1
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Klahn P, Zscherp R, Jimidar CC. Advances in the Synthesis of Enterobactin, Artificial Analogues, and Enterobactin-Derived Antimicrobial Drug Conjugates and Imaging Tools for Infection Diagnosis. SYNTHESIS-STUTTGART 2022. [DOI: 10.1055/a-1783-0751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
AbstractIron is an essential growth factor for bacteria, but although highly abundant in nature, its bioavailability during infection in the human host or the environment is limited. Therefore, bacteria produce and secrete siderophores to ensure their supply of iron. The triscatecholate siderophore enterobactin and its glycosylated derivatives, the salmochelins, play a crucial role for iron acquisition in several bacteria. As these compounds can serve as carrier molecules for the design of antimicrobial siderophore drug conjugates as well as siderophore-derived tool compounds for the detection of infections with bacteria, their synthesis and the design of artificial analogues is of interest. In this review, we give an overview on the synthesis of enterobactin, biomimetic as well as totally artificial analogues, and related drug-conjugates covering up to 12/2021.1 Introduction2 Antibiotic Crisis and Sideromycins as Natural Templates for New Antimicrobial Drugs3 Biosynthesis of Enterobactin, Salmochelins, and Microcins4 Total Synthesis of Enterobactin and Salmochelins5 Chemoenzymatic Semi-synthesis of Salmochelins and Microcin E492m Derivatives6 Synthesis of Biomimetic Enterobactin Derivatives with Natural Tris-lactone Backbone7 Synthesis of Artificial Enterobactin Derivatives without Tris-lactone Backbone8 Conclusions
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Affiliation(s)
- Philipp Klahn
- Institute of Organic Chemistry, Technische Universität Braunschweig
- Department for Chemistry and Molecular Biology, University of Gothenburg
| | - Robert Zscherp
- Institute of Organic Chemistry, Technische Universität Braunschweig
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2
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Johann T, Keth J, Bros M, Frey H. A general concept for the introduction of hydroxamic acids into polymers. Chem Sci 2019; 10:7009-7022. [PMID: 31588268 PMCID: PMC6676332 DOI: 10.1039/c9sc02557j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 06/04/2019] [Indexed: 12/28/2022] Open
Abstract
Polyethers (PEG) with hydroxamic acid groups enable chelation of a variety of metal ions, coating of metal oxide surfaces and stabilization of nanoparticles. In contrast to catechol, hydroxamic acids are oxidation stable and biocompatible.
Hydroxamic acids (HA) form stable complexes with a large variety of metal-ions, affording hydroxamates with high complexation constants. Hydroxamic acid moieties play a crucial role in the natural iron metabolism. In this work, 1,4,2-dioxazoles linked to a hydroxyl group are introduced as key compounds for the installation of hydroxamic acids at synthetic polymers in well-defined positions. A general synthetic scheme is developed that gives access to a series of novel functional key building blocks that can be universally used to obtain hydroxamic acid-based monomers and polymers, for instance as protected HA-functional initiators or for the synthesis of a variety of novel HA-based monomers, such as epoxides or methacrylates. To demonstrate the excellent stability of the dioxazole-protected hydroxamic acids, direct incorporation of the dioxazole-protected hydroxamic acids into polyethers is demonstrated via oxyanionic polymerization. Convenient subsequent deprotection is feasible under mild acidic conditions. α-Functional HA-polyethers, i.e. poly ethylene glycol, polypropylene glycol and polyglycerol based on ethylene oxide, propylene oxide and ethoxy ethyl glycidyl ether, respectively are prepared with low dispersities (<1.2) in the molecular weight range of 1000 to 8500 g mol–1. Water-soluble hydroxamic acid functional poly(ethylene glycol) (HA-PEG) is explored for a variety of biomedical applications and surface coating. Complexation of Fe(iii) ions, coating of various metal surfaces, enabling e.g., solubilization of FeOx nanoparticles by HA-PEGs, are presented. No impact of the polyether chain on the chelation properties was observed, while significantly lower anti-proliferative effects were observed than for deferoxamine. HA-PEGs show the same complexation behavior as their low molecular weight counterparts. Hydroxamic acid functional polymers are proposed as an oxidatively stable alternative to the highly established catechol-based systems.
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Affiliation(s)
- Tobias Johann
- Institute of Organic Chemistry , Johannes Gutenberg University , Duesbergweg 10-14 , 55128 Mainz , Germany .
| | - Jennifer Keth
- Institute of Organic Chemistry , Johannes Gutenberg University , Duesbergweg 10-14 , 55128 Mainz , Germany .
| | - Matthias Bros
- Department of Dermatology , University Medical Center of the Johannes Gutenberg University Mainz , Langenbeckstrasse 1 , 55131 Mainz , Germany
| | - Holger Frey
- Institute of Organic Chemistry , Johannes Gutenberg University , Duesbergweg 10-14 , 55128 Mainz , Germany .
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3
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Cilibrizzi A, Abbate V, Chen YL, Ma Y, Zhou T, Hider RC. Hydroxypyridinone Journey into Metal Chelation. Chem Rev 2018; 118:7657-7701. [DOI: 10.1021/acs.chemrev.8b00254] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Agostino Cilibrizzi
- Institute of Pharmaceutical Science, King’s College London, Stamford Street, London SE1 9NH, United Kingdom
| | - Vincenzo Abbate
- Institute of Pharmaceutical Science, King’s College London, Stamford Street, London SE1 9NH, United Kingdom
- King’s Forensics, School of Population Health & Environmental Sciences, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Yu-Lin Chen
- Institute of Pharmaceutical Science, King’s College London, Stamford Street, London SE1 9NH, United Kingdom
| | - Yongmin Ma
- College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, P. R. China 311402
| | - Tao Zhou
- Department of Applied Chemistry, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, P. R. China 310018
| | - Robert C. Hider
- Institute of Pharmaceutical Science, King’s College London, Stamford Street, London SE1 9NH, United Kingdom
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4
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De Serrano LO. Biotechnology of siderophores in high-impact scientific fields. Biomol Concepts 2017; 8:169-178. [DOI: 10.1515/bmc-2017-0016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/29/2017] [Indexed: 01/06/2023] Open
Abstract
AbstractDifferent aspects of bacterial and fungal siderophore biotechnological applications will be discussed. Areas of application presented include, but are not limited to agriculture, medicine, pharmacology, bioremediation, biodegradation and food industry. In agriculture-related applications, siderophores could be employed to enhance plant growth due to their uptake by rhizobia. Siderophores hindered the presence of plant pathogens in biocontrol strategies. Bioremediation studies on siderophores discuss mostly the mobilization of heavy metals and radionuclides; the emulsifying effects of siderophore-producing microorganisms in oil-contaminated environments are also presented. The different applications found in literature based in medicine and pharmacological approaches range from iron overload to drug delivery systems and, more recently, vaccines. Additional research should be done in siderophore production and their metabolic relevance to have a deeper understanding for future biotechnological advances.
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Affiliation(s)
- Luis O. De Serrano
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT 59812, USA
- Center for Translational Medicine, University of Montana, 32 Campus Dr., Missoula, MT 59801, USA
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5
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El-Shahawi MS, Ahmad W, Mohammed GI, Moustafa YM, Al-Hazmi GA, El-Asmy AA. Impact and correlation of pKaand dnelectrons of some selected thiosemicarbazone Schiff base metal Co, Ni, Cu complexes: a study of electrochemical behavior, excitation and optical energies. NEW J CHEM 2017. [DOI: 10.1039/c7nj00073a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The electron-transfer and coordination mechanism of thiosemicarbazone Schiff bases with metal ions (Co, Ni, Cu), correlation of the electrochemical and optical properties for their potential applications in various fields of chemistry and biochemistry are underexplored.
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Affiliation(s)
- M. S. El-Shahawi
- Department of Chemistry
- Faculty of Science
- King Abdulaziz University
- Jeddah 21589
- Saudi Arabia
| | - W. Ahmad
- Department of Chemistry
- Faculty of Science
- King Abdulaziz University
- Jeddah 21589
- Saudi Arabia
| | - G. I. Mohammed
- Faculty of Applied Science
- Umm Al-Qura University
- Makkah 21955
- Saudi Arabia
| | - Y. M. Moustafa
- Faculty of Applied Science
- Umm Al-Qura University
- Makkah 21955
- Saudi Arabia
| | - G. A. Al-Hazmi
- Department of Chemistry
- Faculty of Science
- King Khaled University
- Abha
- Saudi Arabia
| | - A. A. El-Asmy
- Department of Chemistry
- Faculty of Science
- Kuwait University
- Kuwait
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6
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Eckshtain-Levi M, Lavi R, Yufit DS, Daniel B, Green O, Fleker O, Richman M, Rahimipour S, Gruzman A, Benisvy L. A versatile water-soluble chelating and radical scavenging platform. Chem Commun (Camb) 2016; 52:2350-3. [DOI: 10.1039/c5cc08198j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The reported water-soluble, non-cytotoxic phenol-diamide compound, 1OH, is capable of both, trapping ROS species and chelating Cu(ii)/Fe(iii) ions; thereby inducing a protective effect against ROS induced cell death.
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Affiliation(s)
| | - Ronit Lavi
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | | | - Bareket Daniel
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Omer Green
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Ohad Fleker
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Michal Richman
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Shai Rahimipour
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Arie Gruzman
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
| | - Laurent Benisvy
- Department of Chemistry
- Bar-Ilan University
- Ramat Gan 52900
- Israel
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7
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The Influence of the Amide Linkage in the FeIII-Binding Properties of Catechol-Modified Rosamine Derivatives. Chemistry 2015; 21:15692-704. [DOI: 10.1002/chem.201502093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Indexed: 12/18/2022]
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8
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Merlot AM, Kalinowski DS, Richardson DR. Novel chelators for cancer treatment: where are we now? Antioxid Redox Signal 2013; 18:973-1006. [PMID: 22424293 DOI: 10.1089/ars.2012.4540] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SIGNIFICANCE Under normal circumstances, cellular iron levels are tightly regulated due to the potential toxic effects of this metal ion. There is evidence that tumors possess altered iron homeostasis, which is mediated by the perturbed expression of iron-related proteins, for example, transferrin receptor 1, ferritin and ferroportin 1. The de-regulation of iron homeostasis in cancer cells reveals a particular vulnerability to iron-depletion using iron chelators. In this review, we examine the absorption of iron from the gut; its transport, metabolism, and homeostasis in mammals; and the molecular pathways involved. Additionally, evidence for alterations in iron processing in cancer are described along with the perturbations in other biologically important transition metal ions, for example, copper(II) and zinc(II). These changes can be therapeutically manipulated by the use of novel chelators that have recently been shown to be highly effective in terms of inhibiting tumor growth. RECENT ADVANCES Such chelators include those of the thiosemicarbazone class that were originally thought to target only ribonucleotide reductase, but are now known to have multiple effects, including the generation of cytotoxic radicals. CRITICAL ISSUES Several chelators have shown marked anti-tumor activity in vivo against a variety of solid tumors. An important aspect is the toxicology and the efficacy of these agents in clinical trials. FUTURE DIRECTIONS As part of the process of the clinical assessment of the new chelators, an extensive toxicological assessment in multiple animal models is essential for designing appropriate dosing protocols in humans.
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Affiliation(s)
- Angelica M Merlot
- Department of Pathology and Bosch Institute, University of Sydney, Sydney, Australia
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9
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Frullano L, Caravan P. Strategies for the preparation of bifunctional gadolinium(III) chelators. Curr Org Synth 2011; 8:535-565. [PMID: 22375102 DOI: 10.2174/157017911796117250] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications.
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Affiliation(s)
- Luca Frullano
- Case Western Reserve University. 11100 Euclid Ave Cleveland, OH 44106
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10
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Floyd WC, Klemm PJ, Smiles DE, Kohlgruber AC, Pierre VC, Mynar JL, Fréchet JMJ, Raymond KN. Conjugation effects of various linkers on Gd(III) MRI contrast agents with dendrimers: optimizing the hydroxypyridinonate (HOPO) ligands with nontoxic, degradable esteramide (EA) dendrimers for high relaxivity. J Am Chem Soc 2011; 133:2390-3. [PMID: 21294571 DOI: 10.1021/ja110582e] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
One essential requirement for more sensitive gadolinium-based MRI contrast agents is to slow the molecular tumbling of the gadolinium(III) ion, which increases the gadolinium's relaxivity (i.e., its ability to speed up the NMR relaxation of nearby water molecules). One route to this is through conjugation to high-molecular-weight polymers such as dendrimers. In this work, amine-functionalized TREN-bis(1,2-HOPO)-TAM-ethylamine and TREN-bis(1-Me-3,2-HOPO)-TAM-ethylamine ligands have been synthesized and attached to biocompatible 40 kDa esteramide (EA)- and poly-l-lysine (PLL)-based dendrimers capable of binding up to eight gadolinium complexes. These conjugates have T(1) relaxivities of up to 38.14 ± 0.02 mM(-1) s(-1) per gadolinium at 37 °C, corresponding to relaxivities of up to 228 mM(-1) s(-1) per dendrimer molecule. This relaxivity expressed on a "per Gd" basis is several times that of the small-molecule complexes and an order of magnitude higher than that of current commercial agents. Because of their high performance and low toxicity, these macromolecules may constitute an attractive complement to currently available gadolinium(III)-based contrast agents.
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Affiliation(s)
- William C Floyd
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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11
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Arumugam J, Brown HA, Jacobs HK, Gopalan AS. New Synthetic Approach for the Incorporation of 3,2-Hydroxypyridinone (HOPO) Ligands: Synthesis of Structurally Diverse Poly HOPO Chelators. SYNTHESIS-STUTTGART 2011; 2011:57-64. [PMID: 21709749 DOI: 10.1055/s-0030-1258337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The HOPO sulfonamide reagent, 3, was prepared from commercial 2,3-dihydroxypyridine in four steps in good yields. Sulfonamide 3 readily underwent selective alkylation with dibromides in the presence of base or could be coupled to alcohols using Mitsunobu conditions. The utility of this nucleophilic HOPO reagent was demonstrated by the synthesis some tris and tetraHOPO chelators. This approach for tethering HOPO ligands is unique and flexible as shown by the preparation of HOPO/iminocarboxylic acid chelator 17.
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Affiliation(s)
- Jayanthi Arumugam
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003-8001
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12
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Samuel APS, Lunkley JL, Muller G, Raymond KN. Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution. Eur J Inorg Chem 2010; 2010:3343-3347. [PMID: 20730030 PMCID: PMC2922774 DOI: 10.1002/ejic.201000309] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Indexed: 11/11/2022]
Abstract
Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb(III) complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb(III) complexes that display both large luminescence quantum yield (Φ) values and strong circularly polarized luminescence (CPL) activities. Both Tb(III) complexes are highly emissive, with Φ values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H(2)O and D(2)O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H(2)O molecule directly bound to the Tb(III) ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb(III) complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.
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Affiliation(s)
- Amanda P. S. Samuel
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA, Fax: +1-510-486-5283,
| | - Jamie L. Lunkley
- Department of Chemistry, San José State University, San José, CA 95192-0101
| | - Gilles Muller
- Department of Chemistry, San José State University, San José, CA 95192-0101
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA, Fax: +1-510-486-5283,
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13
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Abergel RJ, Zawadzka AM, Hoette TM, Raymond KN. Enzymatic hydrolysis of trilactone siderophores: where chiral recognition occurs in enterobactin and bacillibactin iron transport. J Am Chem Soc 2009; 131:12682-92. [PMID: 19673474 PMCID: PMC2782669 DOI: 10.1021/ja903051q] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacillibactin and enterobactin are hexadentate catecholate siderophores produced by bacteria upon iron limitation to scavenge ferric ion and seem to be the ultimate siderophores of their two respective domains: Gram-positive and Gram-negative. Iron acquisition mediated by these trilactone-based ligands necessitates enzymatic hydrolysis of the scaffold for successful intracellular iron delivery. The esterases BesA and Fes hydrolyze bacillibactin and enterobactin, respectively, as well as the corresponding iron complexes. Bacillibactin binds iron through three 2,3-catecholamide moieties linked to a trithreonine scaffold via glycine spacers, whereas in enterobactin the iron-binding moieties are directly attached to a tri-l-serine backbone; although apparently minor, these structural differences result in markedly different iron coordination properties and iron transport behavior. Comparison of the solution thermodynamic and circular dichroism properties of bacillibactin, enterobactin and the synthetic analogs d-enterobactin, SERGlyCAM and d-SERGlyCAM has determined the role of each different feature in the siderophores' molecular structures in ferric complex stability and metal chirality. While opposite metal chiralities in the different complexes did not affect transport and incorporation in Bacillus subtilis, ferric complexes formed with the various siderophores did not systematically promote growth of the bacteria. The bacillibactin esterase BesA is less specific than the enterobactin esterase Fes; BesA can hydrolyze the trilactones of both siderophores, while only the tri-l-serine trilactone is a substrate of Fes. Both enzymes are stereospecific and cannot cleave tri-d-serine lactones. These data provide a complete picture of the microbial iron transport mediated by these two siderophores, from initial recognition and transport to intracellular iron release.
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Affiliation(s)
- Rebecca J Abergel
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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14
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Scott LE, Orvig C. Medicinal Inorganic Chemistry Approaches to Passivation and Removal of Aberrant Metal Ions in Disease. Chem Rev 2009; 109:4885-910. [DOI: 10.1021/cr9000176] [Citation(s) in RCA: 266] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Lauren E. Scott
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, Vancouver, Canada
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15
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Rogachevskii IV, Plakhova VB, Shelykh TN. Quantum-chemical study on the electronic structure and ligand-receptor binding mechanisms of some pyridin-4(1H)-one and pyran-4-one derivatives. RUSS J GEN CHEM+ 2009. [DOI: 10.1134/s1070363209010162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Crumbliss AL, Harrington JM. Iron sequestration by small molecules: Thermodynamic and kinetic studies of natural siderophores and synthetic model compounds. ADVANCES IN INORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0898-8838(09)00204-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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17
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Abergel RJ, Clifton MC, Pizarro JC, Warner JA, Shuh DK, Strong RK, Raymond KN. The siderocalin/enterobactin interaction: a link between mammalian immunity and bacterial iron transport. J Am Chem Soc 2008; 130:11524-34. [PMID: 18680288 PMCID: PMC3188318 DOI: 10.1021/ja803524w] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The siderophore enterobactin (Ent) is produced by enteric bacteria to mediate iron uptake. Ent scavenges iron and is taken up by the bacteria as the highly stable ferric complex [Fe (III)(Ent)] (3-). This complex is also a specific target of the mammalian innate immune system protein, Siderocalin (Scn), which acts as an antibacterial agent by specifically sequestering siderophores and their ferric complexes during infection. Recent literature suggesting that Scn may also be involved in cellular iron transport has increased the importance of understanding the mechanism of siderophore interception and clearance by Scn; Scn is observed to release iron in acidic endosomes and [Fe (III)(Ent)] (3-) is known to undergo a change from catecholate to salicylate coordination in acidic conditions, which is predicted to be sterically incompatible with the Scn binding pocket (also referred to as the calyx). To investigate the interactions between the ferric Ent complex and Scn at different pH values, two recombinant forms of Scn with mutations in three residues lining the calyx were prepared: Scn-W79A/R81A and Scn-Y106F. Binding studies and crystal structures of the Scn-W79A/R81A:[Fe (III)(Ent)] (3-) and Scn-Y106F:[Fe (III)(Ent)] (3-) complexes confirm that such mutations do not affect the overall conformation of the protein but do weaken significantly its affinity for [Fe (III)(Ent)] (3-). Fluorescence, UV-vis, and EXAFS spectroscopies were used to determine Scn/siderophore dissociation constants and to characterize the coordination mode of iron over a wide pH range, in the presence of both mutant proteins and synthetic salicylate analogues of Ent. While Scn binding hinders salicylate coordination transformation, strong acidification results in the release of iron and degraded siderophore. Iron release may therefore result from a combination of Ent degradation and coordination change.
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Affiliation(s)
- Rebecca J. Abergel
- Department of Chemistry, University of California, Berkeley, CA 94720-1460
| | - Matthew C. Clifton
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Juan C. Pizarro
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Jeffrey A. Warner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - David K. Shuh
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Roland K. Strong
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109
| | - Kenneth N. Raymond
- Department of Chemistry, University of California, Berkeley, CA 94720-1460
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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18
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Samuel APS, Moore EG, Melchior M, Xu J, Raymond KN. Water-soluble 2-hydroxyisophthalamides for sensitization of lanthanide luminescence. Inorg Chem 2008; 47:7535-44. [PMID: 18671388 DOI: 10.1021/ic800328g] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of octadentate ligands featuring the 2-hydroxyisophthalamide (IAM) antenna chromophore to sensitize Tb(III) and Eu(III) luminescence has been prepared and characterized. The length of the alkyl amine scaffold that links the four IAM moieties has been varied to investigate the effect of the ligand backbone on the stability and photophysical properties of the Ln(III) complexes. The amine backbones utilized in this study are N,N,N',N'-tetrakis-(2-aminoethyl)-ethane-1,2-diamine [H(2,2)-], N,N,N',N'-tetrakis-(2-aminoethyl)-propane-1,3-diamine [H(3,2)-], and N,N,N',N'-tetrakis-(2-aminoethyl)-butane-1,4-diamine [H(4,2)-]. These ligands also incorporate methoxyethylene [MOE] groups on each of the IAM chromophores to increase their water solubility. The aqueous ligand protonation constants and Tb(III) and Eu(III) formation constants were determined from solution thermodynamic studies. The resulting values indicate that at physiological pH the Eu(III) and Tb(III) complexes of H(2,2)-IAM-MOE and H(4,2)-IAM-MOE are sufficiently stable to prevent dissociation at nanomolar concentrations. The photophysical measurements for the Tb(III) complexes gave overall quantum yield values of 0.56, 0.39, and 0.52 respectively for the complexes with H(2,2)-IAM-MOE, H(3,2)-IAM-MOE, and H(4,2)-IAM-MOE, while the corresponding Eu(III) complexes displayed significantly weaker luminescence, with quantum yield values of 0.0014, 0.0015, and 0.0058, respectively. Analysis of the steady state Eu(III) emission spectra provides insight into the solution symmetries of the complexes. The combined solubility, stability, and photophysical performance of the Tb(III) complexes in particular make them well suited to serve as the luminescent reporter group in high sensitivity time-resolved fluoroimmunoassays.
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Affiliation(s)
- Amanda P S Samuel
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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19
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Mies KA, Gebhardt P, Möllmann U, Crumbliss AL. Synthesis, siderophore activity and iron(III) chelation chemistry of a novel mono-hydroxamate, bis-catecholate siderophore mimic: Nα,-Nε-Bis[2,3-dihydroxybenzoyl]-l-lysyl-(γ-N-methyl-N-hydroxyamido)-l-glutamic acid. J Inorg Biochem 2008; 102:850-61. [DOI: 10.1016/j.jinorgbio.2007.11.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 11/30/2007] [Accepted: 11/30/2007] [Indexed: 01/19/2023]
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20
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Pierre VC, Botta M, Aime S, Raymond KN. Tuning the coordination number of hydroxypyridonate-based gadolinium complexes: implications for MRI contrast agents. J Am Chem Soc 2007; 128:5344-5. [PMID: 16620097 PMCID: PMC3188315 DOI: 10.1021/ja057805x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Eight-coordinate hydroxypyridinone/terephthalamide GdIII complexes display high relaxivities due to their two inner sphere water molecules. This relaxivity can be further increased by functionalizing the terephthalamide moiety with an amine. A significant hydrogen bonding interaction between the amine and another water molecule close to the GdIII apparently facilitates its coordination on the open site of the metal. The resulting nine-coordinate complex has three inner sphere water molecules, while maintaining high stability and fast ligand exchange rates.
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Affiliation(s)
- Valérie C Pierre
- Department of Chemistry, University of California, Berkeley, California 94720-1460, USA
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21
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Abergel RJ, Warner JA, Shuh DK, Raymond KN. Enterobactin protonation and iron release: structural characterization of the salicylate coordination shift in ferric enterobactin. J Am Chem Soc 2007; 128:8920-31. [PMID: 16819888 PMCID: PMC3188320 DOI: 10.1021/ja062046j] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The siderophore enterobactin (Ent) is produced by many species of enteric bacteria to mediate iron uptake. This iron scavenger can be reincorporated by the bacteria as the ferric complex [Fe(III)(Ent)](3)(-) and is subsequently hydrolyzed by an esterase to facilitate intracellular iron release. Recent literature reports on altered protein recognition and binding of modified enterobactin increase the significance of understanding the structural features and solution chemistry of ferric enterobactin. The structure of the neutral protonated ferric enterobactin complex [Fe(III)(H(3)Ent)](0) has been the source of some controversy and confusion in the literature. To demonstrate the proposed change of coordination from the tris-catecholate [Fe(III)(Ent)](3)(-) to the tris-salicylate [Fe(III)(H(3)Ent)](0) upon protonation, the coordination chemistry of two new model compounds N,N',N''-tris[2-(hydroxybenzoyl)carbonyl]cyclotriseryl trilactone (SERSAM) and N,N',N''-tris[2-hydroxy,3-methoxy(benzoyl)carbonyl]cyclotriseryl trilactone (SER(3M)SAM) was examined in solution and solid state. Both SERSAM and SER(3M)SAM form tris-salicylate ferric complexes with spectroscopic and solution thermodynamic properties (with log beta(110)() values of 39 and 38 respectively) similar to those of [Fe(III)(H(3)Ent)](0). The fits of EXAFS spectra of the model ferric complexes and the two forms of ferric enterobactin provided bond distances and disorder factors in the metal coordination sphere for both coordination modes. The protonated [Fe(III)(H(3)Ent)](0) complex (d(Fe)(-)(O) = 1.98 A, sigma(2)(stat)(O) = 0.00351(10) A(2)) exhibits a shorter average Fe-O bond length but a much higher static Debye-Waller factor for the first oxygen shell than the catecholate [Fe(III)(Ent)](3)(-) complex (d(Fe)(-)(O) = 2.00 A, sigma(2)(stat)(O) = 0.00067(14) A(2)). (1)H NMR spectroscopy was used to monitor the amide bond rotation between the catecholate and salicylate geometries using the gallic complexes of enterobactin: [Ga(III)(Ent)](3)(-) and [Ga(III)(H(3)Ent)](0). The ferric salicylate complexes display quasi-reversible reduction potentials from -89 to -551 mV (relative to the normal hydrogen electrode NHE) which supports the feasibility of a low pH iron release mechanism facilitated by biological reductants.
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Affiliation(s)
- Rebecca J. Abergel
- Contribution from the Department of Chemistry, University of California, Berkeley, CA 94720-1460
| | - Jeffrey A. Warner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - David K. Shuh
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Kenneth N. Raymond
- Contribution from the Department of Chemistry, University of California, Berkeley, CA 94720-1460
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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22
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Abergel RJ, Raymond KN. Synthesis and thermodynamic evaluation of mixed hexadentate linear iron chelators containing hydroxypyridinone and terephthalamide units. Inorg Chem 2007; 45:3622-31. [PMID: 16634594 PMCID: PMC3685440 DOI: 10.1021/ic052111a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of new linear iron chelators containing hydroxypyridinone and terephthalamide (TAMmeg) moieties have been prepared. All are hexadentate ligands composed of a systematically varied combination of methyl-3,2-hydroxypyridinone and 2,3-dihydroxyterephthalamide binding units; most are based on a spermidine scaffold, but one incorporates the bifunctional 2,3-dihydroxyterephthalamide unit as an integral part of the backbone. Protonation and ferric iron complex formation constants have been determined from solution thermodynamic studies, giving log beta(110) values of 25.7, 30.7, 36.3, 43.8, and 45.0, respectively. The ferric complexes display reversible reduction potentials from -276 to -1032 mV (measured relative to the normal hydrogen electrode) in alkaline solution. The incremental replacement of hydroxypyridinone units by terephthalamide binding groups progressively reduces the ligand acidity, markedly increases the iron-chelate stability, and improves the selectivity for the ferric ion over the ferrous ion. While the majority of iron chelators forming very stable ferric complexes are based on a tripodal backbone such as TREN, the ferric 5-LIO(TAMmeg)(2)(TAM) complex, despite its nontripodal scaffold, is one of the most stable iron complexes yet reported. Moreover, the high affinity for the ferric ion of the discussed linear ligands strongly correlates with their ability to remove iron in vivo.
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23
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Affiliation(s)
- K.M. Clarke Jurchen
- a Department of Chemistry , University of California at Berkeley , CA 94720-1460, USA
| | - K.N. Raymond
- a Department of Chemistry , University of California at Berkeley , CA 94720-1460, USA
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24
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Chittamuru S, Lambert TN, Martinez G, Jacobs HK, Gopalan AS. New methodology for the preparation of 3-hydroxy-2-pyridinone (3,2-HOPO) chelators and extractants. Part 2. Reactions of alcohols, phenols, and thiols with an electrophilic 3,2-HOPO reagent(). Tetrahedron Lett 2007; 48:567-571. [PMID: 23162171 DOI: 10.1016/j.tetlet.2006.11.128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The reactions of the electrophilic iminium ester mesylate salt 1 with alcohols, phenols and thiols has been investigated. In the presence of base, thiols, phenols and thiophenol react with 1 to give the corresponding ether linked HOPO derivatives in good yields. However, the ring opening of salt 1 with alcohols could only be accomplished efficiently using a large excess of the alcohol in the presence of methanesulfonic acid at 80°C. The synthetic utility of HOPO precursor, 1, has been demonstrated by the synthesis of two polyHOPO chelators 7 and 9.
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Affiliation(s)
- Sumathi Chittamuru
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University, Las Cruces, NM 88003-8001
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25
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Kinetics and mechanism of the formation of (1,8)bis(2-hydroxybenzamido)3,6-diazaoctaneiron(III) and its reactions with thiocyanate, azide, acetate, sulfur(IV) and ascorbic acid in solution, and the synthesis and characterization of a novel oxo bridged diiron(III) complex. The role of phenol–amide–amine coordination. TRANSIT METAL CHEM 2006. [DOI: 10.1007/s11243-006-0079-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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d'Hardemare ADM, Torelli S, Serratrice G, Pierre JL. Design of Iron chelators: Syntheses and iron (III) complexing abilities of tripodal tris-bidentate ligands. Biometals 2006; 19:349-66. [PMID: 16841245 DOI: 10.1007/s10534-005-2997-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Accepted: 09/07/2005] [Indexed: 10/24/2022]
Abstract
The interest in synthetic siderophore mimics includes therapeutic applications (iron chelation therapy), the design of more effective agents to deliver Fe to plants and the development of new chemical tools in order to study iron metabolism and iron assimilation processes in living systems. The design of ligands needs a rational approach for the understanding of the metal ion complexing abilities. The octahedral arrangement of donor atoms is the most favourable geometry, allowing the maximum possible distance between their formal or partial negative charges. Hexadentate chelators, usually of the tris-bidentate type, can accommodate the metal coordination sphere and are well-suited to obtain high pFe values. The first part of this review is dedicated to selected synthetic routes, taking into account (i) the nature of the chelating subunits, connecting groups and spacers, (ii) the water-solubility and hydrophilic/lipophilic balance, (iii) the chirality and (iv) the possibility of grafting probes or vectors. In the second part, we discuss the role of the molecular design on complexing abilities (thermodynamics and kinetics). The bidentate 8-hydroxyquinoline moiety offers an alternative to the usual coordinating hydroxamic acids, catechols and/or alpha-hydroxycarboxylic acids groups encountered in natural siderophores. The promizing results obtained with the tris-hydroxyquinoline-based ligand O-TRENSOX are summarized. O-TRENSOX exhibits a high and selective affinity for Fe(III) complexation. Its efficiency in delivering Fe to plants, iron mobilization, cell protection, and antiproliferative effects has been evidenced. Other chelators derived from O-TRENSOX (mixed catechol/8-hydroxyquinoline ligands, lipophilic ligands) are also described. Some results question the relevance of partition coefficients to foresee the activity of iron chelators. The development of probes (fluorescent, radioactive, spin labelled) based on the O-TRENSOX backbone is in progress in order to get insights in the complicated iron metabolism processes.
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Affiliation(s)
- Amaury du Moulinet d'Hardemare
- Laboratoire de Chimie Biomimétique, ICMG, LEDSS, UMR CNRS 5616, Université J. Fourier BP 53, 38041, Grenoble Cedex 9, France
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27
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Thompson KH, Barta CA, Orvig C. Metal complexes of maltol and close analogues in medicinal inorganic chemistry. Chem Soc Rev 2006; 35:545-56. [PMID: 16729148 DOI: 10.1039/b416256k] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The family of hydroxypyrones and close congeners, the hydroxypyridinones, is a particularly versatile class of ligands. The most widely investigated for medicinal applications are the 3-hydroxy-4-pyrones and the 1,2- 3,2- and 3,4-hydroxypyridinones. Key features of these ligands are: a six-membered ring, with a ring N or O atom either ortho or para to a ketone group, and two ortho exocyclic oxygen atoms. Readily functionalizable, the hydroxypyrones and hydroxypyridinones allow one to achieve a range of di- and trivalent metallocomplex stabilities and can include tissue or molecular targeting features by design. Research over the past several decades has greatly expanded the array of ligands that are the subject of this critical review. Ligand applications as diverse as iron removal or supplementation, contrast agents in imaging applications, and mobilization of undesirable excess metal ions will be surveyed herein.
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Affiliation(s)
- Katherine H Thompson
- Medicinal Inorganic Chemistry Group, Chemistry Department, University of British Columbia, Vancouver, BC, Canada V6T 1Z1.
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Mixed Intramolecular Hydrogen Bonding in Dihydroxythiophene-based Units and Boron and Technetium Chelation. B KOREAN CHEM SOC 2006. [DOI: 10.5012/bkcs.2006.27.2.243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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29
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Kalinowski DS, Richardson DR. The Evolution of Iron Chelators for the Treatment of Iron Overload Disease and Cancer. Pharmacol Rev 2005; 57:547-83. [PMID: 16382108 DOI: 10.1124/pr.57.4.2] [Citation(s) in RCA: 554] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The evolution of iron chelators from a range of primordial siderophores and aromatic heterocyclic ligands has lead to the formation of a new generation of potent and efficient iron chelators. For example, various siderophore analogs and synthetic ligands, including ICL670A [4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid], 4'-hydroxydesazadesferrithiocin, and Triapine, have been developed from predecessors and illustrate potent iron-mobilizing or antineoplastic activities. This review focuses on the evolution of iron chelators from initial lead compounds through to the development of novel chelating agents, many of which show great potential to be clinically applied in the treatment of iron overload disease and cancer.
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Affiliation(s)
- Danuta S Kalinowski
- The Iron Metabolism and Chelation Program, Children's Cancer Institute Australia for Medical Research, Sydney, New South Wales, Australia
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Esteves M, Cachudo A, Chaves S, Santos M. Synthesis and Metal-Complexation Properties of a New Hydroxypyrimidinone-Functionalized Sepharose. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200400355] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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31
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Lewis JA, Tran BL, Puerta DT, Rumberger EM, Hendrickson DN, Cohen SM. Synthesis, structure and spectroscopy of new thiopyrone and hydroxypyridinethione transition-metal complexes. Dalton Trans 2005:2588-96. [PMID: 16025179 DOI: 10.1039/b505034k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The coordination chemistry of several O,S mixed donor ligands, namely thiopyrone and hydroxypyridinethione chelators, with a variety of middle and late first-row transition-metal ions is described. Complexes of 3-hydroxy-2-methyl-4-thiopyrone (thiomaltol) with cobalt(II), copper(II) and zinc(II); 3-hydroxy-1,2-dimethyl-4(1H)-pyridinethione (3,4-HOPTO) with iron(III), nickel(II), copper(II) and zinc(II); and 3-hydroxy-1-methyl-2(1H)-pyridinethione (3,2-HOPTO) with iron(III), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. The structures, absorbance spectroscopy, cyclic voltammetry and superconducting quantum interferometer device (SQUID) measurements of selected metal complexes, as well as ligand protonation constants, are reported. Most of the metal complexes show coordination geometries indicative of a strong trans influence by the O,S chelators. The data presented herein provide the most detailed study of the transition-metal coordination chemistry of both thiopyrone and hydroxypyridinethione O,S donor ligands to date, and provide the basis for the investigation of these ligands in realm of biological inorganic chemistry.
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Affiliation(s)
- Jana A Lewis
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
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Gorden AEV, Xu J, Raymond KN, Durbin P. Rational Design of Sequestering Agents for Plutonium and Other Actinides. Chem Rev 2003; 103:4207-82. [PMID: 14611263 DOI: 10.1021/cr990114x] [Citation(s) in RCA: 432] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anne E V Gorden
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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Albrecht-Gary AM, Blanc S, Biaso F, Thomas F, Baret P, Gellon G, Pierre JL, Serratrice G. Iron(III) Chelation: Tuning of the pH Dependence by Mixed Ligands. Eur J Inorg Chem 2003. [DOI: 10.1002/ejic.200200643] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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34
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Xu J, O'Sullivan B, Raymond KN. Hexadentate hydroxypyridonate iron chelators based on TREN-Me-3,2-HOPO: variation of cap size. Inorg Chem 2002; 41:6731-42. [PMID: 12470069 DOI: 10.1021/ic025610+] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
TREN-Me-3,2-HOPO, TR322-Me-3,2-HOPO, TR332-Me-3,2-HOPO, and TRPN-Me-3,2-HOPO correspond to stepwise replacement of ethylene by propylene bridges. A series of tripodal, hexadentate hydroxypyridinone ligands are reported. These incorporate 1-methyl-3,2-hydroxypyridinone (Me-3,2-HOPO) bidentate chelating units for metal binding. They are varied by systematic enlargement of the capping scaffold which connects the binding units. The series of ligands and their iron complexes are reported. Single crystal X-ray structures are reported for the ferric complexes of all four tripodal ligands: FeTREN-Me-3,2-HOPO.0.375C(4)H(10)O.0.5CH(2)Cl(2) [P2(1)/n (No. 14), Z = 8, a = 20.478(3) A, b = 12.353(2) A, c = 27.360(3) A; beta = 91.60(1) degrees ]; FeTR322-Me-3,2-HOPO.CHCl(3).0.5C(6)H(14).CH(3)OH.0.5H(2)O [P2(1)/n (No. 14), Z = 4, a = 12.520(3) A, b = 22.577(5) A, c = 16.525(3) A; beta = 111.37(3) degrees ]; FeTR332-Me-3,2-HOPO.3.5CH(3)OH [C2/c (No. 15), Z = 8, a = 13.5294(3) A, b = 19.7831(4) A, c = 27.2439(4) A; beta = 101.15(3) degrees ]; FeTRPN-Me-3,2-HOPO.C(3)H(7)NO.2C(4)H(10)O [P1 (No. 2), Z = 2, a = 11.4891(2) A, b = 12.3583(2) A, c = 15.0473(2) A; alpha = 86.857(1) degrees, beta = 88.414(1) degrees, gamma = 70.124(1) degrees ]. The structures show the importance of intermolecular hydrogen bonds and the effect of cap enlargement to the stability and geometry of the metal complexes throughout the series. All protonation and iron complex formation constants have been determined from solution thermodynamic studies. The TREN-capped derivative is the most acidic, with a cumulative protonation constant, log beta(014), of 25.95. Corresponding values of 26.35, 26.93, and 27.53 were obtained for the TR322, TR332, and TRPN derivatives, respectively. The protonation constants and NMR spectroscopic data are interpreted as being due to the influence of specific hydrogen-bond interactions. The incremental enlargement of ligand size results in a decrease in iron-chelate stability, as reflected in the log beta(110) values of 26.8, 26.2, 26.42, and 24.48 for the TREN, TR322, TR332, and TRPN derivatives, respectively. The metal complex formation constants are also affected by the acidity of a proximal (non-metal-binding) amine in the complexes, a trend consistent with the effects of internal hydrogen bonding. The ferric complexes display reversible reduction potentials (measured relative to the normal hydrogen electrode (NHE)) between -0.170 and -0.223 V.
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Affiliation(s)
- Jide Xu
- Department of Chemistry, University of California at Berkeley, California 94720-1460, USA
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35
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Lambert TN, Chittamuru S, Jacobs HK, Gopalan AS. New methodology for the preparation of 3-hydroxy-2-pyridinone (3,2-HOPO) chelators - Reaction of amines with a novel electrophilic 3,2-HOPO precursor. Tetrahedron Lett 2002; 43:7379-7383. [PMID: 23125467 PMCID: PMC3486744 DOI: 10.1016/s0040-4039(02)01730-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The preparation of the new electrophilic iminium ester mesylate salt 5 and its reaction with primary and secondary amines have been investigated. Aniline, t-butylamine, and secondary amines react with 5 via ring opening to give the corresponding HOPO derivatives in high yields. The usefulness of this methodology has been demonstrated by the preparation of two new di-HOPO derivatives 19 and 21. This method allows the introduction of the HOPO ligand onto a variety of amine platforms without the concomitant formation of an amide bond and provides access to HOPO chelators of increased water solubility.
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Affiliation(s)
- Timothy N. Lambert
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University Las Cruces, NM 88003-8001
| | - Sumathi Chittamuru
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University Las Cruces, NM 88003-8001
| | - Hollie K. Jacobs
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University Las Cruces, NM 88003-8001
| | - Aravamudan S. Gopalan
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University Las Cruces, NM 88003-8001
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Van Horn J, Gramer CJ, O’Sullivan B, Jurchen KM, Doble DM, Raymond KN. Iron(III) 2,3-dihydroxyterephthalamides revisited. Charge effects on highly stable ferric complexes. CR CHIM 2002. [DOI: 10.1016/s1631-0748(02)01394-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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