Evaluation of the Antioxidant Activity of Copper(II) Complexes containing Tris‐(hydroxymethyl)aminomethane (TRIS) Units

The structural analysis and the SOD‐like activity of Cu^II complexes [(Cu)(C₁₆H₁₈N₃O₅)]ClO₄ ( 1 ) and [(Cu)₄(C₃₆H₅₂N₈O₁₂)] ( 2 ) are described with ligands obtained from the condensation of picolinaldehyde and 2‐formylpyrrole with tris(hydroxymethyl)aminomethane (TRIS). Finally, complex 1 catalyzes the dismutation of superoxide efficiently with IC₅₀ values in the range of 0.43 micromolar solution, evaluated through the inhibition of the photoreduction of nitro blue tetrazolium (NBT) (superoxide dismutase assay).     

Crystal Structure and Superoxide Dismutase Activity of [Cu(ethylenediamine)<Subscript>2</Subscript>Cl][PF<Subscript>6</Subscript>]

Summary. The preparation, spectroscopic properties, and crystal structure of chlorobis(ethylenediamine)copper(II) hexafluorophosphate [Cu(en)₂Cl][PF₆], (en=ethylendiamine) are reported. The complex crystallizes in the monoclinic system, space group P2₁/c, with cell constants a=6.1488(9) Å, b=12.696(2) Å, c=17.7424(17) Å, =97.265(12)°, and Z=4. The copper(II) ion is coordinated to two bidentate en molecules, to one chlorine ion, and to a more distant fluorine atom of the PF₆ group, leaving the copper ion in a distorted octahedral coordination geometry. The superoxide dismutase mimetic activity of the complex was investigated using the indirect xanthine-xanthine oxidase- nitroblue tetrazolium method and compared to that of the native enzyme.     

Synthesis,Structure, and SOD‐like Activity of a Copper(II) Complex Containing a Bistriazole Group

The dinuclear complex [Cu₂(HL)₂(H₂O)₂](ClO₄)₂ ( 1 ) [H₂L = 5′‐(pyridin‐2‐yl)‐1‐H,2′‐H‐3, 3′‐bis(1, 2,4‐triazole)] was obtained and fully characterized. It exhibits a centrosymmetry configuration, in which each copper(II) ion is pentacoordinate with four nitrogen atoms of two triazole ligands and one oxygen atom from a water molecule. The net atomic charges distribution and atomic orbital contribution to frontier molecular orbitals were obtained using the Gaussian 98 program with Hartree‐Fock method at LANL2DZ level, indicating that the copper(II) ion has the potential to accept the electron of O₂ ^{· –}. The complex showed quasi‐reversible one‐electron Cu^II/Cu^I redox waves with redox potentials of –0.034 V. The SOD‐like activity (IC₅₀) of 1 was measured to be 0.18 ± 0.01 μM by xanthine/xanthine oxidase‐NBT assay at pH 7.8. The relatively high SOD activity suggests that the positive charge of protonated triazole can effectively steer O₂ ^{· –} to and from the active copper ion.     

A Study on Some Copper (II) Complexes of Polyaza Cryptands and Planar Macrocycles—Synthesis,Characterization and Superoxide Dismutase Activity

Two kinds of macrocyclic copper(II) complexes were synthesized. One of them is composed of copper(II) cryptates of ligands L¹‐L⁴ which are condensation products of 5‐R‐2‐methoxy‐1,3‐phenyldialdehyde (R=OCH₃, L¹) with tris(2‐aminoethyl) amine and 5‐R‐2‐methothoxy‐1, 3‐phenyldialdehyde (R= CH₃, L³) with tris(2‐aminopropyl)amine as well as their reduced products of L¹ and L³ (L² and L⁴). The other is composed of two‐dimensional macrocyclic copper(II) complexes of ligands L⁵‐L⁸ of condensation products of diethylene triamine with 4‐R‐l‐methoxy‐2,6‐phenyldialdehyde (R= Cl, Br. CH₃, OCH₃). The relationship between their structures and superoxide dismutase (SOD) activity was investigated. The results can provide some clues to the synthesis of SOD mimics.     

Purification and Properties of Superoxide Dismutase（SOD） in Allium Sativum

Superoxide dismutases(SODs) were purified to homogeneity from Allium Sativum by means of ammoni-um sulfate precipitation and column chromatography with DEAE--cellulose (DE52) and Sephadex G-75. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-AGE), Allium Sativum is predicted to contain four SODs. The molecular weights of the native SODs are 41.3 kD, 37. 0 kD, 35.2 kD and 31.0 kD, which consist of subunits of 20. 7 kD, 18. 4 kD, 17. 7 kD and 15.4 kD respectively. Because of their specific sensitivity to hydrogen peroxide, cyanogens potassium and chloroform-alcohol, the SODs in Allium Sativum appear to be Cu, Zn-SOD isoenzymes. The isoelectric analysis indicates that three of the four isoermymes are acidic proteins with isoelectric points at pH 3.5, 3.7 and 4. 0, respectively, and the fourth one is a basic pro-tein with isoeletric point at pH 8. 5.     

Purification and Characterization of Superoxide Dismutase （SOD） from Camellia Pollen

A superoxide dismutase（ SOD ） was purified to homogeneity from fresh camellia pollen by means of ammonium sulfate precipitation and column chromatography with DEAE-cellulose（ DE52 ）, Sephadex G-100 and phenyl sepharose^TM 6 Fast Flow columns. Its specific activity could reach to 4034 U/mg protein and it was determined to be Cu/ Zn-SOD according to its different sensitivities to different inhibitors. The molecular weight of the SOD and its subunit were 69500 and 34700, respectively, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS- PAGE）, which implicates that the SOD in camellia pollen is a dimmer composed of two identical subunits. The isoelectric point of the enzyme was determined to be 4. 1 by isoelectric focusing electrophoresis and the N-terminal amino acid was identified to be Gly by the DNS-Cl method. Its α-Helix was also calculated to be approximately 21.8% according to the circular dichroism（CD） spectra.     

水溶性席夫碱型锰配合物的合成、表征及其模拟超氧化物歧化酶活性研究

以水杨醛为母体, 与胺类化合物缩合形成席夫碱配体, 用分子自组装法合成了一系列水溶性席夫碱型金属锰单核、双核配合物. 通过元素分析、红外光谱对配合物进行了表征, 采用邻苯三酚自氧化法测定了配合物的超氧化物歧化酶(SOD)活性. 结果表明, 这些水溶性锰配合物具有良好的SOD活性.     

Copper(II) complexes of hydroxyflavone derivatives as potential bioactive molecule to combat antioxidants: synthesis,characterization and pharmacological activities

A variety of novel copper complexes were synthesized and characterized of the formulae [Cu(L¹)(OAc)], [CuL²(H₂O)], [CuL³(H₂O)], [CuL⁴(OAc)], [CuL⁵(H₂O)] [CuL⁶], [CuL⁷], [CuL⁸](OAc) and [CuL⁹], where L¹ L⁹ represents Schiff base ligands [derived by the condensation of 5‐hydroxyflavone with 4‐aminoantipyrine (L¹), o‐aminophenol (L²), o‐aminobenzoic acid (L³), o‐aminothiazole (L⁴), thiosemicarbazide (L⁵), 4‐aminoantipyrine‐o‐aminophenol (L⁶), 4‐aminoantipyrine‐o‐aminobenzoic acid (L⁷), 4‐aminoantipyrine‐o‐aminothiazole(L⁸) and 4‐aminoantipyrine‐thiosemicarbazide (L⁹)]. The spectral and magnetic results of the Cu(II) complexes exhibit square planar geometry. The DNA binding properties of copper complexes were studied by using electronic absorption spectra, viscosity and thermal denaturation experiments. The results show that the complexes were interacting with calf thymus (CT DNA). The in vitro antimicrobial activities of the investigated compounds were tested against the bacterial species and fungal species. Superoxide dismutase and antioxidant activities of the copper complexes have also been studied. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct Voltammetry of Copper,Zinc‐Superoxide Dismutase Immobilized onto Electrodeposited Nickel Oxide Nanoparticles: Fabrication of Amperometric Superoxide Biosensor

Direct electron transfer of immobilized copper, zinc‐superoxide dismutase (SOD) onto electrodeposited nickel‐oxide (NiOx) nanoparticle modified glassy carbon (GC) electrode displays a well defined redox process with formal potential of ?0.03 V in pH 7.4. Cyclic voltammetry was used for deposition of (NiOx) nanoparticles and immobilization of SOD onto GC electrode. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k_s) of immobilized SOD are 1.75×10^?11 mol cm^?2 and 7.5±0.5 s^?1, respectively. The biosensor shows a fast amperometric response (3 s) toward superoxide at a wide concentration range from 10 µM to 0.25 mM with sensitivity of 13.40 nA µM^?1 cm^?2 and 12.40 nA µM^?1 cm^?2, detection limit of 2.66 and 3.1 µM based on anodically and cathodically detection. This biosensor exhibits excellent stability, reproducibility and long life time.     

Syntheses,Structures and Anticancer Activity of NNO‐Tridentate Schiff Base Copper(II) Complexes

A series of heteroleptic copper(II) complexes [Cu( ^R QYMP )(Py]] ( 1a ‐ 4d ) supported on NNO‐tridentate Schiff base ( ^R QYMP ‐H) and bipyridine (Py=bpy, a ; phen, b ; dpq, c ; dppz, d ) co‐ligands have been synthesized and characterized. X‐ray crystal structural studies of complexes 1b , 2c , 3d and 4a displays that these complexes are mononuclear with a distorted square pyramidal geometry around the copper center. Cytotoxicity results indicate that all of these complexes have much higher activity against HeLa, SCC15, BCC and Ca9‐22 cancer cell lines as compared to cisplatin. Further, copper complex bearing suitable bulky group Schiff base ligands with dppz co‐ligand could be considered in designing efficient metalbased anticancer agents.     

Synthesis,Characterization, DNA Binding Properties,and Antioxidant Activity of Novel Copper(II) and Zinc(II) Complexes with Bis(pyrrol‐2‐yl‐methylamine) Ligands

Three novel ligands H₄Lⁿ (n = 1–3) and their copper(II) and zinc(II) complexes were prepared and characterized on the basis of elemental analyses, molar conductivity, ¹H NMR, UV/Vis, and IR spectroscopy as well as mass spectrometry. DNA binding properties of the ligands and their complexes were investigated by absorption spectroscopy, ethidium bromide displacement experiments, and viscosity measurements. The experimental results indicate that the new ligands and their complexes can bind to DNA and the binding affinities of the complexes are higher than those of the ligands. In addition, the antioxidant activity of the ligands and complexes was determined by superoxide and hydroxyl radical scavenging methods in vitro, indicating that the complexes exhibit more effective antioxidant activity than the ligands alone.     

Mixed‐Ligand Complexes of Copper(II) with α‐Hydroxycarboxylic Acids and 1,10‐Phenanthroline

Eight new two‐ligand complexes of copper(II) with 1,10‐phenanthroline and one of four different α‐hydroxy‐carboxylic acids (glycolic, lactic, mandelic and benzylic) were prepared. The complexes of general formula [Cu(HL)₂(phen)] · nH₂O (HL = monodeprotonated acid) ( 1 – 4 ) were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermo‐gravimetric analysis. The complexes of general formulae [Cu(HL)(phen)₂](HL) · H₂L · nSolv [ 1 a (HL = HGLYO^–, n = 1, Solv = MeCN) and 3 a (HL = HMANO^–, n = 0)] and [Cu(L)(phen)(OH₂)] · nH₂O [ 2 a (L = LACO^2–, n = 4) and 4 a (L = BENO^2–, n = 2)] were characterized by X‐ray diffractometry. In all these latter a pentacoordinated copper atom has a basically square pyramidal coordination polyhedron, the distortion of which towards a trigonal bipyramidal configuration has been evaluated in terms of the parameter τ. In 1 a and 3 a there are three forms of α‐hydroxycarboxylic acid: a monodentate monoanion, a monoanionic counterion, and a neutral molecule lying in the outer coordination sphere; in 2 a and 4 a the α‐hydroxycarboxylic acid is a bidentate dianion coordinating through carboxyl and hydroxyl oxygens.     

Synthesis,Characterization and Structure of Bis‐ and Tetrakis‐Aziridine‐Nickel(II) and Copper(II) Complexes

The synthesis and characterization of mononuclear tetrakis‐aziridine nickel(II ) and copper(II ) complexes as well as of a dinuclear bis‐aziridine copper(II ) complex are described. The reactions of anhydrous MCl₂ (M = Ni^II, Cu^II) with aziridine (= az = C₂H₄NH, C₂H₃MeNH, CH₂CMe₂NH) in CH₂Cl₂ at room temperature in a 1:5 and 1:2 molar ratio, respectively, afforded the tetrakis‐aziridine complexes [M(az)₄Cl₂] (M = Ni, Cu) or the dimeric bis‐aziridine complex [Cu(az)₂Cl₂]₂. After purification, all of the complexes were fully characterized. The single crystal structure analysis revealed two different coordination modes. Whereas both nickel(II ) complexes can be classified as showing an elongated octahedral structure, copper(II ) complexes show either an elongated octahedral or a square pyramidal arrangement forming dimers with chlorido bridges in axial positions. Furthermore, the results of magnetic measurements of the nickel(II ) and copper(II ) compounds are presented.     

Construction of Mononuclear Copper(II) and Trinuclear Cobalt(II) Complexes Based on Asymmetric Salamo‐Type Ligands

Mononuclear copper(II) and trinuclear cobalt(II) complexes, namely [Cu(L¹)]₂ · CH₂Cl₂ and [{Co(L²)(EtOH)}₂Co(H₂O)] · EtOH {H₂L¹ = 4,6‐dichloro‐6′‐methyoxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol and H₃L² = 6‐ethyoxy‐6′‐hydroxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol}, were synthesized and characterized by elemental analyses, IR and UV/Vis spectroscopy, and single‐crystal X‐ray diffraction. In the Cu^II complex, the Cu^II atom is four‐coordinate, with a N₂O₂ coordination sphere, and has a slightly distorted square‐planar arrangement. Interestingly, the obtained trinuclear Co^II complex is different from the common reported 2:3 (L:Co^II) salamo‐type Co^II complexes. Infinite 2D layer supramolecular structures are formed via abundant intermolecular hydrogen bonding and π ··· π stacking interactions in the Cu^II and Co^II complexes.     

Characterization of Two New Copper(II) Complexes with Saccharinate and Benzimidazole as Ligands

The crystal structure of the complexes [Cu(sac)₂(bzim)₂(H₂O)] ( 1 ) and [Cu(sac)₂(bzim)(H₂O)(EtOH)] · 2 EtOH ( 2 ) (sac = saccharinate anion; bzim = benzimidazole; EtOH = ethanol) was determined by single crystal X‐ray diffractometry. Complex 1 crystallizes in the monoclinic C2/c space group with Z = 8 whereas complex 2 belongs to the triclinic P1 space group with Z = 2. Room temperature magnetic susceptibilities as well as electronic and IR spectra of both complexes were discussed. Their thermal behaviour was investigated by means of TG and DTA methods.     

Influence of Electrostatic Interactions and Hydrogen Bonding on the Activity of Cyclodextrin-based Superoxide Dismutase Models

Abstract

The influence of electrostatic interactions and hydrogen bonding between the substrate and the active site in superoxide dismutase (SOD) models based on Cu(II) complexes of cyclodextrin dithiocarbamates is studied. Polar and positively charged groups present in the structure of the complexes were found to increase its activity in 35–70%. Our studies reveal the importance of these two features in enhancing the activity of SOD model complexes.     

Synthesis of a One‐dimensional Coordination Polymer Based on Copper(II) Nitrate and 1,2‐Bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane

A one‐dimensional coordination polymer based on copper(II) nitrate and 1,2‐bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane as ligand was prepared. The thermal and physical stability was determined by differential scanning calorimetry and BAM methods. The polymer was investigated by vibrational spectroscopy and single X‐ray diffraction. Moreover, the ligand itself and the 1,2‐bis(1H‐tetrazolyl)ethane were characterized as energetic material by bomb calorimetric measurements along with calculations using the EXPLO5 software. Both compounds have moderate energetic properties along with a high thermal and physical stability. These findings render these compounds into promising environment friendly gas generating agents.     

外源铜增强天然铜锌超氧化物歧化酶断裂DNA的活性

铜锌超氧化物歧化酶（CuZnSOD）作为一种抗氧化酶, 最重要的功能是催化超氧阴离子歧化为过氧化氢和氧气。然而最近研究发现CuZnSOD具有过氧化物酶活性,能导致核酸、蛋白质和细胞膜的损伤。本工作采用光谱学和酶学方法研究外源Cu(Ⅱ)与CuZnSOD之间的相互作用,以及H₂O₂存在下外源Cu(Ⅱ)对 CuZnSOD断裂DNA活性的增强效应。比较CuZnSOD + nCu(Ⅱ) (n=0, 1, 2, 4, 6, 8)和单独Cu(Ⅱ)分别断裂DNA的活性,表明外源Cu(Ⅱ)的加入可显著增强CuZnSOD断裂DNA的活性。相对酶活力和稳态动力学的测定证实了这种增强效应。pH依赖性实验表明断裂DNA的最适pH范围为pH3.6-5.6和pH9.0-10,在不同的pH区域CuZnSOD + nCu(Ⅱ)断裂DNA途径可能不同。