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  1. Chikira M, Ng CH, Palaniandavar M
    Int J Mol Sci, 2015;16(9):22754-80.
    PMID: 26402668 DOI: 10.3390/ijms160922754
    The interaction of simple and ternary Cu(II) complexes of 1,10-phenanthrolines with DNA has been studied extensively because of their various interesting and important functions such as DNA cleavage activity, cytotoxicity towards cancer cells, and DNA based asymmetric catalysis. Such functions are closely related to the DNA binding modes of the complexes such as intercalation, groove binding, and electrostatic surface binding. A variety of spectroscopic methods have been used to study the DNA binding mode of the Cu(II) complexes. Of all these methods, DNA-fiber electron paramagnetic resonance (EPR) spectroscopy affords unique information on the DNA binding structures of the complexes. In this review we summarize the results of our DNA-fiber EPR studies on the DNA binding structure of the complexes and discuss them together with the data accumulated by using other measurements.
    Matched MeSH terms: DNA Cleavage
  2. Hussein MA, Guan TS, Haque RA, Khadeer Ahamed MB, Abdul Majid AM
    Spectrochim Acta A Mol Biomol Spectrosc, 2015 Feb 05;136 Pt C:1335-48.
    PMID: 25456676 DOI: 10.1016/j.saa.2014.10.021
    Four dioxomolybdenum(VI) complexes were synthesized by reacting [MoO2(acac)2] with N-ethyl-2-(5-bromo-2-hydroxybenzylidene) hydrazinecarbothioamide (1), N-ethyl-2-(5-allyl-3-methoxy-2-hydroxybenzylidene) hydrazinecarbothioamide (2), N-methyl-2-(3-tert-butyl-2-hydroxybenzylidene) hydrazinecarbothioamide (3), and N-ethyl-2-(3-methyl-2-hydroxybenzylidene) hydrazinecarbothioamide (4). The molecular structures of 1, 2, and all the synthesized complexes were determined using single crystal X-ray crystallography. The binding properties of the ligand and complexes with calf thymus DNA (CT-DNA) were investigated via UV, fluorescence titrations, and viscosity measurement. Gel electrophoresis revealed that all the complexes cleave pBR 322 plasmid DNA. The cytotoxicity of the complexes were studied against the HCT 116 human colorectal cell line. All the complexes exhibited more pronounced activity than the standard reference drug 5-fluorouracil (IC50 7.3μM). These studies show that dioxomolybdenum(VI) complexes could be potentially useful in chemotherapy.
    Matched MeSH terms: DNA Cleavage/drug effects*
  3. Nanjundan N, Selvakumar P, Narayanasamy R, Haque RA, Velmurugan K, Nandhakumar R, et al.
    J. Photochem. Photobiol. B, Biol., 2014 Dec;141:176-85.
    PMID: 25463665 DOI: 10.1016/j.jphotobiol.2014.10.009
    Two nickel(II) complexes with formula NiL1 and NiL2 (HL1 = S-allyl-4-methoxybenzylidene hydrazinecarbodithioate, HL2 = S-allyl-1-napthylidenehydrazinecarbodithioate) have been synthesized and characterized by elemental analysis, FT-IR, NMR, UV-vis spectroscopy and ESI mass spectrometry. The crystal structure of complex 1 has been determined by single crystal X-ray diffractometry. Both HL1 and HL2 ligands are coordinated to the metal in thiolate form. In complexes, squareplanar geometry of the nickel is coordinated with two bidentate ligand units acting through azomethine nitrogen and thiolato sulfur atoms. To explore the potential medicinal value of the complexes with calf thymus DNA and bovine serum albumin (BSA) were studied at normal physiological conditions using fluorescence spectral techniques. The DNA binding constant values of the complexes were found in the range from 5.02 × 10(4), 3.54 × 10(4), and the binding affinities are in the following order 1 > 2. In addition, nickel complexes 1 and 2 shows better binding propensity to the bovine serum albumin (BSA) protein, giving a Ksv value 5.8 × 10(4), 4.47 × 10(4) respectively. From the oxidative cleavage of the complexes with pBR322 DNA, it is inferred that the effects of cleavage are dose-dependent. In addition, in vitro cytotoxicity of the complexes assayed against Vero and HeLa cell lines have shown higher cytotoxic activity with the lower IC50 values indicating their efficiency in killing cancer cells even at various concentrations.
    Matched MeSH terms: DNA Cleavage/drug effects
  4. Ali AQ, Teoh SG, Salhin A, Eltayeb NE, Khadeer Ahamed MB, Abdul Majid AM
    PMID: 24607427 DOI: 10.1016/j.saa.2014.01.086
    New derivatives of thiosemicarbazone Schiff base with isatin moiety were synthesized L1-L6. The structures of these compounds were characterized based on the spectroscopic techniques. Compound L6 was further characterized by XRD single crystal. The interaction of these compounds with calf thymus (CT-DNA) exhibited high intrinsic binding constant (k(b)=5.03-33.00×10(5) M(-1)) for L1-L3 and L5 and (6.14-9.47×10(4) M(-1)) for L4 and L6 which reflect intercalative activity of these compounds toward CT-DNA. This result was also confirmed by the viscosity data. The electrophoresis studies reveal the higher cleavage activity of L1-L3 than L4-L6. The in vitro anti-proliferative activity of these compounds against human colon cancer cell line (HCT 116) revealed that the synthesized compounds (L3, L6 and L2) exhibited good anticancer potency.
    Matched MeSH terms: DNA Cleavage/drug effects*
  5. Netalkar PP, Netalkar SP, Budagumpi S, Revankar VK
    Eur J Med Chem, 2014 May 22;79:47-56.
    PMID: 24721314 DOI: 10.1016/j.ejmech.2014.03.083
    Air and moisture stable coordination compounds of late first row transition metals, viz. Co(II), Ni(II), Cu(II) and Zn(II), with a newly designed ligand, 2-(2-benzo[d]thiazol-2-yl)hydrazono)propan-1-ol (LH), were prepared and successfully characterized using various spectro-analytical techniques. The molecular structures of the ligand and nickel complex were unambiguously determined by single-crystal X-ray diffraction method. The [Ni(LH)2]Cl2.3H2O complex is stabilized by intermolecular CH⋯π stacking interactions between the methyl hydrogen and the C18 atom of the phenyl ring (C11-H11B⋯C18) forming 1D zig-zag chain structure. Both, the ligand and its copper complex, were electrochemically active in the working potential range, showing quasi-reversible redox system. The interactions of all the compounds with calf thymus DNA have been comprehensively investigated using electronic absorption spectroscopy, viscosity, electrochemistry and thermal denaturation studies. The cleavage reaction on pBR322 DNA has been monitored by agarose gel electrophoresis. The results showed that the ligand can bind to CT-DNA through partial intercalation, whereas the complexes bind electrostatically. Further, [Ni(LH)2]Cl2.3H2O and [CuLCl(H2O)2] complexes in the series have high binding and cleavage affinity towards pBR322 DNA. Additionally, all the compounds were screened for anti-tuberculosis activity. All the complexes revealed an MIC value of 0.8 μg/mL, which is almost 8 times active than standard used (Streptomycin, 6.25 μg/mL).
    Matched MeSH terms: DNA Cleavage
  6. Seng HL, Ong HK, Rahman RN, Yamin BM, Tiekink ER, Tan KW, et al.
    J Inorg Biochem, 2008 Nov;102(11):1997-2011.
    PMID: 18778856 DOI: 10.1016/j.jinorgbio.2008.07.015
    The binding selectivity of the M(phen)(edda) (M=Cu, Co, Ni, Zn; phen=1,10-phenanthroline, edda=ethylenediaminediacetic acid) complexes towards ds(CG)(6), ds(AT)(6) and ds(CGCGAATTCGCG) B-form oligonucleotide duplexes were studied by CD spectroscopy and molecular modeling. The binding mode is intercalation and there is selectivity towards AT-sequence and stacking preference for A/A parallel or diagonal adjacent base steps in their intercalation. The nucleolytic properties of these complexes were investigated and the factors affecting the extent of cleavage were determined to be: concentration of complex, the nature of metal(II) ion, type of buffer, pH of buffer, incubation time, incubation temperature, and the presence of hydrogen peroxide or ascorbic acid as exogenous reagents. The fluorescence property of these complexes and its origin were also investigated. The crystal structure of the Zn(phen)(edda) complex is reported in which the zinc atom displays a distorted trans-N(4)O(2) octahedral geometry; the crystal packing features double layers of complex molecules held together by extensive hydrogen bonding that inter-digitate with adjacent double layers via pi...pi interactions between 1,10-phenanthroline residues. The structure is compared with that of the recently described copper(II) analogue and, with the latter, included in molecular modeling.
    Matched MeSH terms: DNA Cleavage
  7. Kosiha A, Lo KM, Parthiban C, Elango KP
    Mater Sci Eng C Mater Biol Appl, 2019 Jan 01;94:778-787.
    PMID: 30423764 DOI: 10.1016/j.msec.2018.10.021
    Three metal(II) complexes [CoLCl2], [CuLCl2] and [ZnL2Cl2] {L = 2‑chloro‑3‑((3‑dimethylamino)propylamino)naphthalene‑1,4‑dione} have been synthesized and characterized using analytical, thermal and spectral techniques (FT-IR, UV-Vis, ESR and ESI-MS). The structure of the L has been confirmed by single crystal XRD study. The complexes show good binding propensity to bovine serum albumin (BSA) having relatively higher binding constant values (104 M-1) than the ligand. Fluorescence spectral studies indicate that [CoLCl2] binds relatively stronger with CT DNA through intercalative mode, exhibiting higher binding constant (2.22 × 105 M-1). Agarose gel electrophoresis run on plasmid DNA (pUC18) prove that all the complexes showed efficient DNA cleavage via hydroxyl radical mechanism. The complexes were identified as potent anticancer agents against two human cancer cell lines (MCF7 and A549) by comparing with cisplatin. Co(II) complex demonstrated greater cytotoxicity against MCF7 and A549 cells with IC50 values at 19 and 22 μM, respectively.
    Matched MeSH terms: DNA Cleavage
  8. Asekunowo PO, Haque RA, Razali MR, Avicor SW, Wajidi MFF
    Eur J Med Chem, 2018 Apr 25;150:601-615.
    PMID: 29550733 DOI: 10.1016/j.ejmech.2018.03.029
    A series of four benzimidazolium based nitrile-functionalized mononuclear-Ag(I)-N-heterocyclic carbene and binuclear-Ag(I)-N-heterocyclic carbene (Ag(I)-NHC) hexafluorophosphate complexes (5b-8b) were synthesized by reacting the corresponding hexafluorophosphate salts (1b-4b) with Ag2O in acetonitrile, respectively. These compounds were characterized by 1H NMR, 13C NMR, IR, UV-visible spectroscopic techniques, elemental analyses and molar conductivity. Additionally, 8b was structurally characterized by single crystal X-ray diffraction technique. Preliminary in vitro antibacterial evaluation was conducted for all the compounds against two standard bacteria; gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacterial strains. Most of the Ag(I)-NHC complexes (5b-8b) showed moderate to good antibacterial activity with MIC values in the range of 12.5-100 μg/mL. Especially, compound 8b exhibited promising anti-Staphylococcus aureus activity with a low MIC value (12.5 μg/mL). However, all the hexafluorophosphate salts (1b-4b) were inactive against the bacteria strains. The preliminary interactive investigation revealed that the most active compound, 8b, could effectively intercalate into DNA to form 8b-DNA complex which shows a better binding ability for DNA (Kb = 3.627 × 106) than the complexes 5b-7b (2.177 × 106, 8.672 × 105 and 6.665 × 105, respectively). Nuclease activity of the complexes on plasmid DNA and Aedes albopictus genomic DNA was time-dependent, although minimal. The complexes were larvicidal to the mosquito, with 5b, 6b and 8b being highly active. Developmental progression from the larval to the adult stage was affected by the complexes, progressively being toxic to the insect's development with increasing concentration. These indicate the potential use of these complexes as control agents against bacteria and the dengue mosquito Ae. albopictus.
    Matched MeSH terms: DNA Cleavage
  9. Seng HL, Von ST, Tan KW, Maah MJ, Ng SW, Rahman RN, et al.
    Biometals, 2010 Feb;23(1):99-118.
    PMID: 19787298 DOI: 10.1007/s10534-009-9271-y
    Crystal structure analysis of the zinc complex establishes it as a distorted octahedral complex, bis(3-methylpicolinato-kappa(2) N,O)(2)(1,10-phenanthroline-kappa(2) N,N)-zinc(II) pentahydrate, [Zn(3-Me-pic)(2)(phen)]x5H(2)O. The trans-configuration of carbonyl oxygen atoms of the carboxylate moieties and orientation of the two planar picolinate ligands above and before the phen ligand plane seems to confer DNA sequence recognition to the complex. It cannot cleave DNA under hydrolytic condition but can slightly be activated by hydrogen peroxide or sodium ascorbate. Circular Dichroism and Fluorescence spectroscopic analysis of its interaction with various duplex polynucleotides reveals its binding mode as mainly intercalation. It shows distinct DNA sequence binding selectivity and the order of decreasing selectivity is ATAT > AATT > CGCG. Docking studies lead to the same conclusion on this sequence selectivity. It binds strongly with G-quadruplex with human tolemeric sequence 5'-AG(3)(T(2)AG(3))(3)-3', can inhibit topoisomerase I efficiently and is cytotoxic against MCF-7 cell line.
    Matched MeSH terms: DNA Cleavage
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