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  Subjects -> CHEMISTRY (Total: 838 journals)
    - ANALYTICAL CHEMISTRY (48 journals)
    - CHEMISTRY (587 journals)
    - CRYSTALLOGRAPHY (22 journals)
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    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (68 journals)

INORGANIC CHEMISTRY (41 journals)

Acta Polymerica     Hybrid Journal   (Followers: 6)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 4)
Advances in Polymer Technology     Hybrid Journal   (Followers: 11)
Annual Reports Section A (Inorganic Chemistry)     Full-text available via subscription   (Followers: 2)
Bioinorganic Chemistry and Applications     Open Access   (Followers: 4)
Comments on Inorganic Chemistry: A Journal of Critical Discussion of the Current Literature     Hybrid Journal  
Current Methods in Inorganic Chemistry     Full-text available via subscription  
European Journal of Inorganic Chemistry     Hybrid Journal   (Followers: 7)
European Polymer Journal     Hybrid Journal   (Followers: 41)
Heterocyclic Communications     Hybrid Journal   (Followers: 2)
High Performance Polymers     Hybrid Journal  
Indian Journal of Chemistry - Section A     Open Access   (Followers: 5)
Inorganic Chemistry     Full-text available via subscription   (Followers: 20)
Inorganic Chemistry Communications     Hybrid Journal   (Followers: 8)
Inorganic Chemistry Frontiers     Full-text available via subscription   (Followers: 1)
Inorganic Materials     Hybrid Journal   (Followers: 2)
Inorganic Materials: Applied Research     Hybrid Journal   (Followers: 1)
Inorganica Chimica Acta     Hybrid Journal   (Followers: 4)
Inorganics     Open Access  
International Journal of Inorganic Chemistry     Open Access   (Followers: 1)
JBIC Journal of Biological Inorganic Chemistry     Hybrid Journal   (Followers: 3)
Journal of Inorganic and Organometallic Polymers and Materials     Partially Free   (Followers: 6)
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 2)
Journal of Inorganic Chemistry     Open Access   (Followers: 1)
Journal of Polymer Engineering     Hybrid Journal   (Followers: 9)
Journal of Polymers and the Environment     Hybrid Journal   (Followers: 3)
Journal of Separation Science     Hybrid Journal   (Followers: 8)
Metallodrugs     Open Access  
Open Journal of Inorganic Chemistry     Open Access   (Followers: 2)
Plasmas and Polymers     Hybrid Journal  
Polymer Bulletin     Hybrid Journal   (Followers: 7)
Polymer Composites     Hybrid Journal   (Followers: 10)
Polyoxometalate Chemistry     Open Access  
Reviews in Inorganic Chemistry     Hybrid Journal  
Russian Journal of Inorganic Chemistry     Hybrid Journal  
Studies in Inorganic Chemistry     Full-text available via subscription  
Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry     Hybrid Journal   (Followers: 3)
Topics in Inorganic and General Chemistry     Full-text available via subscription  
Zeitschrift für anorganische und allgemeine Chemie     Hybrid Journal   (Followers: 1)
Zeitschrift für Kristallographie - New Crystal Structures     Open Access  
Journal Cover   Journal of Inorganic Biochemistry
  [SJR: 0.96]   [H-I: 87]   [2 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0162-0134
   Published by Elsevier Homepage  [2812 journals]
  • A versatile salicyl hydrazonic ligand and its metal complexes as antiviral
           agents
    • Abstract: Publication date: Available online 27 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): D. Rogolino , M. Carcelli , A. Bacchi , C. Compari , Laura Contardi , E. Fisicaro , A. Gatti , M. Sechi , A. Stevaert , L. Naesens
      Acylhydrazones are very versatile ligands and their coordination properties can be easily tuned, giving rise to metal complexes with different nuclearities. In the last few years, we have been looking for new pharmacophores able to coordinate simultaneously two metal ions, because many enzymes have two metal ions in the active site and their coordination can be a successful strategy to inhibit the activity of the metalloenzyme. As a part of this ongoing research, we synthesised the acylhydrazone H2L and its complexes with Mg(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Their characterization, both in solution - also by means of potentiometric studies - and in the solid state, evidenced the ability of the o-vanillin hydrazone scaffold to give rise to different types of metal complexes, depending on the metal and the reaction conditions. Furthermore, we evaluated both the free ligand and its metal complexes in in vitro studies against a panel of diverse DNA- and RNA-viruses. In particular, the Mg(II), Mn(II), Ni(II) and Zn(II) complexes had EC50 values in the low micromolar range, with a pronounced activity against vaccinia virus.
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      PubDate: 2015-05-28T07:22:58Z
       
  • Cellular trafficking, accumulation and DNA platination of a series of
           cisplatin-based dicarboxylato Pt(IV) prodrugs
    • Abstract: Publication date: Available online 26 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Mauro Ravera , Elisabetta Gabano , Ilaria Zanellato , Ilaria Bonarrigo , Manuela Alessio , Fabio Arnesano , Angela Galliani , Giovanni Natile , Domenico Osella
      A series of Pt(IV) anticancer prodrug candidates, having the equatorial arrangement of cisplatin and bearing two aliphatic carboxylato axial ligands, has been investigated to prove the relationship between lipophilicity, cellular accumulation, DNA platination and antiproliferative activity on the cisplatin-sensitive A2780 ovarian cancer cell line. Unlike cisplatin, no facilitate influx/efflux mechanism appears to operate in the case of the Pt(IV) complexes under investigation, thus indicating that they enter by passive diffusion. While Pt(IV) complexes having lipophilicity comparable to that of cisplatin (negative values of log P o/w) exhibit a cellular accumulation similar to that of cisplatin, the most lipophilic complexes of the series show much higher cellular accumulation (stemming from enhanced passive diffusion), accompanied by greater DNA platination and cell growth inhibition. Even if the Pt(IV) complexes are removed from the culture medium in the recovery process, the level of DNA platination remains very high and persistent in time, indicating efficient storing of the complexes and poor detoxification efficiency.
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      PubDate: 2015-05-28T07:22:58Z
       
  • Impact of Cu2+ ions on the structure of colistin and cell-free system
           nucleic acids degradation
    • Abstract: Publication date: Available online 26 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Kamila Stokowa-Sołtys , Aleksandra Kasprowicz , Jan Wrzesiński , Jerzy Ciesiołka , Nicola Gaggelli , Elena Gaggelli , Gianni Valensin , Małgorzata Jeżowska-Bojczuk
      Colistin and transition metal ions are commonly used as feed additives for livestock animals. This work presents the results of an analysis of combined potentiometric and spectroscopic (UV–vis, EPR, CD, NMR) data which lead to conclude that colistin is able to effectively chelate copper(II) ions. In cell-free system the oxidative activity of the complex manifests itself in the plasmid DNA destruction with simultaneous generation of reactive •OH species, when accompanied by hydrogen peroxide or ascorbic acid. The degradation of RNA occurs most likely via an hydrolytic mechanism not only for complexed compound but also colistin alone. Therefore, huge amounts of the used antibiotic for nontherapeutic purposes might have a potential influence on livestock health.
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      PubDate: 2015-05-28T07:22:58Z
       
  • Spectroscopic Studies on Peptides and Proteins with Cysteine-Containing
           Heme Regulatory Motifs (HRM)
    • Abstract: Publication date: Available online 22 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Erik Schubert , Nicole Florin , Fraser Duthie , H. Henning Brewitz , Toni Kühl , Diana Imhof , Gregor Hagelueken , Olav Schiemann
      The role of heme as a cofactor in enzymatic reactions has been studied for a long time and in great detail. Recently it was discovered that heme can also serve as a signalling molecule in cells but so far only few examples of this regulation have been studied. In order to discover new potentially heme-regulated proteins, we screened protein sequence databases for bacterial proteins that contain sequence features like a Cystein-Proline (CP) motif, which is known for its heme-binding propensity. Based on this search we synthesized a series of these potential heme regulatory motifs (HRMs). We used cw EPR spectroscopy to investigate whether these sequences do indeed bind to heme and if the spin state of heme is changed upon interaction with the peptides. The corresponding proteins of two potential HRMs, FeoB and GlpF, were expressed and purified and their interaction with heme was studied by cw EPR and UV-Visible (UV-Vis) spectroscopy.
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      PubDate: 2015-05-23T07:09:57Z
       
  • Reactivity of dinuclear copper(II) complexes towards melanoma cells:
           correlation with its stability, tyrosinase mimicking and nuclease activity
           
    • Abstract: Publication date: Available online 19 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Cléia Justino Nunes , Beatriz Essenfelder Borges , Lia Sumie Nakao , Eugénie Peyroux , Renaud Hardré , Bruno Faure , Marius Réglier , Michel Giorgi , Marcela Bach Prieto , Carla Columbano Oliveira , Ana M. Da Costa Ferreira
      In this work, the influence of two new dinuclear copper(II) complexes in the viability of melanoma cells (B16F10 and TM1MNG3) was investigated, with the aim of verifying possible correlations between their cytotoxicity and their structure. One of the complexes had a polydentate dinucleating amine-imine ligand (complex 2), and the other a tridentate imine and a diamine-bridging ligand (complex 4). The analogous mononuclear copper(II) species (complexes 1 and 3, respectively) were also prepared for comparative studies. Crystal structure determination of complex 2 indicated a square-based pyramidal geometry around each copper, coordinated to three N atoms from the ligand and the remaining sites being occupied by either solvent molecules or counter-ions. Complex 4 has a tetragonal geometry. Interactions of these complexes with human albumin protein (HSA) allowed an estimation of their relative stabilities. Complementary studies of their reactivity towards DNA indicated that all of them are able of causing significant oxidative damage, with single and double strand cleavages, in the presence of hydrogen peroxide. However, nuclease activity of the dinuclear species were very similar and much higher than that of the corresponding mononuclear compounds. Although complex 2, with a more flexible structure, exhibits a much higher tyrosinase activity than complex 4, having a more rigid environment around the metal ion, both complexes showed comparable cytotoxicity towards melanoma cells. Corresponding mononuclear complexes showed to be remarkably less reactive as tyrosinase mimics as well as cytotoxic agents. Morever, the dinuclear complexes showed higher cytotoxicity towards more melanogenic cells. The obtained results indicated that the structure of these species is decisive for its activity towards the malignant tumor cells tested.
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      PubDate: 2015-05-23T07:09:57Z
       
  • CuII-selective bispidine-dye conjugates
    • Abstract: Publication date: Available online 22 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Dominik Brox , Peter Comba , Dirk-Peter Herten , Esther Kimmle , Michael Morgen , Carmen Rühl , Arina Rybina , Holger Stephan , Golo Storch , Hubert Wadepohl
      The substitution of pentadentate bispidine ligands with rhodamine and cyanine dye molecules, coupled to an amine donor, forming an amide as potential fifth donor, is described. Bispidines are known to lead to very stable CuII complexes, and the coordination to CuII was expected to efficiently quench the fluorescence of dye molecules. However, at physiological pH the amide is not coordinated, as shown by titration experiments and crystallographic structural data of three possible isomers of these complexes. This may be due to the specific cavity shape of bispidines and the Jahn-Teller lability of the CuII center. While CuII coordination in aqueous solution leads to efficient fluorescence quenching, experiments show that the complex stabilities are not large enough for CuII sensing in biological media, and possibilities are discussed, how this may be achieved by optimized bispidine-dye conjugates.
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      PubDate: 2015-05-23T07:09:57Z
       
  • Editorial Board
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146




      PubDate: 2015-05-18T17:32:13Z
       
  • Tuning the interactions of PEG-coated gold nanorods with BSA and model
           proteins through insertion of amino or carboxylate groups
    • Abstract: Publication date: Available online 5 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Federica Scaletti , Alessandro Feis , Sonia Centi , Roberto Pini , Vincent M. Rotello , Luigi Messori
      Gold nanorods (GNRs) are important platforms for biosensing and drug delivery. As for most nanomaterials, appropriate coatings such as polyethylene glycol (PEG) are needed to stabilize GNRs within biological fluids. We show here that the interactions of GNRs with proteins can be finely modulated through surface modification using PEG-containing chains bearing charged headgroups. Interestingly, introduction of amino or carboxylate groups produces relevant and differential changes in GNR interactions with three representative proteins: lysozyme, cytochrome c, and bovine serum albumin. These effects were explored through the direct monitoring of plasmonic bands of the GNRs and are supported by independent dynamic light scattering (DLS) and circular dichroism (CD) determinations. Notably, GNR–protein interactions observed for these charged GNRs can be almost completely reversed by salt addition. These observations demonstrate the importance of electrostatic effects in governing GNR–protein interactions, and provide a basis for new sensing and delivery platforms.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Gold nanostars coated with neutral and charged polyethylene glycols: A
           comparative study of in-vitro biocompatibility and of their interaction
           with SH-SY5Y neuroblastoma cells
    • Abstract: Publication date: Available online 8 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Piersandro Pallavicini , Elisa Cabrini , Gennara Cavallaro , Giuseppe Chirico , Maddalena Collini , Laura D’Alfonso , Giacomo Dacarro , Alice Donà , Nicoletta Marchesi , Chiara Milanese , Alessia Pascale , Laura Sironi , Angelo Taglietti
      Gold nanostars (GNS) have been coated with four different polyethyleneglycols (PEGs) equipped with a –SH function for grafting on the gold surface. These PEGs have different chain lengths with average MW=2000, 3000, 5000 and average number of –O-CH2-CH2- units 44, 66 and 111, respectively. Two are neutral and two are terminated with –COOH and –NH2 functions, thus bearing negative and positive charges at physiological pH, thanks to the formation of carboxylate and ammonium groups. The negative charge of the GNS coated with PEG carboxylate has also been exploited to further coat the GNS with the PAH (polyallylamine hydrochloride) cationic polymer. Vitality tests have been carried out on SH-SY5Y cells treated with the five differently coated GNS for 4, 24 and 48h, at Au concentrations ranging from 1.25 to 100 μg/mL. The same tests have been repeated with the pure PEGs and PAH. Excellent biocompatibility was found for all PEGs, independently on charge and chain length, both for coated GNS and for the pure polymers. On the contrary, poor biocompatibility was found for PAH overcoated GNS and for pure PAH, although the latter only at high concentrations. Exploiting the two-photon luminescence of GNS, we have found by confocal laser scanning microscopy that when GNS are coated with PEGs they do not enter SH-SY5Y cells, while when overcoated with PAH they massively penetrate into the cytoplasm. This causes cell death by dramatically changing cell morphology, as demonstrated also by atomic force microscopy.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Magnetic susceptibility of Mn(III) complexes of hydroxamate siderophores
    • Abstract: Publication date: Available online 9 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Stephen D. Springer , Alison Butler
      The hydroxamate siderophores putrebactin, desferrioxamine B, and desferrioxamine E bind Mn(II) and promote the air oxidation of Mn(II) to Mn(III) at pH>7.1. The magnetic susceptibility of the manganese complexes were determined by the Evans method and the stoichiometry was probed with electrospray ionization mass spectrometry (ESIMS). The room temperature magnetic moments (μeff) for the manganese complexes of desferrioxamines B and E were 4.85BM and 4.84BM, respectively, consistent with a high spin, d4, Mn(III) electronic configuration. The manganese complex of putrebactin had a magnetic moment of 4.98BM, consistent with incomplete oxidation of Mn(II), as confirmed by X band EPR spectroscopy. Mass spectra of the Mn(III) desferrioxamine B and E complexes showed complexes at m/z 613.26 and 653.26, respectively, consistent with 1:1 complexation. Mass spectral peaks for manganese putrebactin at m/z 797.31 and 1221.41 corresponds to 1:2 and 2:3 Mn:putrebactin complexation. This study directly confirms the Mn(III) oxidation state in hydroxamate siderophore complexes.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Mg(II) and Ni(II) induce aggregation of poly(rA)poly(rU) to either
           tetra-aggregate or triplex depending on the metal ion concentration
    • Abstract: Publication date: Available online 9 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Tarita Biver , Natalia Busto , Begoña García , José Maria Leal , Luisa Menichetti , Fernando Secco , Marcella Venturini
      The ability of magnesium(II) and nickel(II) to induce dramatic conformational changes in the synthetic RNA, poly(a)poly(U), has been investigated. Kinetic experiments, spectrofluorometric titrations, melting experiments and DSC measurements contribute in shedding light on a complex behaviour where the action of metal ions (Na+, Mg2+, Ni2+), in synergism with other operators, as the intercalating dye coralyne and temperature, all concur in stabilizing a peculiar RNA form. Mg2+ and Ni2+ (M) bind rapidly and almost quantitatively to the duplex (AU) to give a RNA/metal ion complex (AUM). Then, by the union of two AUM units, an unstable tetra-aggregate (UAUA(M2)*) is formed which, in the presence of a relatively modest excess of metal, evolves to the UAUM triplex by releasing a single AM strand. On the other hand, under conditions of high metal content, the UAUA(M2)* intermediate rearranges to give a more stable tetra-aggregate (UAUA(M2)). As concerns the role of coralyne (D), it is found that D strongly interacts with UAUA(M2). Also, in the presence of coralyne, the ability of divalent ions to promote the transition of AUD into UAUD is enhanced, according to the efficiency sequence [Ni2+] >>[Mg2+] >>[Na+].
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Mixed copper–platinum complex formation could explain synergistic
           antiproliferative effect exhibited by binary mixtures of cisplatin and
           copper-1,10-phenanthroline compounds: An ESI–MS study
    • Abstract: Publication date: Available online 14 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Tiziana Pivetta , Viola Lallai , Elisa Valletta , Federica Trudu , Francesco Isaia , Daniela Perra , Elisabetta Pinna , Alessandra Pani
      Cisplatin, cis-diammineplatinum(II) dichloride, is a metal complex used in clinical practice for the treatment of cancer. Despite its great efficacy, it causes adverse reactions and most patients develop a resistance to cisplatin. To overcome these issues, a multi-drug therapy was introduced as a modern approach to exploit the drug synergy. A synergistic effect had been previously found when testing binary combinations of cisplatin and three copper complexes in vitro, namely, Cu(phen)(OH2)2(OClO3)2 , [Cu(phen)2(OH2)](ClO4)2 and [Cu(phen)2(H2dit)](ClO4)2,(phen = 1,10-phenanthroline, H2dit = imidazolidine-2-thione), against the human acute T-lymphoblastic leukaemia cell line (CCRF-CEM). In this work [Cu(phen)2(OH2)](ClO4)2 was also tested in combination with cisplatin against cisplatin-resistant sublines of CCRF-CEM (CCRF-CEM-res) and ovarian (A2780-res) cancer cell lines. The tested combinations shown a synergistic effect against both the types of resistant cells. The possibility that this effect was caused by the formation of new adducts was considered and mass spectra of solutions containing cisplatin and one of the three copper complexes at a time were measured using electrospray ionisation at atmospheric-pressure mass spectroscopy (ESI–MS). A mixed complex was detected and its stoichiometry was assessed on the basis of the isotopic pattern and the results of tandem mass spectrometry experiments. The formed complex was found to be [Cu(phen)(OH)μ-(Cl)2Pt(NH3)(H2O)]+.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Reduced accumulation of platinum drugs is not observed in drug-resistant
           ovarian cancer cell lines derived from cisplatin-treated patients
    • Abstract: Publication date: Available online 14 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Marina Stukova , Matthew D. Hall , Samantha D. Tsotsoros , James P. Madigan , Nicholas P. Farrell , Michael M. Gottesman
      The resistance of ovarian cancer towards front-line chemotherapy, usually cisplatin or carboplatin in combination with paclitaxel or docetaxel, remains a major clinical challenge. Resistance to these agents has been largely studied using cell lines selected for resistance to agents in vitro. We examined a series of paired cell lines derived from patients with ovarian cancer prior to chemotherapy (PEO1, PEO4, PEO14 and PEA1), and following the acquisition of resistance to a platinum-based chemotherapy regimen (PEO6, PEO23 and PEA2, respectively). All resistant patient lines showed resistance to cisplatin (2-5-fold), but this did not correspond with lowered accumulation. No general cross-resistance was observed for oxaliplatin, paclitaxel or docetaxel, and paclitaxel accumulation was not affected. PEO1 cells carrying BRCA2 mutations were hypersensitive to the PARP inhibitors olaparib and velaparib, but all other cell lines expressing functional forms of BRCA2 were less sensitive. While reduced drug accumulation was not observed, we believe these pairs of lines are of use to researchers studying Pt drug resistance and experimental therapeutics against drug-resistant ovarian cancer.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Oxidovanadium(IV) Sulfate-induced Glucose Uptake in HepG2 Cells through
           IR/Akt Pathway and Hydroxyl Radicals
    • Abstract: Publication date: Available online 15 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Qian Zhao , Deliang Chen , Pingsheng Liu , Taotao Wei , Fang Zhang , Wenjun Ding
      The insulin-mimetic and anti-diabetic properties of vanadium and related compounds have been well documented both in vitro and in vivo. However, the molecular basis of the link between vanadium and the insulin signaling pathway in diabetes mellitus is not fully described. We investigated the effects of reactive oxygen species (ROS) induced by oxidovanadium(IV) sulfate (VOSO4) on glucose uptake and the insulin signaling pathway in human hepatoma cell line HepG2. Exposure of cells to VOSO4 (5-50 μM) resulted in an increase in glucose uptake, insulin receptor (IR) and protein kinase B (Akt) phosphorylation and intracellular ROS generation. Using Western blot, we found that catalase and sodium formate, but not superoxide dismutase, prevented the increase of hydroxyl radical (·OH) generation and significantly decreased VOSO4-induced IR and Akt phosphorylation. These results suggest that VOSO4-induced ·OH radical, which is a signaling species, promotes glucose uptake via the IR/Akt signaling pathway.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Synthesis, crystal structure and investigation of mononuclear copper(II)
           and zinc(II) complexes of a new carboxylate rich tripodal ligand and their
           interaction with carbohydrates in alkaline aqueous solution
    • Abstract: Publication date: August 2015
      Source:Journal of Inorganic Biochemistry, Volume 149
      Author(s): Christopher D. Stewart , Mayra Pedraza , Hadi Arman , Hua-Jun Fan , Eduardo Luiz Schilling , Bruno Szpoganicz , Ghezai T. Musie
      A new carboxylate rich asymmetric tripodal ligand, N-[2-carboxybenzomethyl]-N-[carboxymethyl]-β-alanine (H3camb), and its di-copper(II), (NH4)2[1]2, and di-zinc(II), ((CH3)4 N)2[2]2, complexes have been synthesized as carbohydrate binding models in aqueous solutions. The ligand and complexes have been fully characterized using several techniques, including single crystal X-ray diffraction. The interactions of (NH4)2[1]2 and ((CH3)4 N)2[2]2 with d-glucose, d-mannose, d-xylose and xylitol in aqueous alkaline media were investigated using UV–Vis and 13C-NMR spectroscopic techniques, respectively. The molar conductance, NMR and ESI–MS studies indicate that the complexes dissociate in solution to produce the respective complex anions, 1 − and 2 −. Complexes 1 − and 2 − showed chelating ability towards the naturally abundant and biologically relevant sugars, d-glucose, d-mannose, d-xylose, and xylitol. The complex ions bind to one molar equivalent of the sugars, even in the presence of stoichiometric excess of the substrates, in solution. Experimentally obtained spectroscopic data and computational results suggest that the substrates bind to the metal center in a bidentate fashion. Apparent binding constant values, pK app, between the complexes and the substrates were determined and a specific mode of substrate binding is proposed. The pK app and relativistic density functional theory (DFT) calculated Gibbs free energy values indicate that d-mannose displayed the strongest interaction with the complexes. Syntheses, characterizations, detailed substrate binding studies using spectroscopic techniques, single crystal X-ray diffraction and geometry optimizations of the complex-substrates with DFT calculations are also reported.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Insights into the mechanisms underlying the antitumor activity of an
           oxidovanadium(IV) compound with the antioxidant naringenin. Albumin
           binding studies
    • Abstract: Publication date: August 2015
      Source:Journal of Inorganic Biochemistry, Volume 149
      Author(s): María S. Islas , Luciana G. Naso , Luis Lezama , María Valcarcel , Clarisa Salado , Meritxell Roura-Ferrer , Evelina G. Ferrer , Patricia A.M. Williams
      Naringenin, a natural antioxidant present in grapefruit, oranges and the skin of tomatoes showed low antioxidant properties among other flavonoids due to its structural characteristics. Since many flavonoids were shown to have cell-killing and antioxidant activities, naringenin was investigated herein. In parallel with its antioxidant activities the flavonoid showed very low cytotoxicity at concentrations up to 100μM against lung (A549) and breast (SKBr3 and MDAMB231) cancer cell lines. Furthermore, a newly-synthesized and characterized complex of naringenin and oxidovanadium(IV) ([VIVO(nar)2]·2H2O, VOnar, with weak ferromagnetic coupling) was also studied. As a result, VOnar acted as a better compound on cell-killing and antioxidant activities (in vitro) than naringenin. The anti-proliferative effect of VOnar was accompanied by reactive oxygen species (ROS) generation, cell membrane and DNA damages, cell cycle arrest, caspase 3/7 activation and mitochondrial potential reduction. The higher parameters observed for the MDAMB231 cell line have been related to its low glutathione (GSH) content. The assays of the interaction of bovine serum albumin (BSA) with the complex showed the affinity of protein toward it and that there is only one binding site on the BSA molecule. However, metal complexation decreased the binding affinity to BSA of naringenin probably due to a steric hindrance of the complex.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Inhibitory effects of nitrite on the reactions of bovine carbonic
           anhydrase II with CO2 and bicarbonate consistent with zinc-bound nitrite
    • Abstract: Publication date: August 2015
      Source:Journal of Inorganic Biochemistry, Volume 149
      Author(s): Per M. Nielsen , Angela Fago
      Carbonic anhydrase (CA) is a zinc enzyme that catalyzes hydration of carbon dioxide (CO2) and dehydration of bicarbonate in red blood cells, thus facilitating CO2 transport and excretion. Bovine CA II may also react with nitrite to generate nitric oxide, although nitrite is a known inhibitor of the CO2 hydration reaction. To address the potential in vivo interference of these reactions and the nature of nitrite binding to the enzyme, we here investigate the inhibitory effect of 10–30mM nitrite on Michaelis–Menten kinetics of CO2 hydration and bicarbonate dehydration by stopped-flow spectroscopy. Our data show that nitrite significantly affects the apparent dissociation constant K M for CO2 (11mM) and bicarbonate (221mM), and the turnover number k cat for the CO2 hydration (1.467×106 s−1) but not for the bicarbonate dehydration (7.927×105 s−1). These effects demonstrate mixed and competitive inhibition for the reaction with CO2 and bicarbonate, respectively, and are consistent with nitrite binding to the active site zinc. The high apparent dissociation constant found here for CO2, bicarbonate and nitrite (16–120mM) are all overall consistent with published data and reveal a large capacity of free enzyme available for binding each of the three substrates at their in vivo levels, with little or no significant interference among reactions. The low affinity of the enzyme for nitrite suggests that the in vivo interaction between red blood cell CA II and nitrite requires compartmentalization at the anion exchanger protein of the red cell membrane to be physiologically relevant.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Contents
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146




      PubDate: 2015-05-18T17:32:13Z
       
  • Macrophage and colon tumor cells as targets for a binuclear silver(I)
           N-heterocyclic carbene complex, an anti-inflammatory and apoptosis
           mediator
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Muhammad Adnan Iqbal , Muhammad Ihtisham Umar , Rosenani A. Haque , Mohamed B. Khadeer Ahamed , Mohd Zaini Bin Asmawi , Amin Malik Shah Abdul Majid
      Chronic inflammation intensifies the risk for malignant neoplasm, indicating that curbing inflammation could be a valid strategy to prevent or cure cancer. Cancer and inflammation are inter-related diseases and many anti-inflammatory agents are also used in chemotherapy. Earlier, we have reported a series of novel ligands and respective binuclear Ag(I)–NHC complexes (NHC= N-heterocyclic carbene) with potential anticancer activity. In the present study, a newly synthesized salt (II) and respective Ag(I)–NHC complex (III) of comparable molecular framework were prepared for a further detailed study. Preliminarily, II and III were screened against HCT-116 and PC-3 cells, wherein III showed better results than II. Both the compounds showed negligible toxicity against normal CCD-18Co cells. In FAM-FLICA caspase assay, III remarkably induced caspase-3/7 in HCT-116 cells most probably by tumor necrosis factor-alpha (TNF-α) independent intrinsic pathway and significantly inhibited in vitro synthesis of cytokines, interleukin-1 (IL-1) and TNF-α in human macrophages (U937 cells). In a cell-free system, both the compounds inhibited cyclooxygenase (COX) activities, with III being more selective towards COX-2. The results revealed that III has strong antiproliferative property selectively against colorectal tumor cells which could be attributed to its pro-apoptotic and anti-inflammatory abilities.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Design, synthesis and anticancer activity of diam(m)ine platinum(II)
           complexes bearing a small-molecular cell apoptosis inducer dichloroacetate
           
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Weiping Liu , Jing Jiang , Yongping Xu , Shuqian Hou , Liping Sun , Qingsong Ye , Liguang Lou
      Four new diam(m)ine platinum complexes containing the dichloroacetate moiety in 3-dichoroacetoxylcyclobutane-1,1-dicarboxylate as the leaving group were synthesized, characterized by elemental analysis as well as by ESI+-MS (electrospray ionization mass spectrometry in positive mode), FT-IR, 1H- and 13C-NMR, and evaluated for their in vitro anticancer activity against human lung cancer cell line (A549) and ovarian cancer cell lines (SK-OV-3, SK-OV-3/DDP). Diam(m)ines used in the present study belong to the carriers of six clinically approved platinum drugs. Among the complexes synthesized, complex 2, cis-[Pt(II)(1R,2R-diaminocyclohexane)·(3-dichoroacetoxylcyclobutane-1,1-dicarboxylate)] is the most promising in terms of water solubility and potential of being totally devoid of cross-drug resistance with cisplatin. Therefore, complex 2 was selected for the dichloroacetate release test. The test shows dichloroacetate can be efficiently released from complex 2 under physiological conditions via the hydrolysis of an ester bond bridging the dichloroacetate moiety and platinum pharmacophores together. Our study supports the further evaluation of this complex as a drug candidate.
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      PubDate: 2015-05-18T17:32:13Z
       
  • (Aminophosphane)gold(I) and silver(I) complexes as antibacterial agents
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Lourdes Ortego , Jesús Gonzalo-Asensio , Antonio Laguna , M. Dolores Villacampa , M. Concepción Gimeno
      This manuscript describes the synthesis of new Au(I) and Ag(I) complexes with aminophosphane ligands and a study of their antibacterial activity against Gram-negative Salmonella enterica serovar typhimurium and Escherichia coli and Gram-positive Listeria monocytogenes and Staphylococcus aureus. The bactericidal assays revealed the effectiveness of these compounds on paradigm Gram-negative and Gram-positive pathogens, showing a moderate antimicrobial activity, comparable with the antibiotics of reference, for all gold(I) complexes and the silver(I) complexes without coordinated PPh3 groups. For those complexes that were found to show inhibitory activity, serial dilutions in liquid broth method were performed for determination of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration).
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      PubDate: 2015-05-18T17:32:13Z
       
  • Europium-doped Gd2O3 nanotubes cause the necrosis of primary mouse bone
           marrow stromal cells through lysosome and mitochondrion damage
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Yi Jin , Shizhu Chen , Jianlei Duan , Guang Jia , Jinchao Zhang
      With the wide applications of europium-doped Gd2O3 nanoparticles (Gd2O3:Eu3+ NPs) in biomedical fields, it will inevitably increase the chance of human exposure. It was reported that Gd2O3:Eu3+ NPs could accumulate in bone. However, there have been few reports about the potential effect of Gd2O3:Eu3+ NPs on bone marrow stromal cells (BMSCs). In this study, the Gd2O3:Eu3+ nanotubes were prepared and characterized by powder X-ray diffraction (XRD), photoluminescence (PL) excitation and emission spectra, scanning electron microscope (SEM), and transmission electron microscopy (TEM). The cytotoxicity of Gd2O3:Eu3+ nanotubes on BMSCs and the associated mechanisms were further studied. The results indicated that they could be uptaken into BMSCs by an energy-dependent and macropinocytosis-mediated endocytosis process, and primarily localized in lysosome. Gd2O3:Eu3+ nanotubes effectively inhibited the viability of BMSCs in concentration and time-dependent manners. A significant increase in the percentage of late apoptotic/necrotic cells, lactate dehydrogenase (LDH) leakage and the number of PI-stained cells was found after BMSCs were treated by 10, 20, and 40μg/mL of Gd2O3:Eu3+ nanotubes for 12h. No obvious DNA ladders were detected, but a dispersed band was observed. The above results revealed that Gd2O3:Eu3+ nanotubes could trigger cell death by necrosis instead of apoptosis. Two mechanisms were involved in Gd2O3:Eu3+ nanotube-induced BMSCs necrosis: lysosomal rupture and release of cathepsins B; and the overproduction of reactive oxygen species (ROS) injury to the mitochondria and DNA. The study provides novel evidence to elucidate the toxicity mechanisms and may be beneficial to more rational applications of these nanomaterials in the future.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Platinated oligomers of bovine pancreatic ribonuclease: Structure and
           stability
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Delia Picone , Federica Donnarumma , Giarita Ferraro , Irene Russo Krauss , Andrea Fagagnini , Giovanni Gotte , Antonello Merlino
      The reaction between cis-diamminedichloroplatinum(II) (CDDP), cisplatin, a common anticancer drug, and bovine pancreatic ribonuclease (RNase A), induces extensive protein aggregation, leading to the formation of one dimer, one trimer and higher oligomers whose yields depend on cisplatin/protein ratio. Structural and functional properties of the purified platinated species, together with their spontaneous dissociation and thermally induced denaturation, have been characterized. Platinated species preserve a significant, although reduced, ribonuclease activity. The high resistance of the dimers against dissociation and the different thermal unfolding profiles suggest a quaternary structure different from those of the well-known swapped dimers of RNase A.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Quantification of bindings of organometallic ruthenium complexes to
           GSTπ by mass spectrometry
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Yu Lin , Yongdong Huang , Wei Zheng , Kui Wu , Qun Luo , Yao Zhao , Shaoxiang Xiong , Fuyi Wang
      Electrospray ionization mass spectrometry (ESI-MS) has been widely used to identify binding sites of metal complexes to proteins. However, the MS quantification of the metal–protein coordination remains a challenge. We have recently demonstrated by ESI-MS analysis that organometallic ruthenium complexes [(η6-arene)Ru(en)Cl]+ (arene= p-cymene (1), biphenyl (2) or 9,10-dihydrophenanthrene (3); en=ethylenediamine) bound to human glutathione-S-transferase π (GSTπ) at Cys15 and Cys48 within the G-site, and Cys102 and Met92 on the interface of the GSTπ dimer, showing inhibitory potency against the enzyme (J. Inorg. Biochem., 128 (2013) 77–84). Herein, we developed a mass spectrometric method to quantify the binding stoichiometry of the three complexes to GSTπ. The differences in signal intensities of the heavy-labelled peptides produced by tryptic digestion of the ruthenated GSTπ complexes and the respective light-labelled peptides in the tryptic digest of equimolar GSTπ were used to calculate the binding stoichiometry at specific residues. The results indicated that the pre-complexation of GSTπ with its substrate GSH significantly reduced the bindings of the ruthenium complexes at Met92 and Cys102, but had little impact on the bindings at Cys15 and Cys48. As the inhibitory activities of the ruthenium complexes against GSTπ are similar to those against GSTπ in complexation with GSH, these results suggest that the inhibition of the ruthenium complexes on GSTπ is attributed to the ruthenation at Cys15 and Cys48. The present work provides not only insights into the understanding on the inhibitory mechanism of ruthenium complexes GSTπ, but also a general method for quantitative characterization of metal–protein interactions.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Association of structural modifications with bioactivity in three new
           copper(II) complexes of Schiff base ligands derived from
           5-chlorosalicylaldehyde and amino acids
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Ang Li , Ya-Hong Liu , Ling-Zhi Yuan , Zhong-Ying Ma , Chun-Lai Zhao , Cheng-Zhi Xie , Wei-Guo Bao , Jing-Yuan Xu
      Three novel structurally associated copper(II) complexes [CuII(SalCl-Gly)(H2O)2] (1), [CuII(SalCl-Ala)(H2O)] (2) and [CuII(SalCl-Gly)(bipy)]·0.5H2O (3) (SalCl-Gly=5-chloro-2-hydroxybenzylidene-glycine, SalCl-Ala=5-chloro-2-hydroxybenzylidene-alanine, bipy=2,2′-bipyridine) have been synthesized and characterized by X-ray crystallography, elemental analysis, IR and fluorescence spectroscopy. Single-crystal diffraction reveals that complex 1 is an infinite 1D zigzag chain in which SalCl-Gly serves as both a chelating and a bridging ligand, while complexes 2 and 3 are mononuclear. Cu(II) ions in complexes 1–3 exhibit distorted quasi-hexacoordinated octahedral, tetracoordinated square planar, and pentacoordinated square pyramid geometry, respectively. Their interactions with calf thymus DNA (CT-DNA) have been investigated by viscosity measurements and fluorescence spectroscopy. The apparent binding constant (K app) values for 1–3 are 1.02×105, 0.98×105 and 1.57×105 M−1, respectively. All complexes displayed efficient oxidative cleavage of supercoiled DNA in the presence of H2O2. Complex 2, whose ligand can be regarded as a methyl-modification of SalCl-Gly of 1, showed a reduced DNA cleavage activity and a little-changed DNA-binding ability compared with 1. While attaching a 2,2′-bipyridine group to 1, the resulting complex 3 was conferred an enhanced intercalation into DNA. Moreover, cytotoxicity studies of three complexes against HepG-2 (human liver hepatocellular carcinoma) and NCI-H460 (human large-cell lung carcinoma) cells indicated that, thereto, complex 3 possessed the highest inhibition on viability of tested cells.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Hypobromous acid, a powerful endogenous electrophile: Experimental and
           theoretical studies
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Valdecir Farias Ximenes , Nelson Henrique Morgon , Aguinaldo Robinson de Souza
      Hypobromous acid (HOBr) is an inorganic acid produced by the oxidation of the bromide anion (Br−). The blood plasma level of Br− is more than 1,000-fold lower than that of chloride anion (Cl−). Consequently, the endogenous production of HOBr is also lower compared to hypochlorous acid (HOCl). Nevertheless, there is much evidence of the deleterious effects of HOBr. From these data, we hypothesized that the reactivity of HOBr could be better associated with its electrophilic strength. Our hypothesis was confirmed, since HOBr was significantly more reactive than HOCl when the oxidability of the studied compounds was not relevant. For instance: anisole (HOBr, k2 =2.3×102 M−1 s−1, HOCl non-reactive); dansylglycine (HOBr, k2 =7.3×106 M−1 s−1, HOCl, 5.2×102 M−1 s−1); salicylic acid (HOBr, k2 =4.0×104 M−1 s−1, non-reactive); 3-hydroxybenzoic acid (HOBr, k2 =5.9×104 M−1 s−1, HOCl, k2 =1.1×101 M−1 s−1); uridine (HOBr, k2 =1.3×103 M−1 s−1, HOCl non-reactive). The compounds 4-bromoanisole and 5-bromouridine were identified as the products of the reactions between HOBr and anisole or uridine, respectively, i.e. typical products of electrophilic substitutions. Together, these results show that, rather than an oxidant, HOBr is a powerful electrophilic reactant. This chemical property was theoretically confirmed by measuring the positive Mulliken and ChelpG charges upon bromine and chlorine. In conclusion, the high electrophilicity of HOBr could be behind its well-established deleterious effects. We propose that HOBr is the most powerful endogenous electrophile.
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      PubDate: 2015-05-18T17:32:13Z
       
  • A new mononuclear manganese(III) complex of an unsymmetrical hexadentate
           N3O3 ligand exhibiting superoxide dismutase and catalase-like activity:
           synthesis, characterization, properties and kinetics studies
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Gabriela N. Ledesma , Hélène Eury , Elodie Anxolabéhère-Mallart , Christelle Hureau , Sandra R. Signorella
      A mononuclear MnIII complex MnL·4H2O (H3L=1-[N-(2-pyridylmethyl),N-(2-hydroxybenzyl)amino]-3-[N′-(2-hydroxybenzyl),N′-(4-methylbenzyl)amino]propan-2-ol) has been prepared and characterized. This complex catalyzes the dismutation of superoxide efficiently, with catalytic rate constant kcat =1.7×106 M−1 s−1 and IC 50 1.26μM, obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutase assay, in aqueous solution of pH7.8. MnL is also able to disproportionate more than 300 equivalents of H2O2 in CH3CN, with initial rate of H2O2 decomposition given by ri = kcat [MnL]2 [H2O2] and kcat =1.32(2)mM−2 min−1. The accessibility of the MnIV state (E p =0.53V vs. saturated calomel electrode), suggests MnL employs a high-valent catalytic cycle to decompose O2 − and H2O2.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Synthesis, characterization, hydrolase and catecholase activity of a
           dinuclear iron(III) complex: Catalytic promiscuity
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Tiago P. Camargo , Fernanda F. Maia , Cláudia Chaves , Bernardo de Souza , Adailton J. Bortoluzzi , Nathalia Castilho , Tiago Bortolotto , Hernán Terenzi , Eduardo E. Castellano , Wolfgang Haase , Zbigniew Tomkowicz , Rosely A. Peralta , Ademir Neves
      Herein, we report the synthesis and characterization of the new di-iron(III) complex [(bbpmp)(H2O)(Cl)FeIII(μ-Ophenoxo)FeIII(H2O)Cl)]Cl (1), with the symmetrical ligand 2,6-bis{[(2-hydroxybenzyl)(pyridin-2-yl)methylamino]methyl}-4-methylphenol (H3bbpmp). Complexes 2 with the unsymmetrical ligand H2bpbpmp — {2-[[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl]-6-bis(pyridylmethyl) aminomethyl}-4-methylphenol and 3 with the ligand L1 =4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam were included for comparison purposes. Complex 1 was characterized through elemental analysis, X-ray crystallography, magnetochemistry, electronic spectroscopy, electrochemistry, mass spectrometry and potentiometric titration. The magnetic data show a very weak antiferromagnetic coupling between the two iron centers of the dinuclear complex 1 (J =−0.29cm−1). Due to the presence of labile coordination sites in both iron centers the hydrolysis of both the diester model substrate 2,4-BDNPP and DNA was studied in detail. Complex 1 was also able to catalyze the oxidation of the substrate 3,5-di-tert-butylcatechol (3,5-DTBC) to give the corresponding quinone, and thus it can be considered as a catalytically promiscuous system.
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      PubDate: 2015-05-18T17:32:13Z
       
  • A ruthenium(II) complex inhibits tumor growth in vivo with fewer
           side-effects compared with cisplatin
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Jin-Quan Wang , Ping-Yu Zhang , Liang-Nian Ji , Hui Chao
      The antitumor activity of a ruthenium(II) polypyridyl complex, Δ-[Ru(bpy)2(HPIP)](ClO4)2 (Δ-Ru1, where bpy=2,2′-bipyridine, HPIP=2-(2-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline), was evaluated. The in vivo experiments showed that Δ-Ru1 inhibited the growth of a human cervical carcinoma cell line (HeLa) xenotransplanted into nude mice with efficiency similar to that of cisplatin. Histopathology examination of the tumors from treated xenograft models was consistent with apoptosis in tumor cells. Importantly, in striking contrast with cisplatin, Δ-Ru1 did not cause any detectable side effects on the kidney, liver, peripheral neuronal system, or the hematological system at the pharmacologically effective dose. The preclinical studies reported here provide support for the clinical use of Δ-Ru1 as an exciting new drug candidate with lower toxicity than cisplatin, endowed with proapoptotic properties.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Controlling diabetes by chromium complexes: The role of the ligands
    • Abstract: Publication date: May 2015
      Source:Journal of Inorganic Biochemistry, Volume 146
      Author(s): Mei Peng , Xiaoping Yang
      Diabetes, particularly type II diabetes, is a severe disease condition which affects human health worldwide, with a dramatically increasing trend in Asian countries including China. Currently, no efficient drugs other than those with observable side effects are available. Chromium complexes, with the most known representative chromium picolinate, have been listed as one of most attractive health supplements to attenuate this disease condition in western countries. Recent efforts have been made to develop new chromium complexes with novel ligands. Although fair amounts of reviews have been published to emphasize the biological activity, preclinical and clinical information of chromium picolinate, this mini-review is trying to cover the entire picture of updated research efforts on various chromium complexes highlighting the role of ligands. Chromium phenylalanine sensitizes insulin cell signaling pathway via the activation of phosphorylation of Akt (protein kinase B (PKB)) and/or AMPK (AMP-activated protein kinase). The biological activities, toxicity, pharmacological features and clinical implications, including the effect of anti-oxidative capacities, protective effect on obese-induced heart dysfunction, and efficacy and safety of chromium supplementation in diabetes are discussed as well.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Novel mixed metal Ag(I)-Sb(III)-metallotherapeutics of the NSAIDs, aspirin
           and salicylic acid. Enhancement of their solubility and bioactivity by
           using the surfactant CTAB
    • Abstract: Publication date: Available online 1 May 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): E.I. Gkaniatsou , C.N. Banti , N. Kourkoumelis , S. Skoulika , M. Manoli , A.J. Tasiopoulos , S.K. Hadjikakou
      The already known Ag(I)-Sb(III) compound of the formula {Ag(Ph3Sb)3(NO3)} (1) and two novel mixed metal Ag(I)-Sb(III) metallotherapeutics of the formulae {Ag(Ph3Sb)3(SalH)}(2) and {Ag(Ph3Sb)3(Asp)}(3) (SalH2 =salicylic acid, AspH=aspirin or 2-acetylsalicylic acid and Ph3Sb=triphenyl antimony(III)) have been synthesised and characterised by m.p., vibrational spectroscopy (mid-FT-IR), 13C-,1H-NMR, UV-visible (UV-vis) spectroscopic techniques, high resolution mass spectroscopy (HRMS) and X-ray crystallography. Compounds 1,-3 were treated with the surfactant cetyltrimethylammonium bromide (CTAB) in order to enhance their solubility and as a consequence their bioactivity. The resulting micelles a-c were characterised with X-ray powder diffraction (XRPD) analysis, X-ray fluorescence (XRF) spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), conductivity, Thermal gravimetry–differential thermal analysis (TG–DTA), and atomic absorption. Compounds 1-3 and the relevant micelles a-c were evaluated for their in vitro cytotoxic activity against human cancer cell lines: MCF-7 (breast, estrogen receptor (ER) positive), MDA-MB-231 (breast, ER negative) and MRC-5 (normal human fetal lung fibroblast cells) with sulforhodamine B (SRB) colorimetric assay. The results show significant increase in the activity of micelles compared to that of the initial compounds. Moreover, micelles exhibited lower activity against normal cells than tumor cells. The binding affinity of a-c towards the calf thymus (CT)-DNA, lipoxygenase (LOX) and glutathione (GSH) was studied by the fluorescent emission light and UV-vis spectroscopy.
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      PubDate: 2015-05-18T17:32:13Z
       
  • The effect of phosphate on the nuclease activity of vanadium compounds
    • Abstract: Publication date: Available online 25 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Nataliya Butenko , José Paulo Pinheiro , José Paulo Da Silva , Ana Isabel Tomaz , Isabel Correia , Vera Ribeiro , João Costa Pessoa , Isabel Cavaco
      The nuclease activity of VO(acac)2 (1, acac = acetylacetone) and its derivatives VO(hd)2 (2, hd = 3,5-heptanedione), VO(Cl-acac)2 (3, Cl-acac = 3-chloro-2,4-pentanedione), VO(Et-acac)2 (4, Et-acac = 3-ethyl-2,4-pentanedione) and VO(Me-acac)2 (5, Me-acac = 3-methyl-2,4-pentanedione), is studied by agarose gel electrophoresis, UV–visible spectroscopy, cyclic and square wave voltammetry and 51V NMR. The mechanism is shown to be oxidative and associated with the formation of reactive oxygen species (ROS). Hydrolytic cleavage of the phosphodiester bond is also promoted by 1, but at much slower rate which cannot compete with the oxidative mechanism. The generation of ROS is much higher in the presence of phosphate buffer when compared with organic buffers and this was attributed to the formation of a mixed-ligand complex containing phosphate, (VIVO)(VVO)(acac)2(HnPO4 n-3), presenting a quasi-reversible voltammetric behavior. The formation of this species was further observed by Electrospray Ionization Mass Spectrometry (ESI-MS). Phosphate being an essential species in most biological media, the importance of the formation of mixed-ligand species in other vanadium systems is emphasized.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Activating tert-butyl hydroperoxide by chelated vanadates for
           stereoselectively preparing sidechain-functionalized tetrahydrofurans
    • Abstract: Publication date: Available online 23 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Maike Dönges , Matthias Amberg , Mark Niebergall , Jens Hartung
      tert-Butyl hydroperoxide (TBHP) stereoselectively oxidizes substituted 4-pentenols, when activated by (ethyl)[cis-(piperidine-2,6-diyl)dimethyl] vanadates. The reaction affords (tetrahydrofuran-2-yl)methanols in up to 89% yield, and in stereoselectivity ranging between moderate (cis:trans =32:68) to excellent (>99:1). Correlating structures of 4-pentenols, differing by substitution at tetragonal and trigonal stereocenters, to configuration of products obtained from oxidative cyclization provides a reaction model explaining the origin of stereoselectivity by (i) intramolecular oxygen atom transfer to (ii) a chair-like folded alkenol, being (iii) hydrogen-bonded to one of the two aminodiolate oxygens of the chelated vanadate, having (iv) substituents in the chair-like transition structure preferentially aligned equatorially. Substituents at trigonal stereocenters improve 2,5-cis- and 2,4-trans-selectivity for oxidative 4-pentenol cyclization in case of (Z)-configuration. An (E)-substituent does not alter selectivity exerted by a terminal (Z)-substituent of similar steric size. Larger (E)-groups increase the fraction of 2,5-trans-cyclized products. The reaction model additionally implements results from vanadium-51 NMR spectroscopy and density functional theory. According to theory, the (dialkoxy)(oxo)vanadium substituent exerts in the preferred end-on conformation almost no effect on structure and bonding of the peroxide group in tert-butylperoxy vanadates. Changing conformation to a higher in energy side-on arrangement puts the vanadate-bound tert-butylperoxy group into a position to serve in a concerted reaction as combined electron acceptor and oxygen atom donor.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Ru(II)-based complexes with
           N-(acyl)-N’,N’-(disubstituted)thiourea ligands: Synthesis,
           characterization, BSA- and DNA-binding studies of new cytotoxic agents
           against lung and prostate tumour cells
    • Abstract: Publication date: Available online 22 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Rodrigo S. Correa , Katia M. de Oliveira , Fábio G. Delolo , Anislay Alvarez , Raúl Mocelo , Ana M. Plutin , Marcia R. Cominetti , Eduardo E. Castellano , Alzir A. Batista
      Four ruthenium(II)-based complexes with N-(acyl)-N’,N’-(disubstituted)thiourea derivatives (Th) were obtained. The compounds, with the general formula trans-[Ru(PPh3)2(Th)(bipy)]PF6, interact with bovine serum albumin (BSA) and DNA. BSA-binding constants, which were in the range of 3.3–6.5 x 104 M−1, and the thermodynamic parameters (ΔG, ΔH and ΔS), suggest spontaneous interactions with this protein by electrostatic forces due to the positive charge of the complexes. Also, binding constant by spectrophotometric DNA titration (Kb = 0.8–1.8 x 104 M−1) and viscosity studies indicate weak interactions between the complexes and DNA. Cytotoxicity assays against DU-145 (prostate cancer) and A549 (lung cancer) tumour cells revealed that the complexes are more active in tumour cells than in normal (L929) cells, and that they present high cytotoxicity (low IC50 values) compared with the reference metallodrug, cisplatin.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Metalated nucleotides chemisorption on hydroxyapatite
    • Abstract: Publication date: Available online 19 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Michele Benedetti , Daniela Antonucci , Federica De Castro , Chiara R. Girelli , Marco Lelli , Norberto Roveri , Francesco P. Fanizzi
      The experiments here reported evidence the importance of the residual charge of a nucleotide derivative, for the adsorption on nHAP (hydroxyapatite nanocrystals), in water solution. We found that the simple presence of phosphates on the nucleotide derivative does not guarantee adsorption on nHAP. On the other hand, we demonstrated that a cationic or neutral charge on a nucleotide derivative produces a strongly reduced chemical adsorption (chemisorption) whereas, in the presence of a net negative charge, relevant adsorption on nHAP is observed. The number of phosphates can only modulate the adsorption efficiency of a molecule provided that this latter bears an overall negative charge. The neutral zwitterionic nucleotide Pt(II) complexes, bearing negatively charged phosphates, are unable to give stable chemisorption. Previous considerations are important to model the binding ability of phosphate bearing nucleotide derivatives or molecules on hydroxyapatite. The findings reported in the present paper could be relevant in bone tissue targeting or nHAP mediated drug delivery.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Synthesis and luminescence properties of salicylaldehyde isonicotinoyl
           hydrazone derivatives and their europium complexes
    • Abstract: Publication date: Available online 19 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Wenfei Shan , Fen Liu , Jiang Liu , Yanwen Chen , Zehui Yang , Dongcai Guo
      Four novel salicylaldehyde isonicotinoyl hydrazone derivatives and their corresponding europium ion complexes were synthesized and characterized, while the luminescence properties and the fluorescence quantum yields of the target complexes were investigated. The results indicated that the ligands favored energy transfers to the emitting energy level of europium ion, and four target europium complexes showed the characteristic luminescence of central europium ion. Besides the luminescence intensity of the complex with methoxy group, which possessed the highest fluorescence quantum yield (0.522), was stronger than that of other complexes. Furthermore, the electrochemical properties of the target complexes were further investigated by cyclic voltammetry, the results indicated that the highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels and the oxidation potential of the complexes with electron donating group increased, however, that of the complexes with accepting electron group decreased.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Evaluating transition state structures of vanadium–phosphatase
           protein complexes using shape analysis
    • Abstract: Publication date: Available online 17 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Irma Sánchez-Lombardo , Santiago Alvarez , Craig C. McLauchlan , Debbie C. Crans
      Shape analysis of coordination complexes is well-suited to evaluate the subtle distortions in the trigonal bipyramidal (TBPY-5) geometry of vanadium coordinated in the active site of phosphatases and characterized by X-ray crystallography. Recent studies using the tau (τ) analysis support the assertion that vanadium is best described as a trigonal bipyramid, because this geometry is the ideal transition state geometry of the phosphate ester substrate hydrolysis (C.C. McLauchlan, B.J. Peters, G.R. Willsky, D.C. Crans, Coord. Chem. Rev. http://dx.doi.org/10.1016/j.ccr.2014.12.012 ; D.C. Crans, M.L. Tarlton, C.C. McLauchlan, Eur. J. Inorg. Chem. 2014, 4450–4468). Here we use continuous shape measures (CShM) analysis to investigate the structural space of the five-coordinate vanadium–phosphatase complexes associated with mechanistic transformations between the tetrahedral geometry and the five-coordinate high energy TBPY-5 geometry was discussed focusing on the protein tyrosine phosphatase 1B (PTP1B) enzyme. No evidence for square pyramidal geometries was observed in any vanadium–protein complexes. The shape analysis positioned the metal ion and the ligands in the active site reflecting the mechanism of the cleavage of the organic phosphate in a phosphatase. We identified the umbrella distortions to be directly on the reaction path between tetrahedral phosphate and the TBPY-5-types of high-energy species. The umbrella distortions of the trigonal bipyramid are therefore identified as being the most relevant types of transition state structures for the phosphoryl group transfer reactions for phosphatases and this may be related to the possibility that vanadium is an inhibitor for enzymes that support both exploded and five-coordinate transition states.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Photoinduced reduction of the medial FeS center in the hydrogenase small
           subunit HupS from Nostoc punctiforme
    • Abstract: Publication date: Available online 14 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Patrícia Raleiras , Leif Hammarström , Peter Lindblad , Stenbjörn Styring , Ann Magnuson
      The small subunit from the NiFe uptake hydrogenase, HupSL, in the cyanobacterium Nostoc punctiforme ATCC 29133, has been isolated in the absence of the large subunit (P. Raleiras, P. Kellers, P. Lindblad, S. Styring, A. Magnuson, J. Biol. Chem. 288 (2013) 18,345–18,352). Here, we have used flash photolysis to reduce the iron-sulfur clusters in the isolated small subunit, HupS. We used ascorbate as electron donor to the photogenerated excited state of Ru(II)-trisbipyridine (Ru(bpy)3), to generate Ru(I)(bpy)3 as reducing agent. Our results show that the isolated small subunit can be reduced by the Ru(I)(bpy)3 generated through flash photolysis.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Complexes of N-hydroxyethyl-N-benzimidazolylmethylethylenediaminediacetic
           acid with group 12 metals and vanadium—Synthesis, structure and
           bioactivity of the vanadium complex
    • Abstract: Publication date: Available online 11 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Ladislav Habala , Caroline Bartel , Gerald Giester , Michael A. Jakupec , Bernhard K. Keppler , Annette Rompel
      Four new complexes of group 12 metals [Zn(II), Cd(II) and Hg(II)], along with vanadyl bound to the ligand N-hydroxyethyl-N-benzimidazolylmethylethylenediaminediacetic acid, have been synthesized and characterized. The structure of the complexes with Zn(II), Hg(II) and V(IV) was determined by X-ray structural analysis. In all observed cases, the symmetry of these complexes was found to be distorted octahedral. The inhibition of protein tyrosine phosphatase 1B by the vanadium(IV) complex was demonstrated. The cytotoxicity of the vanadium(IV) complex was tested in vitro against three cancer cell lines, with a comparison of the activity of the free ligand and of vanadyl acetylacetonate and sodium orthovanadate. The IC50 values of the complex were in the range of 9 to 21μM. Remarkably, cytotoxic potency in the multidrug-resistant non-small cell lung cancer cell line A549 was at least as high as in the broadly chemosensitive ovarian teratocarcinoma cell line CH1(PA-1).
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
  • Selective nuclei accumulation of ruthenium(II) complex enantiomers that
           target G-quadruplex DNA
    • Abstract: Publication date: Available online 11 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Dongdong Sun , Yanan Liu , Qianqian Yu , Du Liu , Yanhui Zhou , Jie Liu
      Different enantiomers exhibit large differences in their biological activity and/or toxicity, but they rarely involve the relationship of the agents for molecular and cellular imaging with the chiral structure of ruthenium complexes. Here, we report that an enantiomer of a polypyridyl ruthenium complex can selectively accumulate in the nucleus of HepG2 cells. Confocal laser scanning microscopy studies show that this phenomenon occurs via a non-endocytotic, but temperature-dependent, mechanism of cellular uptake in HepG2 cells. DNA oligonucleotides with repetitive tracts of guanine bases that can form G-quadruplex structures have aroused interest as therapeutic agents and as targets for anticancer drug design. Various biophysical techniques show that the Λ-enantiomer of ruthenium complexes can selectively stabilize human telomeric G-quadruplex DNA and has a strong preference for G-quadruplex over duplex DNA. Judged from the NMR results, we speculate that at higher 4:1 ligand/G-quadruplex stoichiometry, complex Λ–Ru is likely to bind with each groove of the tetraplex in a dimeric form or intercalate with the G-tetrad in the 3′ terminal face and coexist with other modes. The molecular modeling analysis is in agreement with the NMR titrations performed in this investigation indicating that ruthenium complexes are actually characterized by a mixed binding mode. The results provide many opportunities for the development of novel agents for living cell-related studies.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Hypoglycemic, lipid-lowering and metabolic regulation activities of
           metforminium decavanadate (H2Metf)3 [V10O28]·8H2O using
           hypercaloric-induced carbohydrate and lipid deregulation in Wistar rats as
           biological model
    • Abstract: Publication date: Available online 10 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Samuel Treviño , Eduardo Sánchez-Lara , Víctor Enrique Sarmiento-Ortega , Irma Sánchez-Lombardo , José Ángel Flores-Hernández , Aarón Pérez-Benítez , Eduardo Brambila-Colombres , Enrique González-Vergara
      Because of the increasing global spread of type 2 diabetes mellitus, there is a need to develop new antidiabetic agents. Recently we have synthesized new decavanadates using metformin as counterion. In particular, the compound containing three metforminium dications has been obtained in high yield and has been completely characterized. Biological studies using Wistar rats that have been fed with a high caloric diet inducing insulin resistance and metabolic syndrome were carried out. Results of the impact on key biochemical parameters mediated by metformin alone and the new compound are here presented. The metforminium decavanadate (H2Metf)3[V10O28]·8H2O, abbreviated as Metf-V10O28, was shown to have pharmacological potential as a hypoglycemic, lipid-lowering and metabolic regulator, since the resulting compound made of the two components with antidiabetic activities, reduces both dosage and time of administration (twice a week). Hence, due to the beneficial effects induced by the metforminium decavanadate we recommend to continue the exploration into the mechanism and toxicology of this new compound.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Preorganization of the catalytic Zn2+-binding site in the HNH nuclease
           motif—A solution study
    • Abstract: Publication date: Available online 9 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Eszter Németh , Milan Kožíšek , Gabriella K. Schilli , Béla Gyurcsik
      The structure of the active site in a metalloenzyme can be a key determinant of its metal ion binding affinity and catalytic activity. In this study, the conformational features of the Zn2+-binding HNH motif were investigated by CD-spectroscopy in combination with isothermal microcalorimetric titrations. Various point mutations, including T454A, K458A and W464A, were introduced into the N-terminal loop of the nuclease domain of colicin E7 (NColE7). We show that the folding of the proteins was severely disturbed by the mutation of the tryptophan residue. This points to the importance of W464, being a part of the hydrophobic core located close to the HNH-motif. ITC demonstrated that the Zn2+-binding of the mutants including the W464 site became weak, and according to CD-spectroscopic measurements the addition of the metal ion itself cannot fully recover the functional structure. Titrations with Zn2+-ion in the presence and absence of the Im7 protein proved that the structural changes in the unfolded mutant included the HNH-motif itself. The metal-binding of the NColE7 mutants could be, however, fully rescued by the complexation of Im7. This suggests that the formation of a preorganized metal-binding site – existing in the wild-type enzyme but not in the W464 mutants – was induced by Im7. The low nuclease activity of all W464A mutants, however, implies that the interactions of this tryptophan residue are required for precise location of the catalytic residues, i.e. for stabilization of the fine-structure and of the tertiary structure. Our results contribute to the understanding of the metal binding site preorganization.
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      PubDate: 2015-05-18T17:32:13Z
       
  • The bacteriohemerythrin from Methylococcus capsulatus (Bath): Crystal
           structures reveal that Leu114 regulates a water tunnel
    • Abstract: Publication date: Available online 9 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Kelvin H.-C. Chen , Phimonphan Chuankhayan , Hsin-Hui Wu , Chun-Jung Chen , Mitsuhiro Fukuda , Steve S.-F. Yu , Sunney I. Chan
      The bacteriohemerythrin (McHr) from Methylococcus capsulatus (Bath) is an oxygen carrier that serves as a transporter to deliver O2 from the cytosol of the bacterial cell body to the particulate methane monooxygenase residing in the intracytoplasmic membranes for methane oxidation. Here we report X-ray protein crystal structures of the recombinant wild type (WT) McHr and its L114A, L114Y and L114F mutants. The structure of the WT reveals a possible water tunnel in the McHr that might be linked to its faster autoxidation relative to hemerythrin in marine invertebrates. With Leu114 positioned at the end of this putative water tunnel, the hydrophobic side chain of this residue seems to play a prominent role in controlling the access of the water molecule required for autoxidation. This hypothesis is examined by comparing the autoxidation rates of the WT McHr with those of the L114A, L114Y and L114F mutants. The biochemical data are correlated with structural insights derived from the analysis of the putative water tunnels in the various McHr proteins provided by the X-ray structures.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Vanadium(V) and -(IV) complexes of anionic polysaccharides: Controlled
           release pharmaceutical formulations and models of vanadium
           biotransformation products
    • Abstract: Publication date: Available online 7 April 2015
      Source:Journal of Inorganic Biochemistry
      Author(s): Lauren E. Kremer , Andrew I. McLeod , Jade B. Aitken , Aviva Levina , Peter A. Lay
      Uncontrolled reactions in biological media are a main obstacle for clinical translation of V-based anti-diabetic or anti-cancer pro-drugs. We investigated the use of controlled-release pharmaceutical formulations to ameliorate this issue with a series of V(V) and (IV) complexes of anionic polysaccharides. Carboxymethyl cellulose, xanthan gum, or alginic acid formulations were prepared by the reactions of [VO4]3− with one or two molar equivalents of biological reductants, L-ascorbic acid (AA) or L-cysteine (Cys), in the presence of excess polysaccharide at pH~7 or pH~4. XANES studies with the use of a previously developed library of model V(V), V(IV) and V(III) complexes showed that reactions in the presence of AA led mostly to the mixtures of five- and six-coordinate V(IV) species, while the reactions in the presence of Cys led predominantly to the mixtures of five- and six-coordinate V(V) species. The XANES spectra of some of these samples closely matched those reported previously for [VO4]3− biotransformation products in isolated blood plasma, red blood cells, or cultured adipocytes, which supports the hypothesis that modified polysaccharides are major binders of V(V) and V(IV) in biological systems. Studies by EPR spectroscopy suggested predominant V(IV)-carboxylato binding in complexes with polysaccharides. One of the isolated products (a V(IV)-alginato complex) showed selective release of low-molecular-mass V species at pH~8, but not at pH~2, which makes it a promising lead for the development of V-containing formulations for oral administration that are stable in the stomach, but release the active ingredient in the intestines.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Editorial board
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145




      PubDate: 2015-05-18T17:32:13Z
       
  • Contents
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145




      PubDate: 2015-05-18T17:32:13Z
       
  • Sulfur and selenium antioxidants: Challenging radical scavenging
           mechanisms and developing structure–activity relationships based on
           metal binding
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145
      Author(s): Matthew T. Zimmerman , Craig A. Bayse , Ria R. Ramoutar , Julia L. Brumaghim
      Because sulfur and selenium antioxidants can prevent oxidative damage, numerous animal and clinical trials have investigated the ability of these compounds to prevent the oxidative stress that is an underlying cause of cardiovascular disease, Alzheimer's disease, and cancer, among others. One of the most common sources of oxidative damage is metal-generated hydroxyl radical; however, very little research has focused on determining the metal-binding abilities and structural attributes that affect oxidative damage prevention by sulfur and selenium compounds. In this review, we describe our ongoing investigations into sulfur and selenium antioxidant prevention of iron- and copper-mediated oxidative DNA damage. We determined that many sulfur and selenium compounds inhibit CuI-mediated DNA damage and that DNA damage prevention varies dramatically when FeII is used in place of CuI to generate hydroxyl radical. Oxidation potentials of the sulfur or selenium compounds do not correlate with their ability to prevent DNA damage, highlighting the importance of metal coordination rather than reactive oxygen species scavenging as an antioxidant mechanism. Additional gel electrophoresis, mass spectrometry, and UV–visible studies confirmed sulfur and selenium antioxidant binding to CuI and FeII. Ultimately, our studies established that both the hydroxyl-radical-generating metal ion and the chemical environment of the sulfur or selenium significantly affect DNA damage prevention and that metal coordination is an essential mechanism for these antioxidants.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Synthetic, potentiometric and spectroscopic studies of chelation between
           Fe(III) and 2,5-DHBA supports salicylate-mode of siderophore binding
           interactions
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145
      Author(s): Suheel K. Porwal , Emilia Furia , Michael E. Harris , Rajesh Viswanathan , L. Devireddy
      Catecholate type enterobactin, a prototype siderophore, comprises 2,3-dihydroxybenzoic acid (2,3-DHBA) cyclically linked to serine in E. coli. The existence of iron-chelating ligands in humans is a recent discovery, however, the basic chemical interactions between 2,5-dihydroxybenzoic acid and Fe(III) ion remain poorly understood. Achieving an accurate description of the fundamental Fe(III) binding properties of 2,5-DHBA is essential for understanding its role in iron transport mechanisms. Here, we show that 2,5-DHBA binds iron in a salicylate mode via a two-step kinetic mechanism by UV spectroscopy. Complexation between Fe(III) salt and 2,5-DHBA initially occurs at 1:1 ratio (of ligand to metal) and binding resulting in higher-order complexes continues at higher concentrations. Through potentiometric measurements we quantify the distribution of Fe(III)-2,5-DHBA complexes with 1:1, 1:2 and 1:3 stoichiometry. The formation of 1:3 complexes is further supported through high-resolution mass spectrometry. Further, using kinetic and equilibrium UV spectroscopy, we report Fe(III)-2,5-DHBA complex formation at a pH range of 2.5–9.0 at 298.15K in water. Maximum complexation occurred at a pH range of 4.5–6.5 consistent with deprotonation of the carboxylic acid proton. Equilibrium measurements and stopped-flow kinetics show that complexation rate constants were independent of concentrations of 2,5-DHBA. Together the data supports a model in which the rate-determining step involves rearrangement of ligands on an initial complex formed by reversible binding between the carboxylate group of 2,5-DHBA and Fe(III).
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      PubDate: 2015-05-18T17:32:13Z
       
  • pH-metric chemical speciation modeling and studies of in vitro
           antidiabetic effects of bis[(imidazolyl)carboxylato]oxidovanadium(IV)
           complexes
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145
      Author(s): Isaac Z. Gundhla , Ryan S. Walmsley , Vital Ugirinema , Nandipha O. Mnonopi , Eric Hosten , Richard Betz , Carminita L. Frost , Zenixole R. Tshentu
      A range of bidentate N,O-donor ligands of the imidazolyl-carboxylate moiety, which partially mimic naturally occurring bioligands, were prepared and reacted with the oxidovanadium(IV) ion to form the corresponding bis-coordinated oxidovanadium(IV) complexes. The aqueous pH-metric chemical speciation was investigated using glass electrode potentiometry, which allowed for the determination of protonation and stability constants of the ligands and complexes, respectively. The species distribution diagrams generated from this information gave evidence that the bis[(imidazolyl)carboxylato]oxovanadium(IV) complexes possess a broad pH-metric stability. The complexes improved glucose uptake in cell cultures using 3T3-L1 adipocytes, C2C12 muscle cells and Chang liver cells. The PTP inhibition studies indicated that the mechanism underlying insulin-stimulated glucose uptake was possibly via the protein tyrosine phosphorylation through the inhibition of the protein tyrosine phosphatase 1B (PTP 1B). The vanadium compounds also demonstrated the inhibition of D-dimer formation, suggesting that these compounds could potentially relieve a hypercoagulative state in diabetic patients.
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      PubDate: 2015-05-18T17:32:13Z
       
  • Bio-relevant cobalt(II) complexes with compartmental polyquinoline ligand:
           Synthesis, crystal structures and biological activities
    • Abstract: Publication date: April 2015
      Source:Journal of Inorganic Biochemistry, Volume 145
      Author(s): Jun-Ling Li , Lin Jiang , Bi-Wei Wang , Jin-Lei Tian , Wen Gu , Xin Liu , Shi-Ping Yan
      Three new Co(II) complexes, [Co4(L)2(μ 3-CrO4)2](ClO4)2 ·2CH3CN (1), [Co2(L)(μ 2-na)(H2O)](ClO4)2 (2) and [Co2(L)(μ 2-ba)](ClO4)2 ·0.5CH3CN (3) (Hna=nicotinic acid, Hba=benzoic acid, HL = N,N,N′,N′-tetrakis (2-quinolylmethyl)-1,3-diaminopropan-2-ol), have been synthesized and characterized by various physicochemical techniques. The Co(II) centers are connected by endogenous alkoxy bridge from L− and various extrinsic auxiliary linkers, some of which display coordination number asymmetry (5, 6-coordinated for 1 and 2; 5, 5-coordinated for 3). It is worth mentioning that complex 1 contains two rare reported μ 3-η 1, η 1, η 1-CrO4 2− moieties. Susceptibility data of three complexes indicated intramolecular antiferromagnetic coupling of high-spin Co(II) atoms with exchange integral values (J) −14.94cm−1, −11.26cm−1 and −13.66cm−1 for 1, 2 and 3, respectively. Interaction of compounds with calf thymus DNA (CT-DNA) have been investigated by absorption spectral titration, ethidium bromide (EB) displacement assay and viscosity measurement, which revealed that compounds bound to CT-DNA with a moderate intercalative mode, accompanied the affinities order: 1 > 2 ≈ 3. Three complexes exhibit oxidative cleavage of pBR322 plasmid DNA including a reliance on H2O2 as the activator. Compound 1 demonstrates an increased DNA cleavage activity as compared with 2 and 3, which could degrade super coiled DNA (SC DNA) into nicked coiled DNA (NC DNA) in lower concentration (5μM). Moreover, all compounds could quench the intrinsic fluorescence of bovine serum albumin (BSA) in a static quenching process. Complex 1 also shows higher anticancer activity than cisplatin with lower IC50 value of incubation for both 24h and 48h.
      Graphical abstract image

      PubDate: 2015-05-18T17:32:13Z
       
 
 
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