Intercalative Binding Mode Research Articles

Heteroleptic silver(I) complexes with 2,2′:6′,2″-terpyridines and naproxen: DNA interaction, EGFR/VEGFR2 kinase, growth inhibition and cell cycle arrest studies

A series of heteroleptic silver(I) complexes of the type [Ag(L1−3)(nap)] (1–3), where L1–3=4′-(4-substituted)-2,2′:6′,2″-terpyridines and nap=naproxen have been synthesized and characterized by elemental analysis and spectroscopic methods. The geometric parameters of the complexes were determined using UV–Vis and DFT calculations together with the IR spectral data. All the complexes adopted distorted tetrahedral geometry around silver(I) ion. The small HOMO-LUMO energy gap supports the bioefficacy of the complexes. DNA binding and melting experiments suggest the intercalative binding mode of the complexes to CT–DNA, which was further supported by molecular docking studies. The molecular docking studies of the heteroleptic silver(I) complexes with EGFR/VEGFR2 kinase receptors show hydrophobic, π-π, σ-π and hydrogen bonding interactions. All the complexes have been found to promote DNA cleavage through hydrolytic pathway. In vitro cytotoxicity activity of the complexes was tested against four human breast adenocarcinoma (MCF-7), cervical (HeLa), epithelioma (Hep-2) and hepatoma (HepG2) cancerous, and one normal human dermal fibroblasts (NHDF) cell lines by MTT reduction assay. The morphological study by Hoechst 33258 staining revealed that the complex 3 induces apoptosis much more effectively than the other complexes. Further, all the complexes increases the DNA synthesis in S phase with the corresponding reduction in G0–G1 and G2/M phase, which suggest the growth inhibition mechanism on HepG2 cells was DNA damage mediated S phase arrest.

Synthesis, spectroscopic, theoretical study, and biological activities of vanadium(IV) and vanadium(V) complexes with isonipecotic acid

Vanadium(IV) and vanadium(V) complexes 1–7 have been synthesized by the reaction of isonipecotic acid with VOSO4 · 3 H2O, VCl3(THF)3, and NH4VO3 at different metal/ligand ratios under stirring/ reflux conditions. The synthesized complexes have been characterized by elemental analyses and UV/Vis and FT-IR spectra. The FT-IR spectroscopic data suggest bidentate nature of the ligand, which is also confirmed by semiempirical study. Electrostatic surface potential (ESP) map shows that the coordinating oxygen atoms in complex 1 have more negative charges than the V=O oxygen atom. The dipole moment vectors of the optimized structures of complexes 1 and 5 are not aligned along the V=O bond due to the lack of symmetry. DNA binding study of complexes 1–7 showed that increase of the DNA concentration is accompanied by considerable decrease of the absorbance and by a 1–4-nm blue shift of the absorption maximum, indicating intercalative binding mode of the complexes to the DNA base pairs. In vitro DNA damage protection assay showed that complexes 1 and 3 exhibited plasmid DNA protection by scavenging oxidation products.

Synthesis, Characterization and DNA-Binding Studies of Hydroxyl Functionalized Platinum(II) Salphen Complexes.

The platinum(II) salphen complex N,N'-Bis-4-(hydroxysalicylidene)-phenylenediamine-platinum(II); (1) and its two derivatives containing hydroxyl functionalized side chains N,N'-bis-[4-[[1-(2-hydroxyethoxy)] salicylidene] phenylenediamine-platinum(II); (2) and N,N'-bis-[4-[[1-(3-hydroxypropoxy)] salicylidene] phenylenediamine-platinum(II); (3) were synthesized and characterized. The structures of the complexes were confirmed by 1H and 13C NMR spectroscopy, FTIR, ESI-MS and CHN elemental analyses. The effects of the hydroxyl substituent on the spectral properties and the DNA binding behaviors of the Pt(II) complexes were explored. The binding mode and interactions of these complexes with duplex DNA (calf thymus DNA and porcine DNA) and also single-stranded DNA were studied by UV-Vis and emission DNA titration. The complexes interact with DNA by intercalation binding mode with the binding constants in the order of magnitude (Kb=104M-1, CT-DNA) and (Kb=105M-1, porcine DNA). The intercalation of the complex in the DNA structure was proposed to happen by π-π stacking due to its square-planar geometry and aromatic rings structure. The phosphorescence emission spectral characteristics of Pt(II) complexes when interacted with DNA have been studied. Also, the application of the chosen hydroxypropoxy side chains complex (3) as an optical DNA biosensor, specifically for porcine DNA was investigated. These findings will be valuable for the potential use of the platinum(II) salphen complex as an optical DNA biosensor for the detection of porcine DNA in food products.

Synthesis, structural characterization and DNA-binding studies of a new cobalt (II) complex: (HAcr)4[Co(Sal)3

A new cobalt (II) coordination compound was synthesized using proton transfer mechanism. The reaction between CoCl2·2H2O, Salicylic acid (H2Sal) and acridine (Acr) gave a new coordination compound formulated as (HAcr)4[Co(Sal)3], which was characterized by elemental analysis, NMR, IR and UV/Vis spectroscopies. The interaction of this complex with DNA has been investigated in vitro using UV absorption, fluorescence spectroscopy, viscosity measurements and gel electrophoresis methods. The intrinsic binding constant has been estimated to be 5.8 × 105 M−1 using UV absorption. The interaction of DNA–Co (II) complex caused quenching in fluorescence. The binding constant, the number of binding site and Stern–Volmer quenching constant have been calculated to be 7.7 × 104 M−1, 1.143 and 1.5 × 104 Lmol−1, respectively. The increase in the viscosity of DNA with increasing the concentration of the Co (II) complex and the observations of other experiments suggest that the cobalt (II) complex binds to DNA by partial intercalation binding mode. Furthermore, the interaction of DNA–Co (II) complex was confirmed using gel electrophoresis studies. Moreover, molecular docking technique predicted partial intercalation binding mode for the complex.

Deciphering the intercalative binding modes of benzoyl peroxide with calf thymus DNA.

The binding of benzoyl peroxide (BPO), a flour brightener, with calf thymus DNA (ctDNA) was predicted by molecular simulation, and this were confirmed using multi-spectroscopic techniques and a chemometrics algorithm. The molecular docking result showed that BPO could insert into the base pairs of ctDNA, and the adenine bases were the preferential binding sites which were validated by the analysis of Fourier transform infrared spectra. The mode of binding of BPO with ctDNA was an intercalation as supported by the results from ctDNA melting and viscosity measurements, iodide quenching effects and competitive binding investigations. The circular dichroism and DNA cleavage assays indicated that BPO induced a conformational change from B-like DNA structure towards to A-like form, but did not lead to significant damage in the DNA. The complexation was driven mainly by hydrogen bonds and hydrophobic interactions. Moreover, the ultraviolet-visible (UV-vis) spectroscopic data matrix was resolved by a multivariate curve resolution-alternating least-squares algorithm. The equilibrium concentration profiles for the components (BPO, ctDNA and BPO-ctDNA complex) were extracted from the highly overlapping composite response to quantitatively monitor the BPO-ctDNA interaction. This study has provided insights into the mechanism of the interaction of BPO with ctDNA and potential hazards of the food additive.

In Vitro DNA-Binding, Anti-Oxidant and Anticancer Activity of Indole-2-Carboxylic Acid Dinuclear Copper(II) Complexes.

Indole-2-carboxylic acid copper complex (ICA-Cu) was successfully prepared and characterized through elemental analysis, IR, UV-Vis, 1H-NMR, TG analysis, and molar conductance, and its molecular formula was [Cu2(C9H6O2N)4(H2O)2]·2H2O. The binding ability of ICA-Cu to calf thymus DNA (CT-DNA) was examined by fluorescence spectrometry and the viscosity method. The results indicated that, upon the addition of increasing amounts of CT-DNA, the excitation and emission intensity of ICA-Cu decreased obviously and the excitation spectra shifted towards a long wavelength. ICA-Cu could displace ethidium bromide (EB) from the EB-DNA system, making the fluorescence intensity of the EB-DNA system decrease sharply; the quenching constant KSV value was 3.99 × 104 M−1. The emission intensity of the ICA-Cu-DNA system was nearly constant, along with the addition of Na+ in a series of concentrations. The fluorescence of the complex could be protected after the complex interacted with DNA. A viscosity measurement further supported the result that the ICA-Cu complex may interact with DNA in an intercalative binding mode. The antioxidant activities of ICA-Cu were evaluated by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, a hydroxyl radical (OH) scavenging assay, and a 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay. The ICA-Cu exhibited the highest inhibitory effects on the ABTS radical (94% inhibition at 60 µM), followed by OH and DPPH radicals (the degrees of inhibition being 71% and 56%, respectively). The in vitro cytotoxicity activity of ICA-Cu against two human breast cancer cell lines, MDA-MB-231 and MCF-7, was investigated by 3-[4,5-dimethyltiazol2-yl]-2.5-diphenyl-tetrazolium bromide (MTT) assay and cellular morphological analysis. The results showed that, upon increasing the concentration of ICA-Cu, an increase was observed in growth-inhibitory activity and the inhibition percentage were greater than 90% at 20 µM in both cell lines. Also, cellular morphological changes in the two cell lines agreed with the cytotoxicity results.

Synthesis and structural characterization of a vanadium(V)-pyridylbenzimidazole complex: DNA binding and anticancer activity

Synthesis and structural characterization of a new pyridylimidazole based vanadyl compound [VO2(L)(L−)] (1) [L=2-(2-pyridyl)benzimidazole] (1) are reported. It crystallizes in P1¯ space group. The molecular geometry of 1 around vanadium(V) is found to be distorted octahedron. 1 interacts with DNA in a intercalative fashion. Hypochromism of the absorption band of the complex with increasing concentration of DNA and the steady increase in DNA viscosity with increasing concentration of 1 indicates intercalative mode of binding. The binding constant is calculated as 2.76×105M−1. 1 also shows cytotoxicity against human breast cancer, human lung cancer and human keratinocyte cancer cell lines.

Design, synthesis, MTT assay, DNA interaction studies of platinum(II) complexes

The square planar Pt(II) complexes of the type [Pt(Ln)(Cl2)] (where Ln = L1−3 = thiophene-2-carboxamide derivatives and L4−6 = thiophene-2-carbothioamide derivatives) have been synthesized and characterized by physicochemical and various spectroscopic studies. MIC method was employed to inference the antibacterial potency of complexes in reference to free ligands and metal salt. Characteristic binding constant (Kb) and binding mode of complexes with calf thymus DNA (CT-DNA) were determined using absorption titration (0.76–1.61 × 105 M−1), hydrodynamic chain length assay and fluorescence quenching analysis, deducing the partial intercalative mode of binding. Molecular docking calculation displayed free energy of binding in the range of –260.06 to –219.63 kJmol−1. The nuclease profile of complexes towards pUC19 DNA shows that the complexes cleave DNA more efficiently compared to their respective metal salt. Cytotoxicity profile of the complexes on the brine shrimp shows that all the complex exhibit noteworthy cytotoxic activity with LC50 values ranging from 7.87 to 15.94 μg/mL. The complexes have been evaluated for cell proliferation potential in human colon carcinoma cells (HCT 116) and IC50 value of complexes by MTT assay (IC50 = 125–1000 μg/mL).

Synthesis, characterization, crystal structure and DNA-binding study of four cadmium(II) pyridine-carboxamide complexes

Treatment of perchlorate or nitrate salt of cadmium(II) with carboxamide derivatives (L) generated four novel mononuclear metal complexes, represented as [Cd(L )4](ClO4)2 (1a and 1b) and [Cd(L)2(ONO2)2] (2a and 2b) in appreciable yields (L = L 1 = N-(furan-2-ylmethyl)-2-pyridine carboxamide and L = L 2 = N-(thiophen-2-ylmethyl)-2-pyridine carboxamide). The complexes have been characterized by FT-IR, UV-Visible, elemental analysis and single crystal X-ray crystallographic analysis which revealed eight coordinated cadmium ions, but in different coordination environments, depending on the counter anion used. In addition, electronic absorption, fluorescence spectroscopy and viscosity measurements revealed a significant interaction of the four complexes with CT-DNA via intercalative/groove binding mode. The intrinsic binding constant K b obtained varies from 0.4 × 10 4 to 1.11 × 10 5 M−1. The results suggest that neutral complexes 2a and 2b bind to DNA in an intercalative mode. On the other hand, cationic complexes 1a and 1b bind with DNA via weak electrostatic/covalent interaction. Synthesis and characterization of four mononuclear eight coordinated cadmium(II) complexes with newly explored carboxamide derivatives and study of interaction with calf-thymus DNA are reported. The results suggest that neutral complexes 2a and 2b bind to DNA in an intercalative mode. On the other hand, cationic complexes 1a and 1b interact with DNA via weak intercalative or groove binding mode.

Synthesis, characterization and biological applications of new copper(II) complexes of aryl hydrazones

On treatment of copper(II) acetate with aryl hydrazone ligands, four new solid derivatives of copper(II) were produced in appreciable yields. Various characterization techniques including infrared, UV–visible, NMR, electron paramagnetic resonance and mass spectroscopies, elemental analysis, scanning electron microscopy, powder X‐ray diffraction and thermogravimetric analysis revealed a tetra‐coordination in all the mononuclear crystalline complexes with high thermal stability. Further, significant interaction of these novel complexes with calf thymus DNA via intercalative mode of binding was revealed by electronic absorption spectroscopy. The chemical nuclease activity of the complexes on pBR322 DNA was investigated in the presence and absence of oxidizing agent (H2O2). A potent nuclease activity was observed only in the presence of H2O2. Further, antibacterial and antifungal studies of the new ligands and complexes revealed that the latter possessed comparatively better activity.

DNA as a Target for Anticancer Phen-Imidazole Pd(II) Complexes.

Imidazole ring is a known structure in many natural or synthetic drug molecules and its metal complexes can interact with DNA and do the cleavage. Hence, to study the influence of the structure and size of the ligand on biological behavior of metal complexes, two water-soluble Pd(II) complexes of phen and FIP ligands (where phen is 1,10-phenanthroline and FIP is 2-(Furan-2-yl)-1H-Imidazo[4,5-f][1, 10]phenanthroline) with the formula of [Pd(phen)(FIP)](NO3)2 and [Pd(FIP)2]Cl2, that were activated against chronic myelogenous leukemia cell line, K562, were selected. Also, the interaction of these anticancer Pd(II) complexes with highly polymerized calf thymus DNA was extensively studied by means of electronic absorption, fluorescence, and circular dichroism in Tris-buffer. The results showed that the binding was positive cooperation and [Pd(phen)(FIP)](NO3)2 (K f=127 M-1 G=1.2) exhibited higher binding constant and number of binding sites than [Pd(FIP)2]Cl2 (K f=13 M-1 G=1.03) upon binding to DNA. The fluorescence data indicates that quenching effect for [Pd(phen)(FIP)](NO3)2 (K SV=58mM-1) was higher than [Pd(FIP)2]Cl2 (K SV=12mM-1). Also, [Pd(FIP)2]Cl2 interacts with ethidium bromide-DNA, as non-competitive inhibition, and can bind to DNA via groove binding and [Pd(phen)(FIP)](NO3)2 can intercalate in DNA. These results were confirmed by circular dichroism spectra. Docking data revealed that longer complexes have higher interaction energy and bind to DNA via groove binding. Graphical Abstract Two anticancer Pd(II) complexes of imidazole derivative have been synthesized and interacted with calf thymus DNA. Modes of binding have been studied by electronic absorption, fluorescence, and CD measurements. [Pd(FIP)2]Cl2 can bind to DNA via groove binding while intercalation mode of binding is observed for [Pd(phen)(FIP)](NO3)2.

Evaluation of DNA/Protein interactions and cytotoxic studies of copper(II) complexes incorporated with N, N donor ligands and terpyridine ligand

A series of four new copper(II) heteroleptic complexes, [Cu(2‴-pytpy) (L)] (NO3)2·2H2O (1–4), where 2‴-pytpy=4′-(2′′′-Pyridyl)-2, 2′:6′, 2′′-terpyridine, L=bipyridyl (bpy), 1, 10 phenanthroline(phen), dipyridoquinoxaline(dpq) and dipyridophenazine (dppz) were synthesized and characterized by spectroscopic techniques. Further, the molecular structure of the complex (2) was confirmed by single crystal X-ray diffraction technique and the data revealed a penta coordinated, distorted square-pyramidal geometry with triclinic system. The interactions of four complexes with calf thymus DNA and bovine serum albumin (BSA) were investigated by electronic absorption, fluorescence and circular dichroism spectroscopy techniques. Spectral studies substantiated an intercalative binding mode of metal complexes with ct-DNA. Significant binding interactions of the complexes with protein have been further revealed from fluorescence studies. Furthermore, all the four complexes show potential cytotoxicity towards the human liver carcinoma cell line (HepG-2).

Some new nano-sized Fe(II), Cd(II) and Zn(II) Schiff base complexes as precursor for metal oxides: Sonochemical synthesis, characterization, DNA interaction, in vitro antimicrobial and anticancer activities

The complexes of Fe(II), Cd(II) and Zn(II) with Schiff base derived from 2-amino-3-hydroxypyridine and 3-methoxysalicylaldehyde have been prepared. Melting points, decomposition temperatures, Elemental analyses, TGA, conductance measurements, infrared (IR) and UV–Visible spectrophotometric studies were utilized in characterizing the compounds. The UV–Visible spectrophotometric analysis revealed 1:1 (metal-ligand) stoichiometry for the three complexes. In addition to, the prepared complexes have been used as precursors for preparing their corresponding metal oxides nanoparticles via thermal decomposition. The structures of the nano-sized complexes and their metal oxides were characterized by X-ray powder diffraction and transmittance electron microscopy. Moreover, the prepared Schiff base ligand, its complexes and their corresponding nano-sized metal oxides have been screened in vitro for their antibacterial activity against three bacteria, gram-positive (Microccus luteus) and gram-negative (Escherichia coli, Serratia marcescence) and three strains of fungus. The metal chelates were shown to possess more antimicrobial activity than the free Schiff-base chelate and their nano-sized metal oxides have the highest activity. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity mensuration and gel electrophoresis. The DNA binding constants reveal that all these complexes interact with DNA through intercalative binding mode. Furthermore, the cytotoxic activity of the prepared Schiff base complexes on human colon carcinoma cells, (HCT-116 cell line) and hepatic cellular carcinoma cells, (HepG-2) showed potent cytotoxicity effect against growth of carcinoma cells compared to the clinically used Vinblastine standard.

Synthesis, X-ray crystal structure, DNA/protein binding and cytotoxicity studies of five α-aminophosphonate N-derivatives

Five new α-aminophosphonates are synthesized and characterized by EA, FT-IR, 1H NMR, 13C NMR, 31P NMR, ESI-MS and X-ray crystallography. The X-ray analyses reveal that the crystal structures of 1–5 are monoclinic or triclinic system with the space group P 21/c, P−1, P−1, P2(1)/c and P−1, respectively. All P atoms of 1–5 have tetrahedral geometries involving two O-ethyl groups, one Cα atom, and a double bond O atom. The binding interaction of five new α-aminophosphonate N-derivatives (1–5) with calf thymus(CT)-DNA have been investigated by UV–visible and fluorescence emission spectrometry. The apparent binding constant (Kapp) values follows the order: 1 (3.38×105M−1)>2 (3.04×105M−1)>4 (2.52×105M−1)>5 (2.32×105M−1)>3 (2.10×105M−1), suggesting moderate intercalative binding mode between the compounds and DNA. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the compounds 1–5 showed that the quenching mechanism might be a static quenching procedure. For the compounds 1–5, the number of binding sites were about one for BSA and the binding constants follow the order: 1 (2.72×104M−1)>2 (2.27×104M−1)>4 (2.08×104M−1)>5 (1.79×104M−1)>3 (1.17×104M−1). Moreover, the DNA cleavage abilities of 1 exhibit remarkable changes and the in vitro cytotoxicity of 1 on tumor cells lines (MCF-7, HepG2 and HT29) have been examined by MTT and shown antitumor effect on the tested cells.

A triphenylamine derivative as a naked-eye and light-up fluorescent probe for G-quadruplex DNA

G-quadruplex (G4) DNAs have attracted considerable interest because of their important biological functions and medical applications. Searching for highly specific binding molecules is important for the basic research of G4 DNA, as well as the design of novel anticancer drugs. Previous, we have developed a quinolone-substituted triphenylamine probe (TPA-2b) with selectivity to G4 DNAs. Herein, we further designed and synthesized a hydroxyethyl functionalized derivative (TPA-3) and investigated the interactions with G4 DNAs and living cells. TPA-3 was found to express significant fluorescence enhancement upon its interaction with G4 DNAs while shows almost no response to non-quadruplex DNAs. The distinction can even be easily distinguished by the naked eye under UV light. The spectral analysis showed TPA-3 bound to G4 DNAs mainly through intercalative binding mode. CD study results indicated TPA-3 did not disturb the conformation of G4 structure. Cellular uptake assay suggested that TPA-3 could pass through membrane and enter living cells. Our results suggested the side chain of core structure could change the binding affinity to G4 DNAs, as well as the interaction with living cells. Thus, this study gives some clues to design new G4 DNA probes with high selectivity, sensitivity, and biological imaging applications.

Acetyl pyridine-based palladium(II) compounds as an artificial metallonucleases

Palladium(II) complexes of type [Pd(Ln)Cl2] and [Pd(bdt)(Ln)] have been synthesized using 2-acetyl pyridine derivatives(Ln) and benzene-12-dithiol(bdt). The synthesized complexes have been characterized by various analytical techniques like thermo gravimetric analysis, elemental analysis, conductance measurement, and spectroscopic techniques like elemental analysis, mass spectra, absorption spectra, IR, 1H NMR, energy-dispersive X-ray spectroscopy. The interaction of the complexes with calf-thymus DNA (CT-DNA) has been explored by absorption titration, viscosity measurement methods. Based on the observations, an intercalative binding mode of DNA has been proposed. In order to provide additional evidence for the intercalation mode of binding between the complex and CT-DNA, fluorescence titration experiment was performed. In addition, molecular modeling study has been carried out with the aim of establishing the complex’s binding mode. Antibacterial activity study of the complexes have been screened against pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Serratia marcescens, and Pseudomonas aeruginosa. Gel electrophoresis assay demonstrates that all the complexes can cleave the pUC19 plasmid DNA.

DNA Interaction Studies of Selected Polyamine Conjugates.

The interaction of polyamine conjugates with DNA double helix has been studied. Binding properties were examined by ethidium bromide (EtBr) displacement and DNA unwinding/topoisomerase I/II (Topo I/II) activity assays, as well as dsDNA thermal stability studies and circular dichroism spectroscopy. Genotoxicity of the compounds was estimated by a comet assay. It has been shown that only compound 2a can interact with dsDNA via an intercalative binding mode as it displaced EtBr from the dsDNA-dye complex, with Kapp = 4.26 × 106 M−1; caused an increase in melting temperature; changed the circular dichroism spectrum of dsDNA; converted relaxed plasmid DNA into a supercoiled molecule in the presence of Topo I and reduced the amount of short oligonucleotide fragments in the comet tail. Furthermore, preliminary theoretical study has shown that interaction of the discussed compounds with dsDNA depends on molecule linker length and charge distribution over terminal aromatic chromophores.

2,2′- bipyridine coplanar with coordination square of Pd(II) nonyldithiocarbamato antitumor complex interacting with DNA in two distinct steps

Cisplatin is one of the most effective chemotherapy drugs, and has been widely employed for more than four decades in the treatment of different forms of human tumors. In recent years, various examples of metal complex-based compounds have been used for medicinal purposes. In this context, the novel palladium(II) complex, [Pd(non-dtc)(bpy)]NO3, (non-dtc = nonyldithiocarbamate and bpy = 2,2′- bipyridine) has been synthesized and characterized by means of elemental analysis, conductivity measurements, FT-IR, 1H NMR, 13C NMR, and electronic spectroscopy studies. The 50% cytotoxic concentrations (Ic50) of this Pd(II) complex (0.53 mM) and cisplatin (154 mM) against human cell tumor line (K562) indicates its interaction with DNA of cancer cell at quite low concentration. Thus, binding characteristics of this compound to calf thymus DNA (CT-DNA) has been investigated by UV–vis absorption spectroscopy and fluorescence spectra. The exciting observation of this work in the UV–visible studies was that the Pd(II) complex exhibit two or more types of interaction with CT-DNA. Such properties have rarely been observed in the literature. This complex cooperatively binds with DNA and denatures it too. Fluorescence studies proved the intercalation mode of binding and the other modes seems to be hydrophobic and electrostatic interactions. Binding parameters and thermodynamics of the interaction with CT-DNA are also described. Finally, multifunctional interactions of [Pd(non-dtc)(bpy)]NO3 make it suitable to interact with DNA of cancer cell at quite low concentration and if it is used as anticancer agent, very low doses will be needed which may have fewer side effects.

DNA(CT), protein(BSA) binding studies, anti-oxidant and cytotoxicity studies of new binuclear Ni(II) complexes containing 4(N)-substituted thiosemicarbazones

Four new Ni(II) complexes [Ni2(Msal-tsc)2(μ-dppm)] (1), [Ni2(Msal-mtsc)2(μ-dppm)] (2), [Ni2(Msal-etsc)2(μ-dppm)] (3) and [Ni2(Msal-ptsc)2(μ-dppm)] (4) containing 3-methoxy-salicylaldehyde-4(N)-substituted thiosemicarbazones having the general formula [H2-MSal-tsc-R],(where R=H, Me, Et or Ph) and 1,1′-bis(diphenylphosphino)methane (dppm) were synthesized and characterized by various spectral, analytical techniques and X-ray crystallography. Crystallographic studies of the complexes 1 and 3 revealed the square planar geometry around the nickel ion. The binding ability of the complexes with CT-DNA was carried out by absorption/emission titration and which an intercalative mode of binding was observed. Further, their ability to interact with BSA protein has been explored. Investigations of antioxidation properties showed that all the compounds have strong radical scavenging properties. Further, anticancer activity of the compounds on the lung cancer cell line A549 has also been investigated. From the results it is observed that the complexes (2 (IC50=23μM), 3 (IC50=12μM) &4 (IC50=20μM)) exhibited a significant anticancer activity over complex 1 (IC50=26μM), ligands, NiCl2·6H2O and the standard drug, Cisplatin (IC50=25μM).

DNA interaction, antimicrobial and molecular docking studies of biologically interesting Schiff base complexes incorporating 4‐formyl‐N,N‐dimethylaniline and propylenediamine

Four new transition metal complexes incorporating a Schiff base ligand derived from propylenediamine and 4‐formyl‐N,N‐dimethylaniline have been synthesized using transition metal salts. The characterization of the newly formed complexes was done from physicochemical parameters and using various techniques like 1H NMR, 13C NMR, IR, UV, electron paramagnetic resonance and mass spectroscopies, powder X‐ray diffraction and magnetic susceptibility. All the complexes were found to be monomeric in nature with square planar geometry. X‐ray powder diffraction illustrates that the complexes have a crystalline nature. The interaction of metal complexes with calf thymus DNA was investigated using UV–visible absorption, viscosity measurements, cyclic voltammetry, emission spectroscopy and docking analysis. The results indicate that the Cu(II), Co(II), Ni(II) and Zn(II) complexes interact with DNA by intercalative binding mode with optimum intrinsic binding constants of 4.3 × 104, 3.9 × 104, 4.7 × 104 and 3.7 × 104 M−1, respectively. These DNA binding results were rationalized using molecular docking in which the docked structures indicate that the metal complexes fit well into the A‐T rich region of target DNA through intercalation. The metal complexes exhibit an effective cleavage with pUC19 DNA by an oxidative cleavage mechanism. The synthesized ligand and the complexes were tested for their in vitro antimicrobial activity. The complexes show enhanced antifungal and antibacterial activities compared to the free ligand.