Ferrocene-modified amino acids: synthesis and in vivo bioeffects on hippocampus

Anticancer activity promoted by ligand diversity in diiron thiocarbyne complexes

Mononuclear iron (II) complexes have been intensively investigated with the aim of developing efficacious anticancer drugs that can overcome the serious limitations associated with the platinum complexes currently employed in chemotherapy. Combining a promising antitumor potential with appropriate physicochemical properties, such as aqueous stability and a balanced hydrophilic/lipophilic character, is essential for clinical progression. We prepared six highly functionalized diiron(I) complexes from the μ-thiocarbyne precursor [Fe2Cp2(CO)2(μ-CO)(μ-CSMe)]CF3SO3, 1 (Cp = η5-C5H5), through the substitution of one carbonyl ligand with isocyanides (2-4) and the subsequent substitution of a second CO with N- or P-ligands (5-7). All products 2-7 were structurally characterized using IR and multinuclear NMR spectroscopy. One compound from series (7) was also characterized by single crystal X-ray diffraction. Complexes 2-7 exhibit outstanding stability in physiological-like solutions, with 92-97 % of the compounds unchanged after storing in DMEM at 37 °C for 24 h, and substantial amphiphilicity, with most of Log Pow values falling in the range -1 to +1. Complexes 3, 4, 5 and 7 exhibited cytotoxic activity against human (HCT 116, MCF-7, A2780) and murine (CT26, 4T1, B16-F1, B16-F10) cancer cell lines with IC50 values up to the nanomolar range, along with moderate selectivity toward the malignant phenotype. The induction of cell differentiation, senescence, and apoptotic cell death with cell-specific redox response were in the background of cytotoxic activity. However, limited tumor volume reduction and observed systemic toxicity in vivo indicated the need for additional structure-activity relationship studies to optimize the compounds anticancer profile.

The choice of μ-vinyliminium ligand substituents is key to optimize the antiproliferative activity of related diiron complexes

Diiron vinyliminium complexes constitute a large family of organometallics displaying a promising anticancer potential. The complexes [Fe2Cp2(CO)(μ-CO){μ-η1:η3-C(R3)C(R4)CN(R1)(R2)}]CF3SO3 (2a-c, 4a-d) were synthesized, assessed for their behavior in aqueous solutions (D2O solubility, Log Pow, stability in D2O/Me2SO-d6 mixture at 37°C over 48 h) and investigated for their antiproliferative activity against A2780 and A2780cisR ovarian cancer cell lines and the nontumoral one Balb/3T3 clone A31. Cytotoxicity data collected for 50 vinyliminium complexes were correlated with the structural properties (i.e. the different R1-R4 substituents) using the partial least squares methodology. A clear positive correlation emerged between the octanol-water partition coefficient and the relative antiproliferative activity on ovarian cancer cell lines, both of which appear as uncorrelated to the cancer cell selectivity. However, the different effects played by the R1-R4 substituents allow tracing guidelines for the development of novel, more effective compounds. Based on these results, three additional complexes (4p-r) were designed, synthesized and biologically investigated, revealing their ability to hamper thioredoxin reductase enzyme and to induce cancer cell production of reactive oxygen species.

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.

Enantiomeric-Enriched Ferrocenes: Synthesis, Chiral Resolution, and Mathematic Evaluation of CD-chiral Selector Energies with Ferrocene-Conjugates

Enantiomeric-enriched ferrocene-modified pyrazoles were synthesized via the reaction of the ferrocene alcohol, (S)-FcCH(OH)CH₃ (Fc = ferrocenyl), with various pyrazoles in acidic conditions at room temperature within several minutes. X-ray structural data for racemic (R,S)-1N-(3,5-dimethyl pyrazolyl)ethyl ferrocene (1) and its (S)-enantiomer (S)-1 were determined. A series of racemic pyrazolylalkyl ferrocenes was separated into enantiomers by analytical HPLC on β- and γ-cyclodextrins (CD) chiral stationary phases. The quantum chemical calculations of interaction energies of β-CD were carried out for both (R)- and (S)-enantiomers. A high correlation between experimental HPLC data and calculated interaction energies values was obtained.

The Influence of Lead on Generation of Signalling Molecules and Accumulation of Flavonoids in Pea Seedlings in Response to Pea Aphid Infestation

The aim of this study was to investigate the effect of an abiotic factor, i.e., lead at various concentrations (low causing a hormesis effect and causing high toxicity effects), on the generation of signalling molecules in pea (Pisum sativum L. cv. Cysterski) seedlings and then during infestation by the pea aphid (Acyrthosiphon pisum Harris). The second objective was to verify whether the presence of lead in pea seedling organs and induction of signalling pathways dependent on the concentration of this metal trigger defense responses to A. pisum. Therefore, the profile of flavonoids and expression levels of genes encoding enzymes of the flavonoid biosynthesis pathway (phenylalanine ammonialyase and chalcone synthase) were determined. A significant accumulation of total salicylic acid (TSA) and abscisic acid (ABA) was recorded in the roots and leaves of pea seedlings growing on lead-supplemented medium and next during infestation by aphids. Increased generation of these phytohormones strongly enhanced the biosynthesis of flavonoids, including a phytoalexin, pisatin. This research provides insights into the cross-talk between the abiotic (lead) and biotic factor (aphid infestation) on the level of the generation of signalling molecules and their role in the induction of flavonoid biosynthesis.