A new copper(II) complex with 2-thenoyltrifluoroacetone and 2,2-bipyridine: Crystal structure, spectral properties and cytotoxic activity

A new copper(II) complex containing long-chain aliphatic hydrazide and 1,10-phenanthroline upregulates ADP hydrolysis in triple-negative breast cancer cells

Copper can be opportunely complexed to modulate oncogenic pathways, being a promising strategy for cancer treatment. Herein, three new copper(II) complexes containing long-chain aliphatic hydrazides and 1,10-phenanthroline (1,10-phen), namely, [Cu(octh)(1,10-phen)(H2O)](NO3)21, [Cu(dech)(1,10-phen)(H2O)](NO3)22 and [Cu(dodh)(1,10-phen)(H2O)](NO3)2.H2O 3 (where octh = octanoic hydrazide, dech = decanoic hydrazide, dodh = dodecanoic hydrazide) were successfully prepared and characterized by several physical-chemical methods. Furthermore, X-ray structural analysis of complex 2 indicated that the geometry around the copper(II) ion is distorted square-pyramidal, in which hydrazide and 1,10-phenanthroline act as bidentate ligands. A water molecule in the apical position completes the coordination sphere of the metal ion. All new copper(II) complexes were cytotoxic to breast cancer cell lines (MCF7, MDA-MB-453, MDA-MB-231, and MDA-MB-157) and selective when compared to the non tumor lineage MCF-10A. In particular, complex 2 showed half-maximal inhibitory concentration (IC50) values ranging between 2.7 and 13.4 μM in MDA-MB231 cells after 24 and 48 h of treatment, respectively. Furthermore, this complex proved to be more selective for tumor cell lines when compared to doxorubicin and docetaxel. Complex 2 inhibited the clonogenicity of MDA-MB231 cells, increasing adenosine diphosphate (ADP) hydrolysis and upregulating ecto-nucleoside triphosphate diphosphohydrolase 1 (ENTPD1) transcriptional levels. In this sense, we suggest that the inhibitory effect on cell proliferation may be related to the modulation of adenosine monophosphate (AMP) levels. Thus, a novel copper(II) complex with increased cytotoxic effects and selectivity against breast cancer cells was obtained, contributing to medicinal chemistry efforts toward the development of new chemotherapeutic agents.

Mixed-ligand complexes of copper(ii) with thienoyltrifluoroacetonate and nitrogen containing ligands: synthesis, structures, antimicrobial activity, cytotoxicity, Hirshfeld surface analysis and DFT studies

Mixed-ligand complexes of copper(ii) with thienoyltrifluoroacetonate (TTA-H), 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), and tetramethylethylenediamine (tmen), associated with counter ions such as Cl⁻, and NO₃⁻ have been synthesized and characterized by molar conductance measurements, elemental analysis, mass spectrometry, IR and UV-Vis spectroscopy, antimicrobial activity, cytotoxicity assay studies, and single-crystal X-ray diffraction. The UV-Vis spectra and crystal structures are consistent with the adoption of square pyramidal geometry for all of the complexes except [Cu(TTA)tmen]NO₃ and [Cu(TTA)₂tmen] which have square planar and octahedral geometries, respectively. Conductance measurements of the mixed-ligand complexes indicated that they were all non-electrolytes, with the ligands and anions being coordinated to Cu except [Cu(TTA)tmen]NO₃ which is a 1 : 1 electrolyte. All of the complexes were moderately active on all the fungi tested (Candida albicans, Aspergillus niger, Penicillium notatum, Rhizopus stolonifer) except [Cu(TTA)bipyCl] which showed increased activity in Candida albicans and Aspergillus niger. All of the compounds tested showed LC₅₀ values greater than 100 with [Cu(TTA)(phen)NO₃] being the least toxic of the compounds. Molecular geometries of the complexes were optimized at the PBE1PBE/def2SVP and PBE1PBE/6-311g(d,p) level of theory and the results were compared with the single-crystal X-ray diffraction data. Electronic properties such as HOMO, LUMO, HOMO–LUMO gaps and global reactivity descriptors are reported at the PBE1PBE/6-311g(d,p) level of theory. Hirshfeld surface analysis was carried out to investigate the cooperative non-covalent supramolecular interactions within the various complexes.

Mixed-ligand complexes of copper(ii) with thienoyltrifluoroacetonate, 2,2′-bipyridine, 1,10-phenanthroline, and tetramethylethylenediamine, associated with counter ions such as Cl⁻ and NO₃ have been synthesized and characterized.

A selective CuII complex with 4-fluorophenoxyacetic acid hydrazide and phenanthroline displays DNA-cleaving and pro-apoptotic properties in cancer cells

The thin line between efficacy and toxicity has challenged cancer therapy. As copper is an essential micronutrient and is important to tumor biology, CuII complexes emerged as an alternative to chemotherapy; however, its biological properties need to be better understood. Thus, we report in vitro the antitumor effects of two CuII complexes named [Cu(4-fh)(phen)(ClO4)2] (complex 1) and [Cu(4-nh)(phen)(ClO4)2]·H2O (complex 2), in which 4-fh = 4-fluorophenoxyacetic acid hydrazide; 4-nh = 4-nitrobenzoic hydrazide and phen = 1,10-phenanthroline. Both complexes presented cytotoxic activity against tumor cells, but only complex 1 showed significant selectivity. Complex 1 also induced DNA-damage, led to G0/G1 arrest and triggered apoptosis, which was initiated by an autophagy dysfunction. The significant in vitro selectivity and the action mechanism of complex 1 are noteworthy and reveal this prodrug as promising for anticancer therapy.

Synthesis, characterization, DNA/BSA interactions and in vitro cytotoxicity study of palladium(II) complexes of hispolon derivatives

Thirteen novel palladium(II) complexes of the general formula [Pd(bipy)(O,O'-dkt)](PF₆), (where bipy is 2,2'-bipyridine and O,O'-dkt is β-diketonate ligand hispolon or its derivative) have been prepared through a metal-ligand coordination method that involves spontaneous formation of the corresponding diketonate scaffold. The obtained palladium(II) complexes have been characterized by NMR spectroscopy, ESI-mass spectrometry as well as elemental analysis. The cytotoxicity analysis indicates that most of the obtained palladium(II) complexes show promising growth inhibition in three human cancer cell lines. Flow cytometry analysis shows complex 3e could promote intracellular reactive oxygen species (ROS) accumulation and lead cancer cell death. And the suppression of ROS accumulation and the rescue of cell viability in HeLa cells by N-acetyl-L-cysteine (NAC) suggest the possible link between the increase in ROS generation and cytotoxicity of complex 3e. Flow cytometry analysis also reveal that complex 3e cause cell cycle arrest in the G2/M phase and collapse of the mitochondrial membrane potential, promote the generation of ROS and lead to tumor cell apoptosis. The interactions of complex 3e with calf thymus DNA (CT-DNA) have been evaluated by UV-Vis spectroscopy, fluorescence quenching experiments and viscosity measurements, which reveal that the complex interact with CT-DNA through minor groove binding and/or electrostatic interactions. Further, the results of fluorescence titration and site marker competitive experiment on bovine serum albumin (BSA) suggest that complex 3e can quench the fluorescence of BSA via a static quenching process and bind to BSA in Sudlow's site II.

Action of copper(II) complex with β-diketone and 1,10-phenanthroline (CBP-01) on sarcoma cells and biological effects under cell death

This work reports the biological evaluation of a copper complex of the type [Cu(O-O)(N-N)ClO₄], in which O-O = 4,4,4-trifluoro-1-phenyl-1,3-butanedione (Hbta) and N-N = 1,10-phenanthroline (phen), whose generic name is CBP-01. The cytotoxic effect of CBP-01 was evaluated by resazurin assay and cell proliferation was determined by MTT assay. DNA fragmentation was analyzed by gel electrophoresis. Cell cycle progression was detected through propidium iodide (PI) staining. Apoptosis and autophagy were determined by, respectively, Annexin V and 7-AAD staining and monodansylcadaverine (MDC) staining. The changes in intracellular reactive oxygen species levels were detected by DCFDA analysis. The copper complex CBP-01 showed in vitro antitumor activity with IC₅₀s values of 7.4 μM against Sarcoma 180 and 26.4 against murine myoblast cells, displaying selectivity toward the tumor cell tested in vitro (SI > 3). An increase in reactive oxygen species (ROS) generation was observed, which may be related to the action mechanism of the complex. The complex CBP-01 may induce DNA damage leading cells to accumulate at G0/G1 checkpoint where, apparently, cells that are not able to recover from the damage are driven to cell death. Evidence has shown that cell death is initiated by autophagy dysfunction, culminating in apoptosis induction. The search for new metal-based drugs is focused on overcoming the drawbacks of already used agents such as acquired resistance and non-specificity; thus, the results obtained with CBP-01 show promising effects on cancer cells.

Copper complexes formed by 3,5-bis(2,2′-bipyridin-4-ylethynyl)benzoic acid and its methyl and ethyl esters as studied by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry was used to study the complexes of ligands containing two bipyridine units, namely 3,5-bis(2,2-bipyridin-4-ylethynyl)benzoic acid (1) and its methyl and ethyl esters (2, 3), with copper cation, with CuCl2 as a source of copper. It was found that the type of complexes formed strongly depends on CuCl2 concentration. At lower CuCl2 concentration, the detected complexes were rather simple and some of them were formed upon electrospray ionization conditions e.g. ions [22+Cu2]2+ and [32+Cu2]2+ (complexes ligand-Cu(I) of stoichiometry 2:2) which are analogical to the well known, for quaterpyridine, helical complexes. At higher CuCl2 concentration, the detected complexes were more complicated, and most of them contained copper cations bridged by chlorides. The largest ions were [L2+Cu4Cl6]2+. The CID MS/MS spectra of these ions allowed determination of their mass spectrometric fragmentation pathways and as a consequence their structure elucidation.