Synthesis, Electronic Structure, DNA and Protein Binding, DNA Cleavage, and Anticancer Activity of Fluorophore-Labeled Copper(II) Complexes

Unfolding biological properties of a versatile dicopper(II) precursor and its two mononuclear copper(II) derivatives

Synthesis, inter-conversions and biological study of the dichloro bridged dicopper(II) compound [CuLCl]₂ (1) and its two mononuclear derivatives [CuLCl(H₂O)]·H₂O (2) and [CuLCl(py)] (3) (HL=2-(2-pyridylmethyleneamino)benzenesulfonic acid) are described. The dimeric compound 1 collapses into monomers 2 and 3 in the presence of coordinating solvents, water and pyridine, respectively, and 1 is regenerated upon simple stirring of 2 or 3 in methanol. The reactions of 1 with neutral (present study) and charged (earlier studies) ligands result in monomeric and multimeric compounds, respectively, attesting that it is a versatile dicopper(II) precursor. The anticancer activity of these copper complexes (1-3) was screened against lung (A-549) and breast (MDA-MB-231) human cancer cell lines. The IC₅₀ (half maximal inhibitory concentration) value for one (3) of the compounds suggests preferential cytotoxicity against breast cancer MDA-MB-231 cell line. Furthermore, the IC₅₀ value obtained for complex 3 is found to be almost two-fold times cytotoxic than the standard drug cisplatin. In addition, the underlying possible mechanism of its apoptosis-inducing efficacy in MDA-MB-231 cells has been rationalized by using flow cytometry (FACS) and Hoechst 33342/propidium iodide (PI) fluorescence staining. The stimulation of apoptotic induction for complex 3 has further been affirmed by reactive oxygen species (ROS) generation and mitochondrial aggregations studies.

Investigation of the complex structure, comparative DNA-binding and DNA cleavage of two water-soluble mono-nuclear lanthanum(III) complexes and cytotoxic activity of chitosan-coated magnetic nanoparticles as drug delivery for the complexes

Two water-soluble mono-nuclear macrocyclic lanthanum(III) complexes of 2,6-diformyl-4-methylphenol with 1,3-diamino-2-propanol (C₁) or 1,3-propylenediamine (C₂) were synthesized and characterized by UV-Vis, FT-IR, ¹³C and ¹H NMR spectroscopy and elemental analysis. C₁ complex was structurally characterized by single-crystal X-ray diffraction, which revealed that the complex was mononuclear and ten-coordinated. The coordination sites around lanthanum(III) were occupied with a five-dentate ligand, two bidentate nitrates, and one water molecule. The interaction of complexes with DNA was studied in buffered aqueous solution at pH7.4. UV-Vis absorption spectroscopy, emission spectroscopy, circular dichroism (CD) and viscometric measurements provided clear evidence of the intercalation mechanism of binding. The obtained intrinsic binding constants (K_b) 9.3×10³ and 1.2×10³M^-1 for C₁ and C₂, respectively confirmed that C₁ is better intercalator than C₂. The DNA docking studies suggested that the complexes bind with DNA in a groove binding mode with the binding affinity of C₁>C₂. Moreover, agarose gel electrophoresis study of the DNA-complex for both compounds revealed that the C₁ intercalation cause ethidium bromide replacement in a competitive manner which confirms the suggested mechanism of binding. Finally, the anticancer experiments for the treated cancerous cell lines with both synthesized compounds show that these hydrophilic molecules need a suitable carrier to pass through the hydrophobic nature of cell membrane efficiently.

A new stepped tetranuclear copper(II) complex: synthesis, crystal structure and photoluminescence properties

Binuclear and tetranuclear copper(II) complexes are of interest because of their structural, magnetic and photoluminescence properties. Of the several important configurations of tetranuclear copper(II) complexes, there are limited reports on the crystal structures and solid-state photoluminescence properties of `stepped' tetranuclear copper(II) complexes. A new Cu^II complex, namely bis{μ₃-3-[(4-methoxy-2-oxidobenzylidene)amino]propanolato}bis{μ₂-3-[(4-methoxy-2-oxidobenzylidene)amino]propanolato}tetracopper(II), [Cu₄(C₁₁H₁₃NO₃)₄], has been synthesized and characterized using elemental analysis, FT-IR, solid-state UV-Vis spectroscopy and single-crystal X-ray diffraction. The crystal structure determination shows that the complex is a stepped tetranuclear structure consisting of two dinuclear [Cu₂(L)₂] units {L is 3-[(4-methoxy-2-oxidobenzylidene)amino]propanolate}. The two terminal Cu^II atoms are four-coordinated in square-planar environments, while the two central Cu^II atoms are five-coordinated in square-pyramidal environments. The solid-state photoluminescence properties of both the complex and 3-[(2-hydroxy-4-methoxybenzylidene)amino]propanol (H₂L) have been investigated at room temperature in the visible region. When the complex and H₂L are excited under UV light at 349 nm, the complex displays a strong blue emission at 469 nm and H₂L displays a green emission at 515 nm.

Silver(I) complexes with chromone-derived hydrazones: investigation on the antimicrobial and cytotoxic effects

Complexes [Ag(HCrPh)₂]NO₃·2H₂O (1) and [Ag(HCrpClPh)₂]NO₃ (2) were obtained with 3-formyl-6-methylchromone-phenyl hydrazone (HCrPh, HL1) and 3-formyl-6-methylchromone-para-chloro-phenyl hydrazone (HCrpClPh, HL2). Although the hydrazones were inactive, upon coordination to silver(I) antifungal activity significantly improved against several Candida strains. Complexes (1-2) revealed to be more active than silver nitrate, silver sulfadiazine and the reference drug nystatin against Candida parapsilosis. The cytotoxic activities of the hydrazones and their silver(I) complexes were evaluated in comparison with cisplatin on B16F10 (metastatic melanoma) and Melan-a (non-tumorigenic melanocyte) cells. The hydrazones showed low cytotoxicity against B16F10 cells, reducing only about 20% of cell viability at the concentration of 10 μM. Upon coordination to silver(I) the cytotoxic effect did not appreciably change in complex (1) while complex (2) proved to be as cytotoxic as cisplatin and much more cytotoxic than both the free ligand and silver nitrate at 1 μM. Both complexes (1) and (2) were less active than cisplatin on non-malignant Melan-a cells, indicating that these compounds might promote less damage on normal cells.

Mixed-ligand copper(ii) Schiff base complexes: the vital role of co-ligands in DNA/protein interactions and cytotoxicity

Four new mixed-ligand copper(ii) complexes display an antibacterial mechanism of cell death via cell-wall rupture and cytotoxicity via apoptotic cell death.

Fluorescent zinc(ii) complexes for gene delivery and simultaneous monitoring of protein expression

Two new zinc(ii) complexes, [Zn(l-His)(NIP)]+(1) and [Zn(acac)2(NIP)](2) (where NIP is 2-(naphthalen-1-yl)-1H-imidazo[4,5-f][1,10]phenanthroline, acac = acetyl acetone), have been synthesized and characterized by elemental analysis, UV-vis, fluorescence, IR, 1H NMR and electron spray ionization mass spectroscopies. Gel retardation assay, atomic force microscopy and dynamic light scattering studies show that 1 and 2 can induce the condensation of circular plasmid pBR322 DNA into nanometer size particles under ambient conditions. Treatment of 2 with 5 mM EDTA restored 30% of the supercoiled form of DNA, revealing partial reversibility of DNA condensation. The in vitro transfection experiment demonstrates that the complexes can be used to deliver pCMV-tdTomato-N1 plasmid which expresses red fluorescent protein. The confocal studies show that the fluorescent nature of complexes is advantageous for visualizing the intracellular delivery of metal complexes as well as transfection efficiency using two distinct emission windows.

Synthesis of copper and zinc 2-(pyridin-2-yl)imidazo[1,2-a]pyridine complexes and their potential anticancer activity

A small library of novel copper and zinc imidazo[1,2-a]pyridine complexes have been synthesized. Their structures were confirmed by X-ray diffraction crystallography and a selection of these compounds was tested against five cancer cell lines originating from breast cancer (MCF-7 and MDA-MB-231), leukemia (K562 and HL-60) and colorectal cancer (HT-29). The imidazo[1,2-a]pyridines and their zinc complexes showed poor anticancer activity, while the copper complexes were active against the cancer cell lines with IC₅₀ values comparable to and lower than camptothecin. For example, copper 6-bromo-N-cyclohexyl-2-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amine acetate 21 had an IC₅₀ value lower than 1 μM against the HT-29 cells. Fluorescence microscopy with acridine orange, Hoechst 33342 and ethidium bromide, used in a preliminary investigation to evaluate morphological changes showed that copper 6-bromo-N-cyclohexyl-2-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amine acetate 21 caused both apoptosis, necrosis and paraptosis in the MCF-7 and HL-60 cells. A select group of copper N-cyclohexyl-2-(pyridin-2-yl)imidazo[1,2-a]pyridin-3-amines (26, 27, 29 and 31) induced apoptosis, paraptosis and deformed nuclei in MCF-7 cells.

Copper (II) complexes possessing alkyl-substituted polypyridyl ligands: Structural characterization and in vitro antitumor activity

In an effort to find alternatives to the antitumor drug cisplatin, a series of copper (II) complexes possessing alkyl-substituted polypyridyl ligands have been synthesized. Eight new complexes are reported herein: μ-dichloro-bis{2,9-di-sec-butyl-1,10-phenanthrolinechlorocopper(II)} {[(^di-sec-butylphen)ClCu(μ-Cl)₂CuCl(^di-sec-butylphen)]}(1), 2-sec-butyl-1,10-phenanthrolinedichlorocopper(II) {^{[mono-sec-butyl}phen) CuCl₂} (2), 2,9-di-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[^di-n-butylphen) CuCl₂}(3), 2-n-butyl-1,10-phenanthrolinedichlorocopper(II) {[^mono-n-butylphen) CuCl₂} (4), 2,9-di-methyl-1,10-phenanthrolineaquadichlorocopper(II) {[^di-methylphen) Cu(H₂O)Cl₂}(5), μ-dichloro-bis{6-sec-butyl-2,2'-bipyridinedichlorocopper(II)} {(^{mono-sec-butyl}bipy) ClCu(μ-Cl)₂CuCl(^{mono-sec-butyl}bipy)} (6), 6,6'-di-methyl-2,2'-bipyridinedichlorocopper(II) {^{6,6'-di-methyl}bipy) CuCl₂} (7), and 4,4'-dimethyl-2,2'-bipyridinedichlorocopper(II) {^{4,4'-di-methyl}bipy) CuCl₂} (8). These complexes have been characterized via elemental analysis, UV-vis spectroscopy, and mass spectrometry. Single crystal X-ray diffraction experiments revealed the complexes synthesized with the ^di-sec-butylphen ligand (1) and ^{mono-sec-butyl}bipy ligand (6) crystallized as dimers in which two copper(II) centers are bridged by two chloride ligands. Conversely, complexes 2, 7, and 8 were isolated as monomeric species possessing distorted tetrahedral geometries, and the [(^di-methylphen)Cu(H₂O)Cl₂] (5) complex was isolated as a distorted square pyramidal monomer possessing a coordinating aqua ligand. Compounds 1-8 were evaluated for their in vitro antitumor efficacy. Compounds 1, 5, and 7 in particular were found to exhibit remarkable activity against human derived lung cancer cells, yet this class of copper(II) compounds had minimal cytotoxic effect on non-cancerous cells. In vitro control experiments indicate the activity of the copper(II) complexes most likely does not arise from the formation of CuCl₂ and free polypyridyl ligand, and preliminary solution state studies suggest these compounds are generally stable in biological buffer. The results presented herein suggest further development of this class of copper-based drugs as potential anti-cancer therapies should be pursued.

Fighting Cancer with Corroles

Corroles are exceptionally promising platforms for the development of agents for simultaneous cancer-targeting imaging and therapy. Depending on the element chelated by the corrole, these theranostic agents may be tuned primarily for diagnostic or therapeutic function. Versatile synthetic methodologies allow for the preparation of amphipolar derivatives, which form stable noncovalent conjugates with targeting biomolecules. These conjugates can be engineered for imaging and targeting as well as therapeutic function within one theranostic assembly. In this review, we begin with a brief outline of corrole chemistry that has been uniquely useful in designing corrole-based anticancer agents. Then we turn attention to the early literature regarding corrole anticancer activity, which commenced one year after the first scalable synthesis was reported (1999-2000). In 2001, a major advance was made with the introduction of negatively charged corroles, as these molecules, being amphipolar, form stable conjugates with many proteins. More recently, both cellular uptake and intracellular trafficking of metallocorroles have been documented in experimental investigations employing advanced optical spectroscopic as well as magnetic resonance imaging techniques. Key results from work on both cellular and animal models are reviewed, with emphasis on those that have shed new light on the mechanisms associated with anticancer activity. In closing, we predict a very bright future for corrole anticancer research, as it is experiencing exponential growth, taking full advantage of recently developed imaging and therapeutic modalities.

Synthesis and structure of a new trinuclear nickel(II) complex bridged by N-[3-(Dimethylamino)propyl]-N'-(2-hydroxyphenyl)oxamido: in vitro anticancer activities, and reactivities toward DNA and protein

A new trinickel(II) complex bridged by N-[3-(dimethylamino)propyl]- N'-(2-hydroxylphenyl)oxamido (H₃ pdmapo), namely [Ni₃ (pdmapo)₂ (H₂ O)₂ ]⋅4CH₃ OH, was synthesized and characterized by X-ray single-crystal diffraction and other methods. In the molecule, two symmetric cis-pdmapo^3- mononickel(II) complexes as a "complex ligand" using the carbonyl oxygen atoms coordinate to the center nickel(II) ion situated on an inversion point. The Ni···Ni distance through the oxamido bridge is 5.2624(4) Å. The center nickel(II) ion and the lateral ones have octahedral and square-planar coordination geometries, respectively. In the crystal, a three-dimensional supramolecular network dominated by hydrogen bonds is observed. The reactivity toward DNA/protein bovine serum albumin (BSA) revealed that the complex could interact with herring sperm DNA (HS-DNA) through the intercalation mode and quench the intrinsic fluorescence of BSA via a static mechanism. The in vitro anticancer activities suggested that the complex is active against the selected tumor cell lines.

Fluorophore ATCUN complexes: combining agent and probe for oxidative DNA cleavage

DNA can be oxidatively cleaved by copper complexes of the ATCUN peptide (amino terminal Cu(II)- and Ni(II)-binding motif). In order to investigate the fate of the metal ion throughout this process, we have exploited quenching/dequenching effects of conjugated fluorophores.

Copper(ii) mixed-ligand polypyridyl complexes with doxycycline – structures and biological evaluation

Structures and biological evaluation of Cu(ii) mixed-ligand polypyridyl complexes with doxycycline of the type [Cu(doxycycline)(L)(H₂O)₂](NO₃)₂, L = 2,2′-bipyridine (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).

Synthesis of a novel trinuclear palladium complex: the influence of an oxime chelate ligand on biological evaluation towards double-strand DNA, BSA protein and molecular modeling studies

Synthesis of a novel cluster palladium complex containing an oxime ligand. Study of the ability of the complex to interact with DNA via groove mechanism. The molecular docking indicates high binding affinity between DNA and BSA with the Pd complex.

Development of trackable metal-based drugs: new generation of therapeutic agents

Today, it is not sufficient to conceive an efficient drug, its mechanism of action have to be understood. To tackle this issue, trackable therapeutic agents are an interesting solution.

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.

Synthesis and structure elucidation of new μ-oxamido-bridged dicopper(II) complex with in vitro anticancer activity: A combined study from experiment verification and docking calculation on DNA/protein-binding property

A new oxamido-bridged dicopper(II) complex with formula of [Cu2(deap)(pic)2], where H2deap and pic represent N,N'-bis[3-(diethylamino)propyl]oxamide and picrate, respectively, was synthesized and characterized by elemental analyses, molar conductance measurements, IR and electronic spectral study, and single-crystal X-ray diffraction. The crystal structure analyses revealed that the two copper(II) atoms in the dicopper(II) complex are bridged by the trans-deap(2-) ligand with the distances of 5.2116(17)Å, and the coordination environment around the copper(II) atoms can be described as a square-planar geometry. Hydrogen bonding and π-π stacking interactions link the dicopper(II) complex into a three-dimensional infinite network. The DNA/protein-binding properties of the complex are investigated by molecular docking and experimental assays. The results indicate that the dicopper(II) complex can interact with HS-DNA in the mode of intercalation and effectively quench the intrinsic fluorescence of protein BSA by 1:1 binding with the most possible binding site in the proximity of Trp134. The in vitro anticancer activities suggest that the complex is active against the selected tumor cell lines, and IC50 values for SMMC-7721 and HepG2 are lower than cisplatin. The effects of the electron density distribution of the terminal ligand and the chelate ring arrangement around copper(II) ions bridged by symmetric N,N'-bis(substituted)oxamides on DNA/BSA-binding ability and in vitro anticancer activity are preliminarily discussed.

Pyrazolone incorporating bipyridyl metallointercalators as effective DNA, protein and lung cancer targets: Synthesis, characterization and in vitro biocidal evaluation

Pyrazolone based metal complexes have strong bio-activity but the anti-cancer mechanism of these derivatives is not fully understood. In recent years, Cu(II) complexes have attracted the interest of researchers increasingly because of their high antitumor activities that are usually related to DNA binding. The reaction of three different derivatives (I) PPMP [3-methyl-1-phenyl-4-propionyl-1H-pyrazol-5(4H)-one], (II) TMCPMP [1-(3-chlorophenyl)-3-methyl-4-(4-methylbenzoyl)-1H-pyrazol-5(4H)-one] and (III) PPTPMP [3-methyl-4-propionyl-1-p-tolyl-1H-pyrazol-5(4H)-one] of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and 2.2' bipyridyl along with Cu(NO3)2·3H2O under methanolic condition allowed us to isolate and characterize a series of new mixed ligand complexes [Cu(TMCPMP) (Bipy)NCS] (1) [Cu(PPMP) (Bipy)NCS] (2) and [Cu(PPTPMP) (Bipy)NCS] (3). All complexes are well characterized by elemental analysis, metal estimation, molar conductivity, FT-IR and UV-Vis spectroscopy. The molecular geometry of these complexes has been determined by single crystal X-ray study. The single-crystal X-ray structures of complexes 1 and 2 exhibit square pyramidal geometry, while complex 3 revealed slightly distorted square-pyramidal geometry. The DNA binding of these compounds with Calf-Thymus DNA (CT-DNA) has been explored by emission titration methods, which revealed that 1-3 could interact with CT-DNA through intercalation mode. The complexes also exhibited a strong binding with Bovine Serum Albumin (BSA) over the ligands. Complexes were evaluated for their in vitro cytotoxic activities against lung cancer cell lines (A549) as well as noncancerous rat cardiomyocytes (H9C2) cell lines, which showed that all three complexes exhibited substantial cytotoxic activity with minimum effect on noncancerous cells. Complex 1 with more hydrophobic environment exhibited relatively high cytotoxic activity towards A549 cells. In summary, this new series of compounds belongs to a class of copper-pyrazolonate complexes that target many biochemical sites and with potential anti-cancer activity. All these results collectively suggested that complexes could serve as promising pharmacologically active substance against lung cancer.

Spectroscopic Study on the Interaction between Naphthalimide-Polyamine Conjugates and Bovine Serum Albumin (BSA)

The effect of a naphthalimide pharmacophore coupled with diverse substituents on the interaction between naphthalimide-polyamine conjugates 1–4 and bovine serum albumin (BSA) was studied by UV absorption, fluorescence and circular dichroism (CD) spectroscopy under physiological conditions (pH = 7.4). The observed spectral quenching of BSA by the compounds indicated that they could bind to BSA. Furthermore, caloric fluorescent tests revealed that the quenching mechanisms of compounds 1–3 were basically static type, but that of compound 4 was closer to a classical type. The K_sv values at room temperature for compound-BSA complexes-1-BSA, 2-BSA, 3-BSA and 4-BSA were 1.438 × 10⁴, 3.190 × 10⁴, 5.700 × 10⁴ and 4.745 × 10⁵, respectively, compared with the value of MINS, 2.863 × 10⁴ at Ex = 280 nm. The obtained quenching constant, binding constant and thermodynamic parameter suggested that the binding between compounds 1–4 with BSA protein, significantly affected by the substituted groups on the naphthalene backbone, was formed by hydrogen bonds, and other principle forces mainly consisting of charged and hydrophobic interactions. Based on results from the analysis of synchronous three-dimensional fluorescence and CD spectra, we can conclude that the interaction between compounds 1–4 and BSA protein has little impact on the BSA conformation. Calculated results obtained from in silico molecular simulation showed that compound 1 did not prefer either enzymatic drug sites I or II over the other. However, DSII in BSA was more beneficial than DSI for the binding between compounds 2–4 and BSA protein. The binding between compounds 1–3 and BSA was hydrophobic in nature, compared with the electrostatic interaction between compound 4 and BSA.

Synthesis and crystal structure of new dicopper(II) complexes having asymmetric N,N'-bis(substituted)oxamides with DNA/protein binding ability: In vitro anticancer activity and molecular docking studies

Two new dicopper(II) complexes bridged by asymmetric N,N'-bis(substituted)oxamide ligands: N-(5-chloro-2-hydroxyphenyl)-N'-[2-(dimethylamino)ethyl]oxamide (H3chdoxd) and N-hydroxypropyl-N'-(2-carboxylatophenyl)oxamide (H3oxbpa), and end-capped with 2,2'-bipyridine (bpy), namely [Cu2(ClO4)(chdoxd)(CH3OH)(bpy)]·H2O (1) and [Cu2(pic)(oxbpa)(CH3OH)(bpy)]·0.5CH3OH (2) (pic denotes picrate anion), have been synthesized and characterized by elemental analysis, molar conductivity measurement, IR and electronic spectral studies, and single-crystal X-ray diffraction. The X-ray diffraction analysis revealed that both the copper(II) ions bridged by the cis-oxamido ligands in dicopper(II) complexes 1 and 2 are all in square-pyramidal environments with the corresponding Cu⋯Cu separations of 5.194(3) and 5.1714(8)Å, respectively. In the crystals of the two complexes, there are abundant hydrogen bonds and π-π stacking interactions contributing to the supramolecular structure. The reactivities toward herring sperm DNA (HS-DNA) and bovine serum albumin (BSA) of the two complexes are studied both theoretically and experimentally, indicating that both the two complexes can interact with the DNA in the mode of intercalation, and effectively bind to BSA via the favored binding sites Trp134 for the complex 1 and Trp213 for the complex 2. Interestingly, the in vitro anticancer activities of the two complexes against the selected tumor cell lines are consistent with their DNA/BSA-binding affinities following the order of 1>2. The effects of coordinated counterions in the two complexes on DNA/BSA-binding ability and in vitro anticancer activity are preliminarily discussed.

Synthesis and Structure of a New Copper(II) Coordination Polymer Alternately Bridged by Oxamido and Carboxylate Groups: Evaluation of DNA/BSA Binding and Cytotoxic Activities

A new one-dimensional (1D) copper(II) coordination polymer {[Cu2 (dmaepox)(dabt)](NO3) · 0.5 H2 O}n , where H3 dmaepox and dabt denote N-benzoato-N'-(3-methylaminopropyl)oxamide and 2,2'-diamino-4,4'-bithiazole, respectively, was synthesized and characterized by single-crystal X-ray diffraction and other methods. The crystal structure analysis revealed that the two copper(II) ions are bridged alternately by cis-oxamido and carboxylato groups to form a 1-D coordination polymer with the corresponding Cu · · · Cu separations of 5.1946(19) and 5.038(2) Å. There is a three-dimensional supramolecular structure constructed by hydrogen bonding and π-π stacking interactions in the crystal. The reactivity towards herring sperm DNA (HS-DNA) and bovine serum albumin (BSA) indicated that the copper(II) polymer can interact with the DNA in the mode of intercalation, and bind to BSA responsible for quenching of tryptophan fluorescence by the static quenching mechanism. The in vitro cytotoxicity suggested that the copper(II) polymer exhibits cytotoxic effects against the selected tumor cell lines.

Synthesis, spectral characterization and DNA bindings of tridentate N2O donor Schiff base metal(II) complexes

To evaluate the biological preference of synthetic small drugs towards DNA target, new metal based chemotherapeutic agents of Cu(II), Co(II), Ni(II) and Zn(II), 2,4-diiodo-6-((pyridin-2-ylmethylimino)methyl)phenol (L) Schiff base complexes (1, 2, 3 &4) having N,N,O donor system respectively were synthesized and thoroughly characterized. The IR results confirmed the tridentate binding of the ligand with metal centre during complexation and reflects the proposed structure. The density function theory calculations were also used to further investigate the electronic structure and properties of ligand and complexes. The preliminary investigation of herring Sperm (HS-DNA) interaction propensity of complexes 1-4 were carried out in Tris-HCl buffer at pH 7.1 to demonstrate their mode of interactions. The obtained results reveal that these complexes significantly interact with DNA on the grooves, further, this observed mode of interactions was also confirmed by molecular docking evaluations. The complexes 1-4 were also screened for antimicrobial evaluations which demonstrated that their significant activity against various human pathogens. The cleavage studies with pBR322 plasmid DNA revealed higher nuclease activity of 1 as compared to other complexes.

Synthesis and structure of dicopper(II) complexes bridged by N-(5-chloro-2-hydroxyphenyl)-N'-[3-(methy lamino)propyl]oxamide: evaluation of DNA/protein binding, DNA cleavage, and in vitro anticancer activity

Three new dicopper(II) complexes bridged by N-(5-chloro-2-hydroxyphenyl)-N'-[3-(methylamino)-propyl]oxamide (H3chmpoxd) and end-capped with 1,10-phenanthroline (phen); 2,2'-diamino-4,4'-bithiazole (dabt); and 2,2'-bipyridine (bpy), namely [Cu2(chmpoxd)(H2O)(phen)](ClO4)⋅CH3CN (1), [Cu2(chmpoxd)(dabt)(C2H5OH)](NO3) (2) and [Cu2(chmpoxd)(H2O)(bpy)](NO3)⋅CH3CN (3), were synthesized and structurally characterized. The single-crystal X-ray diffraction analysis revealed that both the copper(II) ions bridged by the cis-chmpoxd(3-) ligands in the three complexes are in square-planar and square-pyramidal environments, respectively. The reactivity towards herring sperm DNA (HS-DNA) and protein bovine serum albumin (BSA) indicated that these copper(II) complexes can interact with the DNA in the mode of intercalation, and bind to BSA responsible for quenching of tryptophan fluorescence by the static quenching mechanism. The cytotoxicity and DNA cleavage suggested that all the dicopper(II) complexes are active against the selected tumor cell lines, and the complex 1 exhibits the cleavage capacity for plasmid DNA.