Pyrazolone-Based Zn(II) Complexes Display Antitumor Effects in Mutant p53-Carrying Cancer Cells.

The synthesis and characterization of nine Schiff bases of pyrazolone ligands HLn (n = 1-9) and the corresponding zinc(II) complexes 1-9 of composition [Zn(Ln)2] (n = 1-9) are reported. The molecular structures of complexes 2, 3, 4, 8, and 9 were determined by single-crystal X-ray diffraction analysis, highlighting in all cases a distorted tetrahedral geometry around the Zn(II) ion. Density functional theory studies are performed on both the HLn ligands and the derived complexes. A mechanism of dissociation and hydrolyzation of the coordinated Schiff base ligands is suggested, confirmed experimentally by powder X-ray diffraction study and photophysical studies. Complexes 1-9 were investigated in vitro as anticancer agents, along with mutant p53 (mutp53) protein levels in human cancer cell lines carrying R175H and R273H mutp53 proteins. Only those complexes with the highest Zn(II) ion release via dissociation have shown a significant cytotoxic activity with reduction of mutp53 protein levels.

Bioactive Ag(I) coordination complexes as dopants for castor oil plasticized ethylcellulose films.

The effects exerted by new bioactive acylpyrazolonate Ag(I) derivatives of the general formula [Ag(QPy,CF3)(R-Im)] containing different substituents on the imidazole (R-Im) ancillary ligands and the natural plasticizer castor oil when both are added to the ethylcellulose (EC) biopolymer in the preparation of thin films as potential active food packaging materials are presented. The Ag(I) complexes [Ag(QPy,CF3)(Bn-Im)] and [Ag(QPy,CF3)(Bu-Im)], having benzyl and butyl substituents, whose single crystal molecular structures are reported, have proved to be highly compatible for efficient incorporation between the EC polymer and the hydrophobic plasticizer chains, giving rise, even at low concentrations, to homogeneous, robust and elastic films. The concomitant presence of these Ag(I) complexes and castor oil in the polymer EC matrix gives rise to thin films with improved antibacterial activity against Escherichia coli (E. coli) as a model of Gram-negative bacterial strains when compared to the non-plasticized ones, with very low Ag(I) migration in the three food simulants used (distilled water, ethanol 10% v/v and acetic acid 3% v/v) under two assay conditions (70 °C for 2 h and 40 °C for 10 days).

Invasiveness modulation of glioma cells by copper complex-loaded nanoarchitectures.

Among the tumors with the highest lethality, gliomas are primary brain tumors associated with common recurrence inclined to metastasize along the neuraxis and occasionally out of the central nervous system. Even though metastasis is the main responsible for death in oncological patients, few dedicated treatments are approved. Therefore, the establishment of effective anti-metastasis agents is the final frontier in cancer research. Interestingly, some copper complexes have demonstrated promising efficacy as antimetastatic agents, but they may cause off-site effects such as the alteration of copper homeostasis in healthy tissues. Thus, the incorporation of copper-based antimetastatic agents in rationally designed nano-architectures can increase the treatment localization reducing the side effects. Here, copper complex loaded hybrid nano-architectures (CuLNAs) are presented and employed to assess the impact of an intracellular copper source on glioma cell invasiveness. The novel CuLNAs are fully characterized and exploited for cell migration modulation in a glioma cell line. The results demonstrate that CuLNAs significantly reduce cell migration without impairing cell proliferation compared to standard gold and copper NAs. A concomitant antimigratory-like regulation of the epithelial-to-mesenchymal transition genes confirmed these results, as the gene encoding for the epithelial protein E-cadherin was upregulated and the other explored mesenchymal genes were downregulated. These findings, together with the intrinsic behaviors of NAs, demonstrate that the inclusion of metal complexes in the nano-architectures is a promising approach for the composition of a family of agents with antimetastatic activity.

Understanding Stabilization Factors in Heterodinuclear Ln-Al Complexes from DFT Simulations on Thermochemistry Data: A Counterintuitive Conclusion.

This study validates a computational protocol to predict the stability of heterodinuclear complexes by varying ligands on both moieties and analyzing the reaction Gibbs free energy (ΔGr) values. To this purpose, a series of Eu-Al complexes with the general formula [Eu(LEu)3Al(LAl)3], where LEu is the ligand of europium and LAl is an oxygen donor ligand of aluminum, is used. The nature of the bridging bonds and thermochemical characteristics (ΔGr, enthalpy, and entropy) of the complexes were evaluated via DFT calculations. We demonstrated that both entropic and enthalpic effects play a relevant role in the stability. The analysis of the series allows us to identify three ΔGr ranges where heterodinuclear complexes are (i) stable and easy to characterize, (ii) fragile and difficult to characterize, and (iii) not observed (unreacted precursors are recovered). To rationalize the trend of the stability and correlate it with the chemical nature of the ligands, we investigated the condensed Fukui function on the Al fragment. Results suggest that to obtain stable heteronuclear complexes, it is necessary to consider ligands with small condensed Fukui function values. This corresponds to a less nucleophilic oxygen site, yet counterintuitively, it allows the ligand to delocalize the received electronic charge and stabilize the complex.

Enhanced DNA damage and anti-proliferative activity of a novel ruthenium complex with a chlorambucil-decorated ligand.

Triphenylphosphine substitution reactions of [RuCl(PPh3)2(tpm)]Cl, 1, featuring tris(pyrazolyl)methane (tpm) as ligand, with the chlorambucil-decorated pyridine ligand PyCA, 3-aminopyridine (PyNH2) and 4-pyridinemethanol (PyOH) afforded the corresponding pyridine complexes 2-4 in high yields. PyCA was preliminarily obtained via esterification of 4-pyridinemethanol with chlorambucil. The new compounds PyCA and 2-3 were characterized by IR and multinuclear NMR spectroscopy. Additionally, the structure of 3 was ascertained by single crystal X-ray diffraction. The in vitro anti-proliferative activity of 2-4 and PyCA was determined against a panel of cancer cell lines, outlining 2 as the most performing compound. Targeted studies were subsequently undertaken using 2 to elucidate mechanistic aspects, including the assessment of ruthenium cellular uptake, cell cycle arrest, production of reactive oxygen species (ROS), western blotting and DNA damage (comet test). Overall, data highlight that the anticancer activity provided by 2 primarily affects the mitochondria pathway with a potential additional contribution from DNA damage.

1,3,5-Triaza-7-phosphaadamantane and Cyclohexyl Groups Impart to Di-Iron(I) Complex Aqueous Solubility and Stability, and Prominent Anticancer Activity in Cellular and Animal Models.

Using a multigram-scalable synthesis, we obtained nine dinuclear complexes based on nonendogenous iron(I) centers and featuring variable aminocarbyne and P-ligands. One compound from the series (FEACYP) emerged for its strong cytotoxicity in vitro against four human cancer cell lines, surpassing the activity of cisplatin by 3-6 times in three cell lines, with an average selectivity index of 6.2 compared to noncancerous HEK293 cells. FEACYP demonstrated outstanding water solubility (15 g/L) and stability in physiological-like solutions. It confirmed its superior antiproliferative activity when tested in 3D spheroids of human pancreatic cancer cells and showed a capacity to inhibit thioredoxin reductase (TrxR) similar to auranofin. In vivo treatment of murine LLC carcinoma with FEACYP (8 mg kg-1 dose) led to excellent tumor growth suppression (88%) on day 15, with no signs of systemic toxicity and only limited body weight loss.

Exploring metal carbamates as precursors for the synthesis of metal-organic frameworks.

In the synthesis of metal-organic frameworks (MOFs), the choice of the metal precursor plays a key role because of the influence that it can exert on the crystallization kinetics. The present work explores the use of metal-carbamato complexes for the synthesis of benchmark MOFs, namely HKUST-1 and UiO-66. Cu2(O2CNEt2)4·2NHEt2 and Zr(O2CNEt2)4, prepared using straightforward CO2 fixation reactions starting from the corresponding metal chlorides and diethylamine, were employed as metal precursors for MOF formation. The synthesis conditions, including the solvent, temperature, and ligand protonation degree, were systematically investigated, revealing metal carbamates as highly reactive precursors due to their prompt release of CO2 and amine upon reaction with protic species, i.e., the polycarboxylic linkers. This property of metal carbamates allowed us to identify room temperature protocols to achieve MOFs with comparable properties to those obtained using traditional metal precursors. Subsequent optimization of the reaction conditions led to the design of a one-pot synthetic strategy for HKUST-1, starting directly from copper(II) chloride and diethylamine under a CO2 atmosphere. The MOFs were characterized using various techniques, including powder X-ray diffraction, N2 sorption analysis, 1H nuclear magnetic resonance spectroscopy, and CHN elemental analysis, and compared to reference samples prepared according to literature procedures.

Anticancer potential of NSAID-derived tris(pyrazolyl)methane ligands in iron(II) sandwich complexes.

Tris(pyrazolyl)methane (tpm), 2,2,2-tris(pyrazolyl)ethanol (tpmOH) and its esterification derivatives with ibuprofen and flurbiprofen (tpmIBU and tpmFLU) were used as ligands to obtain complexes of the type [Fe(tpmX)2]Cl2 (1-4). The tpmIBU and tpmFLU ligands and corresponding complexes 3 and 4 were characterized by IR and multinuclear NMR spectroscopy, and the structure of tpmIBU was elucidated by single crystal X-ray diffraction. Complexes 1-4 were also assessed for their behaviour in aqueous media (solubility in D2O, octanol/water partition coefficient, stability in physiological-like conditions). The antiproliferative activity of ligands and complexes was determined on A2780, A2780cis and A549 cancer cell lines and the non-cancerous HEK 293T and BJ cell lines. The ligands and complexes were investigated for their ability to inhibit COX-2 (cyclooxygenase) and HNE (4-hydroxynonenal) enzymes. Complexes 3 and 4 exhibited cytotoxicity that may be attributed predominantly to their bioactive fragments, while DNA binding and enhancement of ROS production do not appear to play any significant role.

Aminocarbyne-Alkyne Coupling in Diruthenium Complexes: Exploring the Anticancer Potential of the Resulting Vinyliminium Complexes and Comparison with Diiron Homologues.

New diruthenium complexes based on the scaffold Ru2Cp2(CO)2 (Cp = η5-C5H5) and containing a bridging vinyliminium ligand, [2a-d]CF3SO3, were synthesized through regioselective coupling of alkynes with an aminocarbyne precursor (85-90% yields). The reaction involving phenylacetylene proceeded with the formation of a diruthenacyclobutene byproduct, [4]CF3SO3 (10% yield). Complexes [2a-d]+ undergo partial alkyne extrusion in contact with alumina or CDCl3. All products were characterized by elemental analysis, infrared and multinuclear NMR spectroscopy, and single crystal X-ray diffraction in two cases. Complexes [2a-d]+ revealed an outstanding stability in DMEM cell culture medium at 37 °C (<1% degradation over 72 h). These complexes exhibited cytotoxicity in human colon colorectal adenocarcinoma HT-29 cells in the low micromolar range, with lower IC50 values than those obtained with the homologous diiron complexes previously reported. Evaluation of ROS (reactive oxygen species) production and O2 consumption rate (OCR) highlighted the higher potential of Ru2 complexes, compared to the Fe2 counterparts, to impact mitochondrial activity, with the heterometallic Ru2-ferrocenyl complex [2d]+ showing the best performance.

FETPY: a Diiron(I) Thio-Carbyne Complex with Prominent Anticancer Activity In Vitro and In Vivo.

FETPY, an organo-diiron(I) complex, showed strong cytotoxicity across a panel of human and mouse cancer cell lines, combined with an outstanding selectivity compared to nonmalignant cells. Enhanced iron uptake in aggressive, low-differentiated cell lines, caused membrane lipid peroxidation, which resulted in ferroptosis in human ovarian cancer cells. FETPY induced significant morphological changes in murine B16-F1 and B16-F10 melanoma cells, leading to senescence and/or trans-differentiation into Schwann-like cells, thus significantly reducing their tumorigenic potential. Additionally, FETPY substantially suppressed tumor growth in low- and high-grade syngeneic melanoma models when administered in a therapeutic regimen. FETPY is featured by satisfactory water solubility (millimolar range), an amphiphilic character (Log Pow = -0.17), and excellent stability in a biological medium (DMEM). These important requisites for drug development are rarely met in iron complexes investigated so far as possible anticancer agents. Overall, FETPY holds promise as a safe and potent targeted antitumor agent.

Quality of Life and Its Psychosocial Predictors among Patients with Disorders of Gut-Brain Interaction: A Comparison with Age- and Sex-Matched Controls.

The disorders of gut-brain interaction (DGBIs) are a heterogeneous group of chronic conditions that greatly reduce patients' quality of life (QoL). To date, biopsychosocial factors (such as gastrointestinal symptoms, alexithymia, and interpersonal problems) are believed to contribute to the development and maintenance of DGBIs, but their role in affecting patients' QoL is still under investigation. Out of 141 patients seeking treatment for their gastrointestinal symptoms, 71 were diagnosed with a DGBI (47 females, 66.2%; Mage: 41.49 ± 17.23 years) and were age- and sex-matched to 71 healthy controls (47 females, 66.2%; Mage: 40.45 ± 16.38 years) without any current gastrointestinal symptom or diagnosis. Participants completed a sociodemographic and clinical questionnaire and a survey investigating several psychosocial risk factors. We found greater symptom severity and difficulties in identifying feelings among patients compared to controls. Further, multiple linear regression analyses evidenced that, among patients, higher expressive suppression of emotions, difficulties in identifying feelings and interpersonal problems, and a lower cognitive reappraisal of emotions predicted lower QoL. Data suggest that the QoL of patients with DGBIs is affected not only by common risk factors (e.g., interpersonal problems) but also by specific difficulties in processing and regulating emotions. The implications of these findings are discussed.

Mononuclear Rare-Earth Metalloligands Exploiting a Divergent Ligand.

Rare-earth tris-diketonato [RE(dike)3pyterpy] metalloligands can be prepared reacting at room temperature [RE(dike)3dme] (dme = 1,2-dimethoxyethane; dike = tta with Htta = 2-thenoyltrifluoroacetone and RE = La, 1; Y, 2; Eu, 3; Dy, 4; or dike = hfac with Hhfac hexafluoroacetylacetone, and RE = Eu, 5; Tb, 6; Yb 7) with 4'-(4‴-pyridil)-2,2':6',2″-terpyridine (pyterpy). The molecular structures of 1, 5, 6, and 7 have been studied through single-crystal X-ray diffraction showing mononuclear neutral complexes with the rare-earth ion in coordination number nine and with a muffin-like coordination geometry. [RE(tta)3pyterpy] promptly reacts with [M(tta)2dme] with formation of [Mpyterpy2][RE(tta)4]2 (M = Zn, RE = Y, 8; M = Co, RE = Dy, 9). Consistently, [Zn(hfac)2dme] reacts at room temperature with 2 equiv of pyterpy yielding [Znpyterpy2][hfac]2 10 that easily can be transformed by reaction with 2 equiv of [Eu(hfac)3] in [Znpyterpy2][Eu(hfac)4]2 11 that has been structurally characterized. Finally, 1, 2, 3, 5, and 7 metalloligands react at room temperature in few minutes with [PtCl(µ-Cl)PPh3]2 yielding the heterometallic molecular complexes [RE(dike)3pyterpyPtCl2PPh3] (dike = tta, RE = La, 12; Y, 13; Eu; 14; dike = hfac, RE = Eu, 15; Yb, 16).

Ru(II)-Arene Complexes of Curcumin and Bisdesmethoxycurcumin Metabolites.

Curcuminoids and their complexes continue to attract attention in medicinal chemistry, but little attention has been given to their metabolic derivatives. Here, the first examples of (arene)Ru(II) complexes with curcuminoid metabolites, tetrahydrocurcumin (THcurcH), and tetrahydrobisdesmethoxycurcumin (THbdcurcH) were prepared and characterized. The neutral complexes [Ru(arene)(THcurc)Cl] and [Ru(arene)(THbdcurc)Cl] (arene = cymene, benzene, or hexamethylbenzene) were characterized by NMR spectroscopy and ESI mass spectrometry, and the crystal structures of the three complexes were determined by X-ray diffraction analysis. Compared to curcuminoids, these metabolites lose their conjugated double bond system responsible for their planarity, showing unique closed conformation structures. Both closed and open conformations have been analyzed and rationalized by using density functional theory (DFT). The cytotoxicity of the complexes was evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR), human breast adenocarcinoma cells (MCF-7 and MCF-7CR), as well as against non-tumorigenic human embryonic kidney cells (HEK293) and human breast (MCF-10A) cells and compared to the free ligands, cisplatin, and RAPTA-C. There is a correlation between cellular uptake and the cytotoxicity of the compounds, suggesting that cellular uptake and binding to nuclear DNA may be the major pathway for cytotoxicity. However, the levels of complex binding to DNA do not strictly correlate with the cytotoxic potency, indicating that other mechanisms are also involved. In addition, treatment of MCF-7 cells with [Ru(cym)(THcurc)Cl] showed a significant decrease in p62 protein levels, which is generally assumed as a noncisplatin-like mechanism of action involving autophagy. Hence, a cisplatin- and a noncisplatin-like concerted mechanism of action, involving both apoptosis and autophagy, is possible.

Mixed valence triiron complexes from the conjugation of [FeIFeI] and [FeII] complexes via intermolecular carbyne/alkyne coupling.

We present a new synthetic strategy for obtaining mixed-valence triiron complexes where the metal centers are bridged by a novel, highly functionalized hydrocarbyl ligand. The alkynyl-vinyliminium complexes [Fe2Cp2(CO)(µ-CO){µ-η1:η3-C(X-CCH)CHCNMe2}]CF3SO3 (X = 4-C6H4, [2a1]CF3SO3; X = (CH2)3, [2a2]CF3SO3) were synthesized in almost quantitative yields from the aminocarbyne precursor [Fe2Cp2(CO)2(µ-CO){µ-CNMe2}]CF3SO3, [1a]CF3SO3, and the di-alkynes HCC-X-CCH. Then, the ferracycle [Fe(Cp)(CO){C(NMe2)CHC(4-C6H4CCH)C(O)}], 4a1, was produced in 47% yield from the cleavage of [2a1]CF3SO3 promoted by pyrrolidine. Subsequent reactions of the acetonitrile adducts [Fe2Cp2(CO)(µ-CO)(NCMe){µ-CNMe(R)}]CF3SO3 (R = Me, [1aACN]CF3SO3; R = Xyl, [1bACN]CF3SO3) ([FeIFeI]) with 4a1 ([FeII]) at room temperature resulted in the formation of [FeIFeIFeII] complexes [Fe2Cp2(CO)(µ-CO){µ-η1:η3-C(X-CCHC(NMe2)FeCp(CO)CO)CHCNMe(R)}]CF3SO3 (R = Me, [5a1]CF3SO3; R = Xyl, [5b1]CF3SO3) in yields ranging from 56% to 64%. The new products were characterized by IR and multinuclear NMR spectroscopy, and the structures of [2a2]CF3SO3 and 4a1 were confirmed by single crystal X-ray diffraction. Cyclic voltammetry and spectroelectrochemical studies on [5a1]+ have revealed that reduction and oxidation events occur almost independently at the [FeIFeI] and [FeII] units, respectively. This observation underscores a minimal electronic interaction between the two fragments within the triiron complex. Accordingly, DFT studies pointed out that the HOMO and LUMO orbitals are predominantly localized in the two distinct compartments of [5a1]+.

Triiron Complex with N-Ferrocenyl Aminocarbyne Ligand Bridging a Diiron Core: DFT, Electrochemical, and Biological Insights.

The first N-ferrocenyl aminocarbyne complex, [Fe2Cp2(CO)2(µ-CO){µ-CN(Me)(Fc)}]CF3SO3 ([2]CF3SO3), was synthesized with an 88% yield from [Fe2Cp2(CO)4], isocyanoferrocene (CNFc), and methyl triflate. The synthesis proceeded through the intermediate formation of [Fe2Cp2(CO)3(CNFc)], 1. Multinuclear NMR experiments revealed the presence of cis and trans isomers for [2]CF3SO3 in organic solvents, in agreement with DFT outcomes. Electrochemical and spectroelectrochemical studies demonstrated one reduction process occurring prevalently at the diiron core and one oxidation involving the ferrocenyl substituent. The oxidation process is expected to favor the redox activation of [2]+ in a biological environment. Both [2]CF3SO3 and its phenyl analogue [Fe2Cp2(CO)2(µ-CO){µ-CN(Me)(Ph)}]CF3SO3 ([3]CF3SO3), prepared for comparison, exerted moderate antiproliferative activity against the human cancer cell lines A431, HCT-15, PSN-1, 2008, and U1285. However, [2]CF3SO3 exhibited a higher cytotoxicity than [3]CF3SO3, showed a substantial ability to induce intracellular ROS production, and outperformed cisplatin in a three-dimensional SCLC cell model.

Aluminium 8-Hydroxyquinolinate N-Oxide as a Precursor to Heterometallic Aluminium-Lanthanide Complexes.

A reaction in anhydrous toluene between the formally unsaturated fragment [Ln(hfac)3] (Ln3+ = Eu3+, Gd3+ and Er3+; Hhfac = hexafluoroacetylacetone) and [Al(qNO)3] (HqNO = 8-hydroxyquinoline N-oxide), here prepared for the first time from [Al(OtBu)3] and HqNO, affords the dinuclear heterometallic compounds [Ln(hfac)3Al(qNO)3] (Ln3+ = Eu3+, Gd3+ and Er3+) in high yields. The molecular structures of these new compounds revealed a dinuclear species with three phenolic oxygen atoms bridging the two metal atoms. While the europium and gadolinium complexes show the coordination number (CN) 9 for the lanthanide centre, in the complex featuring the smaller erbium ion, only two oxygens bridge the two metal atoms for a resulting CN of 8. The reaction of [Eu(hfac)3] with [Alq3] (Hq = 8-hydroxyquinoline) in the same conditions yields a heterometallic product of composition [Eu(hfac)3Alq3]. A recrystallization attempt from hot heptane in air produced single crystals of two different morphologies and compositions: [Eu2(hfac)6Al2q4(OH)2] and [Eu2(hfac)6(µ-Hq)2]. The latter compound can be directly prepared from [Eu(hfac)3] and Hq at room temperature. Quantum mechanical calculations confirm (i) the higher stability of [Eu(hfac)3Al(qNO)3] vs. the corresponding [Eu(hfac)3Alq3] and (ii) the preference of the Er complexes for the CN 8, justifying the different behaviour in terms of the Lewis acidity of the metal centre.

NRF2 activation in BON­1 neuroendocrine cancer cells reduces the cytotoxic effects of a novel Ruthenium(II)­curcumin compound: A pilot study.

Gastroenteropancreatic neuroendocrine neoplasms (GEP­NEN) are a group of rare tumors whose specific pathogenetic mechanisms of resistance to therapies have not been completely revealed yet. Chemotherapy is the main therapeutic approach in patients with GEP­NEN, however, novel combination regimens and targeted therapy are continuously explored. In the present study, the anticancer effect of a novel Ruthenium (Ru)(II)­Bisdemethoxycurcumin (Ru­bdcurc) compound was evaluated in BON­1 cell line, one of the few cell lines derived from GEP­NEN, largely used in experimental research of this type of tumors. The experimental data revealed that the Ru­bdcurc compound induced cell death in a dose­dependent manner, in vitro. Biochemical studies demonstrated that, in response to the lower dose of treatment, BON­1 cells activated the nuclear factor erythroid 2­related factor 2 (NRF2) pathway with induction of some of its targets including catalase and p62 as well as of the antiapoptotic marker Bcl2, all acting as chemoresistance mechanisms. NRF2 induction associated also with increased expression of endogenous p53 which is reported to be dysfunctional in BON­1 cells and to inhibit apoptosis. Genetic or pharmacologic targeting of NRF2 inhibited the activation of the NRF2 pathway, as well as of endogenous dysfunctional p53, in response to the lower dose of Ru­bdcurc, increasing the cell death. To assess the interplay between NRF2 and dysfunctional p53, genetic targeting of p53 showed reduced activation of the NRF2 pathway in response to the lower dose of Ru­bdcurc, increasing the cell death. These findings identified for the first time a possible dysfunctional p53/NRF2 interplay in BON­1 cell line that can be a novel key determinant in cell resistance to cytotoxic agents to be evaluated also in GEP­NEN.

N-Indolyl diiron vinyliminium complexes exhibit antiproliferative effects in cancer cells associated with disruption of mitochondrial homeostasis, ROS scavenging, and antioxidant activity.

The indole scaffold has been established as a key organic moiety for developing new drugs; on the other hand, a range of diiron bis-cyclopentadienyl complexes have recently emerged for their promising anticancer potential. Here, we report the synthesis of novel diiron complexes with an indole-functionalized vinyliminium ligand (2-5) and an indole-lacking analogue for comparative purposes (6), which were characterized by analytical and spectroscopic techniques. Complexes 2-6 are substantially stable in DMSO­d6 and DMEM-d solutions at 37 °C (8% average degradation after 48 h) and display a balanced hydrophilic/lipophilic behaviour (LogPow values in the range -0.32 to 0.47), associated with appreciable water solubility. The complexes display selective antiproliferative potency towards several cancer cells in monolayer cultures, mainly in the low micromolar range, with reduced toxicity towards noncancerous epithelial cells. Thus, the cytotoxicity of the complexes is comparable to or better than clinically used metallopharmaceutical cisplatin. Comparing the antiproliferative activity obtained for complexes containing different ligands, we confirmed the importance of the indolyl group in the mechanism of antiproliferative activity of these complexes. Cell-based mechanistic studies suggest that the investigated diiron vinyliminium complexes (DVCs) show cytostatic rather than cytotoxic effects and subsequently induce a population of cells to undergo apoptosis. Furthermore, the molecular mechanism of action involves interactions with mitochondrial DNA and proteins, the reactive oxygen species (ROS)-scavenging properties and antioxidant activity of these complexes in cancer cells. This study highlights the importance of DVCs to their cancer cell activity and reinforces their prospective therapeutic potential as anticancer agents.

Anticancer Potential of Diruthenium Complexes with Bridging Hydrocarbyl Ligands from Bioactive Alkynols.

Diruthenacyclopentenone complexes of the general composition [Ru2Cp2(CO)2{µ-η1:η3-CH═C(C(OH)(R))C(═O)}] (2a-c; Cp = η5-C5H5) were synthesized in 94-96% yields from the reactions of [Ru2Cp2(CO)2{µ-η1:η3-C(Ph)═C(Ph)C(═O)}] (1) with 1-ethynylcyclopentanol, 17α-ethynylestradiol, and 17-ethynyltestosterone, respectively, in toluene at reflux. Protonation of 2a-c by HBF4 afforded the corresponding allenyl derivatives [Ru2Cp2(CO)3{µ-η1:η2-CH═C═R}]BF4 (3a-c) in 85-93% yields. All products were thoroughly characterized by elemental analysis, mass spectrometry, and IR, UV-vis, and nuclear magnetic resonance spectroscopy. Additionally, 2a and 3a were investigated by cyclic voltammetry, and the single-crystal diffraction method was employed to establish the X-ray structures of 2b and 3a. The cytotoxicity in vitro of 2b and 3a-c was evaluated against nine human cancer cell lines (A2780, A2780R, MCF-7, HOS, A549, PANC-1, Caco-2, PC-3, and HeLa), while the selectivity was assessed on normal human lung fibroblast (MRC-5). Overall, complexes exert stronger cytotoxicity than cisplatin, and 3b (comprising 17α-estradiol derived ligand) emerged as the best-performing complex. Inductively coupled plasma mass spectrometry cellular uptake studies in A2780 cells revealed a higher level of internalization for 3b and 3c compared to 2b, 3a, and the reference compound RAPTA-C. Experiments conducted on A2780 cells demonstrated a noteworthy impact of 3a and 3b on the cell cycle, leading to the majority of the cells being arrested in the G0/G1 phase. Moreover, 3a moderately induced apoptosis and oxidative stress, while 3b triggered autophagy and mitochondrial membrane potential depletion.

Copper and Zinc Metal-Organic Frameworks with Bipyrazole Linkers Display Strong Antibacterial Activity against Both Gram+ and Gram- Bacterial Strains.

Here, we report a new synthetic protocol based on microwave-assisted synthesis (MAS) for the preparation of higher yields of zinc and copper in MOFs based on different bis(pyrazolyl)-tagged ligands ([M(BPZ)]n where M = Zn(II), Cu(II), H2BPZ = 4,4'-bipyrazole, [M(BPZ-NH2)]n where M = Zn(II), Cu(II); H2BPZ-NH2 = 3-amino-4,4'-bipyrazole, and [Mx(Me4BPZPh)] where M = Zn(II), x = 1; Cu(II), x = 2; H2Me4BPZPh = bis-4'-(3',5'-dimethyl)-pyrazolylbenzene) and, for the first time, a detailed study of their antibacterial activity, tested against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, as representative agents of infections. The results show that all MOFs exert a broad-spectrum activity and strong efficiency in bacterial growth inhibition, with a mechanism of action based on the surface contact of MOF particles with bacterial cells through the so-called "chelation effect" and reactive oxygen species (ROS) generation, without a significant release of Zn(II) and Cu(II) ions. In addition, morphological changes were elucidated by using a scanning electron microscope (SEM) and bacterial cell damage was further confirmed by a confocal laser scanning microscopy (CLSM) test.