Synthesis, X-ray structures and cytotoxic activity of platinum(II), palladium(II) and copper(II) complexes with chelating ligands

Synthesis, structural characterization, QSAR and docking studies of a new binuclear nickel (II) complex based on the flexible tetradentate N-donor ligand as a potent antibacterial and anticancer agent

A new nickel (II)complex namely [Ni₂(Lt)Cl₄] derived from the NiCl₂.6H₂O and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (Lt) has been synthesized and fully characterized by the single crystal X-ray diffraction, elemental analysis, FT-IR, UV-vis, density functional theory (DFT) calculations, antibacterial and anticancer activities. In the title complex, each of the Ni(II) atoms is tetrahedrally coordinated by two N atoms from one of the chelating bidentate bis(3,5-dimethylpyrazolyl)methane units of the Lt ligand and two Cl as terminal ligands. The neighboring [Ni₂(Lt)Cl₄] molecules are linked together by the intermolecular CH⋯Cl hydrogen bonds to generate a 1D chain structure. The chains are further stabilized by the intermolecular CH⋯π interactions to form a two-dimensional non-covalent bonded structure. The antibacterial activity of the free Lt ligand and its Ni (II) complex shows that the ability of these compounds to inhibit growth of the tested bacteria increase from the Lt to binuclear nickel (II) complex. Scanning probe microscopy (SPM) study of the treated B. subtilis and E. coli bacteria was implemented to understand the structural changes caused by the interactions between the nickel (II) complex and the target bacteria. The cytotoxicity test of the Lt ligand and its complex was evaluated against the human carcinoma cell line (Caco-2) using the MTT assay. The results indicate that the Lt ligand and its complex display cytotoxicity against Caco-2 with the IC50 values of 36.29μM and 12.97μM, respectively. Therefore, the complex can be nominated as a potential anticancer agent. Molecular docking investigations on the five standard antibiotic, five standard anticancer drugs, free Lt ligand, title complex and twelve receptors were performed by Autodock vina function. The results of docking and DFT calculations are in line with the in vitro data obtained via the antibacterial and anticancer activity of Lt ligand and its made-complex.

Anticancer copper(II) phosphorus dendrimers are potent proapoptotic Bax activators

A multivalent phosphorus dendrimer 1G₃ and its corresponding Cu-complex, 1G₃-Cu have been recently identified as agents retaining high antiproliferative potency. This antiproliferative capacity was preserved in cell lines overexpressing the efflux pump ABC B1, whereas cross-resistance was observed in ovarian cancer cell lines resistant to cisplatin. Theoretical 3D models were constructed: the dendrimers appear as irregularly shaped disk-like nano-objects of about 22 Å thickness and 49 Å diameter, which accumulated in cells after penetration by endocytosis. To get insight in their mode of action, cell death pathways have been examined in human cancer cell lines: early apoptosis was followed by secondary necrosis after multivalent phosphorus dendrimers exposure. The multivalent plain phosphorus dendrimer 1G₃ moderately activated caspase-3 activity, in contrast with the multivalent Cu-conjugated phosphorus dendrimer 1G₃-Cu which strikingly reduced the caspase-3 content and activity. This decrease of caspase activity is not related to the presence of copper, since inorganic copper has no or little effect on caspase-3. Conversely the potent apoptosis activation could be related to a noticeable translocation of Bax to the mitochondria, resulting in the release of AIF into the cytosol, its translocation to the nucleus and a severe DNA fragmentation, without alteration of the cell cycle. The multivalent Cu-conjugated phosphorus dendrimer is more efficient than its non-complexed analog to activate this pathway in close relationship with the higher antiproliferative potency. Therefore, this multivalent Cu-conjugated phosphorus dendrimer 1G₃-Cu can be considered as a new and promising first-in-class antiproliferative agent with a distinctive mode of action, inducing apoptosis tumor cell death through Bax activation pathway.

Copper(II) complexes with derivatives of pyrazole as potential antioxidant enzyme mimics

A series of six mononuclear Cu(II) complexes with pyrazole-based ligands: 5-(2-hydroxybenzoyl)-3-methyl-1-(2-pyridinyl)-1H-pyrazol-4-phosphonic acid dimethyl ester (1a), 5-(2-hydroxyphenyl)-3-methyl-1-(2-pyridylo)-1H-pyrazole-4-carboxylic acid methyl ester (1b) and 1-benzothiazol-2-yl-5-(2-hydroxyphenyl)-3-methyl-1H-pyrazole-4-carboxylic acid methyl ester (1c) were characterized regarding to electrochemical and antioxidant properties. All complexes exhibit suitable Cu(II)/Cu(I) redox potential (E_1/2) to act as antioxidant enzymes mimic. The five of these complexes were found to be trifunctional enzyme mimics possessing SOD, CAT and GPx-like catalytic activities. Moreover, Cu(II) complexes were capable to decrease ROS level in melanoma cells and observed effects were not merely a reflection of cytotoxicity.

Synthesis of ferrocenyl pyrazole-containing chiral aminoethanol derivatives and their inhibition against A549 and H322 lung cancer cells

A series of novel ethyl 3-ferrocenyl-1-(2-hydroxy-3-(phenylamino)propyl)-1H-pyrazole-5-carboxylate derivatives with optical activity (4) was synthesized by microwave-assisted reaction of substituted aniline and ethyl 3-ferrocenyl-1-(oxiran-2-ylmethyl)-1H-pyrazole-5-carboxylate that was prepared from ethyl 3-ferrocenyl-1H-pyrazole-5-carboxylate and (R)- or (S)-oxiran-2-ylmethyl 4-methylbenzenesulfonate. Structures of the compounds were characterized by means of IR, (1)H NMR and mass spectroscopy. Preliminary biological evaluation showed that all of the compounds could suppress the growth of A549 and H322 lung cancer cells. Among all of the tested compounds 4a, 4b and 4d were more effective and might perform their action through cell cycle arrest. Moreover, although the inhibition differences between R and S enantiomers are mostly not so significant, (R)-4b displayed more effective inhibition than (S)-4b.