Copper(ii) complexes with NNO ligands: synthesis, crystal structures, DNA cleavage, and anticancer activities

Novel tetranuclear grid-like Zn(II) complexes derived from dihydrazone pyrimidine derivatives as antitumor agents

Due to the antitumor properties, Zn(II) complexes have attracted more and more attention. Herein, three novel tetranuclear Zn(II) complexes 1-3 based on dihydrazone pyrimidine derivatives H2L1-H2L3 were synthesized and characterized using IR spectroscopy, 1H NMR spectroscopy, single crystal X-ray diffraction analysis, XRD, TG and elemental analysis. Single crystal X-ray diffraction analysis revealed that 1-3 all displayed a [2 × 2] grid-like topology. The stability in solution, lipophilicity, confocal imaging and antitumor activities were investigated. Complexes 1-3 displayed high structural stability, membrane permeability and different lipophilicities. They can target mitochondria due to the cation charge. The MTT assay indicated that all of them exhibited stronger antiproliferative activity than the corresponding derivatives H2L1-H2L3 and the well-known cisplatin against all the selected tumor cells (BGC-823, BEL-7402, MCF-7 and A549), with IC50 values ranging from 2.83 μM to 7.97 μM. AO/EB double staining, flow cytometry and ROS detection suggested that complexes 1 and 2 could induce BGC-823 apoptosis in a dose-dependent manner. UV-Vis spectra, CD spectra, viscosity analysis and molecular docking revealed that complexes 1 and 2 interact with DNA mainly via partial intercalation and groove binding. Tetranuclear [2 × 2] grid-like Zn(II) complexes have the potential to be promising antitumor agents in the future.

The oxidative nuclease activity of human cytochrome c with mutations in Ω-loop C/D

Natural and artificial nucleases have extensive applications in biotechnology and biomedicine. The exploration of protein with potential DNA cleavage activity also inspires the design of artificial nuclease and helps to understand the physiological process of DNA damage. In this study, we engineered four human cytochrome c (Cyt c) mutants (N52S, N52A, I81N, and I81D Cyt c), which showed enhanced DNA cleavage activity and degradation in comparison with WT Cyt c, especially under acidic conditions. The mechanism assays revealed that the superoxide (O₂^•-) plays an important role in the nuclease reaction. The kinetic assays showed that the peroxidase activity of the I81D Cyt c mutant enhanced up to 9-fold at pH 5. This study suggests that the mutations of Ile81 and Asn52 in Ω-loop C/D are critical for the nuclease activity of Cyt c, which may have physiological significance in DNA damage and potential applications in biomedicine.

Synthesis, Biological Evaluation, DNA Binding, and Molecular Docking of Hybrid 4,6-Dihydrazone Pyrimidine Derivatives as Antitumor Agents

In the present paper, on the basis of molecular hybridization, a series of 4,6-dihydrazone pyrimidine derivatives containing the pyridine moiety were synthesized, structurally characterized, and evaluated in vitro for their antitumor activity. According to the results, all the tested compounds demonstrated broad-spectrum antitumor activity against selected tumor cell lines (MCF-7, BGC-823, A549, and BEL-7402) and no obvious toxicity toward normal cells HL-7702. In particular, compounds 10a and 10f were found to be the most promising antitumor agents among the tested compounds against BGC-823 cells (IC₅₀ = 9.00 μM and 7.89 μM) and BEL-7402 cells (IC₅₀ = 6.70 μM and 7.66 μM), respectively. Compounds 10a and 10f exhibited higher potency against BGC-823 and BEL-7402 than the positive control 5-FU (IC₅₀ = 15.18 μM and 15.81 μM). Further mechanism investigations demonstrated that compounds 10a and 10f could significantly increase the level of cellular ROS and induce early apoptosis of BGC-823 cells in a dose-dependent manner. Moreover, the DNA binding results from UV/Vis, CD spectroscopy, and molecular docking studies indicated that 10a and 10f bind with DNA via groove binding and partial intercalation. These results demonstrated that 10a and 10f may serve as novel lead compounds for the discovery of more dihydrazone pyrimidine derivatives with improved antitumor potency and selectivity.

Crystal structure of (E)-N′-(2-chloro-6-hydroxybenzylidene)-3-hydroxybenzo-hydrazide monohydrate, C14H13ClN2O4

C14H13ClN2O4, monoclinic, P21/n (no. 14), a = 9.7353(13) Å, b = 13.7790(18) Å, c = 10.5227(13) Å, β = 97.961(2)°, V = 1397.9(3) Å3, Z = 4, R gt (F) = 0.0367, wR ref (F 2) = 0.1181, T = 296(2) K.

N, Kumara K, Lokanath NK, Butcher RJ, Kumbar V, Bhat K. Copper(i) complexes with quinolone appended 1,8-naphthalimide conjugates: structural characterization, DNA and protein binding and cytotoxicity studies

Cytotoxicity, cellular uptake of copper(i) complexes containing 1,8-naphthalimide conjugates have been investigated.

Copper in tumors and the use of copper-based compounds in cancer treatment

Copper homeostasis is strictly regulated by protein transporters and chaperones, to allow its correct distribution and avoid uncontrolled redox reactions. Several studies address copper as involved in cancer development and spreading (epithelial to mesenchymal transition, angiogenesis). However, being endogenous and displaying a tremendous potential to generate free radicals, copper is a perfect candidate, once opportunely complexed, to be used as a drug in cancer therapy with low adverse effects. Copper ions can be modulated by the organic counterpart, after complexed to their metalcore, either in redox potential or geometry and consequently reactivity. During the last four decades, many copper complexes were studied regarding their reactivity toward cancer cells, and many of them could be a drug choice for phase II and III in cancer therapy. Also, there is promising evidence of using ⁶⁴Cu in nanoparticles as radiopharmaceuticals for both positron emission tomography (PET) imaging and treatment of hypoxic tumors. However, few compounds have gone beyond testing in animal models, and none of them got the status of a drug for cancer chemotherapy. The main challenge is their solubility in physiological buffers and their different and non-predictable mechanism of action. Moreover, it is difficult to rationalize a structure-based activity for drug design and delivery. In this review, we describe the role of copper in cancer, the effects of copper-complexes on tumor cell death mechanisms, and point to the new copper complexes applicable as drugs, suggesting that they may represent at least one component of a multi-action combination in cancer therapy.

Synthesis, crystal structures, anticancer activities and molecular docking studies of novel thiazolidinone Cu(II) and Fe(III) complexes targeting lysosomes: special emphasis on their binding to DNA/BSA

Novel [CuL₂Cl]Cl·H₂O (1) and [FeL₂Cl₂]Cl·MeOH·CHCl₃·H₂O (2) complexes of (Z)-N'-((E)-3-methyl-4-oxothiazolidin-2-ylidene)picolinohydrazonamide (L) as antitumor agents were designed and synthesized in order to explore DNA and serum albumin interaction. X-ray diffraction revealed that both 1 and 2 were a triclinic crystal system with P1̄ space group, which consisted of a positive electric main unit, a negative chloride ion and some solvent molecules. The complexes with DNA and bovine serum albumin (BSA) were studied by fluorescence and electronic absorption spectrometry. The results indicated that there was moderate intercalative binding mode between the complexes and DNA with K_app values of 2.40 × 10⁵ M^-1 (1) and 6.49 × 10⁵ M^-1 (2). Agarose gel electrophoresis experiment showed that both 1 and 2 exhibited obvious DNA cleavage activity via an oxidative DNA damage pathway, and the cleavage activities of 1 were stronger than those of 2. Cytotoxicity assay showed that 1 had a more effective antitumor activity than 2. The two complexes were bound to BSA by a high affinity and quenched the fluorescence of BSA through a static mechanism. The thermodynamic parameters suggested that hydrophobic interactions played a key role in the binding process. The binding energy xpscore of 1 and 2 were -10.529 kcal mol^-1 and -10.826 kcal mol^-1 by docking studies, and this suggested that the binding process was spontaneous. Complex 1 displayed a lysosome-specific targeting behavior with a Pearson coefficient value of 0.82 by confocal laser scanning microscopy (CLSM), and accumulated in the lysosomes, followed by the disruption of lysosomal integrity.

DNA-interacting properties of two analogous square-planar cis-chlorido complexes: copper versus palladium

Two square-planar coordination compounds, namely [Cu(CPYA)Cl2] (1) and [Pd(CPYA)Cl2] (2), were prepared from the ligand 4-chloro-N-(pyridin-2-ylmethyl)aniline (CPYA) and two chloride salts, and were fully characterized, including by X-ray diffraction. Spectroscopic, electrophoretic and AFM studies revealed that the two isostructural compounds were interacting differently with DNA. In both cases, the initial interaction involves electrostatic contacts of the CPYA ligand in the minor groove (as suggested by molecular docking), but subsequent strong binding occurs with the palladium(II) complex 2, whereas the binding with the copper complex 1 is weaker and concentration dependent. The strong binding of 2 eventually leads to the cleavage of the double strand and the redox activity of 1 allows to oxidatively cleave the biomolecule.

Enantiomeric copper based anticancer agents promoting sequence-selective cleavage of G-quadruplex telomeric DNA and non-random cleavage of plasmid DNA

Copper-based binuclear enantiomeric complexes 1S and 1R were synthesized as anticancer chemotherapeutic agents to target G-quadruplex rich region of DNA and thoroughly characterized by various spectroscopic and single X-ray crystal diffraction studies. The structure elucidation of Schiff base ligand LS and complexes 1S & 1R, was carried out by single crystal X-ray studies which showed that ligand crystallized in the monoclinic P21/n space group while complexes 1S and 1R crystallized in triclinic space groups P1[combining macron] and P1, respectively with two copper units connected to each other via an alkoxide bridge to exhibit square planar geometry which is in good agreement with other spectroscopic studies {IR, ESI-MS, EPR and magnetic moment values}. In vitro binding studies of complexes 1S and 1R were carried out with G-quadruplex DNA and CT-DNA which showed higher binding affinity and selectivity toward quadruplex DNA over the duplex DNA. To validate the potential of complexes to act as therapeutic drug candidates, the cleavage studies of complexes 1S and 1R were carried out with G-quadruplex telomeric DNA by PAGE Gel assay which showed sequence selective cleavage of 22G4via oxidative cleavage pathway. The major cleavage sites identified were G15, T6, G8, G9, G14 for complex 1S whereas for 1R G15, G20, G21, G14 cleavage sites were observed. Furthermore, these complexes were capable of cleaving pUC19 plasmid DNA in double-stranded non-random fashion which is considered to be more potent than single-strand cleavage as a source of lethal DNA lesions. Cellular studies of 1S and 1R were performed on a panel of human cancer cell lines; Huh7, MCF7, BxPC3 and AsPC1, which displayed significant cytotoxicity and differential responses toward different cancer phenotypes.

Identification of potent anticancer copper(ii) complexes containing tripodal bis[2-ethyl-di(3,5-dialkyl-1H-pyrazol-1-yl)]amine moiety

A series of heteroleptic copper(ii) complexes of the composition [Cu(L^1-5)Cl]X, where X = ClO₄ and/or PF₆ and [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl))-(6-methyl-(2-pyridylmethyl))]amine (L¹), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl))-(3,4-dimethoxy-(2-pyridylmethyl))]amine (L²), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl)-(2-quinolymethyl)]amine (L³), [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazolyl)-(di(3,5-dimethyl-1H-pyrazol-1-yl-methyl))]amine (L⁴) and [bis(2-ethyl-di(3,5-dimethyl-1H-pyrazol-1-yl)-(5-methyl-3-phenyl-1H-pyrazol-1-yl-methyl)]amine (L⁵), were prepared and thoroughly characterized including single-crystal X-ray diffraction technique. The in vitro cytotoxicity of complexes against A2780, A2780R, HOS and MCF-7 human cancer cell lines was evaluated using the MTT test. The results revealed that complexes [Cu(L¹)Cl]PF₆ (1-PF₆), [Cu(L²)Cl]ClO₄ (2-ClO₄) and [Cu(L³)Cl]PF₆ (3-PF₆) are the most effective, with IC₅₀ values ranging from 1.4 to 6.3 μM, thus exceeding the cytotoxic potential of metallodrug cisplatin (IC₅₀ values ranging from 29.9 to 82.0 μM). The complexes [Cu(L⁴)Cl]PF₆ (4-PF₆) and [Cu(L⁵)Cl]PF₆ (5-PF₆) showed only moderate cytotoxicity against A2780, with IC₅₀ = 53.6 μM, and 33.8 μM, respectively. The cell cycle profile, time-resolved cellular uptake, interactions with small sulfur-containing biomolecules (cysteine and glutathione), intracellular ROS production, induction of apoptosis and activation of caspases 3/7 were also evaluated in the case of the selected complexes. It has been found that the best performing complexes 1 and 2 cause cell arrest in the G2/M phase and induce apoptosis via the increase in production of ROS, dominantly due to the overproduction of superoxide.

Synthesis, Characterization, DNA/HSA Interactions, and Anticancer Activity of Two Novel Copper(II) Complexes with 4-Chloro-3-Nitrobenzoic Acid Ligand

The purpose of this study was to identify new metal-based anticancer drugs; to this end, we synthesized two new copper(II) complexes, namely [Cu(ncba)₄(phen)] (1) and [Cu(ncba)₄(bpy)] (2), comprised 4-chloro-3-nitrobenzoic acid as the main ligand. The single-crystal XRD approach was employed to determine the copper(II) complex structures. Binding between these complexes and calf thymus DNA (CT-DNA) and human serum albumin (HSA) was explored by electronic absorption, fluorescence spectroscopy, and viscometry. Both complexes intercalatively bound CT-DNA and statically and spontaneously quenched DNA/HSA fluorescence. A CCK-8 assay revealed that complex 1 and complex 2 had substantial antiproliferative influences against human cancer cell lines. Moreover, complex 1 had greater antitumor efficacy than the positive control cisplatin. Flow cytometry assessment of the cell cycle demonstrated that these complexes arrested the HepG2 cell cycle and caused the accumulation of G0/G1-phase cells. The mechanism of cell death was elucidated by flow cytometry-based apoptosis assays. Western blotting revealed that both copper(II) complexes induced apoptosis by regulating the expression of the Bcl-2(Bcl-2, B cell lymphoma 2) protein family.

Inhibitory Effect of Valsartan on Pterygium Fibroblasts

PURPOSE

Angiotensin receptor blockers (ARBs) were shown to have antifibrotic properties in ocular and systemic diseases. In this study, our aim was to investigate the effect of an angiotensin receptor blocker, valsartan, on pterygium fibroblasts and compare this effect with that of mitomycin C (MMC).

METHODS

Pterygium tissue samples were obtained from 3 patients during surgical excision. Primary cultured pterygium fibroblasts and L929 cell cultures were treated with different concentrations of MMC and valsartan.

RESULTS

The cell viability decreased with increasing concentrations of valsartan at 48 hours for both cell types. MMC inhibited the proliferation of both cell types at 48 hours. Both agents significantly decreased the cell migration of the 2 cell types, although it was more prominent in the MMC-treated group.

CONCLUSIONS

Valsartan inhibited the proliferation and migration of pterygium fibroblasts. The known favorable safety profile of these drugs and the results of this study showing inhibitory effect on pterygium fibroblasts make valsartan a potential therapeutic agent for pterygium treatment.

Crystal structure of bis-{2-hy-droxy-N'-[1-(pyrazin-2-yl)ethyl-idene]benzohydrazidato}cadmium(II)

In the title complex mol-ecule, [Cd(C13H11N4O2)2], the Cd atom is coordinated in a distorted octa-hedral geometry by two tridentate ligands synthesized from 2-hy-droxy-benzohydrazide and 1-(pyrazin-2-yl)ethan-1-one. The mol-ecule has twofold crystallographic symmetry and is isomorphous to its Mn, Co, Ni, Cu and Zn counterparts.

Design of γ-AlOOH, γ-MnOOH, and α-Mn2O3 nanorods as advanced antibacterial active agents

In the current study, γ-AlOOH, γ-MnOOH, and α-Mn2O3 nanorods (NRs) were easily synthesized and applied as advanced antibacterial materials. γ-AlOOH NRs with 20 nm width, [100] crystal plane, and 200 nm length were fabricated through a surfactant-directed solvothermal method. γ-MnOOH NRs with 20 nm width, [101] crystal direction and 500 nm length were fabricated through a hydrothermal method. The prepared γ-MnOOH NRs were calcinated (for 5 h) at 700 °C to produce α-Mn2O3 NRs with 20 nm average width and increased surface area. The NRs' structures were confirmed through FT-IR, XRD, XPS, FESEM, and FETEM. The antibacterial activity of the NRs was studied against different Gram-negative and Gram-positive bacterial strains and yeast. The three NRs exhibited antibacterial activity against all of the used strains. Biological studies indicated that the NRs' antimicrobial activity increased in the order of γ-MnOOH < γ-AlOOH < α-Mn2O3 NRs. The α-Mn2O3 NRs exhibited the lowest MIC value (39 μg mL-1) against B. subtilis, B. pertussis, and P. aeruginosa. The prepared NRs exhibited a higher antimicrobial potential toward Gram-positive bacteria than Gram-negative bacteria. The higher antimicrobial activity of the α-Mn2O3 NRs is highlighted based on their larger surface area and smaller diameter. Consequently, uniform NR architectures, single crystallinity, small nanoscale diameters, and more highly exposed [110] Mn-polar surfaces outwards are promising structures for α-Mn2O3 antibacterial agents. These NRs adhered firmly to the bacterial cells causing cell wrapping and morphology disruption, and microbial death. The designed NRs provide a great platform for microbial growth inhibition.

Metal-organic frameworks for virus detection

Virus severely endangers human life and health, and the detection of viruses is essential for the prevention and treatment of associated diseases. Metal-organic framework (MOF), a novel hybrid porous material which is bridged by the metal clusters and organic linkers, has become a promising biosensor platform for virus detection due to its outstanding properties including high surface area, adjustable pore size, easy modification, etc. However, the MOF-based sensing platforms for virus detection are rarely summarized. This review systematically divided the detection platforms into nucleic acid and immunological (antigen and antibody) detection, and the underlying sensing mechanisms were interpreted. The nucleic acid sensing was discussed based on the properties of MOF (such as metal ion, functional group, geometry structure, size, porosity, stability, etc.), revealing the relationship between the sensing performance and properties of MOF. Moreover, antibodies sensing based on the fluorescence detection and antigens sensing based on molecular imprinting or electrochemical immunoassay were highlighted. Furthermore, the remaining challenges and future development of MOF for virus detection were further discussed and proposed. This review will provide valuable references for the construction of sophisticated sensing platform for the detection of viruses, especially the 2019 coronavirus.

Copper (II)-based halogen-substituted chromone antitumor drug entities: Studying biomolecular interactions with ct-DNA mediated by sigma hole formation and cytotoxicity activity

Copper-based antitumor drug entities 1-3 derived from substituted (F^-, Br^-, -CH₃) 3-formylchromone pharmacophore were synthesized and thoroughly characterized by spectroscopic and single X-ray crystallographic studies. These complexes show structural novelty due to presence of the X-bonds in chromone scaffold which could facilitate higher propensity for nucleic acids via sigma σ-hole interactions. Therefore, structure-activity relationship of 1-3 was studied by performing ct-DNA binding, pBR322 cleavage and cytotoxicity activity to validate their potential to act as chemotherapeutic drug entities. The binding studies of 1-3 with ct- DNA were carried out employing many biophysical techniques and the corroborative results of these experiments showed intercalation mode of binding and the order of binding was found to be 2 > 1 > 3. The structure of drug entities could facilitated strong halogen bonding interaction (in case of 1 &2) and stability of X bond was rationalized by sigma hole region of positive electrostatic potential on the surface of C-X covalent bond, as determined by gas phase B3LYP computational DFT studies. Interestingly, 2 exhibited most avid binding affinity due to presence of Br^- electron withdrawing and polarizable group. Further, cleavage studies of 1-3 with pBR322 plasmid DNA were performed which demonstrated significant cleavage activity, the supercoiled form (Form I) of plasmid DNA was converted to nicked form (Form II) with the appearance of linearized form (Form III) in between two, implicating lethal double strand breaks of DNA. 2 showed predominantly higher cleavage activity following the similar trend as observed for binding studies. The cytotoxicity of the complexes 1-3 was evaluated by MTT assay against the human liver carcinoma (Huh-7) and prostate cancer (DU-145) cell lines; complex 2 exhibited specific and selective cytotoxicity for the DU-145 cancer cell line with LC₅₀ value of 1.6 μM.

Crystal structures and biological properties of aroylhydrazone Ni(II) complexes

Three aroylhydrazone ligands ((Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-2-hydroxybenzohydrazide, HL1; (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-3-hydroxybenzohydrazide, HL2; and (Z)-N'-([2,2'-bithiophen]-5-ylmethylene)-4-hydroxybenzohydrazide, HL3) and their complexes with nickel (Ni(L1)₂, 1; Ni(L2)₂, 2; Ni(L3)₂∙DMF, 3) were synthesized and characterized by ESI-MS, NMR, IR, UV-vis and elemental analysis techniques. The molecular structure of ligand (HL2) and complexes 1-3 was confirmed by single crystal X-ray crystallography. The single crystal X-ray structure of complexes 1-3 showed a distorted square planar geometry around the metal center, and the ligands adopt a bidentate chelating mode. The interaction of calf thymus (ctDNA) with nickel(II) complexes was explored using absorption, emission spectrum, viscosity, and circular dichroism methods. These complexes exhibited moderate affinity for ctDNA through groove binding modes. The most efficient DNA binder was complex 2. The interaction of the complexes with DNA has also been supported by molecular docking study and molecular dynamics simulation. An in vitro cytotoxicity study of the complexes found low activity against human cervical (Hela) and breast (MCF-7) cancer cell lines, with the best results for complex 2, where IC50 values are 86 μM and 92 μM respectively.

Copper(ii) complexes containing enoxacin and heterocyclic ligands: synthesis, crystal structures and their biological perspectives

Two copper-based complexes with a distorted square pyramidal geometry show excellent binding and cleavage affinity towards DNA and proteins. Also, these complexes have potential cytotoxicity against MCF-7 cancer cells.