1
|
Mechanistic Insights of Chelator Complexes with Essential Transition Metals: Antioxidant/Pro-Oxidant Activity and Applications in Medicine. Int J Mol Sci 2022; 23:ijms23031247. [PMID: 35163169 PMCID: PMC8835618 DOI: 10.3390/ijms23031247] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/13/2022] [Accepted: 01/20/2022] [Indexed: 12/24/2022] Open
Abstract
The antioxidant/pro-oxidant activity of drugs and dietary molecules and their role in the maintenance of redox homeostasis, as well as the implications in health and different diseases, have not yet been fully evaluated. In particular, the redox activity and other interactions of drugs with essential redox metal ions, such as iron and copper, need further investigation. These metal ions are ubiquitous in human nutrition but also widely found in dietary supplements and appear to exert major effects on redox homeostasis in health, but also on many diseases of free radical pathology. In this context, the redox mechanistic insights of mainly three prototype groups of drugs, namely alpha-ketohydroxypyridines (alpha-hydroxypyridones), e.g., deferiprone, anthraquinones, e.g., doxorubicin and thiosemicarbazones, e.g., triapine and their metal complexes were examined; details of the mechanisms of their redox activity were reviewed, with emphasis on the biological implications and potential clinical applications, including anticancer activity. Furthermore, the redox properties of these three classes of chelators were compared to those of the iron chelating drugs and also to vitamin C, with an emphasis on their potential clinical interactions and future clinical application prospects in cancer, neurodegenerative and other diseases.
Collapse
|
2
|
Timoshnikov VA, Kichigina LA, Selyutina OY, Polyakov NE, Kontoghiorghes GJ. Antioxidant Activity of Deferasirox and Its Metal Complexes in Model Systems of Oxidative Damage: Comparison with Deferiprone. Molecules 2021; 26:molecules26165064. [PMID: 34443652 PMCID: PMC8401497 DOI: 10.3390/molecules26165064] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/28/2022] Open
Abstract
Deferasirox is an orally active, lipophilic iron chelating drug used on thousands of patients worldwide for the treatment of transfusional iron overload. The essential transition metals iron and copper are the primary catalysts of reactive oxygen species and oxidative damage in biological systems. The redox effects of deferasirox and its metal complexes with iron, copper and other metals are of pharmacological, toxicological, biological and physiological importance. Several molecular model systems of oxidative damage caused by iron and copper catalysis including the oxidation of ascorbic acid, the peroxidation of linoleic acid micelles and the oxidation of dihydropyridine have been investigated in the presence of deferasirox using UV-visible and NMR spectroscopy. Deferasirox has shown antioxidant activity in all three model systems, causing substantial reduction in the rate of oxidation and oxidative damage. Deferasirox showed the greatest antioxidant activity in the oxidation of ascorbic acid with the participation of iron ions and reduced the reaction rate by about a 100 times. Overall, deferasirox appears to have lower affinity for copper in comparison to iron. Comparative studies of the antioxidant activity of deferasirox and the hydrophilic oral iron chelating drug deferiprone in the peroxidation of linoleic acid micelles showed lower efficiency of deferasirox in comparison to deferiprone.
Collapse
Affiliation(s)
- Viktor A. Timoshnikov
- Institute of Chemical Kinetics & Combustion, 630090 Novosibirsk, Russia; (V.A.T.); (L.A.K.); (O.Y.S.); (N.E.P.)
| | - Lilia A. Kichigina
- Institute of Chemical Kinetics & Combustion, 630090 Novosibirsk, Russia; (V.A.T.); (L.A.K.); (O.Y.S.); (N.E.P.)
| | - Olga Yu. Selyutina
- Institute of Chemical Kinetics & Combustion, 630090 Novosibirsk, Russia; (V.A.T.); (L.A.K.); (O.Y.S.); (N.E.P.)
| | - Nikolay E. Polyakov
- Institute of Chemical Kinetics & Combustion, 630090 Novosibirsk, Russia; (V.A.T.); (L.A.K.); (O.Y.S.); (N.E.P.)
| | - George J. Kontoghiorghes
- Postgraduate Research Institute of Science, Technology, Environment and Medicine, Limassol CY-3021, Cyprus
- Correspondence:
| |
Collapse
|
3
|
Nowak M, Tryniszewski W, Sarniak A, Wlodarczyk A, Nowak PJ, Nowak D. Effect of Physiological Concentrations of Vitamin C on the Inhibitation of Hydroxyl Radical Induced Light Emission from Fe 2+-EGTA-H 2O 2 and Fe 3+-EGTA-H 2O 2 Systems In Vitro. Molecules 2021; 26:molecules26071993. [PMID: 33915907 PMCID: PMC8037725 DOI: 10.3390/molecules26071993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/20/2022] Open
Abstract
Ascorbic acid (AA) has antioxidant properties. However, in the presence of Fe2+/Fe3+ ions and H2O2, it may behave as a pro-oxidant by accelerating and enhancing the formation of hydroxyl radicals (•OH). Therefore, in this study we evaluated the effect of AA at concentrations of 1 to 200 µmol/L on •OH-induced light emission (at a pH of 7.4 and temperature of 37 °C) from 92.6 µmol/L Fe2+—185.2 µmol/L EGTA (ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid)—2.6 mmol/L H2O2, and 92.6 µmol/L Fe3+—185.2 µmol/L EGTA—2.6 mmol/L H2O2 systems. Dehydroascorbic acid (DHAA) at the same range of concentrations served as the reference compound. Light emission was measured with multitube luminometer (AutoLumat Plus LB 953) for 120 s after automatic injection of H2O2. AA at concentrations of 1 to 50 µmol/L and of 1 to 75 µmol/L completely inhibited light emission from Fe2+-EGTA-H2O2 and Fe3+-EGTA-H2O2, respectively. Concentrations of 100 and 200 µmol/L did not affect chemiluminescence of Fe3+-EGTA-H2O2 but tended to increase light emission from Fe2+-EGTA-H2O2. DHAA at concentrations of 1 to 100 µmol/L had no effect on chemiluminescence of both systems. These results indicate that AA at physiological concentrations exhibits strong antioxidant activity in the presence of chelated iron and H2O2.
Collapse
Affiliation(s)
- Michal Nowak
- Radiation Protection, University Hospital No. 2, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland;
| | - Wieslaw Tryniszewski
- Department of Radiological and Isotopic Diagnostics and Therapy, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland;
| | - Agata Sarniak
- Department of General Physiology, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland;
| | - Anna Wlodarczyk
- Department of Sleep Medicine and Metabolic Disorders, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland;
| | - Piotr J. Nowak
- Department of Nephrology, Hypertension, and Kidney Transplantation, Medical University of Lodz, Pomorska 251, 92-213 Lodz, Poland;
| | - Dariusz Nowak
- Department of Clinical Physiology, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland
- Correspondence: ; Tel.: +48-422-725-656; Fax: +48-422-725-652
| |
Collapse
|
4
|
Two Faces of Vitamin C in Hemodialysis Patients: Relation to Oxidative Stress and Inflammation. Nutrients 2021; 13:nu13030791. [PMID: 33673687 PMCID: PMC7997461 DOI: 10.3390/nu13030791] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/11/2021] [Accepted: 02/24/2021] [Indexed: 02/06/2023] Open
Abstract
Hemodialysis (HD) is the most common method of renal replacement therapy. Besides toxins, it eliminates nutrients from the circulation, such as ascorbic acid (AA). HD-patients present AA deficiency more often than representatives of the general population, also due to dietary restrictions. This condition aggravates oxidative stress and inflammation related to uremia and extracorporeal circulation and increases cardiovascular risk followed by mortality. Supplementation of AA seems to be a promising approach in the treatment of hemodialysis patients. Many successful interventions restored plasma AA concentration in HD patients by enteral or intravenous supplementation, concomitantly inhibiting oxidative stress and inflammation. A significant number of studies reported opposite, serious pro-oxidant effects of AA. In this narrative review, we present studies, commenting on their limitations; on AA plasma or serum concentration and the influence of its supplementation on protein and lipid peroxidation, DNA damage, reactive oxygen species generation, paraoxonase activity, advanced glycation endproducts, and C-reactive protein (CRP) concentration. Moreover, in terms of safety, the possible development of oxalosis in HD patients regarding the intravenous or enteral route of AA administration is discussed. Unequivocal clinical results of recent studies on hemodialysis patients are displayed.
Collapse
|
5
|
Trying to Solve the Puzzle of the Interaction of Ascorbic Acid and Iron: Redox, Chelation and Therapeutic Implications. MEDICINES 2020; 7:medicines7080045. [PMID: 32751493 PMCID: PMC7460366 DOI: 10.3390/medicines7080045] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 07/28/2020] [Accepted: 07/28/2020] [Indexed: 02/06/2023]
Abstract
Iron and ascorbic acid (vitamin C) are essential nutrients for the normal growth and development of humans, and their deficiency can result in serious diseases. Their interaction is of nutritional, physiological, pharmacological and toxicological interest, with major implications in health and disease. Millions of people are using pharmaceutical and nutraceutical preparations of these two nutrients, including ferrous ascorbate for the treatment of iron deficiency anaemia and ascorbate combination with deferoxamine for increasing iron excretion in iron overload. The main function and use of vitamin C is its antioxidant activity against reactive oxygen species, which are implicated in many diseases of free radical pathology, including biomolecular-, cellular- and tissue damage-related diseases, as well as cancer and ageing. Ascorbic acid and its metabolites, including the ascorbate anion and oxalate, have metal binding capacity and bind iron, copper and other metals. The biological roles of ascorbate as a vitamin are affected by metal complexation, in particular following binding with iron and copper. Ascorbate forms a complex with Fe3+ followed by reduction to Fe2+, which may potentiate free radical production. The biological and clinical activities of iron, ascorbate and the ascorbate–iron complex can also be affected by many nutrients and pharmaceutical preparations. Optimal therapeutic strategies of improved efficacy and lower toxicity could be designed for the use of ascorbate, iron and the iron–ascorbate complex in different clinical conditions based on their absorption, distribution, metabolism, excretion, toxicity (ADMET), pharmacokinetic, redox and other properties. Similar strategies could also be designed in relation to their interactions with food components and pharmaceuticals, as well as in relation to other aspects concerning personalized medicine.
Collapse
|
6
|
Redox Interactions of Vitamin C and Iron: Inhibition of the Pro-Oxidant Activity by Deferiprone. Int J Mol Sci 2020; 21:ijms21113967. [PMID: 32486511 PMCID: PMC7312906 DOI: 10.3390/ijms21113967] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/12/2020] [Accepted: 05/28/2020] [Indexed: 02/07/2023] Open
Abstract
Ascorbic acid (AscH2) is one of the most important vitamins found in the human diet, with many biological functions including antioxidant, chelating, and coenzyme activities. Ascorbic acid is also widely used in medical practice especially for increasing iron absorption and as an adjuvant therapeutic in iron chelation therapy, but its mode of action and implications in iron metabolism and toxicity are not yet clear. In this study, we used UV–Vis spectrophotometry, NMR spectroscopy, and EPR spin trapping spectroscopy to investigate the antioxidant/pro-oxidant effects of ascorbic acid in reactions involving iron and the iron chelator deferiprone (L1). The experiments were carried out in a weak acidic (pH from 3 to 5) and neutral (pH 7.4) medium. Ascorbic acid exhibits predominantly pro-oxidant activity by reducing Fe3+ to Fe2+, followed by the formation of dehydroascorbic acid. As a result, ascorbic acid accelerates the redox cycle Fe3+ ↔ Fe2+ in the Fenton reaction, which leads to a significant increase in the yield of toxic hydroxyl radicals. The analysis of the experimental data suggests that despite a much lower stability constant of the iron–ascorbate complex compared to the FeL13 complex, ascorbic acid at high concentrations is able to substitute L1 in the FeL13 chelate complex resulting in the formation of mixed L12AscFe complex. This mixed chelate complex is redox stable at neutral pH = 7.4, but decomposes at pH = 4–5 during several minutes at sub-millimolar concentrations of ascorbic acid. The proposed mechanisms play a significant role in understanding the mechanism of action, pharmacological, therapeutic, and toxic effects of the interaction of ascorbic acid, iron, and L1.
Collapse
|
7
|
Akyüz E, Başkan KS, Tütem E, Apak R. Novel Iron(III)−Induced Prooxidant Activity Measurement Using a Solid Protein Sensor in Comparison with a Copper(II)−Induced Assay. ANAL LETT 2020. [DOI: 10.1080/00032719.2019.1710180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Esin Akyüz
- Faculty of Engineering, Department of Chemistry, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Kevser Sözgen Başkan
- Faculty of Engineering, Department of Chemistry, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Esma Tütem
- Faculty of Engineering, Department of Chemistry, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Reşat Apak
- Faculty of Engineering, Department of Chemistry, Istanbul University-Cerrahpasa, Istanbul, Turkey
| |
Collapse
|
8
|
Schroeter B, Bettermann S, Semken H, Melchin T, Weitzel HP, Pauer W. Kinetic Description of Ascorbic Acid Decomposition in Redox Initiator Systems for Polymerization Processes. Ind Eng Chem Res 2019. [DOI: 10.1021/acs.iecr.9b00710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Baldur Schroeter
- Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany
| | - Sven Bettermann
- Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany
| | - Henning Semken
- Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany
| | - Timo Melchin
- Wacker Chemie AG, Johannes-Hess-Strasse 24, 84489 Burghausen, Germany
| | | | - Werner Pauer
- Institute for Technical and Macromolecular Chemistry, University of Hamburg, Bundesstraße 45, 20146 Hamburg, Germany
| |
Collapse
|
9
|
Leandri V, Daniel Q, Chen H, Sun L, Gardner JM, Kloo L. Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex. Inorg Chem 2018; 57:4556-4562. [PMID: 29608296 DOI: 10.1021/acs.inorgchem.8b00225] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)2](Cl)2 but instead to [Cu(dmp)2Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu(dmp)2Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)2]+, as one may expect. Instead, [Cu(dmp)2]+ is isolated as a product when the reduction of [Cu(dmp)2Cl]PF6 is performed with l-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)2]2+ complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)2](ClO4)2 crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)2(CH3CN)](ClO4)2, in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)2(CH3CN)]2+ is identical to the one of [Cu(dmp)2]+, if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.
Collapse
Affiliation(s)
- Valentina Leandri
- Applied Physical Chemistry, Department of Chemistry , KTH Royal Institute of Technology , SE-10044 , Stockholm , Sweden
| | - Quentin Daniel
- Organic Chemistry, Centre of Molecular Devices, Department of Chemistry, School of Chemical Science and Engineering , KTH Royal Institute of Technology , SE-100 44 , Stockholm , Sweden
| | - Hong Chen
- Organic Chemistry, Centre of Molecular Devices, Department of Chemistry, School of Chemical Science and Engineering , KTH Royal Institute of Technology , SE-100 44 , Stockholm , Sweden
| | - Licheng Sun
- Organic Chemistry, Centre of Molecular Devices, Department of Chemistry, School of Chemical Science and Engineering , KTH Royal Institute of Technology , SE-100 44 , Stockholm , Sweden.,State Key Laboratory of Fine Chemicals, DUT-KTH Joint Research Center on Molecular Devices , Dalian University of Technology (DUT) , 116024 Dalian , China
| | - James M Gardner
- Applied Physical Chemistry, Department of Chemistry , KTH Royal Institute of Technology , SE-10044 , Stockholm , Sweden
| | - Lars Kloo
- Applied Physical Chemistry, Department of Chemistry , KTH Royal Institute of Technology , SE-10044 , Stockholm , Sweden
| |
Collapse
|
10
|
Adam FI, Bounds PL, Kissner R, Koppenol WH. Redox Properties and Activity of Iron–Citrate Complexes: Evidence for Redox Cycling. Chem Res Toxicol 2015; 28:604-14. [DOI: 10.1021/tx500377b] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Fatima I. Adam
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg
1, CH-8093 Zurich, Switzerland
| | - Patricia L. Bounds
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg
1, CH-8093 Zurich, Switzerland
| | - Reinhard Kissner
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg
1, CH-8093 Zurich, Switzerland
| | - Willem H. Koppenol
- Institute of Inorganic Chemistry,
Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg
1, CH-8093 Zurich, Switzerland
| |
Collapse
|
11
|
Tarhonskaya H, Chowdhury R, Leung IKH, Loik ND, McCullagh JSO, Claridge TDW, Schofield CJ, Flashman E. Investigating the contribution of the active site environment to the slow reaction of hypoxia-inducible factor prolyl hydroxylase domain 2 with oxygen. Biochem J 2014; 463:363-72. [PMID: 25120187 DOI: 10.1042/bj20140779] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2024]
Abstract
The prolyl hydroxylase domain proteins (PHDs) catalyse the post-translational hydroxylation of the hypoxia-inducible factor (HIF), a modification that regulates the hypoxic response in humans. The PHDs are Fe(II)/2-oxoglutarate (2OG) oxygenases; their catalysis is proposed to provide a link between cellular HIF levels and changes in O2 availability. Transient kinetic studies have shown that purified PHD2 reacts slowly with O2 compared with some other studied 2OG oxygenases, a property which may be related to its hypoxia-sensing role. PHD2 forms a stable complex with Fe(II) and 2OG; crystallographic and kinetic analyses indicate that an Fe(II)-co-ordinated water molecule, which must be displaced before O2 binding, is relatively stable in the active site of PHD2. We used active site substitutions to investigate whether these properties are related to the slow reaction of PHD2 with O2. While disruption of 2OG binding in a R383K variant did not accelerate O2 activation, we found that substitution of the Fe(II)-binding aspartate for a glutamate residue (D315E) manifested significantly reduced Fe(II) binding, yet maintained catalytic activity with a 5-fold faster reaction with O2. The results inform on how the precise active site environment of oxygenases can affect rates of O2 activation and provide insights into limiting steps in PHD catalysis.
Collapse
Affiliation(s)
- Hanna Tarhonskaya
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Rasheduzzaman Chowdhury
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Ivanhoe K H Leung
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Nikita D Loik
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - James S O McCullagh
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Timothy D W Claridge
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Christopher J Schofield
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Emily Flashman
- *Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| |
Collapse
|
12
|
Lawrence MA, Maragh PT, Dasgupta TP. Mechanistic studies on the intra-molecular electron transfer in the adduct species of some oxo-centred trinuclear iron(III)/chromium(III) cations and l-ascorbic acid in aqueous acetate buffer. Inorganica Chim Acta 2012. [DOI: 10.1016/j.ica.2012.02.038] [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]
|
13
|
Sailani R, Dubey S, Khandelwal C, Sharma P, Khan P. Kinetics and mechanism of oxidation of l-ascorbic acid by peroxomonosulphate in acid perchlorate medium. Role of copper (II) as a trace metal-ion catalyst. CR CHIM 2011. [DOI: 10.1016/j.crci.2011.08.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
|
14
|
Lawrence MAW, Thomas SE, Maragh PT, Dasgupta TP. Mechanistic studies on the intramolecular electron transfer in an adduct species of the oxo-centred trinuclear iron(III) cation and l-ascorbic acid in aqueous solution. TRANSIT METAL CHEM 2011. [DOI: 10.1007/s11243-011-9502-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
15
|
Bhattacharyya J, Das S, Mukhopadhyay S. Mechanistic studies on oxidation of l-ascorbic acid by an oxo-bridged diiron complex in aqueous acidic media. Dalton Trans 2007:1214-20. [PMID: 17353953 DOI: 10.1039/b615593f] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
[Fe2(micro-O)(phen)4(H2O)2]4+ (1) (Fig. 1, phen = 1,10-phenanthroline) equilibrates with [Fe2(micro-O)(phen)4(H2O)(OH)]3+ (2) and [Fe2(micro-O)(phen)4(OH)2]2+ (3) in aqueous solution in the presence of excess phen, where no phen-releasing equilibria from 1, 2 and 3 exist. 1 quantitatively oxidizes ascorbic acid (H2A) to dehydroascorbic acid (A) in the pH range 3.00-5.50 in the presence of excess phen, which buffers the reaction within 0.05 pH units and ensures complete formation of end iron product ferroin, [Fe(phen)3]2+. The reactive species are 1, 2 and HA- and the reaction proceeds through an initial 1 : 1 inner-sphere adduct formation between 1 and 2 with HA-, followed by a rate limiting outer-sphere one electron one proton (electroprotic) transfer from a second HA- to the ascorbate-unbound iron(III).
Collapse
|
16
|
Rao CP, Geetha K, Raghavan M, Sreedhara A, Tokunaga K, Yamaguchi T, Jadhav V, Ganesh K, Krishnamoorthy T, V.A. Ramaiah K, Bhattacharyya R. Transition metal saccharide chemistry and biology: syntheses, characterization, solution stability and putative bio-relevant studies of iron–saccharide complexes. Inorganica Chim Acta 2000. [DOI: 10.1016/s0020-1693(99)00364-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
17
|
|
18
|
Khan M, Shukla R. Kinetic and spectroscopic study of the formation of an intermediate ruthenium(III) ascorbate complex in the oxidation of L-ascorbic acid. Polyhedron 1991. [DOI: 10.1016/s0277-5387(00)86171-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
19
|
Inner sphere oxidation of L-ascorbic acid by Ru(III) ion and its complexes in aqueous acidic medium. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)90572-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
20
|
Hamed MY, Keypour H, Silver J, Wilson MT. Studies of the reactions of iron(II) ascorbate mixtures with molecular oxygen in solution. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)91474-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|