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Mizrahi A, Maimon E, Cohen H, Zilbermann I. Reactions of carbonate radical anion with amino-carboxylate complexes of manganese(II) and iron(III). J COORD CHEM 2018. [DOI: 10.1080/00958972.2018.1496242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Amir Mizrahi
- Chemistry Department, Nuclear Research Centre Negev, Beer-Sheva, Israel
| | - Eric Maimon
- Chemistry Department, Nuclear Research Centre Negev, Beer-Sheva, Israel
- Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Haim Cohen
- Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
- Chemical Sciences Department and the Schlesinger Family Center for Compact Accelerators, Radiation Sources and Applications, Ariel University, Ariel, Israel
| | - Israel Zilbermann
- Chemistry Department, Nuclear Research Centre Negev, Beer-Sheva, Israel
- Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Peng Q, Yuan Y, Zhang H, Bo S, Li Y, Chen S, Yang Z, Zhou X, Jiang ZX. 19F CEST imaging probes for metal ion detection. Org Biomol Chem 2018; 15:6441-6446. [PMID: 28741638 DOI: 10.1039/c7ob01068k] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
For detecting metal ions with 19F chemical exchange saturation transfer magnetic resonance imaging (19F CEST MRI), a class of novel fluorinated chelators with diverse fluorine contents and chelation properties were conveniently synthesized on gram scales. Among them, a DTPA-derived chelator with high sensitivity and selectivity was identified as a novel 19F CEST imaging probe for simultaneously detecting multiple metal ions.
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Affiliation(s)
- Qiaoli Peng
- Hubei Province Engineering and Technology Research Center for Fluorinated Pharmaceuticals and School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China.
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Hernandez JG, Silva AR, Thangarasu P, Najera RH, Moreno AD, Ledesma MTO, Cruz-Borbolla J, Singh N. Theoretical and experimental studies of phenol oxidation by ruthenium complex with N,N,N-tris(benzimidazol-2yl-methyl)amine. J Mol Model 2015; 21:224. [PMID: 26252971 DOI: 10.1007/s00894-015-2759-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 07/06/2015] [Indexed: 11/27/2022]
Abstract
The ruthenium complex with (N,N,N-tris(benzimidazol-2yl-methyl)amine, L(1)) was prepared, and characterized. Fukui data were used to localize the reactive sites on the ligand. The structural and electronic properties of the complex were analyzed by DFT in different oxidation states in order to evaluate its oxidant properties for phenol oxidation. The results show that the hard Ru(IV) cation bonds preferentially with a hard base (Namine = amine nitrogen, or axial chloride ion), and soft Ru(II) with a soft base (Nbzim = benzimidazole nitrogen or axial triphenyl phosphine). Furthermore, the Jahn-Teller effect causes an elongation of the axial bond in the octahedral structure. The bonding nature and the orbital contribution to the electronic transitions of the complex were studied. The experimental UV-visible bands were interpreted by using TD-DFT studies. The complex oxidizes phenol to benzoquinone in the presence of H2O2 and the intermediate was detected by HPLC and (13)C NMR. A possible mechanism and rate law are proposed for the oxidation. The adduct formation of phenol with [Ru(O)L(1)](2+) or [Ru(OH)L(1)](+) is theoretically analyzed to show that [Ru(OH)L(1)-OPh](+) could produce the phenol radical.
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Affiliation(s)
- J Guadalupe Hernandez
- Centro Tecnológico, Facultad de Estudios Superiores Aragón (FES-Aragón), Universidad Nacional Autónoma de México (UNAM), México, Estado de México, CP 57130, Mexico
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Wuttig K, Heller MI, Croot PL. Pathways of superoxide (O2(-)) decay in the Eastern Tropical North Atlantic. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:10249-56. [PMID: 23915117 DOI: 10.1021/es401658t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Superoxide (O2(-): IUPAC name dioxide (•1-)) is an important transient reactive oxygen species (ROS) in the ocean formed as an intermediate in the redox transformation of oxygen (O2) into hydrogen peroxide (H2O2) and vice versa. This highly reactive and very short-lived radical anion can be produced both via photochemical and biological processes in the ocean. In this paper we examine the decomposition rate of O2(-) throughout the water column, using new data collected in the Eastern Tropical North Atlantic (ETNA) Ocean. For this approach we applied a semi factorial experimental design to identify and quantify the pathways of the major identified sinks in the ocean. In this work we occupied six stations, two on the West African continental shelf and four open ocean stations, including the CVOO time series site adjacent to Cape Verde. Our results indicate that, in the surface ocean impacted by Saharan aerosols and coastal sediment resuspension, the main decay pathways for superoxide are via reactions with Mn(II) and organic matter.
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Affiliation(s)
- Kathrin Wuttig
- Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany
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Ouyang Y, Xie CZ, Xu JY, Yu L, Zhang ML, Liao DZ. Three cobalt (II) complexes with triethylenetetraaminehexaacetic acid: From binuclear complex to 3d-4f coordination polymers. INORG CHEM COMMUN 2013. [DOI: 10.1016/j.inoche.2012.10.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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The standard electrode potential (Eθ) predicts the prooxidant activity and the acute toxicity of metal ions. J Inorg Biochem 2011; 105:1438-45. [PMID: 21983258 DOI: 10.1016/j.jinorgbio.2011.08.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 08/12/2011] [Accepted: 08/12/2011] [Indexed: 11/20/2022]
Abstract
The standard electrode potential (E(θ)) has been known for many decades to predict the toxicity of metal ions. We have compiled acute toxicity data from fifteen studies and find that the toxicity of thirty metal ions correlates with E(θ) at r(2)=0.868 when toxicity is expressed as log concentration of comparably effective doses. We have discovered an even stronger relationship between the prooxidant activity (PA) of metal ions and E(θ) (and electronegativity, χ). Data compiled from thirty-four studies demonstrate that the PA of twenty-five metal ions correlates with E(θ) at r(2)=0.983 (and χ at r(2)=0.968). PA was commonly measured as metal-induced peroxidation of cell membranes or accumulation of reactive oxygen species. None of the redox metals (capable of Fenton-like reactions) in our studies (i.e., Mn, Fe, Co, Ni, and Cu) was prooxidative or toxic beyond what was expected from E(θ) or χ. We propose that the formation of superoxide-metal ion complexes is greater at greater E(θ) or χ values and that these complexes, whether free or enzyme-bound, function in PA without redox cycling of the complexed ion.
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Zhang Q, Gorden JD, Beyers RJ, Goldsmith CR. Manganese(II)-containing MRI contrast agent employing a neutral and non-macrocyclic ligand. Inorg Chem 2011; 50:9365-73. [PMID: 21888331 DOI: 10.1021/ic2009495] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ligand N,N'-bis(2-pyridylmethyl)-bis(ethylacetate)-1,2-ethanediamine (debpn) coordinates divalent transition metal ions in either a pentadentate or hexadentate fashion. The coordination number correlates with the ionic radius of the metal ion, with larger cations being heptacoordinate as assessed by solid-state analysis. With Mn(II), the debpn ligand is hexadentate and remains bound to the oxophilic metal ion, even when dissolved in water. The ligand's incomplete coordination of the manganous ion allows water molecules to coordinate to the metal center. These two properties, coupled with the high paramagnetism associated with the S = 5/2 metal center, enable [Mn(debpn)(H(2)O)](ClO(4))(2) to serve as a stable and effective magnetic resonance imaging contrast agent despite the ligand's lack of both a macrocyclic component and an anionic charge.
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Affiliation(s)
- Qiao Zhang
- Department of Chemistry & Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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Nam E, Alokolaro PE, Swartz RD, Gleaves MC, Pikul J, Kovacs JA. Investigation of the mechanism of formation of a thiolate-ligated Fe(III)-OOH. Inorg Chem 2011; 50:1592-602. [PMID: 21284379 DOI: 10.1021/ic101776m] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kinetic studies aimed at determining the most probable mechanism for the proton-dependent [Fe(II)(S(Me2)N(4)(tren))](+) (1) promoted reduction of superoxide via a thiolate-ligated hydroperoxo intermediate [Fe(III)(S(Me2)N(4)(tren))(OOH)](+) (2) are described. Rate laws are derived for three proposed mechanisms, and it is shown that they should conceivably be distinguishable by kinetics. For weak proton donors with pK(a(HA)) > pK(a(HO(2))) rates are shown to correlate with proton donor pK(a), and display first-order dependence on iron, and half-order dependence on superoxide and proton donor HA. Proton donors acidic enough to convert O(2)(-) to HO(2) (in tetrahydrofuran, THF), that is, those with pK(a(HA)) < pK(a(HO(2))), are shown to display first-order dependence on both superoxide and iron, and rates which are independent of proton donor concentration. Relative pK(a) values were determined in THF by measuring equilibrium ion pair acidity constants using established methods. Rates of hydroperoxo 2 formation displays no apparent deuterium isotope effect, and bases, such as methoxide, are shown to inhibit the formation of 2. Rate constants for p-substituted phenols are shown to correlate linearly with the Hammett substituent constants σ(-). Activation parameters ((ΔH(++) = 2.8 kcal/mol, ΔS(++) = -31 eu) are shown to be consistent with a low-barrier associative mechanism that does not involve extensive bond cleavage. Together, these data are shown to be most consistent with a mechanism involving the addition of HO(2) to 1 with concomitant oxidation of the metal ion, and reduction of superoxide (an "oxidative addition" of sorts), in the rate-determining step. Activation parameters for MeOH- (ΔH(++) = 13.2 kcal/mol and ΔS(++) = -24.3 eu), and acetic acid- (ΔH(++) = 8.3 kcal/mol and ΔS(++) = -34 eu) promoted release of H(2)O(2) to afford solvent-bound [Fe(III)(S(Me2)N(4)(tren))(OMe)](+) (3) and [Fe(III)(S(Me2)N(4)(tren))(O(H)Me)](+) (4), respectively, are shown to be more consistent with a reaction involving rate-limiting protonation of an Fe(III)-OOH, than with one involving rate-limiting O-O bond cleavage. The observed deuterium isotope effect (k(H)/k(D) = 3.1) is also consistent with this mechanism.
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Affiliation(s)
- Elaine Nam
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA
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Cunningham TM, Koehl JL, Summers JS, Haydel SE. pH-Dependent metal ion toxicity influences the antibacterial activity of two natural mineral mixtures. PLoS One 2010; 5:e9456. [PMID: 20209160 PMCID: PMC2830476 DOI: 10.1371/journal.pone.0009456] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Accepted: 02/02/2010] [Indexed: 11/18/2022] Open
Abstract
Background Recent studies have demonstrated that several mineral products sold for medicinal purposes demonstrate antimicrobial activity, but little is known about the physicochemical properties involved in antibacterial activity. Methodology/Principal Findings Using in vitro mineral suspension testing, we have identified two natural mineral mixtures, arbitrarily designated BY07 and CB07, with antibacterial activity against a broad-spectrum of bacterial pathogens. Mineral-derived aqueous leachates also exhibited antibacterial activity, revealing that chemical, not physical, mineral characteristics were responsible for the observed activity. The chemical properties essential for bactericidal activity against Escherichia coli were probed by testing antibacterial activity in the presence of metal chelators, the hydroxyl radical scavenger, thiourea, and varying pH levels. Chelation of the BY07 minerals with EDTA or desferrioxamine eliminated or reduced BY07 toxicity, respectively, suggesting a role of an acid-soluble metal species, particularly Fe3+ or other sequestered metal cations, in mineral toxicity. This conclusion was supported by NMR relaxation data, which indicated that BY07 and CB07 leachates contained higher concentrations of chemically accessible metal ions than leachates from non-bactericidal mineral samples. Conclusions/Significance We conclude that the acidic environment of the hydrated minerals significantly contributes to antibacterial activity by increasing the availability and toxicity of metal ions. These findings provide impetus for further investigation of the physiological effects of mineral products and their applications in complementary antibacterial therapies.
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Affiliation(s)
- Tanya M. Cunningham
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- The Biodesign Institute Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, Arizona, United States of America
| | - Jennifer L. Koehl
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Jack S. Summers
- Department of Chemistry, Western Carolina University, Cullowhee, North Carolina, United States of America
| | - Shelley E. Haydel
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- The Biodesign Institute Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, Arizona, United States of America
- * E-mail:
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