer Activity of N-Heterocyclic Carbene Half-Sandwich Complexes

The substitution of phenyl rings in established drugs with ferrocenyl moieties has been reported to yield compounds with improved biological activity and alternative modes of action, often involving the formation of reactive oxygen species (ROS). Translating this concept to N-heterocyclic carbene (NHC) complexes, we report here organometallics with a piano-stool structure that feature di- or tridentate ligand systems. The ligands impacted the cytotoxic activity of the NHC complexes, but the coordination modes seemed to have a limited influence, which may be related to the propensity of forming the same species in solution. In general, the stability of the complexes in an aqueous environment and their reactivity to selected biomolecules were largely dominated by the nature of the metal center. While the complexes promoted the formation of ROS, the levels did not correlate with their cytotoxic activity. However, the introduction of ferrocenyl moieties had a significant impact on the antiproliferative potency of the complexes and, in particular, some of the ferrocenyl-functionalized compounds yielded IC₅₀ values in the low μM range.

Redox-switchable host-guest complexes of metallocenes and [8]cycloparaphenylene

The cycloparaphenylene (CPP) nanocarbons are an appealing family of macrocyclic organic semiconductors with size-tunable structures and unique optoelectronic properties, which can be further modulated by complexation with guest molecules. While many π-π-stabilized CPP-fullerene host-guest complexes are known, CPPs can also host polycyclic guests stabilized by aromatic CH-π interactions. Here we combine experimental and computational results to report that CH-π interactions can also be tapped to include redox-active metallocene guests in [8]cycloparaphenylene ([8]CPP). Oxidation of a metallocene guest is accompanied by an increase in binding affinity and tilt angle. Crystallographically determined solid-state structures reveal CH-π interactions in the ferrocene complex (Fc⊂[8]CPP) and additional π-π interactions in the cobaltocenium complex (CoCp₂⁺⊂[8]CPP). Functionalizing Fc with oxygen-bearing side chains also improves complex stability to a similar extent as oxidation, due to the formation of CH-O hydrogen bonds with the host's p-phenylene units. This work shows that CH-π bonding can be generalized as a driving force for CPP host-guest complexes and combined with other supramolecular forces to enhance stability. Owing to their semiconducting nature, amenability to functionalization, and reversible redox-dependent behavior, the [8]CPP-metallocene host-guest complexes may expand the library of synthons available for designing bespoke nanoelectronics and artificial molecular machines.

[3 + 2] Cycloadditions in Asymmetric Synthesis of Spirooxindole Hybrids Linked to Triazole and Ferrocene Units: X-ray Crystal Structure and MEDT Study of the Reaction Mechanism

Derivatization of spirooxindole having triazole and ferrocene units was achieved by the [3 + 2] cycloaddition (32CA) reaction approach. Reacting the respective azomethine ylide (AY) intermediate generated in situ with the ethylene derivative produced novel asymmetric cycloadducts with four contiguous asymmetric carbons in an overall high chemical yield with excellent regioselectivity and diastereoselectivity. X-Ray single-crystal structure analyses revealed, with no doubt, the success of the synthesis of the target compounds. The 32CA reaction of AY 5b with ferrocene ethylene 1 has been studied within MEDT. This 32CA reaction proceeds via a two-stage one-step mechanism involving a high asynchronous transition state structure, resulting from the nucleophilic attack of AY 5b on the β-conjugated position of ferrocene ethylene 1. The supernucleophilic character of AY 5b and the strong electrophilic character of ferrocene ethylene 1 account for the high polar character of this 32CA reaction. Further, Hirshfeld analyses were used to describe the molecular packing of compounds 4b, 4e, 4h and 4i.

A Molecular Electron Density Theory Study of the [3+2] Cycloaddition Reaction of an Azomethine Ylide with an Electrophilic Ethylene Linked to Triazole and Ferrocene Units

The [3+2] cycloaddition (32CA) reaction of an azomethine ylide (AY) with an electrophilic ethylene linked to triazole and ferrocene units has been studied within the Molecular Electron Density Theory (MEDT) at the ωB97X-D/6-311G(d,p) level. The topology of the electron localization function (ELF) of this AY allows classifying it as a pseudo(mono)radical species characterized by the presence of two monosynaptic basins, integrating a total of 0.76 e, at the C1 carbon. While the ferrocene ethylene has a strong electrophilic character, the AY is a supernucleophile, suggesting that the corresponding 32CA reaction has a high polar character and a low activation energy. The most favorable ortho/endo reaction path presents an activation enthalpy of 8.7 kcal·mol^-1, with the 32CA reaction being exergonic by -42.1 kcal·mol^-1. This reaction presents a total endo stereoselectivity and a total ortho regioselectivity. Analysis of the global electron density transfer (GEDT) at the most favorable TS-on (0.23 e) accounts for the high polar character of this 32CA reaction, classified as forward electron density flux (FEDF). The formation of two intermolecular hydrogen bonds between the two interacting frameworks at the most favorable TS-on accounts for the unexpected ortho regioselectivity experimentally observed.

Succinimido–Ferrocidiphenol Complexed with Cyclodextrins Inhibits Glioblastoma Tumor Growth In Vitro and In Vivo without Noticeable Adverse Toxicity

SuccFerr (N-[4-ferrocenyl,5-5-bis (4-hydroxyphenyl)-pent-4-enyl]-succinimide) has remarkable antiproliferative effects in vitro, attributed to the formation of a stabilized quinone methide. The present article reports in vivo results for a possible preclinical study. SuccFerr is lipophilic and insoluble in water, so the development of a formulation to obviate this inconvenience was necessary. This was achieved by complexation with randomly methylated cyclodextrins (RAMEßCDs). This supramolecular water-soluble system allowed the in vivo experiments below to proceed. Application of SuccFerr on the glioblastoma cancer cell line U87 indicates that it affects the cellular cycle by inducing a blockade at G0/G1 phase, linked to apoptosis, and another one at the S phase, associated with senescence. Using healthy Fischer rats, we show that both intravenous and subcutaneous SuccFerr: RAMEßCD administration at 5 mg/kg lacks toxic effects on several organs. To reach lethality, doses higher than 200 mg/kg need to be administered. These results prompted us to perform an ectopic in vivo study at 1 mg/kg i.v. ferrocidiphenol SuccFerr using F98 cells xenografted in rats. Halting of cancer progression was observed after six days of injection, associated with an immunological defense response linked to the active principle. These results demonstrate that the properties of the selected ferrocidiphenol SuccFerr transfer successfully to in vivo conditions, leading to interesting therapeutic perspectives based on this chemistry.

Synthesis and Structure Elucidation of Novel Spirooxindole Linked to Ferrocene and Triazole Systems via [3 + 2] Cycloaddition Reaction

In the present work, a novel heterocyclic hybrid of a spirooxindole system was synthesized via the attachment of ferrocene and triazole motifs into an azomethine ylide by [3 + 2] cycloaddition reaction protocol. The X-ray structure of the heterocyclic hybrid (1″R,2″S,3R)-2″-(1-(3-chloro-4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carbonyl)-5-methyl-1″-(ferrocin-2-yl)-1″,2″,5″,6″,7″,7a″-hexahydrospiro[indoline-3,3″-pyrrolizin]-2-one revealed very well the expected structure, by using different analytical tools (FTIR and NMR spectroscopy). It crystallized in the triclinic-crystal system and the P-1-space group. The unit cell parameters are a = 9.1442(2) Å, b = 12.0872(3) Å, c = 14.1223(4) Å, α = 102.1700(10)°, β = 97.4190(10)°, γ = 99.1600(10)°, and V = 1484.81(7) ų. There are two molecules per unit cell and one formula unit per asymmetric unit. Hirshfeld analysis was used to study the molecular packing of the heterocyclic hybrid. H···H (50.8%), H···C (14.2%), Cl···H (8.9%), O···H (7.3%), and N···H (5.1%) are the most dominant intermolecular contacts in the crystal structure. O···H, N···H, H···C, F···H, F···C, and O···O are the only contacts that have the characteristic features of short and significant interactions. AIM study indicated predominant covalent characters for the Fe–C interactions. Also, the electron density (ρ(r)) at the bond critical point correlated inversely with the Fe–C distances.

Recent advances in the synthesis of ferrocene derivatives via 3d transition metal-catalyzed C-H functionalization

In recent years, transition-metal-catalyzed C-H functionalization has gradually developed into a powerful tool for the synthesis of ferrocenes in an atom- and step-economic fashion. However, despite significant achievements, the vast majority of these C-H functionalizations required precious 4d or 5d transition metal catalysts. The use of inexpensive and sustainable 3d metals in the C-H functionalization of ferrocenes remains challenging, especially the development of asymmetric versions. Herein, we summarize the remarkable recent progress in the synthesis of ferrocenes by 3d transition metal-catalyzed C-H activation until December 2021.

Stereoselective Synthesis and Anticancer Activity of 2,6-Disubstituted trans-3-Methylidenetetrahydropyran-4-ones

In this report, we present efficient and stereoselective syntheses of 2,6-disubstituted trans-3-methylidenetetrahydropyran-4-ones and 2-(4-methoxyphenyl)-5-methylidenetetrahydropyran-4-one that significantly broaden the spectrum of the available methylidenetetrahydropyran-4-ones with various substitution patterns. Target compounds were obtained using Horner–Wadsworth–Emmons methodology for the introduction of methylidene group onto the pyranone ring. 3-Diethoxyphosphoryltetrahydropyran-4-ones, which were key intermediates in this synthesis, were prepared by fully or highly stereoselective addition of Gilman or Grignard reagents to 3-diethoxyphosphoryldihydropyran-4-ones. Addition occurred preferentially by axial attack of the Michael donors on the dihydropyranone ring. Relative configurations and conformations of the obtained adducts were assigned using a detailed analysis of the NMR spectra. The obtained methylidenepyran-4-ones were evaluated for cytotoxic activity against two cancer cell lines (HL-60 and MCF-7). 2,6-Disubstituted 3-methylidenetetrahydropyran-4-ones with isopropyl and phenyl substituents in position 2 were more cytotoxic than analogs with n-butyl substituent. Two of the most cytotoxic analogs were then selected for further investigation on the HL-60 cell line. Both analogs induced morphological changes characteristic of apoptosis in cancer cells, significantly inhibited proliferation and induced apoptotic cell death. Both compounds also generated DNA damage, and one of the analogs arrested the cell cycle of HL-60 cells in the G2/M phase. In addition, both analogs were able to inhibit the activity of topoisomerase IIα. Based on these findings, the investigated analogs may be further optimized for the development of new and effective topoisomerase II inhibitors.

The crystal structure of (E)-3-(2-chlorophenyl)-1-ferrocenylprop-2-en-1-one, C19H15ClFeO

C19H15ClFeO, triclinic, P 1 ‾ $P\bar{1}$ (no. 2), a = 10.2693(5) Å, b = 11.2568(6) Å, c = 20.8930(10) Å, α = 80.350(2)°, β = 76.9640(10)°, γ = 86.921(2)°, V = 2319.4(2) Å3, Z = 6, R gt (F) = 0.0534, wR ref(F 2) = 0.0968, T = 170 K.

The crystal structure of (E)-1-ferrocenyl-3-(naphthalen-1-yl)prop-2-en-1-one, C23H18FeO

C23H18FeO, orthorhombic, Pna21 (no. 33), a = 28.3217(11) Å, b = 5.7477(2) Å, c = 10.3071(3) Å, β = 90°, V = 1677.84(10) Å3, Z = 4, R gt (F) = 0.0372, wR ref (F 2) = 0.0713, T = 150 K.

Detailed structural and spectroscopic elucidation of ferrocenium coupled N-heterocyclic carbene gold(I) complexes

Unambiguous assignment of redox sites on ferrocene coupled N-heterocyclic carbene gold(I) complexes [(Fc-NHC)2Au(I)]+ is critical to gain a greater mechanistic understanding of their activity in a cellular environment. Such information can be garnered with isolation and detailed characterization of the oxidized version of [(Fc-NHC)2Au(I)]+. Herein we disclose a study that unambiguously illustrates redox events pertaining to [(Fc-NHC)2Au(I)]+ that stem exclusively from ferrocene sites. This work also describes novel synthetic methodologies for isolating ferrocenium coupled N-heterocyclic carbene gold(I) complexes.

Five shades of green: substituent influence on the (spectro-) electrochemical properties of diferrocenyl(phenyl)methylium dyes

Five new, intensely green diferrocenylphenylmethylium complexes 1+-5+ with electron donating (EDG: 4-MeO, 4-Me, 4-Br) or withdrawing (EWG: 3,5-CF₃, 4-ⁿC₆F₁₃) substituents were synthesized and fully characterized. The substituent influence on their electrochemical and spectroscopic properties was investigated by cyclic voltammetry, UV/Vis/NIR and T-dependent EPR spectroscopy of the cationic as well as the oxidized (12+-52+) and reduced (1˙-5˙) species. The reduced forms equilibrate with their corresponding dimers (65-83%) with a clear substituent influence as expressed by their Hammett parameters in an ordering 4+ > 5+ > 3+ > 2+ > 1+. The structures of all five precursor carbinols 1-OH-5-OH and those of three of the diferrocenylphenylmethylium cations (1+, 4+-5+) were established by X-ray crystallography.

Synthesis, docking, machine learning and antiproliferative activity of the 6-ferrocene/heterocycle-2-aminopyrimidine and 5-ferrocene-1H-Pyrazole derivatives obtained by microwave-assisted Atwal reaction as potential anticancer agents

A simple and fast methodology under microwave irradiation for the synthesis of 2-aminopyrimidine and pyrazole derivatives using Atwal reaction is reported. After the optimization of the reaction conditions, eight 2-aminolpyrimidines containing ferrocene and heterocycles and three ferrocene pyrazoles were synthesized from the respective chalcones in good yields. Eight compounds had their structure determined by X-ray diffraction. The molecular hybrid 6a-h and 9a-c were tested on four cancer cell lines - HCT116, PC3, HL60 and SNB19 - where four pyrimidine 6a, 6f-h and one pyrazole 9c derivatives show promising antiproliferative activity. In addition, docking simulation and machine learning methods were carried out to explain the biological activity achieved by the synthetized compounds.

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.

α-Tocopherol-loaded reactive oxygen species-scavenging ferrocene nanocapsules with high antioxidant efficacy for wound healing

The elevated production of reactive oxygen species (ROS) in wounded sites triggers a series of harmful effects, including cellular senescence, fibrotic scar formation, and inflammation. Therefore, alleviating oxidative stress in the microenvironment of wounded sites might promote regenerative wound healing. Generally, ROS-scavenging nanocapsules are effective for treating wounds owing to their anti-oxidative stress activity and targeted effects. In this study, a highly versatile ferrocene functional polymer was synthesized by one-pot radical polymerization, for formulating self-assembled ferrocene nanocapsules (FNCs), which could function as smart carriers of an antioxidant, α-tocopherol (TP), with high stability and loading efficiency. The FNCs showed ROS-sensitive properties, as demonstrated using dynamic light scattering, transmission electron microscopy, and the controlled release of a model drug in an ROS microenvironment. The antioxidant activity of TP-loaded FNCs, analyzed using 2,2-diphenyl-1-picrylhydrazyl assay, was significantly higher than that of unloaded TP. Furthermore, TP-loaded FNCs repressed oxidative damage to mouse NIH 3T3 fibroblasts and reduced intracellular ROS production according to an in vitro antioxidant assay. Most importantly, TP-loaded FNCs showed good biocompatibility and greatly facilitated the healing of infected wounds, as demonstrated using a scratch assay. Therefore, TP-loaded FNCs have potential as an ROS-mediated drug delivery system to treat various oxidative stress-associated diseases.

Exploration of artemisinin derivatives and synthetic peroxides in antimalarial drug discovery research

Malaria is a life-threatening infectious disease caused by protozoal parasites belonging to the genus Plasmodium. It caused an estimated 405,000 deaths and 228 million malaria cases globally in 2018 as per the World Malaria Report released by World Health Organization (WHO) in 2019. Artemisinin (ART), a "Nobel medicine" and its derivatives have proven potential application in antimalarial drug discovery programs. In this review, antimalarial activity of the most active artemisinin derivatives modified at C-10/C-11/C-16/C-6 positions and synthetic peroxides (endoperoxides, 1,2,4-trioxolanes, 1,2,4-trioxanes, and 1,2,4,5-tetraoxanes) are systematically summarized. The developmental trend of ART derivatives, and cyclic peroxides along with their antimalarial activity and how the activity is affected by structural variations on different sites of the compounds are discussed. This compilation would be very useful towards scaffold hopping aimed at avoiding the unnecessary complexity in cyclic peroxides, and ultimately act as a handy resource for the development of potential chemotherapeutics against Plasmodium species.

Antioxidant and Anticancer Properties of Functionalized Ferrocene with Hydroxycinnamate Derivatives-An Integrated Experimental and Theoretical Study

Two ferrocenyl derivatives, Fc-CA and Fc-FA, were synthesized by a condensation reaction between the amino ferrocene and hydroxycinnamic acids, that is, caffeic acid (CA) and ferulic acid (FA). The structures and purity of all compounds were characterized by ¹H- and ¹³C NMR spectroscopies, Mass spectrometry (MS), and elemental analysis. The antioxidant properties of Fc-CA and Fc-FA and of its ligand were studied for free radical scavenging activity toward DPPH^•, superoxide anion (O₂^•-), NO^•, and ABTS^•+ by UV-vis and electron spin resonance spectroscopies. The cytotoxicity of Fc-CA and Fc-FA against MCF-7 and MDA-MB-231 breast cancer cells and MRC-5 human lung fibroblasts cell was higher than that of cisplatin. The geometry and electronic structures of all compounds were then simulated using density functional theory at M05-2X/6-311+G(d,p) level of theory. Thermodynamics of the free radical quenching reactions by common mechanisms reveal the higher antioxidant properties of the Fc-CA and Fc-FA in comparison to their ligands. An in-depth study of the free radical scavenging activity against HOO^• and HO^• radicals was performed for two of the most favorable and competitive mechanisms, the hydrogen transfer (either hydrogen atom transfer or proton-coupled electron transfer mechanisms) and the radical adduct formation. The in silico studies indicated that ferrocenyl derivatives exhibited prominent binding affinity to protein models in comparison to CA and FA. Their dock scores were notable at ligand binding sites of ERα, Erβ, and JAK2 proteins. Dock pose analysis also shed light into the possible mechanism of action for the studied compounds.

Dendrimers against fungi - A state of the art review

Fungal based diseases currently affect nearly a quarter of the population around the world, which diseases are usually limited to superficial infections. Perversely, along with the development of modern medicine, cases of life-threatening systemic fungi are more and more often encountered. Compared to antibacterial drugs, significantly fewer fungicides are tested and introduced to clinical practice. At the same time, the drug resistance of pathological fungi is constantly growing. In addition to obtaining new derivatives of already-established classes of drugs, such as azoles, there is a growing interest in new compounds with potentially new mechanisms and application possibilities. Polymers are included in the flow of these studies, and among them - dendrimers. Dendrimers are a special type of polymers with a strictly defined structure and a plethora of functionalization possibilities. This allows them to not only be used as effective antifungal drug carriers but also enables them to exhibit antifungal activity per se. In this review, we have introduced to the epidemiology of fungal infections and summarized the aspects related to their control and therapy. Various polymers and dendrimers with antifungal activity were presented. In the subsequent sections antifungal acting dendrimers were discussed within three subchapters, based on their chemical structure: (i) amino acid-based dendrimers, (ii) amino based dendrimers, and (iii) other, which do not share similarities in structure. We have gathered and summarized the reports regarding the direct action of dendrimers on infectious fungi, as well as their effect when used as solubilizers, carriers or adjuvants with currently used antifungals. Use of dendrimers for the sensing of fungi or their metabolites are also considered. Special attention was also paid to the applications of dendrimers together with photosensitizers in antimicrobial photodynamic therapy.

Electrochemical Applications of Ferrocene-Based Coordination Polymers

Ferrocene and its derivatives, especially ferrocene-based coordination polymers (Fc-CPs), offer the benefits of high thermal stability, two stable redox states, fast electron transfer, and excellent charge/discharge efficiency, thus holding great promise for electrochemical applications. Herein, we describe the synthesis and electrochemical applications of Fc-CPs and reveal how the incorporation of ferrocene units into coordination polymers containing other metals results in unprecedented properties. Moreover, we discuss the usage of Fc-CPs in supercapacitors, batteries, and sensors as well as further applications of these polymers, for example in electrocatalysts, water purification systems, adsorption/storage systems.

In vitro nematicidal activity of two ferrocenyl chalcones against larvae of Haemonchus contortus (L3) and Nacobbus aberrans (J2)

The main goal of this work was to evaluate the in vitro biological activity of two ferrocenyl chalcones (FcC-1 and FcC-2) against Haemonchus contortus (third-stage larvae (L3)) and Nacobbus aberrans (second-stage juveniles (J2)). Both compounds were synthesized and characterized by usual spectroscopic methods and their molecular structures were confirmed by single-crystal X-ray diffractometry. Nematode strains were examined in terms of percentage mortality of H. contortus (L3) by the action of FcC-1, which showed an effectivity of 100% at a concentration of 342 μM in 24 h, with EC50 = 20.33 μM and EC90 = 162.76 μM, whereas FcC-2 had an effectivity of 72% at a concentration of 342 μM in 24 h, with EC50 = 167.39 μM and EC90 = 316.21 μM. The effect of FcC-1 against nematode phytoparasite N. aberrans showed a better percentage of 95% at a concentration of 342 μM, with EC50 = 7.18 μM and EC90 = 79.25 μM, whereas the effect of FcC-2 was 87% at 342 μM, with EC50 = 168 μM and EC90 = 319.56 μM at 36 h. After treatment, the scanning electron micrographs revealed deformities in the dorsal flank and posterior part close to the tail of H. contortus L3. They showed moderate in vitro nematicidal activity against H. contortus L3 and N. aberrans J2.