Synthesis, characterization and antitumor activity of novel ferrocene derivatives containing pyrazolyl-moiety

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.

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.

Heterocycles in Breast Cancer Treatment: The Use of Pyrazole Derivatives

Among the aromatic heterocycle rings, pyrazole -a five-membered ring with two adjacent nitrogen atoms in its structure has been postulated as a potent candidate in the pharmacological context. This moiety is an interesting therapeutic target covering a broad spectrum of biological activities due to its presence in many natural substances. Hence, the potential of the pyrazole derivatives as antitumor agents has been explored in many investigations, showing promising results in some cases. In this sense, breast cancer, which is already the leading cause of cancer mortality in women in some countries, has been the topic selected for this review, which covers a range of different research from the earliest studies published in 2003 to the most recent ones in 2021.

Concept of Hybrid Drugs and Recent Advancements in Anticancer Hybrids

Cancer is a complex disease, and its treatment is a big challenge, with variable efficacy of conventional anticancer drugs. A two-drug cocktail hybrid approach is a potential strategy in recent drug discovery that involves the combination of two drug pharmacophores into a single molecule. The hybrid molecule acts through distinct modes of action on several targets at a given time with more efficacy and less susceptibility to resistance. Thus, there is a huge scope for using hybrid compounds to tackle the present difficulties in cancer medicine. Recent work has applied this technique to uncover some interesting molecules with substantial anticancer properties. In this study, we report data on numerous promising hybrid anti-proliferative/anti-tumor agents developed over the previous 10 years (2011–2021). It includes quinazoline, indole, carbazole, pyrimidine, quinoline, quinone, imidazole, selenium, platinum, hydroxamic acid, ferrocene, curcumin, triazole, benzimidazole, isatin, pyrrolo benzodiazepine (PBD), chalcone, coumarin, nitrogen mustard, pyrazole, and pyridine-based anticancer hybrids produced via molecular hybridization techniques. Overall, this review offers a clear indication of the potential benefits of merging pharmacophoric subunits from multiple different known chemical prototypes to produce more potent and precise hybrid compounds. This provides valuable knowledge for researchers working on complex diseases such as cancer.

Synthesis, Characterization, and Electrochemistry of Diferrocenyl β-Diketones, -Diketonates, and Pyrazoles

The synthesis of FcC(O)CH(R)C(O)Fc (Fc = Fe(η⁵-C₅H₄)(η⁵-C₅H₅); R = H, 5; ⁿBu, 7; CH₂CH₂(OCH₂CH₂)₂OMe, 9), [M(κ²O,O′-FcC(O)CHC(O)Fc)_n] (M = Ti, n = 3, 10; M = Fe, n = 3, 11; M = BF₂, n = 1, 12), and 1-R′-3,5-Fc₂-^cC₃HN₂ (R′ = H, 13; Me, 14; Ph, 15) is discussed. The solid-state structures of 5, 7, 9, 12, 13, 15, and 16 ([TiCl₂(κ²O,O′-PhC(O)CHC(O)Ph)₂]) show that 7 and 9 exist in their β-diketo form. Compound 13 crystallizes as a tetramer based on a hydrogen bond pattern, including one central water molecule. The electrochemical behavior of 5–7 and 9–16 was studied by cyclic and square-wave voltammetry, showing that the ferrocenyls can separately be oxidized reversibly between −50 and 750 mV (5–7, 9, 12–15: two Fc-related events; 10, 11: six events, being partially superimposed). For complex 10, Ti-centered reversible redox processes appear at −985 (Ti^II/Ti^III) and −520 mV (Ti^III/Ti^IV). Spectro-electrochemical UV-Vis/NIR measurements were carried out on 5, 6, and 12, whereby only 12 showed an IVCT (intervalence charge-transfer) band of considerable strength (ν_max = 6250 cm⁻¹, Δν_½ = 4725 cm⁻¹, ε_max = 240 L·mol⁻¹·cm⁻¹), due to the rigid C₃O₂B cycle, enlarging the coupling strength between the Fc groups.

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.

Ferrocene-appended pharmacophores: an exciting approach for modulating the biological potential of organic scaffolds

The present review article describes the recent developments (2014–18) on the synthesis of ferrocene-based pharmacophores with the specific benefits of introducing/replacing organic pharmacophores with the ferrocene core for desired bioactivities.

The crystal structure of (4-nitrophenyl) (5-ferrocenyl-3-(trifluoromethyl)-1H-pyrazol-1-yl) methanone, C21H12F3FeN3O3

C21H14F3FeN3O3, triclinic, P1̄ (no. 2), a = 7.961(3) Å, b = 11.136(4) Å, c = 11.588(4) Å, α = 76.357(10)°, β = 84.998(10)°, γ = 76.989(10)° V = 972.1(6) Å3, Z = 2, R gt(F) = 0.0509, wR ref(F 2) = 0.1304, T = 273(2) K.

Crystal structure of (4-chlorophenyl)(3-ferrocenyl-5-(trifluoromethyl)-1H-pyrazol-1-yl)methanone, C21H14ClF3FeN2O

C21H14ClF3FeN2O, triclinic, P1̅ (no. 2), a = 7.8754(6) Å, b = 10.9326(10) Å, c = 11.8418(9) Å, α = 73.845(3)°, β = 84.237(2)°, γ = 74.207(3)°, V = 942.00(13) Å3, Z = 2, R gt(F) = 0.0385, wR ref(F 2) = 0.0973, T = 273 K.

Synthesis, X-ray, DFT and photophysical properties of some new ferrocenyl hydrazono thiazolidin-4-ones and their derivatives

Cyclocondensation of thiosemicarbazone of 2-acetylferrocene with α-haloacids and α-haloketones afford new ferrocenyl hydrazono thiazolidin-4-ones and ferrocenyl hydrazono thiazoles respectively. Ferrocenyl hydrazono thiazolidin-4-one is easily converted into enamino ketone with N,N-dimethylformamide dimethyl acetal (DMF-DMA). The compounds were characterized by spectroscopic means and the structure of the new ferrocenyl hydrazono thiazolidin-4-one (3a) was determined by means of X-ray crystallography. The photophysical properties of these compounds were studied by means of UV/visible absorption spectroscopy and fluorescence spectroscopy. Density functional theory (DFT) calculations have been carried out with Gaussian 09W using B3LYP density functional method and 6-31G (d) basis set. (1)H and (13)C Nuclear Magnetic Resonance (NMR) have been calculated and correlated with experimental results. Antimicrobial activity studies of some new compounds have been reported.