A Trinuclear Copper(II) Complex of 2,4,6-Tris(di-2-pyridylamine)-1,3,5-triazine Shows Prominent DNA Cleavage Activity

DNA binding studies and in-vitro anticancer studies of novel lanthanide complexes

Pancreatic cancer, is an aggressive type of cancer and the most common malignancy with a poor prognosis regarding metastatic disease (survival < 10 %). The development of Novel chemotherapeutic drugs holds significant prospects for practical applications. Here, this work focuses on the interaction between two lanthanide complexes, Yb-BZA and Er-BZA, with DNA, as well as their anticancer activity against pancreatic cancer. The relationship between complexes and DNA is revealed by fluorescence, absorption spectral titration, cyclic voltammetric (CV) experiments, indicating that the Yb-BZA and Er-BZA interact with FS-DNA by bind groove. Moreover, molecular docking technology was utilized to confirm the binding of Yb-BZA and Er-BZA with 1BNA and 4AV1. The cytotoxic effects of Yb-BZA and Er-BZA on cancer cells BxPC-3 were evaluated, Yb-BZA (IC50 = 6.459 μg/mL) is more effective than oxaliplatin (IC50 = 16.46 μg/mL) evaluated using cytotoxicity assay. Yb-BZA and Er-BZA has the potential to become a chemotherapy drug for pancreatic cancer cells.

Multi-Hydrogen Bonding on Quaternized-Oligourea Receptor Facilitated Its Interaction with Bacterial Cell Membranes and DNA for Broad-Spectrum Bacteria Killing

Herein, we report a new strategy for the design of antibiotic agents based on the electrostatic interaction and hydrogen bonding, highlighting the significance of hydrogen bonding and the increased recognition sites in facilitating the interaction with bacterial cell membranes and DNA. A series of quaternary ammonium functionalized urea-based anion receptors were studied. While the monodentate mono-urea M1, bisurea M2, and trisurea M3 failed to break through the cell membrane barrier and thus could not kill bacteria, the extended bidentate dimers D1-D3 presented gradually increased membrane penetrating capabilities, DNA conformation perturbation abilities, and broad-spectrum antibacterial activities against E. coli, P. aeruginosa, S. aureus, E. faecalis, and S. epidermidis.

Interaction with CT-DNA and in vitro cytotoxicity of two new copper(II)-based potential drugs derived from octanoic hydrazide ligands

Two copper(II) complexes [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(peoh)(N3)]2 (2) were designed and synthesized by reaction of Cu(NO3)2·3H2O with hydrazone Schiff base ligands,abbreviated with Hpmoh and Hpeoh. Hpmoh and Hpeoh were prepared by condensation reaction of octanoic hydrazide with pyridine-2-carboxyaldehyde and 2-acetylpyridine, respectively. Complexes 1 and 2 were characterized using different analytical techniques such as FT-IR, UV-Vis, IR, EPR and single X-ray diffraction (XRD) analyses as well as computational methods (DFT). The XRD of 1 and 2 shows a mononuclear or a dinuclear structure with the copper(II) centre adopting a slightly distorted square pyramidal geometry. In water-containing solution and in DMSO, 1 and 2 undergo a partial transformation with formation of [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(Hpmoh)(NO3)(H2O/DMSO)] (1a) in one system and [Cu(peoh)(N3)] (2a) in the other one, as supported by DFT calculations. Docking simulations confirmed that the intercalation is the preferred binding mode with DNA for 1, 1a and 2a, but suggested that the minor groove binding is also possible. A significant fluorescence quenching of the DNA-ethidium bromide conjugate was observed upon the addition of complexes 1 and 2 with a quenching constant around 104 M-1 s-1. Finally, both 1 and 2 were examined for anti-cancer activity using MDA-MB-231 (human breast adenocarcinoma) and A375 (malignant melanoma) cell lines through in vitro MTT assay which suggest comparable cancer cell killing efficacy, with the higher effectiveness of 2 due to the dissociation into two [Cu(peoh)(N3)] units.

Novel Cu(II) complexes as DNA-destabilizing agents and their DNA nuclease activity

Here, we report a series of four novel Cu complexes, namely 2-(piperidin-1-ylmethyl)quinoline copper(II) nitrate, [LACu(NO3)2] (Cu1), 4-(quinolin-2-ylmethyl)morpholine copper(II) nitrate, [LBCu(NO3)2] (Cu2), 4-(quinolin-2-ylmethyl)morpholine copper(II) chloride, [LBCuCl2] (Cu3), and 2-(piperidin-1-ylmethyl)pyridine copper(II) chloride, [LCCu(μ-Cl)Cl]2 (Cu4). X-ray diffraction studies revealed that the geometry around the Cu(II) center could be best described as distorted octahedral in Cu1 and Cu2, whereas Cu3 and Cu4 showed distorted tetrahedral and square pyramidal geometries, respectively. DNA binding studies showed that Cu complexes Cu1-3 containing quinoline interacted via minor groove binding, whereas the Cu4 complex containing pyridine interacted via intercalation. All Cu complexes containing quinoline and pyridine caused destabilization of DNA at specific homogeneous G-C regions. The Cu1-3 complexes as groove binders destabilized the DNA structure much more than the Cu4 complex as an intercalator. Regarding groove binders, the Cu2 complex containing quinoline and morpholine caused the highest distortion and destabilization of the DNA structure, leading to high DNA cleavage efficiency.

A Click Chemistry-Based Artificial Metallo-Nuclease

Artificial metallo-nucleases (AMNs) are promising DNA damaging drug candidates. Here, we demonstrate how the 1,2,3-triazole linker produced by the Cu-catalysed azide-alkyne cycloaddition (CuAAC) reaction can be directed to build Cu-binding AMN scaffolds. We selected biologically inert reaction partners tris(azidomethyl)mesitylene and ethynyl-thiophene to develop TC-Thio, a bioactive C3 -symmetric ligand in which three thiophene-triazole moieties are positioned around a central mesitylene core. The ligand was characterised by X-ray crystallography and forms multinuclear CuII and CuI complexes identified by mass spectrometry and rationalised by density functional theory (DFT). Upon Cu coordination, CuII -TC-Thio becomes a potent DNA binding and cleaving agent. Mechanistic studies reveal DNA recognition occurs exclusively at the minor groove with subsequent oxidative damage promoted through a superoxide- and peroxide-dependent pathway. Single molecule imaging of DNA isolated from peripheral blood mononuclear cells shows that the complex has comparable activity to the clinical drug temozolomide, causing DNA damage that is recognised by a combination of base excision repair (BER) enzymes.

Copper(ii) salen-based complexes as potential anticancer agents

The systematic design and synthesis of four Cu(ii) salen compounds and their potential as excellent anticancer agents is discussed using biological studies.

Anticancer activity, DNA binding and docking study of M(ii)-complexes (M = Zn, Cu and Ni) derived from a new pyrazine–thiazole ligand: synthesis, structure and DFT

A series of structurally related Zn(ii), Cu(ii) and Ni(ii) complexes of 4-(2-(2-(1-(pyrazin-2-yl)ethylidene)hydrazinyl)-thiazol-4-yl)-benzonitrile (PyztbH) have been synthesized and characterized by spectroscopy, single crystal X-ray crystallography and density functional theory (DFT).

Molecular docking, DFT and antimicrobial studies of Cu(II) complex as topoisomerase I inhibitor

Herein, we report the synthesis and single crystal X-ray structure of Cu(II)-picolinic acid complex, 1 as a potent topoisomerase I inhibitor. The complex 1 crystallized in the triclinic crystal system with space group P-1. Comparative in vitro binding studies of complex 1 with CT DNA and tRNA were carried out revealing an electrostatic binding mode with higher binding propensity towards tRNA. The intrinsic bonding constant value, K_b was calculated to be 4.36 × 10⁴ and 8.78 × 10⁴ M^-1 with CT DNA and tRNA respectively. DNA cleavage activity was carried out with a pBR322 plasmid DNA substrate to ascertain the cleaving ability. Furthermore, Topo-I inhibition assay of complex 1, performed via gel electrophoresis revealed a significant inhibitory effect on the enzyme catalytic activity at a minimum concentration of 15 µM. The DFT studies were carried out to provide better insight in the electronic transitions observed in the absorption spectrum of the complex 1. Molecular docking studies were carried out with DNA, RNA and Topo-I to determine the specific binding preferences at the target site and complement the spectroscopic studies. The antimicrobial potential of complex 1 was screened against E. coli, S. aureus, P. aeruginosa, B. subtilis and C. albicans; and compared with doxycycline, exhibiting an excellent maximum zone of inhibition of 28 mm against E. coli.Communicated by Ramaswamy H. Sarma.

Coordination of a triazine ligand with CuII and AgI investigated by spectral, structural, theoretical and docking studies

Two complexes of 5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine (PPTA), namely (ethanol-κO)bis(nitrato-κO)[5-phenyl-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN²]copper(II), [Cu(NO₃)₂(C₁₄H₁₀N₄)(C₂H₆O)] or [Cu(NO₃)₂(PPTA)(EtOH)] (1), and bis[μ-5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine]-κ³N¹:N²,N³;κ³N²,N³:N¹-bis[(nitrato-κO)silver(I)], [Ag₂(NO₃)₂(C₁₄H₁₀N₄)₂] or [Ag₂(NO₃)₂(μ-PPTA)₂] (2), were prepared and characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The X-ray structure analysis of 1 revealed a copper complex with square-pyramdial geometry containing two O-donor nitrate ligands along with an N,N'-donor PPTA ligand and one O-donor ethanol ligand. In the binuclear structure of 2, formed by the bridging of two PPTA ligands, each Ag atom has an AgN₃O environment and square-planar geometry. In addition to the four dative interactions, each Ag atom interacts with two O atoms of two nitrate ligands on adjacent complexes to complete a pseudo-octahedral geometry. Density functional theory (DFT) calculations revealed that the geometry around the Cu and Ag atoms in 1^opt and 2^opt (opt is optimized) for an isolated molecule is the same as the experimental results. In 1, O-H...O hydrogen bonds form R₁²(4) motifs. In the crystal network of the complexes, in addition to the hydrogen bonds, there are π-π stacking interactions between the aromatic rings (phenyl, pyridine and triazine) of the ligands on adjacent complexes. The ability of the ligand and complexes 1 and 2 to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies. The results show that the studied compounds can interact with proteins better than doxorubicin (except for TrxR and Top II).

Synthesis, Structural Characterization, Molecular Modeling and DNA Binding Ability of CoII, NiII, CuII, ZnII, PdII and CdII Complexes of Benzocycloheptenone Thiosemicarbazone Ligand

Background & Objective:

Six novel complexes of transition metal namely, [CoLCl2(H2O)2]0.5H2O, [NiLCl2(H2O)2]0.5H2O, [CuLCl2]0.5H2O, [ZnLCl2], [PdLCl2]H2O and [CdLCl2]H2O, where L is benzocycloheptenone thiosemicarbazone ligand, have been obtained. The confirmation of the structures of the obtained metal chelates depends on the different spectral and physicochemical techniques including CHN analysis, infrared spectra, molar conductivity measurement, UV-vis, thermogravimetric analysis and magnetic moment. The infrared spectral results ascertained that the ligand behaved as neutral bidentate connecting the metal centers via N and S atoms of C=N and C=S groups, respectively.

Methods:

The UV-Vis, molar conductivity and magnetic susceptibility results implied that the geometrical structures of the metal chelates are octahedral for Co(II) & Ni(II) complexes, tetrahedral for Zn(II) & Cd(II) complexes and square planar for Cu(II) & Pd(II) complexes which have been confirmed by molecular modeling studies.

Conclusion:

Moreover, the mode of interaction between some chosen metal complexes towards SSDNA has been thoughtful by UV-Vis spectra and viscosity measurements. The value of the intrinsic binding constant (Kb) for the examined compounds has been found to be lower than the binding affinity of the classical intercalator ethedium bromide. Also, the viscosity measurements of the complexes proved that they bind to DNA, most likely, by a non-intercalative mode like H-bonding or electrostatic interactions.

Facile template synthesis of water-soluble triazine-based Schiff base ligand bridged-coordination polymers of Co(ii), Ni(ii), and Cu(ii): structure, biomolecular interactions, and cytotoxic activity

For the first time, a new hydrazone Schiff base ligand and its Co(ii), Ni(ii), and Cu(ii) complexes were synthesised and characterised. Their antioxidant and binding activities towards CT-DNA and BSA were evaluated.

Example of two novel thiocyanato bridged copper (II) complexes derived from substituted thiosemicarbazone ligand: structural elucidation, DNA/albumin binding, biological profile analysis, and molecular docking study

Two novel copper (II) substituted thiosemicarbazone Schiff base complexes [Cu(L₁)(µ-SCN)]_n(NO₃)₂ (1) and [Cu₂(µ-SCN)(SCN)(L₂)₂](NO₃) (2) have been synthesized by condensing substituted thiosemicarbazides like 4-methyl-3-thiosemicarbazide or 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine. Both the metal complexes 1 and 2 are characterized using different spectroscopic techniques like IR, UV-Vis, ESR spectroscopy followed by elemental analysis, cyclic voltammetric measurement and single crystal X-ray structure analysis. X-ray crystal structure analysis reveal that complex 1 is polymeric while complex 2 is dimeric in nature. The coordination geometry around Cu(II) are square pyramidal in which thiosemicarbazone Schiff base ligand coordinate to the central Cu(II) atom in tridentate fashion. The prominent interaction patterns of 1 and 2 with CT-DNA were examined by employing electronic absorption and emission spectral titrations, cyclic voltammetry and viscosity measurements. All the results show that CT-DNA binds with both copper (II) complexes 1 and 2. Furthermore, protein binding ability in vitro of complexes 1 and 2 with both BSA and HSA were carried out using multispectroscopic techniques and a static quenching pattern was observed in both cases. Molecular docking study was employed to ascertain the exact mechanism of action of 1 and 2 with DNA and protein molecules (BSA and HSA). In vitro cytotoxicity activity of complexes 1 and 2 toward AGS and A549 was evaluated using MTT assay which demonstrates that both complexes 1 and 2 have superior prospectus to act as anticancer agents. Communicated by Ramaswamy H. Sarma.

Carbohydrate-based heteronuclear complexes as topoisomerase Iα inhibitor: approach toward anticancer chemotherapeutics

Due to the critical role of cellular enzymes necessary for cell proliferation by deciphering topological hurdles in the process of DNA replication, topoisomerases have been one of the major targets in the anticancer drug development area. A need, therefore, arises for new metallodrugs that specifically recognizes DNA and inhibits the activity of topoisomerase enzymes, herein, we report the synthesis and characterization of new metal-based glycoconjugate entities containing heterobimetallic core Cu^II-Sn^IV (1) and Ni^II-Sn^IV (2) derived from N-glycoside ligand (L). The optimized structure of complex 1 and other significant vibrational modes have been explained using dispersion corrected B3LYP/DFT calculations. In vitro DNA binding profile of the L and both the complexes 1 and 2 were done by various biophysical studies. Complex 1 breaks pBR322 DNA via a hydrolytic means which was validated by T4 DNA enzymatic assay. To get a mechanistic insight of mode of action topoisomerase I (Topo I) inhibition assay was carried out. Also, we have taken the help of molecular modeling studies in accordance with experimental findings. In vitro cytotoxicity of the complex 1 was evaluated against a panel of cancer cells which exhibited remarkably good anticancer activity (GI₅₀ values <10 μg/ml). Moreover, intracellular localization of the complex 1 was visualized by confocal microscopy against HeLa cells.

Syntheses, crystal structures, DNA binding, DNA cleavage, molecular docking and DFT study of Cu(ii) complexes involving N2O4 donor azo Schiff base ligands

DNA binding and cleavage properties of three novel copper(ii) complexes involving azo Schiff base ligands have been studied.

One new azido bridged dinuclear copper(ii) thiosemicarbazide complex: synthesis, DNA/protein binding, molecular docking study and cytotoxicity activity

Biological potential of a copper(ii) complex found to exhibit in vitro antiproliferative activity towards two cell lines, AGS and A549 cancer cells.