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Kovács H, Jakusch T, May NV, Tóth S, Szakács G, Enyedy ÉA. Complex formation of ML324, the histone demethylase inhibitor, with essential metal ions: Relationship between solution chemistry and anticancer activity. J Inorg Biochem 2024; 255:112540. [PMID: 38552361 DOI: 10.1016/j.jinorgbio.2024.112540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/15/2024] [Accepted: 03/22/2024] [Indexed: 04/16/2024]
Abstract
N-(3-(dimethylamino)propyl-4-(8-hydroxyquinolin-6-yl)benzamide (ML324, HL) is a potent inhibitor of the iron-containing histone demethylase KDM4, a recognized potential target of cancer therapeutics. Herein, we report the proton dissociation and complex formation processes of ML324 with essential metal ions such as Fe(II), Fe(III), Cu(II) and Zn(II) using UV-visible, fluorescence, electron paramagnetic resonance and 1H NMR spectroscopic methods. The electrochemical behaviour of the copper and iron complexes was characterized by cyclic voltammetry and spectroelectrochemistry. The solid phase structure of ML324 analysed by X-ray crystallography is also provided. Based on the solution equilibrium data, ML324 is present in solution in H2L+ form with a protonated dimethylammonium moiety at pH 7.4, and this (N,O) donor bearing ligand forms mono and bis complexes with all the studied metal ions and the tris-ligand species is also observed with Fe(III). At pH 7.4 the metal binding ability of ML324 follows the order: Fe(II) < Zn(II) < Cu(II) < Fe(III). Complexation with iron resulted in a negative redox potential (E'1/2 = -145 mV vs. NHE), further suggesting that the ligand has a preference for Fe(III) over Fe(II). ML324 was tested for its anticancer activity in chemosensitive and resistant human cancer cells overexpressing the efflux pump P-glycoprotein. ML324 exerted similar activity in all tested cells (IC50 = 1.9-3.6 μM). Co-incubation and complexation of the compound with Cu(II) and Zn(II) had no impact on the cytotoxicity of ML324, whereas Fe(III) decreased the toxicity in a concentration-dependent manner, and this effect was more pronounced in the multidrug resistant cells.
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Affiliation(s)
- Hilda Kovács
- MTA-SZTE Lendület Functional Metal Complexes Research Group, Department of Molecular and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary; Department of Molecular and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Tamás Jakusch
- Department of Molecular and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary
| | - Nóra V May
- Centre for Structural Science, Research Centre for Natural Sciences, Hungarian Research Network (HUN-REN), Magyar tudósok körútja 2, H-1117 Budapest, Hungary
| | - Szilárd Tóth
- Drug Resistance Research Group, Institute of Molecular Life Sciences, Research Centre for Natural Sciences, Hungarian Research Network (HUN-REN), Magyar Tudósok krt. 2, H-1117 Budapest, Hungary; National Laboratory for Drug Research and Development, Magyar Tudósok krt. 2, H-1117 Budapest, Hungary
| | - Gergely Szakács
- Drug Resistance Research Group, Institute of Molecular Life Sciences, Research Centre for Natural Sciences, Hungarian Research Network (HUN-REN), Magyar Tudósok krt. 2, H-1117 Budapest, Hungary; Center for Cancer Research, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Éva A Enyedy
- MTA-SZTE Lendület Functional Metal Complexes Research Group, Department of Molecular and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary; Department of Molecular and Analytical Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Dóm tér 7-8, H-6720 Szeged, Hungary.
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Jakusch T, Hassoon AA, Kiss T. Characterization of copper(II) specific pyridine containing ligands: Potential metallophores for Alzheimer's disease therapy. J Inorg Biochem 2021; 228:111692. [PMID: 34990971 DOI: 10.1016/j.jinorgbio.2021.111692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/29/2021] [Accepted: 12/03/2021] [Indexed: 10/19/2022]
Abstract
Two amide group containing pyridine derivatives, N-(pyridin-2-ylmethyl)picolinamide (PMPA) and N-(pyridin-2-ylmethyl)-2-((pyridin-2-ylmethyl)amino)acetamide (DPMGA), have been investigated as potential metallo-phores in the therapy of Alzheimer's disease. Their complex formation with Cu(II) and Zn(II) were characterized in details. Unexpectedly not only the Cu(II) but also the Zn(II) was able to induce deprotonation of the amide-NH, however, it occurred only at higher pH or at higher metal ion concentrations than the biological conditions. At μM concentration level mono complexes (MLH-1) dominate with both ligands. Direct fluorescence and reactive oxygen species (ROS) producing measurements prove that both ligands are able to remove Cu(II) from its amyloid-β complexes (CuAβ). Correlation was also established between the conditional stability constant of the Cu(II) complexes with different ligands and their ability of inhibition of ROS production by CuAβ.
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Affiliation(s)
- Tamás Jakusch
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
| | - Azza A Hassoon
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary
| | - Tamás Kiss
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
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Kiss T, Enyedy ÉA, Jakusch T, Dömötör O. Speciation of Metal Complexes of Medicinal Interest: Relationship between Solution Equilibria and Pharmaceutical Properties. Curr Med Chem 2019. [DOI: 10.2174/0929867325666180307113435] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Biospeciation of essential and toxic metal ions, metal complexes with biological or
medicinal activity are discussed in the paper in order to emphasize the importance of the distribution
of metal ions in biological milieu. The exact knowledge of the chemical species present
in the different organs/compartments/fluids/cells may provide essential information about
the pharmacokinetic properties and the biological effect of the metal ion or the drug candidate
metal complex. The transport of essential and toxic metal ions in the blood serum is discussed
first, which is followed by the description of biodistribution of several important metal complexes
with medicinal interest such as (i) anticancer, (ii) insulin-enhancing and (iii) MRI contrast
agents in biological fluids.
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Affiliation(s)
- Tamás Kiss
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dom ter 7, H-6720 Szeged, Hungary
| | - Éva A. Enyedy
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dom ter 7, H-6720 Szeged, Hungary
| | - Tamás Jakusch
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dom ter 7, H-6720 Szeged, Hungary
| | - Orsolya Dömötör
- Department of Inorganic and Analytical Chemistry, University of Szeged, Dom ter 7, H-6720 Szeged, Hungary
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Jakusch T, Kozma K, Enyedy ÉA, May NV, Roller A, Kowol CR, Keppler BK, Kiss T. Complexes of pyridoxal thiosemicarbazones formed with vanadium(IV/V) and copper(II): Solution equilibrium and structure. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.08.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Cobbina E, Mehtab S, Correia I, Gonçalves G, Tomaz I, Cavaco I, Jakusch T, Enyedi E, Kiss T, Costa Pessoa J. Binding of Oxovanadium(IV) Complexes to Blood Serum Albumins. J MEX CHEM SOC 2017. [DOI: 10.29356/jmcs.v57i3.205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In this work the binding of V<sup>IV</sup>O<sup>2+</sup> and V<sup>IV</sup>O-complexes to serum albumins {human serum albumin (HSA), bovine serum albumin (BSA) and porcine serum albumin (PSA)} are studied using circular dichroism (CD), electron paramagnetic resonance (EPR) and visible absorption spectroscopy. The results confirm previous findings that V<sup>IV</sup>O<sup>2+</sup> occupies at least two types of binding sites on albumin: ‘the strong vanadium binding site’ (designated by VBS1) and ‘the weak vanadium binding sites’ (designated by VBS2). VBS1 binds 1 mol equivalent of V<sup>IV</sup>O<sup>2+</sup>. On the other hand VBS2 correspond to binding of several mol equivalents of V<sup>IV</sup>O, and studies done with PSA in the presence of excess Zn<sup>II</sup> ions indicate that VSB2 corresponds to two distinct types of sites. The hyperfine coupling constant A<sub>z</sub> for V<sup>IV</sup>O<sup>2+</sup> binding at VBS2 on HSA and BSA are all very similar (~168 × 10-4 cm<sup>-1</sup>) but differ slightly on PSA (~166 × 10-4 cm<sup>-1</sup>) due to differences in the binding sets. When (V<sup>IV</sup>O)-HSA systems are titrated with maltol ternary species of (maltol)<sub>m</sub>(V<sup>IV</sup>O)<sub>m</sub>HSA and (maltol)<sub>2m</sub>(V<sup>IV</sup>O)<sub>m</sub>HSA stoichiometry form which are clearly distinguishable from the binary (V<sup>IV</sup>O)-HSA system by the type and intensity of the CD spectra recorded. Changes are also observable in the intensity of the X-band EPR spectra, but not much in the hyperfine coupling constants A<sub>z</sub>, which are all in the range 166-167 × 10-4 cm<sup>-1</sup>. The results further demonstrate that the presence of maltol may enhance the binding of VIVO to albumin.
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Kowol CR, Nagy NV, Jakusch T, Roller A, Heffeter P, Keppler BK, Enyedy ÉA. Vanadium(IV/V) complexes of Triapine and related thiosemicarbazones: Synthesis, solution equilibrium and bioactivity. J Inorg Biochem 2015; 152:62-73. [PMID: 26349014 DOI: 10.1016/j.jinorgbio.2015.08.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 07/29/2015] [Accepted: 08/24/2015] [Indexed: 01/07/2023]
Abstract
The stoichiometry and thermodynamic stability of vanadium(IV/V) complexes of Triapine and two related α(N)-heterocyclic thiosemicarbazones (TSCs) with potential antitumor activity have been determined by pH-potentiometry, EPR and (51)V NMR spectroscopy in 30% (w/w) dimethyl sulfoxide/water solvent mixtures. In all cases, mono-ligand complexes in different protonation states were identified. Dimethylation of the terminal amino group resulted in the formation of vanadium(IV/V) complexes with considerably higher stability. Three of the most stable complexes were also synthesized in solid state and comprehensively characterized. The biological evaluation of the synthesized vanadium complexes in comparison to the metal-free ligands in different human cancer cell lines revealed only minimal influence of the metal ion. Thus, in addition the coordination ability of salicylaldehyde thiosemicarbazone (STSC) to vanadium(IV/V) ions was investigated. The exchange of the pyridine nitrogen of the α(N)-heterocyclic TSCs to a phenolate oxygen in STSC significantly increased the stability of the complexes in solution. Finally, this also resulted in increased cytotoxicity activity of a vanadium(V) complex of STSC compared to the metal-free ligand.
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Affiliation(s)
- Christian R Kowol
- University of Vienna, Institute of Inorganic Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria; Research Platform "Translational Cancer Therapy Research" University of Vienna, Waehringer Strasse 42, A-1090 Vienna, Austria.
| | - Nóra V Nagy
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar Tudósok körútja 2, H-1117 Budapest, Hungary
| | - Tamás Jakusch
- Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720 Szeged, Hungary
| | - Alexander Roller
- University of Vienna, Institute of Inorganic Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria
| | - Petra Heffeter
- Research Platform "Translational Cancer Therapy Research" University of Vienna, Waehringer Strasse 42, A-1090 Vienna, Austria; Institute of Cancer Research and Comprehensive Cancer Center, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria
| | - Bernhard K Keppler
- University of Vienna, Institute of Inorganic Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria; Research Platform "Translational Cancer Therapy Research" University of Vienna, Waehringer Strasse 42, A-1090 Vienna, Austria
| | - Éva A Enyedy
- Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720 Szeged, Hungary.
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Jakusch T, Enyedy ÉA, Kozma K, Paár Z, Bényei A, Kiss T. Vanadate complexes of 3-hydroxy-1,2-dimethyl-pyridinone: Speciation, structure and redox properties. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2013.12.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Sija É, Nagy NV, Gandin V, Marzano C, Jakusch T, Dean A, Di Marco VB, Kiss T. Hydroxypyridinecarboxylic acid derivatives influencing metal ion levels in the brain: Equilibrium complexation studies with Cu(II) and Zn(II). Polyhedron 2014. [DOI: 10.1016/j.poly.2013.09.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Enyedy ÉA, Bognár GM, Nagy NV, Jakusch T, Kiss T, Gambino D. Solution speciation of potential anticancer metal complexes of salicylaldehyde semicarbazone and its bromo derivative. Polyhedron 2014. [DOI: 10.1016/j.poly.2013.08.053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Mehtab S, Gonçalves G, Roy S, Tomaz AI, Santos-Silva T, Santos MFA, Romão MJ, Jakusch T, Kiss T, Pessoa JC. Interaction of vanadium(IV) with human serum apo-transferrin. J Inorg Biochem 2013; 121:187-95. [PMID: 23411030 DOI: 10.1016/j.jinorgbio.2012.12.020] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 12/27/2012] [Accepted: 12/28/2012] [Indexed: 10/27/2022]
Abstract
The interaction of V(IV)O-salts as well as of a few V(IV)O(carrier)n complexes with human serum transferrin (hTF) is studied focusing on the determination of the nature and stoichiometry of the binding of V(IV)O(2+) to hTF, as well as whether the conformation of hTF upon binding to V(IV)O(2+) or to its complexes is changed. Circular dichroism (CD) spectra measured for solutions containing V(IV)O(2+) and apo-hTF, and V(IV)O-maltol and apo-hTF, clearly indicate that hTF-V(IV)O-maltol ternary species form with a V(IV)O:maltol stoichiometry of 1:1. For V(IV)O salts and several V(IV)O(carrier)n complexes (carrier ligand=maltolato, dhp, picolinato and dipicolinato) (Hdhp=1,2-dimethyl-3-hydroxy-4-pyridinone) the maximum number of V(IV)O(2+) bound per mole of hTF is determined to be ~2 or lower in all cases. The binding of V(IV)O to apo-hTF most certainly involves several amino acid residues of the Fe-binding site, and as concluded by urea gel electrophoresis experiments, the formation of (V(IV)O)2hTF species may occur with the closing of the hTF conformation as is the case in (Fe(III))2hTF, which is an essential feature for the transferrin receptor recognition.
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Affiliation(s)
- Sameena Mehtab
- Centro Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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Gonçalves G, Tomaz I, Correia I, Veiros LF, Castro MMCA, Avecilla F, Palacio L, Maestro M, Kiss T, Jakusch T, Garcia MHV, Pessoa JC. A novel VIVO–pyrimidinone complex: synthesis, solution speciation and human serum protein binding. Dalton Trans 2013; 42:11841-61. [DOI: 10.1039/c3dt50553g] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lim CS, Tegoni M, Jakusch T, Kampf JW, Pecoraro VL. Clarifying the Mechanism of Cation Exchange in Ca(II)[15-MCCu(II)Ligand-5] Complexes. Inorg Chem 2012; 51:11533-40. [DOI: 10.1021/ic3013798] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Choong-Sun Lim
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
| | - Matteo Tegoni
- Department
of Chemistry, University of Parma, Parma
43124, Italy
| | - Tamás Jakusch
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
| | - Jeff W. Kampf
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055,
United States
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Gabriel C, Perikli M, Raptopoulou CP, Terzis A, Psycharis V, Mateescu C, Jakusch T, Kiss T, Bertmer M, Salifoglou A. pH-Specific Hydrothermal Assembly of Binary and Ternary Pb(II)-(O,N-Carboxylic Acid) Metal Organic Framework Compounds: Correlation of Aqueous Solution Speciation with Variable Dimensionality Solid-State Lattice Architecture and Spectroscopic Signatures. Inorg Chem 2012; 51:9282-96. [DOI: 10.1021/ic300850g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. Gabriel
- Department of Chemical Engineering, Laboratory
of Inorganic Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - M. Perikli
- Department of Chemical Engineering, Laboratory
of Inorganic Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
| | - C. P. Raptopoulou
- Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi 15310, Attiki, Greece
| | - A. Terzis
- Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi 15310, Attiki, Greece
| | - V. Psycharis
- Institute of Materials Science, NCSR “Demokritos”, Aghia Paraskevi 15310, Attiki, Greece
| | - C. Mateescu
- Banat’s University of Agricultural Sciences and Veterinary Medicine, Timisoara 300645,
Romania
| | - T. Jakusch
- Biocoordination
Chemistry Research Group of the Hungarian Academy of Sciences, Department
of Inorganic and Analytical Chemistry, University of Szeged, Szeged H-6720, Hungary
| | - T. Kiss
- Biocoordination
Chemistry Research Group of the Hungarian Academy of Sciences, Department
of Inorganic and Analytical Chemistry, University of Szeged, Szeged H-6720, Hungary
| | - M. Bertmer
- Institut für Experimentelle Physik II, Universität Leipzig, Leipzig 04103, Germany
| | - A. Salifoglou
- Department of Chemical Engineering, Laboratory
of Inorganic Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece
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Correia I, Jakusch T, Cobbinna E, Mehtab S, Tomaz I, Nagy NV, Rockenbauer A, Pessoa JC, Kiss T. Evaluation of the binding of oxovanadium(IV) to human serum albumin. Dalton Trans 2012; 41:6477-87. [PMID: 22476413 DOI: 10.1039/c2dt12193j] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The understanding of the biotransformations of insulin mimetic vanadium complexes in human blood and its transport to target cells is an essential issue in the development of more effective drugs. We present the study of the interaction of oxovanadium(iv) with human serum albumin (HSA) by electron paramagnetic resonance (EPR), circular dichroism (CD) and visible absorption spectroscopy. Metal competition studies were done using Cu(II) and Zn(II) as metal probes. The results show that V(IV)O occupies two types of binding sites in albumin, which compete not only with each other, but also with hydrolysis of the metal ion. In one of the sites the resulting V(IV)O-HSA complex has a weak visible CD signal and its X-band EPR spectrum may be easily measured. This was assigned to amino acid side chains of the ATCUN site. The other binding site shows stronger signals in the CD in the visible range, but has a hardly measurable EPR signal; it is assigned to the multi metal binding site (MBS) of HSA. Studies with fatted and defatted albumin show the complexity of the system since conformational changes, induced by the binding of fatty acids, decrease the ability of V(IV)O to bind albumin. The possibility and importance of ternary complex formation between V(IV)O, HSA and several drug candidates - maltol (mal), picolinic acid (pic), 2-hydroxypyridine-N-oxide (hpno) and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhp) was also evaluated. In the presence of maltol the CD and EPR spectra significantly change, indicating the formation of ternary VO-HSA-maltol complexes. Modeling studies with amino acids and peptides were used to propose binding modes. Based on quantitative RT EPR measurements and CD data, it was concluded that in the systems with mal, pic, hpno, and dhp (V(IV)OL(2))(n)(HSA) species form, where the maximum value for n is at least 6 (mal, pic). The degree of formation of the ternary species, corresponding to the reaction V(IV)OL(2) + HSA -->/<-- V(IV)OL(2)(HSA) is hpno > pic ≥ mal > dhp. (V(IV)OL)(n)(HSA) type complexes are detected exclusively with pic. Based on the spectroscopic studies we propose that in the (V(IV)OL(2))(n)(HSA) species the protein bounds to vanadium through the histidine side chains.
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Affiliation(s)
- Isabel Correia
- Centro de Química Estrutural, Instituto Superior Técnico, Lisbon, Portugal
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Sija É, Dean A, Jakusch T, Di Marco VB, Venzo A, Kiss T. Interactions of pyridinecarboxylic acid chelators with brain metal ions: Cu(II), Zn(II), and Al(III). Monatsh Chem 2011. [DOI: 10.1007/s00706-011-0482-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Menelaou M, Daskalakis M, Mateescu A, Raptopoulou C, Terzis A, Mateescu C, Tangoulis V, Jakusch T, Kiss T, Salifoglou A. In depth investigation of the synthesis, structural, and spectroscopic characterization of a high pH binary Co(II)–N,N-bis(phosphonomethyl)glycine species. Association with aqueous speciation studies of binary Co(II)–(carboxy)phosphonate systems. Polyhedron 2011. [DOI: 10.1016/j.poly.2010.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Correia I, Marcão S, Koci K, Tomaz I, Adão P, Kiss T, Jakusch T, Avecilla F, Costa Pessoa J. Vanadium(IV) and -(V) Complexes of Reduced Schiff Bases Derived from Aromatic o-Hydroxyaldehydes and Tyrosine Derivatives. Eur J Inorg Chem 2011. [DOI: 10.1002/ejic.201000948] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Pallagi A, Sebok P, Forgó P, Jakusch T, Pálinkó I, Sipos P. Multinuclear NMR and molecular modelling investigations on the structure and equilibria of complexes that form in aqueous solutions of Ca(2+) and gluconate. Carbohydr Res 2010; 345:1856-64. [PMID: 20599191 DOI: 10.1016/j.carres.2010.05.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 05/04/2010] [Accepted: 05/10/2010] [Indexed: 11/28/2022]
Abstract
Complexation of d-gluconate (Gluc(-)) with Ca(2+) has been investigated via (1)H, (13)C and (43)Ca NMR spectroscopy in aqueous solutions in the presence of high concentration background electrolytes (1MI4M (NaCl) ionic strength). From the ionic strength dependence of its formation constant, the stability constant at 6pH11 and at I-->0M has been derived (logK(1,1)(0)=1.8+/-0.1). The protonation constant of Gluc(-) at I=1M (NaCl) ionic strength was also determined and was found to be logK(a)=3.24+/-0.01 ((13)C NMR) and logK(a)=3.23+/-0.01 ((1)H NMR). It was found that (1)H and (13)C NMR chemical shifts upon complexation (both with H(+) and with Ca(2+)) do not vary in an unchanging way with the distance from the Ca(2+)/H(+) binding site. From 2D (1)H-(43)Ca NMR spectra, simultaneous binding of Ca(2+) to the alcoholic OH on C2 and C3 was deduced. Molecular modelling results modulated this picture by revealing structures in which the Gluc(-) behaves as a multidentate ligand. The five-membered chelated initial structure was found to be thermodynamically more stable than that derived from a six-membered chelated initial structure.
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Affiliation(s)
- Attila Pallagi
- Department of Inorganic and Analytical Chemistry, University of Szeged, Szeged H-6701, Hungary
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Nikolakis VA, Exarchou V, Jakusch T, Woolins JD, Slawin AMZ, Kiss T, Kabanos TA. Tris-(hydroxyamino)triazines: high-affinity chelating tridentate O,N,O-hydroxylamine ligand for the cis-VVO2+ cation. Dalton Trans 2010; 39:9032-8. [DOI: 10.1039/c0dt00574f] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The speciations of two drug candidate ligands, 2-hydroxypyridine-N-oxide (Hhpno) and 2-mercaptopyridine-N-oxide (Hmpno), with vanadate (V(V)) were determined at 25.0 degrees C and 0.20 mol dm(-3) KCl by pH-metric and (51)V-NMR methods. At pH 7.4, the two predominant compounds with both ligands are the VO(2)L(2) and VO(2)L(OH). NH(4)[VO(2)(hpno)(2)] x 3 H(2)O was prepared in solid form, and its crystal structure was determined by X-ray diffraction. The stabilities of the complexes VO(2)L(2) of five drug candidate ligands were compared at pH 7.4. In view of the stability sequence hpno > maltol approximately hdp (Hhdp: 3-hydroxy-1,2-dimethyl-4-pyridinone) >> mpno > picolinic acid, the first two of these ligands were chosen for equilibrium studies with apotransferrin (apoTf) competition. The V(V)-apoTf stability constants (log K(1) = 6.03 +/- 0.10; log K(2) = 5.46 +/- 0.18) determined by (51)V-NMR spectroscopy were confirmed by ultrafiltration. Both methods proved that there seems to be no hydrogencarbonate-vanadate competition for the apoTf anion-binding positions. The other potential high molecular mass V(V) binder in the serum is human serum albumin (HSA). As no interaction was detected by (51)V-NMR spectroscopy or fluorimetry, the binding properties of HSA were quantified on the basis of literature data. As a final conclusion, speciation modeling calculations suggest that, under serum conditions, apoTf is probably the primary metal ion binder, even in the presence of the most stable V(V) carrier ligands hpno and maltol and HSA plays a negligible role in V(V) binding.
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Affiliation(s)
- Tamás Jakusch
- Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
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Georgantas V, Kotsakis N, Raptopoulou C, Terzis A, Iordanidis L, Zervou M, Jakusch T, Kiss T, Salifoglou A. Synthetic, structural and solution speciation studies on binary Al(III)–(carboxy)phosphonate systems. Relevance to the neurotoxic potential of Al(III). J Inorg Biochem 2009; 103:1530-41. [DOI: 10.1016/j.jinorgbio.2009.05.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 04/30/2009] [Accepted: 05/15/2009] [Indexed: 10/20/2022]
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Jakusch T, Hollender D, Enyedy ÉA, González CS, Montes-Bayón M, Sanz-Medel A, Costa Pessoa J, Tomaz I, Kiss T. Biospeciation of various antidiabetic VIVO compounds in serum. Dalton Trans 2009:2428-37. [DOI: 10.1039/b817748a] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kiss T, Jakusch T, Hollender D, Dörnyei Á, Enyedy ÉA, Pessoa JC, Sakurai H, Sanz-Medel A. Biospeciation of antidiabetic VO(IV) complexes. Coord Chem Rev 2008. [DOI: 10.1016/j.ccr.2007.09.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Affiliation(s)
- Tamás Kiss
- Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
- Bioinorganic Chemistry Research Group of the Hungarian Academy of Sciences, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
| | - Tamás Jakusch
- Bioinorganic Chemistry Research Group of the Hungarian Academy of Sciences, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
| | - Dominik Hollender
- Bioinorganic Chemistry Research Group of the Hungarian Academy of Sciences, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
| | - Ágnes Dönyei
- Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, Szeged, H-6701, Hungary
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Dörnyei Á, Marcão S, Costa Pessoa J, Jakusch T, Kiss T. Interactions of Insulin-Mimetic Vanadium Complexes with the Cell Constituents ATP and Glutathione. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600385] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Costa Pessoa J, Marcão S, Correia I, Gonçalves G, Dörnyei A, Kiss T, Jakusch T, Tomaz I, Castro MMCA, Geraldes CFGC, Avecilla F. Vanadium (IV and V) Complexes of Reduced Schiff Bases Derived from the Reaction of Aromatico-Hydroxyaldehydes and Diamines Containing Carboxyl Groups. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600309] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Correia I, Dornyei A, Jakusch T, Avecilla F, Kiss T, Costa Pessoa J. Water-Soluble Sal2en- and Reduced Sal2en-Type Ligands: Study of Their CuII and NiII Complexes in the Solid State and in Solution. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600030] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Jakusch T, Gajda-Schrantz K, Adachi Y, Sakurai H, Kiss T, Horváth L. Solution equilibrium characterization of insulin-mimetic Zn(II) complexes. J Inorg Biochem 2006; 100:1521-6. [PMID: 16824606 DOI: 10.1016/j.jinorgbio.2006.05.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2005] [Revised: 04/19/2006] [Accepted: 05/10/2006] [Indexed: 10/24/2022]
Abstract
Solution speciation (stoichiometry and stability constants) of the insulin mimetic Zn(II) complexes of several bidentate ligands with (O,O), (N,O) or (S,O) coordination modes have been determined by pH-metry at 25 degrees Celsius and I=0.2M (KCl). All ligands were found to coordinate in a bidentate way forming mono, bis and tris complexes, besides a mixed hydroxo bis complex ZnL(2)(OH) detected in the slightly basic pH range together with the tris complex. Relationships between the stability data, lipophilicity of the complexes and earlier biological data are evaluated. The validity of the linear free energy relationships (LFER) between the proton and Zn(II) complexes and also between the VO(IV) and Zn(II) complexes is tested.
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Affiliation(s)
- T Jakusch
- Bioinorganic Chemistry Research Group of the Hungarian Academy of Sciences, University of Szeged, P.O. Box 440, H-6701 Szeged, Hungary
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Jakusch T, Marcão S, Rodrigues L, Correia I, Pessoa JC, Kiss T. Oxovanadium(iv) complexes of salicyl-l-aspartic acid and salicylglycyl-l-aspartic acid. Dalton Trans 2005:3072-8. [PMID: 16127502 DOI: 10.1039/b506684k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dipeptide and tripeptide analogues salicyl-L-aspartic acid (Sal-L-Asp) and salicylglycyl-L-aspartic acid (SalGly-L-Asp) were synthesized and their protonation and complex formation with V(IV)O2+ were studied in aqueous solution through the use of pH-potentiometry and spectroscopic (UV-Vis, CD and EPR) techniques. The phenolate terminus proved to be a good anchoring site to promote (i) the metal ion-induced deprotonation and subsequent coordination of the peptide amide group(s) in the pH range 4-5 for the dipeptide analogue, (ii) and in the pH range 5-6 in a very cooperative way for the tripeptide analogue. The results suggest that the presence of good anchoring donors on both sides of the amide groups is responsible for the cooperative deprotonation of the two amide-NH groups.
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Affiliation(s)
- Tamás Jakusch
- Bioinorganic Chemistry Research Group of the Hungarian Academy of Sciences, Department of Inorganic and Analytical Chemistry, University of Szeged, POBox 440, H-6701 Szeged, Hungary
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Di Marco V, Kilyen M, Jakusch T, Forgó P, Dombi G, Kiss T. Complexation Properties of Ethylenediaminetetramethylenephosphonic Acid (EDTMP) with AlIII and VIVO. Eur J Inorg Chem 2004. [DOI: 10.1002/ejic.200300693] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Correia I, Costa Pessoa J, Duarte MT, Henriques RT, Piedade MFM, Veiros LF, Jakusch T, Kiss T, Dörnyei A, Castro MMCA, Geraldes CFGC, Avecilla F. N,N′-Ethylenebis(pyridoxylideneiminato) andN,N′-Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes. Chemistry 2004; 10:2301-17. [PMID: 15112220 DOI: 10.1002/chem.200305317] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The Schiff base N,N'-ethylenebis(pyridoxylideneiminato) (H(2)pyr(2)en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H(2)pyr(2)en with NaBH(4) yielded the reduced Schiff base N,N'-ethylenebis(pyridoxylaminato) (H(2)Rpyr(2)en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H(6)L(4+), and all protonation constants were determined by pH-potentiometric and (1)H NMR titrations. Several vanadium(IV) and vanadium(V) complexes of these and other related ligands were prepared and characterized in solution and in the solid state. The X-ray crystal structure of [V(V)O(2)(HRpyr(2)en)] shows the metal in a distorted octahedral geometry, with the ligand coordinated through the N-amine and O-phenolato moieties, with one of the pyridine-N atoms protonated. Crystals of [(V(V)O(2))(2)(pyren)(2)].2 H(2)O were obtained from solutions containing H(2)pyr(2)en and oxovanadium(IV), where Hpyren is the "half" Schiff base of pyridoxal and ethylenediamine. The complexation of V(IV)O(2+) and V(V)O(2) (+) with H(2)pyr(2)en, H(2)Rpyr(2)en and pyridoxamine in aqueous solution were studied by pH-potentiometry, UV/Vis absorption spectrophotometry, as well as by EPR spectroscopy for the V(IV)O systems and (1)H and (51)V NMR spectroscopy for the V(V)O(2) systems. Very significant differences in the metal-binding abilities of the ligands were found. Both 1 and 2 act as tetradentate ligands. H(2)Rpyr(2)en is stable to hydrolysis and several isomers form in solution, namely cis-trans type complexes with V(IV)O, and alpha-cis- and beta-cis-type complexes with V(V)O(2). The pyridinium-N atoms of the pyridoxal rings do not take part in the coordination but are involved in acid-base reactions that affect the number, type, and relative amount of the isomers of the V(IV)O-H(2)Rpyr(2)en and V(V)O(2)-H(2)Rpyr(2)en complexes present in solution. DFT calculations were carried out and support the formation and identification of the isomers detected by EPR or NMR spectroscopy, and the strong equatorial and axial binding of the O-phenolato in V(IV)O and V(V)O(2) complexes. Moreover, the DFT calculations done for the [V(IV)O(H(2)Rpyr(2)en)] system indicate that for almost all complexes the presence of a sixth equatorial or axial H(2)O ligand leads to much more stable compounds.
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Affiliation(s)
- Isabel Correia
- Centro Química Estrutural, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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Pessoa JC, Correia I, Geraldes CF, Castro M, Jakusch T, Kiss T. VIVO and VVO2 complexes of schiff base derivatives of ethylenediamine and vitamine B6. J Inorg Biochem 2003. [DOI: 10.1016/s0162-0134(03)80739-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Jakusch T, Dörnyei Á, Correia I, Rodrigues LM, Tóth G, Kiss T, Pessoa J, Marcão S. Interaction of VIVO, VVO2 and CuII with a Peptide Analogue SalGly-L-Ala. Eur J Inorg Chem 2003. [DOI: 10.1002/ejic.200200511] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kiss E, Kawabe K, Tamura A, Jakusch T, Sakurai H, Kiss T. Chemical speciation of insulinomimetic VO(IV) complexes of pyridine-N-oxide derivatives: binary and ternary systems. J Inorg Biochem 2003; 95:69-76. [PMID: 12763650 DOI: 10.1016/s0162-0134(03)00103-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In order to estimate the impact of the low-molecular-mass (l.m.m.) VO(IV) binders of blood serum on the potentially insulin-enhancing compound VO(HPO)(2) (HPO, 2-hydroxypyridine-N-oxide): and VO(MPO)(2) (MPO, 2-mercaptopyridine-N-oxide), the speciation in the binary system VO(IV)-HPO and VO(IV)-MPO and in the ternary systems VO(IV)-HPO(MPO)-ligand B (B=oxalate, lactate, citrate or phosphate) was studied by pH-potentiometry. The stability constants of the complexes formed were determined in aqueous solution at I=0.2 M (KCl) and T=25 degrees C. The most probable binding modes of the complexes were determined by EPR method. The pyridine-N-oxides were found to form very stable bis complexes, which are predominant in the pH range 2-7. The results in the ternary systems demonstrate that only the citrate is a strong enough VO(IV) binder to compete with the carrier ligands. The binding ability of the high-molecular-mass (h.m.m.) serum proteins albumin and transferrin were also assessed and transferrin was found to be an efficient binder molecule. The actual solution state of these compounds in blood serum is compared with that of other insulin-mimic VO(IV) complexes.
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Affiliation(s)
- Erzsébet Kiss
- Biocoordination Chemistry Research Group of Hungarian Academy of Sciences, University of Szeged, PO Box 440, H-6701 Szeged, Hungary
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Jakusch T, Jin W, Yang L, Kiss T, Crans DC. Vanadium(IV/V) speciation of pyridine-2,6-dicarboxylic acid and 4-hydroxy-pyridine-2,6-dicarboxylic acid complexes: potentiometry, EPR spectroscopy and comparison across oxidation states. J Inorg Biochem 2003; 95:1-13. [PMID: 12706536 DOI: 10.1016/s0162-0134(03)00090-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Evaluation of stability of vanadium(IV) and (V) complexes under similar conditions is critical for the interpretation and assessment of bioactivity of various vanadium species. Detailed understanding of the chemical properties of these complexes is necessary to explain differences observed their activity in biological systems. These studies are carried out to link the chemistry of both vanadium(IV) and (V) complexes of two ligands, 2,6-pyridinedicarboxylic acid (dipicolinic acid, H(2)dipic) and 4-hydroxy-2,6-pyridinedicarboxylic acid (H(2)dipic-OH). Solution speciation of the two 2,6-pyridinedicarboxylic acids with vanadium(IV) and vanadium(V) ions was determined by pH-potentiometry at I=0.2 M (KCl) ionic strength and at T=298 K. The stability and the metal affinities of the ligands were compared. Vanadium(V) complexes were found to form only tridentate coordinated 1:1 complexes, while vanadium(IV) formed complexes with both 1:1 and 1:2 stoichiometries. The formation constant reflects hindered coordination of a second ligand molecule, presumably because of the relatively small size of the metal ion. The most probable binding mode of the complexes was further explored using ambient and low temperature EPR spectroscopy for vanadium(IV) and 51V NMR spectroscopy for vanadium(V) systems. Upon complex formation the pyridinol-OH in position 4 deprotonates with pK approximately 3.7-4.1, which is approximately 6 orders of magnitude lower than that of the free ligand. The deprotonation enhances the ligand metal ion affinity compared to the parent ligand dipicolinic acid. In the light of the speciation and stability data of the metal complexes, the efficiency of the two ligands in transporting the metal ion in the two different oxidation states are assessed and discussed.
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Affiliation(s)
- Tamás Jakusch
- Department of Inorganic and Analytical Chemistry, Biocoordination Chemistry Research Group of the Hungarian Academy of Sciences, P.O. Box 440, University of Szeged, Hungary
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Kotsakis N, Raptopoulou CP, Tangoulis V, Terzis A, Giapintzakis J, Jakusch T, Kiss T, Salifoglou A. Correlations of synthetic, spectroscopic, structural, and speciation studies in the biologically relevant cobalt(II)-citrate system: the tale of the first aqueous dinuclear cobalt(II)-citrate complex. Inorg Chem 2003; 42:22-31. [PMID: 12513074 DOI: 10.1021/ic011272l] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthetic efforts targeting soluble species of Co(II) with the low molecular mass physiological ligand citric acid led to the isolation of the first dinuclear complex [Co(2)(C(6)H(5)O(7))(2)(H(2)O)(4)](2-), at pH approximately 5, in the form of its K+ (1) and Na+ (2) salts. Both 1 and 2 were characterized analytically, spectroscopically (FT-IR, UV/visible, EPR), and magnetically. Complex 1 crystallizes in the monoclinic space group P2(1)/n, with a = 10.348(5) A, b = 11.578(6) A, c = 12.138(6) A, beta = 112.62(2) degrees, V = 1342(1) A(3), and Z = 2. Complex 2 crystallizes in the monoclinic space group P2(1)/c, with a = 9.234(4) A, b = 11.913(4) A, c = 11.728(6) A, beta = 99.93(2) degrees, V = 1271(1) A(3), and Z = 2. X-ray crystallography on 1 and 2 reveals the presence of two Co(II) ions, in a dinuclear assembly, octahedrally coordinated by two citrate ligands in a tridentate fashion. The octahedral environment around each Co(II) is complemented by another singly bonded citrate belonging to the adjacent Co(II) unit and two water molecules. Magnetic susceptibility and EPR studies on 1, in the solid state, corroborate the X-ray results, indicating a weak interaction between the two Co(II) ions. Moreover, EPR and UV/visible studies in solution suggest that 1 does not retain its dimeric structure, yielding a mononuclear octahedral Co(II)-citrate species. Detailed speciation studies suggest the presence of a number of species including the mononuclear complex [Co(C(6)H(5)O(7))](-), optimally present around pH approximately 5. In consonance with EPR and UV/visible spectroscopy, [Co(C(6)H(5)O(7))](-) is likely the scaffolding unit on the basis of which the dimer [Co(2)(C(6)H(5)O(7))(2)(H(2)O)(4)](2-) is isolated from aqueous solutions. Collectively, this comprehensive study offers significant structural insight into the Co(II)-citrate speciation and the elucidation of the role of Co(II) in biological fluids.
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Affiliation(s)
- N Kotsakis
- Department of Chemistry, University of Crete, Heraklion 71409, Greece
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Costa Pessoa J, Correia I, Kiss T, Jakusch T, Castro MMCA, Geraldes CFGC. Oxovanadium(iv and v) and copper(ii) complexes of N-salicyl-glycylglycine and N-salicyl-glycylglycylglycine. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b206835b] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The complexes formed between D-3-phosphoglyceric acid and H(+), Cu(II) and VO(IV) were studied by pH-potentiometric and spectral (UV-Vis, EPR and CD) methods in order to describe the speciation of the metal ions and to determine the most probable binding modes in the complexes formed in these systems. The results show that, in the pH range between 2 and 4, mononuclear 1:1 complexes are formed through bidentate (MAH) or tridentate (MA) coordination of the ligand. At higher pH, when the proton competition for the central alcoholic-OH function decreases, alcoholate-bridged dinuclear species of composition M(2)A(2)H(-n) (n=1-3) become predominant. VO(IV) seems to have a higher tendency than Cu(II) to form such dinuclear complexes.
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Affiliation(s)
- D Hollender
- Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, H-6701 Szeged, Hungary
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Kiss T, Jakusch T, Kilyén M, Kiss E, Lakatos A. [Speciation of bioactive Al(III) and VO(IV) complexes in biological systems]. Acta Pharm Hung 2000; 70:175-86. [PMID: 11379024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
The speciation of the toxic Al(III) and the beneficial VO(IV) in various biofluids and tissues is discussed in order to describe the solution state of these metal ions in the organism. The possibility and the importance of ternary complex formation with relevant biomolecules is emphasised. The importance of the biospeciation of Al(III) ion in its transport and involvement in neurological disorders, and of insulin mimetic VO(IV) complexes is discussed.
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Affiliation(s)
- T Kiss
- Szervetlen és Analitikai Kémiai Tanszék, Szegedi Tudományegyetem, 6701 Szeged, Postafiók 440
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