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

Synthesis of New Cu Complex Based on Natural 5Z,9Z-Eicosadienoic Acid: Effective Topoisomerase I Inhibitor and Cytotoxin against the Cisplatin-Resistant Cell Line

The complex (bipy)2Cu(5,9-eicd) was prepared by the reaction of Cu(OAc)2 with 5Z,9Z-eicosadienoic acid and 2,2'-bipyridine in methanol. The new copper complex showed high antitumor activity in vitro toward A2780cis, A2780, Hek293, K562, HL60, Jurkat, and U937 cell lines and efficiently inhibited human topoisomerase I. Using flow cytofluorometry, (bipy)2Cu(5,9-eicd) was studied for the effect on the cell cycle and apoptosis-inducing activity in tumor cells.

Theoretical study on the DNA interaction properties of copper(II) complexes

Theoretical studies on DNA-cleavage and DNA-binding properties of a series of Cu(II) complexes [Cu(bimda)(diimine)] 1-5 have been carried out by density functional theory (DFT). The optimized structures of Cu(II) complexes were docked into parallel, antiparallel and mixed G-quadruplexes, with which the binding energies of complexes 1-5 were obtained. The cytotoxicities of these complexes can be predicted preliminarily by the binding energies. To explore the energy changes of Cu(II) complexes in duplex DNA, the optimized structures of these complexes were docked into the duplex DNA, and the obtained docking models were further optimized using QM/MM method. The DNA-cleavage abilities of complexes 1-5 can be predicted accurately and explained reasonably by the computed intra-molecular reorganization energies of these complexes. This work reported here has implications for the understanding of the interaction Cu(II) complexes with the DNA, which might be helpful for the future directing the design of novel anticancer Cu(II) complexes.

Tris-chelated complexes of nickel(II) with bipyridine derivatives: DNA binding and cleavage, BSA binding, molecular docking, and cytotoxicity

Two nickel(II) complexes with substituted bipyridine ligand of the type [Ni(NN)₃](ClO₄)₂, where NN is 4,4'-dimethyl-2,2'-bipyridine (dimethylbpy) (1) and 4,4'-dimethoxy-2,2'-bipyridine (dimethoxybpy) (2), have been synthesized, characterized, and their interaction with DNA and bovine serum albumin (BSA) studied by different physical methods. X-ray crystal structure of 1 shows a six-coordinate complex in a distorted octahedral geometry. DNA-binding studies of 1 and 2 reveal that both complexes sit in DNA groove and then interact with neighboring nucleotides differently; 2 undergoes a partial intercalation. This is supported by molecular-docking studies, where hydrophobic interactions are apparent between 1 and DNA as compared to hydrogen bonding, hydrophobic, and π-π interactions between 2 and DNA minor groove. Moreover, the two complexes exhibit oxidative cleavage of supercoiled plasmid DNA in the presence of hydrogen peroxide as an activator in the order of 1 > 2. In terms of interaction with BSA, the results of spectroscopic methods and molecular docking show that 1 binds with BSA only via hydrophobic contacts while 2 interacts through hydrophobic and hydrogen bonding. It has been extensively demonstrated that the nature of the methyl- and methoxy-groups in ligands is a strong determinant of the bioactivity of nickel(II) complexes. This may justify the above differences in biomolecular interactions. In addition, the in vitro cytotoxicity of the complexes on human carcinoma cells lines (MCF-7, HT-29, and U-87) has been examined by MTT assay. According to our observations, 1 and 2 display cytotoxicity activity against selected cell lines. Communicated by Ramaswamy H. Sarma.

Highly active copper(i) complexes of aroylthiourea ligands against cancer cells – synthetic and biological studies

Copper(i) complexes containing sulfur donor monodentate aroylthiourea ligands have been synthesized and evaluated for their biological applications.

Structure and anticancer activities of four Cu(ii) complexes bearing tropolone

The title Cu(ii) complexes of tropolone induce the apoptosis of MGC80-3 through a caspase-dependent mitochondrion pathway and can also induce autophagy.

Synthesis, characterization and nucleic acid binding studies of mononuclear copper(II) complexes derived from azo containing O, O donor ligands

Azo linked salicyldehyde and a new 2-hydroxy acetophenone based ligands (HL¹ and HL²) with their copper(II) complexes [Cu(L¹)₂] (1) and [Cu(L²)₂] (2) were synthesized and characterized by spectroscopic methods such as ¹H, 13C NMR, UV-Vis spectroscopy and elemental analyses. Calculation based on Density Functional Theory (DFT), have been performed to obtain optimized structures. Binding studies of these copper (II) complexes with calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) were analyzed by absorption spectra, emission spectra and Viscosity studies and Molecular Docking techniques. The absorption spectral study indicated that the copper(II) complexes of 1 and 2 had intrinsic binding constants with DNA or RNA in the range of 7.6 ± 0.2 × 10³ M^-1 or 6.5 ± 0.3 × 10³M^-1 and 5.7 ± 0.4 × 10⁴ M^-1 or 1.8 ± 0.5 × 10³ M^-1 respectively. The synthesized compounds and nucleic acids were simulated by molecular docking to explore more details mode of interaction of the complexes and their orientations in the active site of the receptor.

Mononuclear copper(II) complexes with 2-thiophene carboxylate and N-N donors; DNA interaction, antioxidant/anti-inflammatory and antitumor activity

Redox-active compounds such as copper-phenanthroline are known as artificial/chemical nucleases with a great impact and potential for their applications as metallotherapeutics. In that vein, the mononuclear copper(II) complexes [Cu(L)₂(bipy)] (1), [Cu(L)₂(bipy)(H₂O)] (2) and [Cu(L)₂(phen)(H₂O)] (3), where L = 2-thiophene carboxylate, bipy = 2,2΄-bipyridine and phen = 1,10-phenanthroline, have been prepared and pharmacochemically studied, while the crystal structure of 1 is also reported. All the tested complexes preferably bind to CT-DNA via minor groove as resulted from UV spectroscopy studies, luminescent titration, EB competition assays and viscosity measurements. Complexes 2 and 3 in aqua behave like a "light switch" for DNA. The intensity enhancement, with the increase of DNA concentration, reached about 3-fold for 2 and 10-fold for 3. In vitro antioxidant activity of compounds 1-3, was evaluated using two different antioxidant assays: a) interaction with 1,1-diphenyl-2-picryl-hydrazyl (DPPH) stable free radical and b) inhibition of lipid peroxidation. Moreover, their inhibitory activity on soybean lipoxygenase (LOX) was evaluated for their anti-inflammatory potency. The tested complexes showed good activity on both lipid peroxidation and soybean LOX inhibition while complex 2 exhibited the best antioxidant/anti-inflammatory activity. A computational analysis over the LOX protein structure 1JNQ was performed, in an effort to support their possible mode of action. The cytotoxicity of the complexes was determined and their efficacy against several human cancer cell lines (ovarian, OAW-42; lung, A549; colon, HT29; breast, MDA-MB-231; kidney, Caki-2; and cervical, Hela) and human non-tumor cell lines (lung, MRC-5; and breast, MTSV1-7) were evaluated. The best cytotoxic activity was appeared for complex 3. In silico, computational methods support antiestrogen activity of the administered complexes on normal breast cells.

High anticancer potency on tumor cells of dehydroabietylamine Schiff-base derivatives and a copper(II) complex

Five bioactive dehydroabietylamine Schiff-base derivatives (L¹-L⁵) had been synthesized from Dehydroabietylamine (L⁰), and the complex Cu(L¹)₂ had been obtained from the compound L¹ and copper(II) acetate. Their activities against Hela (cervix), MCF-7 (breast), A549 (lung), HepG2 (liver) and HUVEC (umbilical vein, normal cell) in vitro were investigated. The toxicity of L¹-L⁵ and Cu(L¹)₂ was all lower than L⁰. For MCF-7 cell, L¹, L³, L⁴, L⁵ and Cu(L¹)₂ had higher antitumor activity than L⁰. The smallest IC₅₀ value was 2.58 μM of L⁵. For A549 cell, the IC₅₀ value of the compound L⁴ was smaller than L⁰, which indicated that the compound L⁴ had higher anti-A549 activity than L⁰. For HepG2 cell, the IC₅₀ value of L⁴(0.24 μM) and L⁵ (0.14 μM) were much smaller than L⁰, which suggested L⁴ and L⁵ had higher anti-HepG2 activity. L⁵ was 180 times more effective at inhibiting cultured HepG2 cells survival than normal cells, with average IC₅₀ values of 0.14 and 25.56 μM. Furthermore, L⁰, L⁴ and L⁵ contrasting with Doxorubicin had been measured with the ability to induce apoptosis. It turned out that L⁴ and L⁵ could induce more HepG2 cells apoptosis, which suggested they may be potential antitumor drugs.

Mitochondria-localizing BODIPY–copper(ii) conjugates for cellular imaging and photo-activated cytotoxicity forming singlet oxygen

BODIPY–copper(ii) conjugates are prepared and characterized and the complexes showed mitochondrial localization with singlet oxygen mediated visible light-induced apoptotic cell death.

Copper(II) complexes of N3O tripodal ligands appended with pyrene and polyamine groups: Anti-proliferative and nuclease activities

A series of tripodal ligands based on the 2-tert-butyl-4-R-6-phenol was synthesized, where R=aldehyde (HL¹), R=putrescine-pyrene (HL²) and R=putrescine (HL³). A dinucleating ligand wherein a putrescine group connects two tripodal moieties was also prepared (H₂L⁴). The corresponding copper complexes (1, 2, 3, and 4, respectively) were prepared and characterized. We determined the phenol's pKas in the range 2.47-3.93. The DNA binding constants were determined at 6×10⁶, 5.5×10⁵ and 2.7×10⁶ for 2, 3 and 4, respectively. The complexes display a metal-centered reduction wave at E_p^c,red=-0.45 to -0.5V vs. saturated calomel electrode, as well as a ligand-centered oxidation wave above 0.57V at pH7. In the presence of ascorbate they promote an efficient cleavage of DNA, with for example a concentration required to cleave 50% of supercoiled DNA of 1.7μM for 2. The nuclease activity is affected by the nature of the R group: putrescine-pyrene≈bis-ligating>putrescine>aldehyde. The species responsible for strand scission is the hydroxyl radical. The cytotoxicity of the complexes was evaluated on bladder cancer cell lines sensitive or resistant to cis-platin. The IC₅₀ of complexes 2 and 4 span over a short range (1.3-2μM) for the two cell lines. They are lower than those of the other complexes (3.1-9.7μM) and cis-platin. The most active compounds block the cell cycle at the G0/1 phase and promote apoptosis.

DNA binding and in vitro anticarcinogenic activity of a series of newfashioned Cu(II)-complexes based on tricationic metalloporphyrin salicyloylhydrazone ligands

Four novel water-soluble Cu(II) derivatives based on the meso-10, 15, 20-Tris (N-methyl-X-pyridyl)-5-(4'-salicyloylhydrazone) metalloporphyrin ligands (X=4, M=Zn(1) Co(2); X=2, M=Zn(3), Co(4)), have been prepared and isolated. Various physicochemical techniques indicate that complex 2 interacts with calf thymus DNA stronger than the others through partial intercalation, suggesting that Co(II) has no axial ligands at porphyrin core plays a crucial role, interestingly, 2 exhibits higher DNA binding affinity compared to 4, which could be ascribed to the influences of peripheral electronic effect of porphyrin ring. Cytotoxicity studies manifest all conjugates possess superior cytotoxicity towards non-small cell lung cancer (A549) and liver hepatocellular carcinoma (HepG2) but weak toxicity for human normal breast cells (Hs 578Bst) boiled down to the tumor selectivity of porphyrin. In addition, the IC₅₀ value of 1 is lower than its analogues against HepG2 cells when cultivated 72h, thus the effects of representative complex 1 on cell morphological and cell cycle have been tailed.

Heteroleptic metal(II) complexes of hydrotris(methimazolyl)borate and diimines: Synthesis, theoretical calculations, antimicrobial, antioxidant, in vitro cytotoxicity and molecular docking studies

A series of heteroleptic metal(II) complexes of formulation [M(Tm)(diimine)](ClO₄) (1-8), [Tm = hydrotris(methimazolyl)borate, diimine = 2,2'-bipyridyl or 1,10-phenanthroline and M = Mn(II), Ni(II), Cu(II) or Zn(II)] have been synthesized and characterized by spectroscopic methods. The geometric parameters of the complexes were determined using UV-Vis spectroscopy and DFT calculations. The analyses of HOMO and LUMO have been used to explain the charge transfer within the molecule. Antimicrobial activity of the synthesized heteroleptic complexes were evaluated against two Gram (-ve) (Escherichia coli and Klebsiella pneumoniae) and two Gram (+ve) (Bacillus cereus and Staphylococcus aureus) bacterial, and three fungal (Candida albicans, Candida glabrata and Candida krusei) strains with respect to the standard drugs erythromycin and amphotericin-B. The copper(II) complex 6 showed better scavenging activity against DPPH when compared to other complexes. The cytotoxic activity of copper(II) complexes 5 and 6 against MCF-7 cell line was assessed by MTT assay, which showed exponential responses toward increasing concentration of complexes. In the molecular docking studies, the complexes showed π-π, σ-π, hydrogen bonding, van der Waals and electrostatic interactions with FGFR kinase receptor.

DNA and BSA binding and cytotoxic properties of copper(ii) and iron(iii) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands

Copper(ii) and iron(iii) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands show DNA and BSA binding and anticancer abilities.

Mixed-ligand copper(ii)-phenolate complexes: structure and studies on DNA/protein binding profiles, DNA cleavage, molecular docking and cytotoxicity

Copper(ii) complexes with simple and mixed ligands, [Cu(L)(ClO₄)] and [Cu(L)(diimine)]ClO₄ were synthesized and characterized by elemental analysis, UV-vis, FT-IR, electrospray ionization-mass spectrometry (ESI-MS) and electrochemical studies.