Ternary Dinuclear Copper(II) Complexes of a Hydroxybenzamide Ligand with Diimine Coligands: the 5,6-dmp Ligand Enhances DNA Binding and Cleavage and Induces Apoptosis

New pyridazine-based binuclear nickel(ii), copper(ii) and zinc(ii) complexes as prospective anticancer agents

The complexes containing diethylamino substituents exhibit promising cytotoxicity against the estrogen receptor (ER) negative MDA-MB-231 breast cancer cell line.

Synthesis and structure of new dicopper(II) complexes bridged by N-(2-hydroxy-5-methylphenyl)-N'-[3-(dimethylamino)propyl]oxamide with in vitro anticancer activity: A comparative study of reactivities towards DNA/protein by molecular docking and experimental assays

Two new dicopper(II) complexes bridged by N-(2-hydroxy-5-methylphenyl)-N'-[3-(dimethyl-amino)propyl]oxamide (H3hmpoxd), and end-capped with 4,4'-dimethyl-2,2'-bipyridine (Me2bpy) and 2,2'-bipyridine (bpy), were synthesized and structurally characterized, namely [Cu2(hmpoxd)(CH3OH)(Me2bpy)](ClO4) (1) and [Cu2(hmpoxd)(bpy)](ClO4)∙CH3OH (2). The single-crystal X-ray diffraction analysis reveals that the endo- and exo-copper (II) ions bridged by the cis-hmpoxd(3-) ligand are located in square-planar and square-pyramidal geometries, respectively, for 1, and square-planar environments in 2. The DNA/protein-binding natures are studied theoretically and experimentally, indicating that both the two complexes can interact with the DNA in the mode of intercalation, and effectively quench the intrinsic fluorescence of protein BSA via the favored binding sites Trp213 for 1 and Trp134 for 2. In vitro anticancer activities showed that the two complexes are active against the selected tumor cell lines, and the anticancer activities are consistent with their DNA/BSA-binding affinities following the order of 1 > 2. The synergistic hydrophobicity of the bridging and terminal ligands in these complexes on DNA/BSA-binding events and in vitro anticancer activities is preliminarily discussed.

Ternary Dinuclear Copper(II) Complexes of a Reduced Schiff Base Ligand with Diimine Coligands: DNA Binding, Cytotoxic Cell Apoptosis, and Apoptotic Mechanism

A serial of mixed-ligand Cu(II) complexes of the type [Cu(phens)(H2 PDILeu)]H2 O (1-4) containing phens as 2,2'-bipyridyl (bpy, 1), 1,10-phenanthroline (phen, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz, 4) have been isolated and characterized. The interaction of the complexes with calf-thymus DNA has been explored by physical methods to propose modes of DNA binding of the complexes, which indicate that 4 interacts with DNA more strongly than all of the other complexes through intercalation interaction. Furthermore, cell apoptosis was detected by AnnexinV/PI flow cytometry and TUNEL assay and by Western blotting to detect the protein expression of p53, Bax, and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells, which was accompanied with upregulation of the expression of p53 and Bax, while Bcl-2 decreased.

Crystal structure of 1,2-bis[(2-tert-butylphenyl)imino]ethane

The whole molecule of the title compound, C₂₂H₂₈N₂, (I), is generated by inversion symmetry. The mol­ecule is rather similar to that of 2,3-bis­[(2-tert-butyl­phen­yl)imino]­butane, (II), a di­imine ligand comprising similar structural features [Ferreira et al. (2006 ▸). Acta Cryst. E62, o4282–o4284]. Both ligands crystallize with the –N=C(R)—C(R)=N– group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both mol­ecules [the central link, –N=C(R)—C(R)=N–, and the terminal aromatic ring] subtend an angle of 69.6 (1)° in (II) and 49.4 (2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intra­molecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the di­imino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values.

DNA/protein interaction, cytotoxic activity and magnetic properties of amino-alcohol Schiff base derived Cu(ii)/Ni(ii) metal complexes: influence of the nuclearity and metal ions

The reactions of amino-alcohol derived Schiff-base ligands with Cu(ii) and Ni(ii) salts have afforded four novel polynuclear complexes, which exhibited interesting magnetic and cytotoxic properties.

Synthesis and photophysical, electrochemical, antibacterial, and DNA binding studies of triazinocalix[2]arenes

The synthesized calix[2]arene[2]triazine derivatives bind effectively to DNA and exhibit efficient antibacterial activity against B. cereus, S. aureus and E. coli bacteria as supported by docking studies.

DNA/protein binding, DNA cleavage, cytotoxicity, superoxide radical scavenging and molecular docking studies of copper(ii) complexes containing N-benzyl-N′-aryl-N′′-benzoylguanidine ligands

Copper(ii) complexes containing trisubstituted guanidine ligands were prepared, characterized and evaluated for their biological applications.

Oxidative DNA cleavage promoted by two phenolate-bridged binuclear copper(ii) complexes

Both the binuclear copper complexes 1 and 2 could efficiently cleave the supercoiled pUC19 plasmid DNA into its nicked and linear forms in the presence of excessive ascorbic acid (Vc) under nearly physiological conditions. The DNA binding ability and the DNA cleavage efficacy of 1 are superior to 2.

Mixed ligand copper(ii) dicarboxylate complexes: the role of co-ligand hydrophobicity in DNA binding, double-strand DNA cleavage, protein binding and cytotoxicity

Mixed ligand 5,6-dmp and 3,4,7,8-tmp complexes display more prominent cytotoxicity and higher apoptotic inducing ability.

Five water-soluble zwitterionic copper(ii)-carboxylate polymers: role of dipyridyl coligands in enhancing the DNA-binding, cleaving and anticancer activities

Five water-soluble zwitterionic copper-carboxylate polymers were prepared and their DNA-binding, cleaving and anticancer activities were studied.

Four related mixed-ligand nickel(ii) complexes: effect of steric encumbrance on the structure, DNA/BSA binding, DNA cleavage and cytotoxicity

Four new interrelated mixed-ligand nickel(ii) complexes have been synthesized and characterized. The activities of DNA binding/cleavage, BSA binding with complexes and the vitro cytotoxicity also have been explored.

Fluorescent mixed ligand copper(ii) complexes of anthracene-appended Schiff bases: studies on DNA binding, nuclease activity and cytotoxicity

While the phen of [Cu(L1–L5)(phen)(ACN)]²⁺ partially inserts into DNA base pairs the anthracenyl moiety of L1–L5 interacts with DNA hydrophobically.

Synthesis, characterization, and biological activities of two Cu(II) and Zn(II) complexes with one polyquinoline ligand

Two new complexes, [CuLCl]ClO4 (1) and [Zn2L2SO4(H2O)2](ClO4)2 (2) [L=N,N-bis(quinolin-2-ylmethyl)quinolin-8-amine], have been synthesized and structurally characterized. The interactions of two complexes with CT-DNA have been investigated by UV absorption, fluorescence spectroscopy, viscosity measurements and gel electrophoresis under physiological conditions. Results show that the complexes bind to CT-DNA with a moderate intercalative mode and exhibit efficient DNA cleavage activity on UV-A light of 365 nm. Furthermore, two complexes could quench the intrinsic fluorescence of BSA in a static quenching process based on BSA binding experiments. Notably, in vitro cytotoxicity study of two complexes on four human tumor cells lines (7404, HeLa, MCF-7, and HepG-2) indicate that both of them have the potential to act as effective anticancer drugs with low IC50 values.

DNA/BSA binding, DNA cleavage and electrochemical properties of new multidentate copper(ii) complexes

A new series of multidentate copper(ii) complexes [Cu(L¹⁻⁵)](ClO₄) (1–5) were synthesized and characterized for their DNA/BSA binding, DNA cleavage, cytotoxic properties and antimicrobial activities.

Water-soluble Co(III) complexes of substituted phenanthrolines with cell selective anticancer activity

Transition metal complexes with substituted phenanthrolines as ligands represent potential anticancer products without the drawbacks of platinum complexes that are currently marketed. Here, we report the synthesis and cell selective anticancer activity of five new water-soluble Co(III) complexes with methyl substituted phenanthroline ligands. The complexes were characterized by elemental analysis, NMR, FAB-mass spectrometry, FTIR, electronic spectroscopy, and single crystal X-ray diffraction. Possible interaction of these complexes with DNA was assessed by a combination of circular dichroism, UV-vis spectroscopy titration, and ethidium bromide displacement assay, and the results indicated that DNA interaction is weak for these complexes. Cellular uptake and cytotoxicity of complexes at low concentrations were assessed by flow cytometry on PC-3 cells, while their effect on intracellular mitochondrial function was measured by MTS assay on HeLa and PC-3 cell lines. These complexes showed selective cytotoxicity with a significantly higher effect on intracellular mitochondrial function in PC-3 cells than in HeLa cells. At low concentrations, complex 2 had the highest cytotoxic effect on PC-3 cells, inducing around 38% cell death, and the correlation of cytotoxicity of these complexes to their hydrophobicity indicates that an appropriate value of the hydrophobicity is essential for high antitumor activity.

Synthesis, interaction with DNA and antiproliferative activities of two novel Cu(II) complexes with Schiff base of benzimidazole

Two novel copper(II) complexes with Schiff base of benzimidazole [Cu(L)Cl]2·CH3OH have been synthesized. HL(1) (N-(benzimidazol-2-ymethyl)-5-chlorosalicylideneimine, C15H11ClN3O) and HL(2) (N-(benzimidazol-2-ymethyl)-salicylideneimine, C15H12N3O) are ligands of complex (1) and complex (2), respectively. The complexes were characterized by elemental analysis, IR, UV-Vis, TGA and X-ray diffraction. Within the complexes, Cu(II) ions were four coordinated by two nitrogen atom of azomethine and imine, one phenolic oxygen atom from HL and one chloride atom. A distorted quadrilateral structure was formed. Complex (1) crystallized in the triclinic crystal system. Results showed that π-π stacking effect occurred due to the existence of aromatic ring from Schiff base and hydrogen bonding between methanol and adjacent atoms. The DNA binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra and viscosity measurements. Results indicated that complexes bound to DNA via partial intercalation mode. The DNA binding constants Kb/(L mol(-1)) were 1.81×10(4) (1), 1.37×10(4) (2), 6.27×10(3) (HL(1)) and 3.14×10(3) (HL(2)) at 298 K. The title complexes could quench the emission intensities of EB-DNA system significantly. The results of agarose gel electrophoresis indicated complex (1) could cleave supercoiled DNA through the oxidative mechanism. The inhibition ratios revealed that complex (1) and HL(1) had strong antiproliferative activities against human breast cancer cells (MCF-7) lines and human colorectal cancer cells (COLO205) lines in vitro. The antiproliferative activities of complex (1) against MCF-7 lines (IC50=16.9±1.5 μmol L(-1)) and against COLO205 lines (IC50=16.5±3.4 μmol L(-1)) is much stronger than that of HL(1), which had the potential to develop anti-cancer drug.

Two novel copper complexes of 2,2'-bipyridine: evaluation of the DNA binding and cytotoxic activity

Two novel copper-2,2'-bipyridine complexes [Cu(SAL)(2,2'-bipy)ClO4]2 (1) and [Cu(μ2-O)(2,2'-bipy)NO3]2 (2) (HSAL=salicylaldehyde) were synthesized and characterized by X-ray single-crystal diffraction, elemental analysis and IR spectra. The interactions of the complexes with salmon sperm DNA were investigated by viscosity analysis, UV, fluorescence and circular dichroism (CD) spectroscopic techniques. Absorption spectral (Kb=3.00×10(5)M(-1) (1), 3.49×10(5)M(-1)(2)), emission spectral ((Ksv) 3.33×10(4)M(-1) (1), 3.40×10(4)M(-1) (2)), and viscosity measurements reveal that 1 and 2 interact with DNA through intercalation. In fluorimetric studies, the enthalpy (ΔH>0) and entropy (ΔS>0) changes of the reactions between the Cu (II) complexes with DNA demonstrate hydrophobic interactions. In addition, CD study indicates the Cu (II) complexes cause a more B-like to a more A-like conformational change upon binding DNA. All the experimental results show that the interaction mode of the two complexes was greatly affected by the coordination environments of Cu (II) centers. Their in vitro cytotoxicity towards five selected tumor cell lines HepG-2, HeLa, NCI-H460, MCF-7 and HL-60 has been evaluated by MTT method, and 2 exhibits higher growth inhibition of the selected cell lines at concentration of 50 μM, this result is identical with their DNA binding ability order.