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Eltahir SB, Ali IH, Sulfab Y. Kinetics and mechanism of the one‐step, two‐electron oxidation of diaquadichloro(1,10‐phenanthroline)chromium(III) chloride dihydrate by periodate to chromium(V) in aqueous acidic solutions. INT J CHEM KINET 2021. [DOI: 10.1002/kin.21527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Sawsan B. Eltahir
- Department of Chemistry College of Science University of Khartoum Khartoum Sudan
- Chemistry Department Hafr Albatin University Hafr Albatin Saudi Arabia
| | - Ismat H. Ali
- Department of Chemistry College of Science University of Khartoum Khartoum Sudan
- Chemistry Department King Khalid University Abha Saudi Arabia
| | - Yousif Sulfab
- Department of Chemistry College of Science University of Khartoum Khartoum Sudan
- Chemistry Department Alneelain University Khartoum Sudan
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Potential antidiabetic molecule involving a new chromium(III) complex of dipicolinic and metformin as a counter ion: Synthesis, structure, spectroscopy, and bioactivity in mice. ARAB J CHEM 2021. [DOI: 10.1016/j.arabjc.2021.103236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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3
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Synthesis, spectroscopic characterization, and theoretical studies on the substitution reaction of chromium(III) picolinate. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.04.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Chai J, Liu Y, Liu B, Yang B. Effect of substituent groups (R= CH 3 , Br and CF 3 ) on the structure, stability and redox property of [Cr(R-pic) 2 (H 2 O) 2 ]NO 3 ·H 2 O complexes. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2017.08.099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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5
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Levina A, Crans DC, Lay PA. Speciation of metal drugs, supplements and toxins in media and bodily fluids controls in vitro activities. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.01.002] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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Ng VYM, Tse CW, Guan X, Chang X, Yang C, Low KH, Lee HK, Huang JS, Che CM. cis-Dioxorhenium(V/VI) Complexes Supported by Neutral Tetradentate N 4 Ligands. Synthesis, Characterization, and Spectroscopy. Inorg Chem 2017; 56:15066-15080. [PMID: 29190093 DOI: 10.1021/acs.inorgchem.7b02404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A series of cis-dioxorhenium(V) complexes containing chiral tetradentate N4 ligands, including cis-[ReV(O)2(pyxn)]+ (1; pyxn = N,N'-dimethyl-N,N'-bis(2-pyridylmethyl)cyclohexane-1,2-diamine), cis-[ReV(O)2(6-Me2pyxn)]+ (cis-2), cis-[ReV(O)2(R,R-pdp)]+ (3; R,R-pdp = 1,1'-bis((R,R)-2-pyridinylmethyl)-2,2'-bipyrrolidine), cis-[ReV(O)2(R,R-6-Me2pdp)]+ (4), and cis-[ReV(O)2(bqcn)]+ (5; bqcn = N,N'-dimethyl-N,N'-di(quinolin-8-yl)cyclohexane-1,2-diamine), were synthesized. Their structures were established by X-ray crystallography, showing Re-O distances in the range of 1.740(3)-1.769(8) Å and O-Re-O angles of 121.4(2)-124.8(4)°. Their cyclic voltammograms in MeCN (0.1 M [NBu4]PF6) display a reversible ReVI/V couple at E1/2 = 0.39-0.49 V vs SCE. In aqueous media, three proton-coupled electron transfer reactions corresponding to ReVI/V, ReV/III, and ReIII/II couples were observed at pH 1. The Pourbaix diagrams of 1·OTf, 3·OTf, and 5·OTf have been examined. The electronic absorption spectra of the cis-dioxorhenium(V) complexes show three absorption bands at around 800 nm (600-1730 dm3 mol-1 cm-1), 580 nm (1700-5580 dm3 mol-1 cm-1), and 462-523 nm (3170-6000 dm3 mol-1 cm-1). Reaction of 1 with Lewis acids (or protic acids) gave cis-[ReV(O)(OH)(pyxn)]2+ (1·H+), in which the Re-O distances are lengthened to 1.788(5) Å. Complex cis-2 resulted from isomerization of trans-2 at elevated temperature. cis-[ReVI(O)2(pyxn)](PF6)2 (1'·(PF6)2) was obtained by constant-potential electrolysis of 1·PF6 in MeCN (0.1 M [NBu4]PF6) at 0.56 V vs SCE; it displays shorter Re-O distances (1.722(4), 1.726(4) Å) and a smaller O-Re-O angle (114.88(18)°) relative to 1 and shows a d-d transition absorption band at 591 nm (ε = 77 dm3 mol-1 cm-1). With a driving force of ca. 75 kcal mol-1, 1' oxidizes hydrocarbons with weak C-H bonds (75.5-76.3 kcal mol-1) via hydrogen atom abstraction. DFT and TDDFT calculations on the electronic structures and spectroscopic properties of the cis-dioxorhenium(V/VI) complexes were performed.
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Affiliation(s)
- Vicky Yin-Ming Ng
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Chun-Wai Tse
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Xiangguo Guan
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Xiaoyong Chang
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Chen Yang
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Kam-Hung Low
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Hung Kay Lee
- Department of Chemistry, The Chinese University of Hong Kong , New Territories, Hong Kong, People's Republic of China
| | - Jie-Sheng Huang
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa
| | - Chi-Ming Che
- State Key Laboratory of Synthetic Chemistry, Institute of Molecular Functional Materials, and Department of Chemistry, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of Chinaa.,HKU Shenzhen Institute of Research and Innovation , Shenzhen 518053, People's Republic of China
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High cytotoxicity of vanadium(IV) complexes with 1,10-phenanthroline and related ligands is due to decomposition in cell culture medium. J Biol Inorg Chem 2017; 22:663-672. [PMID: 28374136 DOI: 10.1007/s00775-017-1453-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/21/2017] [Indexed: 12/11/2022]
Abstract
Cytotoxic effects of Metvan (cis-[VIVO(OSO3)(Me2phen)2], where Me2phen = 4,7-dimethyl-1,10-phenanthroline) and its analogues with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bpy) ligands in cultured human lung cancer (A549) cells have been re-investigated in conjunction with reactivity of the V(IV) complexes in neutral aerated aqueous solutions and in cell culture medium. All the V(IV) complexes underwent rapid oxidation to the corresponding V(V) species (cis-[VV(O)2L2]+), followed by release of free ligands (shown by electrospray mass spectrometry). Decomposition of V(IV) complexes in cell culture medium within minutes at 310 K was confirmed by UV-Vis and EPR spectroscopies. High cytotoxicities (low μM or sub-μM IC50 range in 72 h assays) were observed for the phen and Me2phen complexes, but they were not different from that of the corresponding free ligands, which confirmed that the original V(IV) complexes played no significant role in the observed biological activities. The cytotoxicities of the ligands were most likely due to their complexation of redox-active essential metal ions, such as Cu(II) and Fe(II), in the medium, and their increased cellular uptake, leading to oxidative stress-related cell death. These results emphasize the need to assess the stability of metal-based drugs under the conditions of biological assays, particularly when biologically active ligands, such as 1,10-phenanthroline and its derivatives, are used. These ligands have high systemic toxicities in vivo and their release in the GI tract and blood makes the complexes unsuitable for use as anti-cancer drugs.
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Spectroscopic characterization of genotoxic chromium(V) peptide complexes: Oxidation of Chromium(III) triglycine, tetraglycine and pentaglycine complexes. J Inorg Biochem 2016; 162:227-237. [DOI: 10.1016/j.jinorgbio.2016.06.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 06/07/2016] [Accepted: 06/14/2016] [Indexed: 11/23/2022]
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Eljack ND, Sulfab Y. Biphasic Oxidation of cis-Diaquabis(1,10-phenanthroline)chromium(III) by N-Bromosuccinimide and the Formation of Chromium(IV) and Chromium(V). INT J CHEM KINET 2016. [DOI: 10.1002/kin.20982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nasma D. Eljack
- Department of Chemistry; Faculty of Science; University of Khartoum; P. O. Box 321 Khartoum Sudan
| | - Yousif Sulfab
- Department of Chemistry; Faculty of Science; University of Khartoum; P. O. Box 321 Khartoum Sudan
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Pham THN, Aitken JB, Levina A, Lay PA. Solid-State Structural Studies of Chromium(III) Nicotinato Nutritional Supplements. Inorg Chem 2014; 53:10685-94. [DOI: 10.1021/ic501818w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- T. H. Nguyen Pham
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Jade B. Aitken
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
- Australian Synchrotron, Clayton, Victoria 3168, Australia
- Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan
| | - Aviva Levina
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Peter A. Lay
- School
of Chemistry, The University of Sydney, Sydney, New South Wales 2006, Australia
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11
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Abstract
Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.
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Affiliation(s)
- Peter A. Lay
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
| | - Aviva Levina
- School of Chemistry, The University of Sydney Sydney NSW 2006 Australia
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Eltahir SB, Sulfab Y. Kinetics and mechanism of the two electron oxidation of cis-CrIII(dipy)2(H2O)2]3+ (dipy = 2,2′-dipyridyl) by periodate ion to cis-[CrV(dipy)2(O)2]+ in aqueous acidic solutions. TRANSIT METAL CHEM 2014. [DOI: 10.1007/s11243-014-9814-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sudhamani CN, Bhojya Naik HS, Girija D. Synthesis, DNA binding, and cleavage studies of Co(III) complexes with fused aromatic NO/NN-containing ligands. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2012; 31:130-46. [PMID: 22303992 DOI: 10.1080/15257770.2011.644369] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Four new Co(III) complexes, namely [Co(cq)(3)](PF(6))(3), [Co(phen)(2)(cq)](PF(6))(3), [Co(bnp)(3)] (PF(6))(3), and [Co(phen)(2)(bnp)](PF(6))(3) (where cq = chromeno[2,3-b]quinoline, phen = 1,10-phenanthroline and bnp = dibenzo[b,g][1,8]naphthyridine), were synthesized and structurally characterized. Spectroscopic data suggested an octahedral geometry for all the complexes. Binding studies of these complexes with double-stranded (ds)DNA were analyzed by absorption spectra, viscosity, and thermal denaturation studies. The results revealed that the metal complex intercalates into the DNA base stack as intercalator. The oxidative cleavage activities of the complexes were studied with supercoiled pUC19 DNA using gel electrophoresis and the results show that the complexes have potent nuclease activity.
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Affiliation(s)
- Chittanahalli N Sudhamani
- Department of Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, Karnataka, India
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Dillon CT. Synchrotron Radiation Spectroscopic Techniques as Tools for the Medicinal Chemist: Microprobe X-Ray Fluorescence Imaging, X-Ray Absorption Spectroscopy, and Infrared Microspectroscopy. Aust J Chem 2012. [DOI: 10.1071/ch11287] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
This review updates the recent advances and applications of three prominent synchrotron radiation techniques, microprobe X-ray fluorescence spectroscopy/imaging, X-ray absorption spectroscopy, and infrared microspectroscopy, and highlights how these tools are useful to the medicinal chemist. A brief description of the principles of the techniques is given with emphasis on the advantages of using synchrotron radiation-based instrumentation rather than instruments using typical laboratory radiation sources. This review focuses on several recent applications of these techniques to solve inorganic medicinal chemistry problems, focusing on studies of cellular uptake, distribution, and biotransformation of established and potential therapeutic agents. The importance of using these synchrotron-based techniques to assist the development of, or validate the chemistry behind, drug design is discussed.
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Ali IH, Sulfab Y. One-step, two-electron oxidation of cis
-diaquabis(1,10-phenanthroline)chromium(III) to cis
-dioxobis(1,10-phenanthroline)chromium(V) by periodate in aqueous acidic solutions. INT J CHEM KINET 2011. [DOI: 10.1002/kin.20593] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ng VWL, Taylor MK, White JM, Young CG. cis-Dioxo- and cis-(Hydroxo)oxo-Mo(V) Complexes Stabilized by Intramolecular Hydrogen-Bonding. Inorg Chem 2010; 49:9460-9. [DOI: 10.1021/ic1011428] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Jonathan M. White
- School of Chemistry
- Bio21 Molecular Science and Biotechnology Institute
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Borthiry GR, Antholine WE, Myers JM, Myers CR. Addition of DNA to Cr(VI) and cytochrome b5 containing proteoliposomes leads to generation of DNA strand breaks and Cr(III) complexes. Chem Biodivers 2008; 5:1545-1557. [PMID: 18729091 PMCID: PMC2715337 DOI: 10.1002/cbdv.200890143] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Chromium (Cr) is a cytotoxic metal that can be associated with a variety of types of DNA damage, including Cr-DNA adducts and strand breaks. Prior studies with purified human cytochrome b(5) and NADPH:P450 reductase in reconstituted proteoliposomes (PLs) demonstrated rapid reduction of Cr(VI) (hexavalent chromium, as CrO(4)(2-), and the generation of Cr(V), superoxide (O(2)(*-)), and hydroxyl radical (HO(*)). Studies reported here examined the potential for the species produced by this system to interact with DNA. Strand breaks of purified plasmid DNA increased over time aerobically, but were not observed in the absence of O(2). Cr(V) is formed under both conditions, so the breaks are not mediated directly by Cr(V). The aerobic strand breaks were significantly prevented by catalase and EtOH, but not by the metal chelator diethylenetriaminepentaacetic acid (DTPA), suggesting that they are largely due to HO(*) from Cr-mediated redox cycling. EPR was used to assess the formation of Cr-DNA complexes. Following a 10-min incubation of PLs, CrO(4)(2-), and plasmid DNA, intense EPR signals at g=5.7 and g=5.0 were observed. These signals are attributed to specific Cr(III) complexes with large zero field splitting (ZFS). Without DNA, the signals in the g=5 region were weak. The large ZFS signals were not seen, when Cr(III)Cl(3) was incubated with DNA, suggesting that the Cr(III)-DNA interactions are different when generated by the PLs. After 24 h, a broad signal at g=2 is attributed to Cr(III) complexes with a small ZFS. This g=2 signal was observed without DNA, but it was different from that seen with plasmid. It is concluded that EPR can detect specific Cr(III) complexes that depend on the presence of plasmid DNA and the manner in which the Cr(III) is formed.
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Affiliation(s)
- Griselda R. Borthiry
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - William E. Antholine
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Judith M. Myers
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Charles R. Myers
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
- Free Radical Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Brückner A, Jabor JK, McConnell AEC, Webb PB. Monitoring Structure and Valence State of Chromium Sites during Catalyst Formation and Ethylene Oligomerization by in Situ EPR Spectroscopy. Organometallics 2008. [DOI: 10.1021/om800316m] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Angelika Brückner
- Leibniz-Institut für Katalyse an der Universität Rostock e. V., Branch Berlin, P.O. Box 961156, D-12474 Berlin, Germany, Sasol Technology R&D, 1 Klasie Havenga Road, P.O. Box, 1947 Sasolburg, South Africa, and Sasol Technology UK Ltd, Purdie Building, North Haugh, St. Andrews, FIFE, KY16 9ST, U.K
| | - Jabor K. Jabor
- Leibniz-Institut für Katalyse an der Universität Rostock e. V., Branch Berlin, P.O. Box 961156, D-12474 Berlin, Germany, Sasol Technology R&D, 1 Klasie Havenga Road, P.O. Box, 1947 Sasolburg, South Africa, and Sasol Technology UK Ltd, Purdie Building, North Haugh, St. Andrews, FIFE, KY16 9ST, U.K
| | - Ann E. C. McConnell
- Leibniz-Institut für Katalyse an der Universität Rostock e. V., Branch Berlin, P.O. Box 961156, D-12474 Berlin, Germany, Sasol Technology R&D, 1 Klasie Havenga Road, P.O. Box, 1947 Sasolburg, South Africa, and Sasol Technology UK Ltd, Purdie Building, North Haugh, St. Andrews, FIFE, KY16 9ST, U.K
| | - Paul B. Webb
- Leibniz-Institut für Katalyse an der Universität Rostock e. V., Branch Berlin, P.O. Box 961156, D-12474 Berlin, Germany, Sasol Technology R&D, 1 Klasie Havenga Road, P.O. Box, 1947 Sasolburg, South Africa, and Sasol Technology UK Ltd, Purdie Building, North Haugh, St. Andrews, FIFE, KY16 9ST, U.K
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González-Baró AC, Pis-Diez R, Piro OE, Parajón-Costa BS. Crystal structures, theoretical calculations, spectroscopic and electrochemical properties of Cr(III) complexes with dipicolinic acid and 1,10-phenantroline. Polyhedron 2008. [DOI: 10.1016/j.poly.2007.10.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Levina A, Harris HH, Lay PA. X-ray absorption and EPR spectroscopic studies of the biotransformations of chromium(VI) in mammalian cells. Is chromodulin an artifact of isolation methods? J Am Chem Soc 2007; 129:1065-75. [PMID: 17263387 DOI: 10.1021/ja063792r] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Very different biological activities are usually ascribed to Cr(VI) (a toxin and carcinogen) and Cr(III) (an antidiabetic agent), although recent evidence suggests that both these types of actions are likely to arise from cellular uptake of varying concentrations of Cr(VI). The first systematic study of XANES spectra of Cr(III) complexes formed in Cr(VI)-treated mammalian cells (A549, HepG2, V79, and C2C12 cell lines), and in subcellular fractions of A549 cells, has been performed using a library of XANES spectra of model Cr(III) complexes. The results of multiple linear regression analyses of XANES spectra, in combination with multiple-scattering fits of XAFS spectra, indicate that Cr(III) formed in Cr(VI)-treated cells is most likely to bind to carboxylato, amine, and imidazole residues of amino acids, and to a lesser extent to hydroxo or aqua ligands. A combination of XANES and EPR spectroscopic data for Cr(VI)-treated cells indicates that the main component of Cr(III) formed in such cells is bound to high-molecular-mass ligands (>30 kDa, probably proteins), but significant redistribution of Cr(III) occurs during the cell lysis, which leads to the formation of a low-molecular-mass (<30 kDa) Cr(III)-containing fraction. The spectroscopic (XANES, XAFS, and EPR) properties of this fraction were strikingly similar to those of the purported natural Cr(III)-containing factor, chromodulin, that was reported to be isolated from the reaction of Cr(VI) with liver. These data support the hypothesis that a chromodulin-like species, which is formed from such a reaction, is an artifact of the reported isolation procedure.
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Affiliation(s)
- Aviva Levina
- Centre for Heavy Metals Research, School of Chemistry, The University of Sydney, NSW 2006, Australia
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22
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Gez S, Luxenhofer R, Levina A, Codd R, Lay PA. Chromium(V) complexes of hydroxamic acids: formation, structures, and reactivities. Inorg Chem 2005; 44:2934-43. [PMID: 15819581 DOI: 10.1021/ic048317d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new family of relatively stable Cr(V) complexes, [Cr(V)O(L)(2)](-) (LH(2) = RC(O)NHOH, R = Me, Ph, 2-HO-Ph, or HONHC(O)(CH(2))(6)), has been obtained by the reactions of hydroxamic acids with Cr(VI) in polar aprotic solvents. Similar reactions in aqueous solutions led to the formation of transient Cr(V) species. All complexes have been characterized by electron paramagnetic resonance spectroscopy and electrospray mass spectrometry. A Cr(V) complex of benzohydroxamic acid (1, R = Ph) was isolated in a pure form (as a K(+) salt) and was characterized by X-ray absorption spectroscopy and analytical techniques. Multiple-scattering analysis of X-ray absorption fine structure spectroscopic data for 1 (solid, 10 K) point to a distorted trigonal-bipyramidal structure with trans-oriented Ph groups and Cr-ligand bond lengths of 1.58 A (Cr-O), 1.88 A (Cr-O(C)), and 1.98 A (Cr-O(N)). Under ambient conditions, 1 is stable for days in aprotic solvents but decomposes within minutes in aqueous solutions (maximal stability at pH approximately 7), which leads predominantly to the formation of Cr(III) complexes. Complex 1 readily undergoes ligand-exchange reactions with biological 1,2-diols, including D-glucose and mucin, in neutral aqueous solutions. It differs from most other types of Cr(V) complexes in its biological activity, since no oxidative cleavage of plasmid DNA in vitro and no significant bacterial mutagenicity (in the TA 102 strain of Salmonella typhimurium) was observed for 1. In natural systems, stabilization of Cr(V) by hydroxamato ligands from bacterial-derived siderophores (followed by ligand-exchange reactions with more abundant carbohydrate ligands) may occur during the biological reduction of Cr(VI) in contaminated soils.
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Affiliation(s)
- Swetlana Gez
- Centre for Heavy Metals Research, School of Chemistry, University of Sydney, NSW, 2006, Australia
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Barnard PJ, Levina A, Lay PA. Chromium(V) Peptide Complexes: Synthesis and Spectroscopic Characterization. Inorg Chem 2005; 44:1044-53. [PMID: 15859285 DOI: 10.1021/ic048322h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of stable Cr(V) model complexes that mimic the binding of Cr(V) to peptide backbones at the C-terminus of proteins have been prepared for N,N-dimethylurea derivatives of the tripeptides Aib3-DMF, AibLAlaAib-DMF, and AibDAlaAib-DMF (Aib = 2-amino-2-methylpropanoic acid, DMF = N,N-dimethylformamide). The Cr(ll) precursor complexes were synthesized by the initial deprotonation of the amide and acid groups of the peptide ligands in DMF with potassium tert-butoxide in the presence of CrCl2. The Cr(II) intermediates thus formed were then immediately oxidized to Cr(V) using tert-butyl hydroperoxide. Spectroscopic and mass-spectrometric analyses of the Cr(V) complexes showed that a new metal-directed organic transformation of the ligand had occurred. This involved a DMF solvent molecule becoming covalently bound to the amine group of the peptide ligand, yielding a urea group, and a third coordinated deprotonated urea nitrogen donor. A metal-directed oxidative coupling has been proposed as a possible mechanism for the organic transformation. The Cr(V/IV) reduction potential was determined for the three Cr(V) complexes using cyclic voltammetry, and in all cases it was quasi-reversible. These are the first isolated and fully characterized Cr(V) complexes with non-sulfur-containing peptide ligands.
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Affiliation(s)
- Peter J Barnard
- Centre for Heavy Metals Research, School of Chemistry, University of Sydney, New South Wales 2006, Australia
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Levina A, Armstrong RS, Lay PA. Three-dimensional structure determination using multiple-scattering analysis of XAFS: applications to metalloproteins and coordination chemistry. Coord Chem Rev 2005. [DOI: 10.1016/j.ccr.2004.10.008] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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