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1.
cis‐Cobalt complexes with salicycaldoxime(SAO), (Z)‐1‐(2‐hydroxyphenyl)ethanonoxime (HEO), (Z)‐1‐(2,5‐dihydroxyphenyl)ethanonoxime (DEO), (Z)‐1‐(2,5‐dihydroxyphenyl)(phenyl)methanonoxime (DPO) and their adducts with pyridine (Py) and imidazole (Im) were synthesized and characterized by elemental analysis, magnetic susceptibility, UV‐Vis and IR spectra. The electrochemical studies were carried by cyclic voltammeter, the peak potential separation and formal potential of complexes were independent of sweep rate or scan rate (ν) indicating a quasi reversible one‐electron redox process. Absorption studies and thermal denature studies revealed that each of these octahedral complexes is an avid binder of calf thymus DNA. The apparent binding constants for mixed ligand complexes are in order of ~103‐103 M?1. Based on the data obtained in the DNA binding studies a partial intercalative mode of binding is suggested for these complexes. The nucleolytic cleavage activity of parent complexes and their pyridine adduct were carried out on double stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment in the presence and absence of oxidant (H2O2). All the metal complexes show enhanced cleavage activity in presence of oxidant. The hydrolytic cleavage of DNA of Co(DEO)2 and Co(DPO)2 is evidenced from the control experiments showing discernable cleavage inhibition in the presence of the hydroxyl radical inhibitor DMSO and EDTA.  相似文献   

2.
The Cu(II) complexes of type [Cu(cpf)(An)Cl] (An = terpyridines, cpf = ciprofloxacin) were synthesized and characterized using IR, mass and reflectance spectra. The free ligands and their complexes were evaluated for their in‐vitro antimicrobial activity against a panel of Gram‐positive and Gram‐negative bacteria. The complexes exhibit better or equal inhibition in comparison to free fluoroquinolones. Binding interactions of the complexes with calf thymus (CT DNA) were investigated by absorption titration, viscosity studies and DNA melting temperature experiment. The cleavage reaction on pUC19 DNA was monitored by agarose gel electrophoresis. The lower concentration of the complexes was catalysed the dismutation of superoxide radical at biological pH, which indicates that the complexes can act as a possible model for superoxide dismutase. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

3.
We have synthesized ciprofloxacin‐based metal complexes of bipyridine derivatives [Cu(CFL)(An)Cl].2H2O (where CFL = ciprofloxacin and A = bipyridines e.g. A1 = 4‐(4‐fluorophenyl)‐6‐p‐tolyl‐2,2′‐bipyridine, A6 = 4‐(4‐(benzyloxy)phenyl)‐6‐(4‐bromophenyl)‐2,2′‐bipyridine, etc.). The ligands and complexes were characterized using analytical (C, H, N elemental analysis, TGA and magnetic measurement) and spectroscopic methods (1H and 13C NMR, FT‐IR, fast atom bombardment mass and reflectance spectroscopy). The products were evaluated by screening for DNA interaction activity on herring sperm DNA and studies suggest intercalative mode of DNA binding. The antimicrobial activity was determined in terms of minimum inhibitory concentration. Superoxide dismutase mimic studies were performed using the NADH/PMS/NBT system. The brine shrimp bioassay was also carried out to study the in vitro cytotoxic properties of the synthesized metal complexes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

4.
任蕤  杨频 《中国化学》1999,17(6):625-636
Hydrolysis of DNA is an important enzymatic reaction , but it is exceedingly difficult to mimic in the laboratory because of the stability of hydrolysis of DNA. In this paper, the cleavage activity of complexes formed between Cu(Ⅱ) and four different amino acid or amino acid methyl ester on DNA is studied by gel elec-trophoresis. It is found that DNA could be cleaved by Cu(Ⅱ)-L-His and Cu(Ⅱ)-L-His methyl ester complexes and the efficiency of cleavage is largely dependent on the metal ion-to-ligand ratio. Further experiments show that the cleavage of DNA mediated by Cu(Ⅱ)-L-His complexes occurs via a hydrolytic mechanism and the active chemical species that affects DNA cleavage is proposed to be MI2H and ML2H22 .  相似文献   

5.
Two new acylhydrazone copper(II) complexes of 4‐hydroxy‐N′‐[(1E)‐1‐(4‐methylphenyl)ethylidene]benzohydrazide (HL1) and 4 ethyl [4‐({(2E)‐2‐[1‐(4‐methylphenyl)ethylidene]hydrazinyl}carbonyl)phenoxy]acetate (HL2) have been synthesized and characterized. The structures of both acylhydrazone and copper(II) complexes were identified by elemental analysis, infrared spectra, UV–visible electronic absorption spectra, magnetic susceptibility measurements, TGA and powder X‐ray diffraction. DNA binding and DNA cleavage activities of the synthesized copper complexes were examined by using UV‐visible titration and agarose gel electrophoresis, respectively. The effect of complex concentration on the DNA cleavage reactions in the absence and presence of H2O2 was also investigated. The results indicate that all the complexes bind slightly to calf thymus DNA and cleavage pBR322 DNA. The mechanistic studies demonstrate that a hydrogen peroxide‐derived species and singlet oxygen (1O2) are the active oxidative species for DNA cleavage. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
The absolute necessity to fight some class of tumor is perceived as serious health concerns, so the discovery and development of effective anticancer agents are urgently needed. (E)‐4‐((2‐hydroxyphenyl)diazenyl)‐3‐phenyl‐1H‐pyrazol‐5(4H)‐one, HL, and its Ni(II), Pd(II) and Pt(II) complexes were synthesized and the biological activity was evaluated for antitumor, antioxidant and antimicrobial activity as well as DNA cleavage. Their structures were assigned depending on the elemental analysis, conductivity, magnetic moment, spectral measurements (IR, 1HNMR, mass and UV–Vis) and thermal analysis. 3D molecular modeling using DFT method confirmed that the geometrical structures agree well with the suggested experimental ones. The antitumor activity was evaluated against four different cell lines using MTT assay. The ligand HL showed a potent cytotoxic activity compared to 5‐fluorouracil as a reference drug. For metal complexes, the order of activity was: Pd(II) > Ni(II) > Pt(II). A remarkable antioxidant activity for the ligand HL was recorded. It was higher than that of the metal complexes. Results of antimicrobial experiments revealed that all compounds were moderate to highly active against selected bacterial strains but inactive as antifungal except Pd(II) which showed a moderate antifungal activity. Gel electrophoresis showed insignificant nucleases activity for the ligand or its metal complexes even in the presence of H2O2 providing protection of DNA from damage. The antitumor activity of our compounds may be not due to DNA cleavage but may be referred to a mechanism similar to that of 5‐fluorouracil which interfere with DNA replication. The present work suggests the use of this ligand in the design and development of new anticancer drugs.  相似文献   

7.
New series of Schiff bases derived from o‐substituted thiosemicarbazides and 8‐formyl‐7‐hydroxy‐4‐methylcoumarin have been synthesized and their coordination tendency toward Co(II), Ni(II), and Cu(II) metal ions is studied. Analytical, spectral (IR, UV‐Vis, ESR, and FAB‐mass), magnetic, and thermal studies suggests octahedral geometry of the type ML2 for all the Co(II), Ni(II), and Cu(II) complexes. The complexes are soluble in DMF/DMSO and are non‐electrolytes. The Schiff bases and their metal complexes have been screened for antibacterial (Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Pseudomonas aeruginosa) and antifungal activities (Aspergillus flavus, Aspergillus niger, and Cladosporium) by minimum inhibitory concentration method. DNA cleavage is studied by agarose gel electrophoresis method. Metal (II) complexes show good anthelmintic activity when compared to Schiff bases.  相似文献   

8.
Two neodymium(III) complexes, [Nd(Phen)(NO3)3(DMF)2] (1) and [Nd(Phen)2(NO3)3] (2) (phen = 1,10-phenanthroline; DMF = dimethylformamide), have been synthesized with a view to design artificial luminescent nucleases and nuclease mimics. The complexes were characterized by spectroscopic, powder, and single crystal XRD studies. The complexes, as expected, have luminescent properties. The DNA binding studies of both complexes have been carried out by spectroscopic studies e.g. electronic absorption (UV–Vis), fluorescence emission as well as viscosity measurements. The nuclease activity of the complexes has been established by gel electrophoresis using pUC19 circular plasmid DNA. The results of DNA binding as well as DNA cleavage activity and the model studies of interaction with pNPP indicate that both neodymium complexes demonstrate nuclease activity through phosphoester bond cleavage.  相似文献   

9.
Square-pyramidal complexes [Cu(NFL)(A n )Cl]?·?5H2O (A n ?=?phenanthroline derivatives and NFL?=?deprotonated norfloxacin) have been synthesized and characterized. Interactions with Herring Sperm DNA and pUC19 DNA have been investigated. Mode and extent of interaction was measured by the perturbation in absorbance of complexes in the absence and presence of DNA. Hydrodynamic volume change and gel electrophoretic results were also kept under consideration. Synthesized complexes bind to DNA via intercalation with binding constant 0.875–1.446?×?104?(mol?L?1)?1 based on bathochromism and hypochromism observed. Intercalative binding of complexes with DNA was further supported by relative viscosity, where 5 intercalates more strongly with most increase in relative viscosity, and K b value of 1.446?×?104?(mol?L?1)?1. Evaluation of electrophoretic separation of plasmid on agarose gel reveals that 5 cleaves more efficiently. Square-pyramidal geometry at the metal center supports superoxide-dismutase (SOD)-mimic behavior in addition to an electron-withdrawing group on the ancillary ligand stabilizing Cu–O bonding.  相似文献   

10.
Mixed ligand complexes having the formulae Cu(RPO)2Py2, Cu(RPO)2Im2 and Cu(DBO)2Py2 [RPO = resacetophenone oxime, DBO = 2,4-dihydroxybenzophenone oxime, Py = pyridine and Im = imidazole] have been synthesized and characterized by UV–Vis, IR, ESR, cyclic voltammetry and magnetic susceptibility methods. Absorption studies revealed that each of these octahedral complexes is an avid binder of calf thymus DNA. The apparent binding constants for mixed ligand complexes are in order of 104–105 M−1. Based on the data obtained in the DNA binding studies a partial intercalative mode of binding is suggested for these complexes. The nucleolytic cleavage activity of the adducts was carried out on double stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment in the presence and absence of oxidant (H2O2). All the metal complexes cleaved supercoiled DNA by hydrolytic and oxidative paths. The oxidative path dominates the hydrolytic cleavage. The hydrolytic cleavage of DNA is evidenced from the control experiments showing discernable cleavage inhibition in the presence of the hydroxyl radical inhibitor DMSO or the singlet oxygen quencher azide ion.  相似文献   

11.
合成并表征了2个不对称大环双核铜配合物[Cu2(L1)Cl2]·CH3CN(1)和[Cu2(L2)Br2]·CH3CN·H2O(2)。配合物与CT-DNA的作用通过紫外-可见光谱,粘度实验,圆二色谱和凝胶电泳实验进行了研究。紫外-可见光谱的结果表明配合物与DNA的结合常数分别为6.2×105和7.2×105,圆二色谱的实验表明配合物能与DNA较好的结合,粘度实验表明配合物与DNA的结合为非典型的插入模式,凝胶电泳实验显示配合物通过氧化机理对DNA有较强的切割活性。  相似文献   

12.
. Five neutral mixed‐ligand mononuclear square‐pyramidal copper(II) complexes of the type [Cu(cpf)(Ln)Cl] (cpf = ciprofloxacin and Ln = phenanthroline derivatives) ( 1 – 5 ) were synthesized and characterized. The complexes were screened for their antibacterial activity and bactericidal activity against two Gram(+ve) and three Gram(–ve) microorganisms and the results showed that all complexes studied are more potent than the quinolone standard drug ciprofloxacin. Absorption titration, viscosity, and thermal denaturation measurement studies revealed that each of these square‐pyramidal complexes moderately interacts with calf thymus DNA. The binding constants for mixed ligand complexes are in order of 1.5 × 104–3.0 × 104 M–1. Based on the data obtained in the DNA binding studies an intercalative mode of binding is suggested for these complexes. The nucleolytic cleavage activity of adducts and gyrase inhibition assay were studied on double stranded pUC19 DNA by gel electrophoresis experiments. From the SOD mimic study; the concentration of complexes ranging from 0.45 μM to 1.45 μM are enough to inhibit the reduction rate of NBT by 50 % (IC50) in NADH/PMS system.  相似文献   

13.
The synthesis, spectral characterization, and biological studies of ruthenium(II) hydrazone complexes [RuCl(CO)(PPh3)2L] (where L = hydrazone ligands) have been carried out. The hydrazones are monobasic bidentate ligands with O and N as the donors and are preferably found in the enol form in all the complexes. The molecular structure of the ligands HL1, HL2, and HL3 were determined by single-crystal X-ray diffraction. The DNA binding studies of the ligands and complexes were carried out by absorption spectroscopic and viscosity measurements. The results revealed that the ligands and complexes bind to DNA via intercalation. The DNA cleavage activity of the complexes, evaluated by gel electrophoresis assay, revealed that the complexes are good DNA cleaving agents. The antioxidant properties of the complexes were evaluated against DPPH, OH, and NO radicals, which showed that the complexes have strong radical-scavenging. Further, the in vitro cytotoxic effect of the complexes examined on HeLa and MCF-7 cancer cell lines showed that the complexes exhibited significant anticancer activity.  相似文献   

14.
The DNA cleavage activities of two coordination polymers of Robson-type macrocycles, {[Cu4L1(4,4′-bipy)2](ClO4)4·H2O} (1) and {[Cu4L2(4,4′-bipy)4](ClO4)4·2CH3CN·2H2O} (2) (where H2L1 and H2L2 are the [2 + 2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been studied. The interactions of the complexes with calf thymus-DNA were investigated by UV–vis spectroscopy, CD spectroscopy, and gel electrophoresis. The binding constants of 1 and 2 are 7.2 × 104 and 2.1 × 105 M?1, respectively. The complexes exhibit DNA cleavage activity, with the cleavage process involving oxidative cleavage of DNA.  相似文献   

15.
Diorganotin(IV) complexes ( 1‐4) of MESNA (sodium 2‐mercaptoethanesulfonate HSCH2CH2SO3Na) and a mixed ligand complex of dibutyltin(IV), 1,10‐phenanthroline and MESNA ( 5 ) were synthesized with thermal and microwave assisted methods. All the complexes were characterized thoroughly with the help of analytical and various spectroscopic techniques viz. FTIR, NMR (1H, 13C, and 119Sn NMR) spectroscopy and ESI‐MS spectrometery. Various spectrophotometric studies were carried out to decipher the binding mode of MESNA and its diorganotin complexes 1 ‐ 5 with calf thymus DNA (CT DNA) and thus, to calculate the binding constant (Kb). Absorption spectrophotometric study confirmed the interaction is through partial intercalation of all the complexes including MESNA, inside the DNA helix and calculated binding constant (Kb) is in the order of 103 M‐1. A series of emission spectrophotometric experiments support the results obtained through the absorption spectrophotometric studies. Circular dichroic (CD) spectroscopic analysis and viscosity measurement of CT DNA further complemented the fact that the partial intercalation plays a major role in the interaction of the studied complexes with CT DNA. All the studies corroborated that complex 2 bound to CT DNA with maximum affinity followed by complex 5 among all the complexes. Involvement of hydroxyl radicals as an active species in the cleavage activity of pBR322 plasmid DNA is proved by carrying out agarose gel electrophoretic technique.  相似文献   

16.
A novel hydrazone ligand derived from condensation reaction of 3‐hydroxy‐2‐naphthoic hydrazide with dehydroacetic acid, and its Ni(II), Cu(II) and Co(II) complexes were synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility and conductivity methods, and screened for antimicrobial, DNA binding and cleavage properties. Spectroscopic analysis and elemental analyses indicated the formula, [MLCl2], for the complexes; square planar geometry for the nickel, and tetrahedral geometry for copper and cobalt complexes. The non‐electrolytic natures of the complexes in Dimethyl Sulphoxide (DMSO) were confirmed by their molar conductance values in the range of 6.11–14.01 Ω?1cm2mol?1. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA, by agarose gel electrophoresis, in the presence and absence of oxidant (H2O2) and free radical scavenger (DMSO), indicated no activity for the ligand, and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H2O2. When the complexes were evaluated for antibacterial and A‐DNA activity using Molecular docking technique, the copper complex was found to be most effective against Gram‐positive (S. aureus) bacteria. [CuLCl2] showed good hydrogen bonding interaction with the major‐groove (C2.G13 base pair) of A‐DNA. Density functional theory (DFT) calculations of the structural and electronic properties of the complexes revealed that [CuLCl2] had a smaller HOMO‐LUMO gap, suggesting a higher tendency to donate electrons to electron‐accepting species of biological targets.  相似文献   

17.
合成并表征了2个不对称大环双核铜配合物[Cu2(L1)Cl2]·CH3CN(1)和[Cu2(L2)Br2]·CH3CN·H2O(2)。配合物与CT-DNA的作用通过紫外-可见光谱,粘度实验,圆二色谱和凝胶电泳实验进行了研究。紫外-可见光谱的结果表明配合物与DNA的结合常数分别为6.2×105和7.2×105,圆二色谱的实验表明配合物能与DNA较好的结合,粘度实验表明配合物与DNA的结合为非典型的插入模式,凝胶电泳实验显示配合物通过氧化机理对DNA有较强的切割活性。  相似文献   

18.
The reaction of the thiosemicarbazones (CH2)4C?NN(H)C(?S)NHR (R = H, Me) with zinc(II) acetate in methanolic solution proceeds readily under mild conditions to form stable mononuclear complexes Zn[(CH2)4C?NN?C(S)NHR]2. DNA interaction studies show that the zinc(II) complexes bind to DNA via groove mode and exhibit efficient DNA cleavage activity in the presence of hydrogen peroxide. Also, the complexes display a binding affinity to bovine serum albumin protein with KBSA values of ca 105 M?1. Topoisomerase catalytic inhibition studies suggest that both complexes are efficient topoisomerase‐I impeders. Furthermore, the anti‐proliferative effects of the two complexes on five human tumor cell lines (Caki‐2, MCF‐7, CaSki, NCI‐H322M and Co‐115) indicate that both complexes have the potential to act as effective anticancer drugs. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

19.
The peptide linkage Schiff base (H2L) and its complexes have been synthesized and fully characterized by elemental analysis, UV–Vis, FTIR, 1H-NMR, 13C-NMR, EPR, and FAB-mass spectra. The stoichiometry of the complexes is [ML] (where M = Cu(II), Co(II), Ni(II), Zn(II), and VO(IV)). All the complexes exhibit square-planar geometry except the vanadyl complex which has square-pyramidal geometry. Interactions of the complexes and free ligand with double-stranded calf thymus DNA (CT-DNA) are studied by UV-spectrophotometric, electrochemical, and viscosity measurements. The data suggest that all the complexes form adducts with DNA and distort the double helix by changing the base stacking. Vanadyl complex forms a weaker adduct to CT-DNA than other complexes, probably due to the square-pyramidal geometry. CT-DNA induces extensive distortion in the planarity of vanadyl complex as EPR spectral calculations reveal. The intrinsic binding constants (K b) of [ZnL], [CuL], [CoL], and [NiL] are 1.1 × 105, 1.4 × 105, 0.8 × 105, and 0.6 × 105 M?1, respectively. Photo-induced DNA cleavage indicates that all complexes cleave DNA effectively. Control DNA cleavage experiments using pUC19 supercoiled (SC) DNA and minor groove binder distamycin suggest major groove binding for the synthesized complexes. The antimicrobial results indicate that the complexes inhibit the growth of bacteria and fungi more than the free ligand.  相似文献   

20.
Three isoxazole Schiff bases 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-methoxyphenol (L1), 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-4,6-diiodophenol (L2), 2-((E)-(3,5-dimethylisoxazol-4-ylimino)methyl)-6-bromo-4-chlorophenol (L3), and their Cu(II) complexes [Cu(L1)2] (1), [Cu(L2)2] (2) and [Cu(L3)2] (3) were synthesized. All the complexes have been characterized by elemental analysis, FT-IR, ESI mass, UV-Visible, ESR, TGA, magnetic moments, and single-crystal X-ray diffraction analysis. Based on analytical data, a square planar geometry is assigned to the Cu(II) complexes with N2O2 donors from the Schiff base ligands. The single-crystal X-ray diffraction measurements of 1 and 2 confirmed the square planar geometry. DNA binding studies from electronic absorption titrations, viscosity measurements, and fluorescence quenching studies indicated an intercalation mode of binding of Cu(II) complexes with CT-DNA. DNA cleavage experiments of Cu(II) complexes with supercoiled plasmid pBR322 DNA have also been investigated by agarose gel electrophoresis in the presence of H2O2 (oxidative cleavage) and UV light (photolytic cleavage). The synthesized compounds were screened for antibacterial (Escherichia coli, Pseudomonas putida, Klebsiella pneumoniae, Bacillus subtillis and Staphylococcus aureus) and antifungal (Candida albicans and Aspergillus niger) activities by the paper disk method. The Cu(II) complexes showed better activity than corresponding Schiff bases.  相似文献   

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