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MacPherson DS, Fung K, Cook BE, Francesconi LC, Zeglis BM. A brief overview of metal complexes as nuclear imaging agents. Dalton Trans 2019; 48:14547-14565. [PMID: 31556418 PMCID: PMC6829947 DOI: 10.1039/c9dt03039e] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metallic radionuclides have been instrumental in the field of nuclear imaging for over half a century. While recent years have played witness to a dramatic rise in the use of radiometals as labels for chelator-bearing biomolecules, imaging agents based solely on coordination compounds of radiometals have long played a critical role in the discipline as well. In this work, we seek to provide a brief overview of metal complex-based radiopharmaceuticals for positron emission tomography (PET) and single photon emission computed tomography (SPECT). More specifically, we have focused on imaging agents in which the metal complex itself rather than a pendant biomolecule or targeting moiety is responsible for the in vivo behavior of the tracer. This family of compounds contains metal complexes based on an array of different nuclides as well as probes that have been used for the imaging of a variety of pathologies, including infection, inflammation, cancer, and heart disease. Indeed, two of the defining traits of transition metal complexes-modularity and redox chemistry-have both been creatively leveraged in the development of imaging agents. In light of our audience, particular attention is paid to structure and mechanism, though clinical data is addressed as well. Ultimately, it is our hope that this review will not only educate readers about some of the seminal work performed in this space over the last 30 years but also spur renewed interest in the creation of radiopharmaceuticals based on small metal complexes.
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Affiliation(s)
- Douglas S MacPherson
- Department of Chemistry, Hunter College of the City University of New York, New York, NY 10028, USA.
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Abstract
Radiometals possess an exceptional breadth of decay properties and have been applied to medicine with great success for several decades. The majority of current clinical use involves diagnostic procedures, which use either positron-emission tomography (PET) or single-photon imaging to detect anatomic abnormalities that are difficult to visualize using conventional imaging techniques (e.g., MRI and X-ray). The potential of therapeutic radiometals has more recently been realized and relies on ionizing radiation to induce irreversible DNA damage, resulting in cell death. In both cases, radiopharmaceutical development has been largely geared toward the field of oncology; thus, selective tumor targeting is often essential for efficacious drug use. To this end, the rational design of four-component radiopharmaceuticals has become popularized. This Review introduces fundamental concepts of drug design and applications, with particular emphasis on bifunctional chelators (BFCs), which ensure secure consolidation of the radiometal and targeting vector and are integral for optimal drug performance. Also presented are detailed accounts of production, chelation chemistry, and biological use of selected main group and rare earth radiometals.
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Affiliation(s)
- Thomas I Kostelnik
- Medicinal Inorganic Chemistry Group, Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z1 , Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry , University of British Columbia , Vancouver , British Columbia V6T 1Z1 , Canada
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Kim DY, Cho SG, Bom HS. Emerging Tracers for Nuclear Cardiac PET Imaging. Nucl Med Mol Imaging 2018; 52:266-278. [PMID: 30100939 PMCID: PMC6066491 DOI: 10.1007/s13139-018-0521-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 03/05/2018] [Accepted: 04/12/2018] [Indexed: 12/16/2022] Open
Abstract
Myocardial perfusion imaging using positron emission tomography (PET) has several advantages over single photon emission computed tomography (SPECT). The recent advances in SPECT technology have shown promise, but there is still a large need for PET in the clinical management of coronary artery disease (CAD). Especially, absolute quantification of myocardial blood flow (MBF) using PET is extremely important. In spite of considerable advances in the diagnosis of CAD, novel PET radiopharmaceuticals remain necessary for the diagnosis of CAD because clinical use of current cardiac radiotracers is limited by their physical characteristics, such as decay mode, emission energy, and half-life. Thus, the use of a radioisotope that has proper characteristics and a proper half-life to develop myocardial perfusion agents could overcome these limitations. In this review, the current state of cardiac PET and a general overview of novel 18F or 68Ga-labeled radiotracers, including their radiosynthesis, in vivo characterization, and evaluation, are provided. The future perspectives are discussed in terms of their potential usefulness based on new image analysis methods and hybrid imaging.
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Affiliation(s)
- Dong-Yeon Kim
- Department of Nuclear Medicine, Chonnam National University Medical School and Hwasun Hospital, 322 Seoyang-ro Hwasun-eup, Hwasun-gun, Jeollanam-do 58128 Republic of Korea
| | - Sang-Geon Cho
- Department of Nuclear Medicine, Chonnam National University Medical School and Hwasun Hospital, 322 Seoyang-ro Hwasun-eup, Hwasun-gun, Jeollanam-do 58128 Republic of Korea
| | - Hee-Seung Bom
- Department of Nuclear Medicine, Chonnam National University Medical School and Hwasun Hospital, 322 Seoyang-ro Hwasun-eup, Hwasun-gun, Jeollanam-do 58128 Republic of Korea
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Wang X, Jaraquemada-Peláez MDG, Cao Y, Pan J, Lin KS, Patrick BO, Orvig C. H2hox: Dual-Channel Oxine-Derived Acyclic Chelating Ligand for 68Ga Radiopharmaceuticals. Inorg Chem 2018; 58:2275-2285. [DOI: 10.1021/acs.inorgchem.8b01208] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Xiaozhu Wang
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - María de Guadalupe Jaraquemada-Peláez
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Yang Cao
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Jinhe Pan
- BC Cancer Agency, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada
| | - Kuo-Shyan Lin
- BC Cancer Agency, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3, Canada
| | - Brian O. Patrick
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Chris Orvig
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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Venkatachalam TK, Bernhardt PV, Stimson DHR, Pierens GK, Bhalla R, Reutens DC. A Novel Strategy to Introduce 18F, a Positron Emitting Radionuclide, into a Gallium Nitrate Complex: Synthesis, NMR, X-Ray Crystal Structure, and Preliminary Studies on Radiolabelling with 18F. Aust J Chem 2018. [DOI: 10.1071/ch17334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A hexan-3,4-dione bis(4N-phenylthiosemicarbazone) gallium nitrate complex was synthesised and the structure was confirmed by NMR studies. The complex was prepared using an appropriately substituted dithiosemicarbazone and sodium methoxide in anhydrous methanol. The structure was further confirmed using single crystal X-ray crystallography. The crystal structure of gallium nitrate complex of diphenylthiosemicarbazone comprise a planar configuration of the tetradentate coordinated thiosemicarbazone with the Ga3+ ion, with the nitrate ligand occupying the apical coordination site. The X-ray structure of the gallium fluoride complex of pentan-2,3-dione bis(4N-phenylthiosemicarbazone) has been determined and confirms exchange of the nitrate can be achieved with fluoride. We show facile exchange of 18F, a positron emitter, to form the 18F-gallium complex under mild conditions, thus providing confirmation that such a transformation can be used to introduce 18F directly into nitrate-coordinated complexes of gallium-thiosemicarbozone complexes, a new labelling strategy for the preparation of imaging agents.
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Howard-Smith KJ, Craze AR, Badbhade M, Marjo CE, Murphy TD, Castignolles P, Wuhrer R, Li F. Syntheses and Structure Investigations of 3d Transition Metal Complexes with a Flexible N4O2-Donor Hexadentate Schiff-Base Ligand. Aust J Chem 2017. [DOI: 10.1071/ch16678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The syntheses and structure investigations of four new 3d transition metal complexes (1–4) with a flexible N4O2-donor hexadentate Schiff-base ligand are described; three complexes (1, 2, and 4) of FeIII, CoIII, and CuII metal ions have been investigated by UV-vis, FT-IR, high-resolution mass spectrometry (HR-MS), and scanning electron microscopy–electron dispersive spectroscopy, as well as single crystal X-ray diffraction. The X-ray structure of NiII complex 3 is also reported. The molecular structures of the complexes (1–3) demonstrate distorted octahedral coordination geometry, each exhibiting 1 : 1 (M : L) ratios and the CuII complex 4 shows a trinuclear structure with a CuII : L ratio of 3 : 2 in the solid state, which has been proven by X-ray diffraction. On the other hand, a mononuclear species of the CuII complex is formed in solution, which has been identified by electrospray ionization HR-MS.
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Sivapackiam J, Harpstrite SE, Rath NP, Sharma V. 67Ga-metalloprobes: monitoring the impact of geometrical isomers on accumulation profiles in rat cardiomyoblasts and human breast carcinoma cells. MEDCHEMCOMM 2016; 8:158-161. [PMID: 30108701 DOI: 10.1039/c6md00474a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/10/2016] [Indexed: 11/21/2022]
Abstract
Geometrically similar monocationic gallium(iii) complexes and their radiolabeled SPECT counterparts were obtained from Schiff base precursor ligands using ligand exchange reactions to evaluate the impact of cis and trans-isomers on their cellular accumulation profiles in rat cardiomyoblasts (H9c2(2-1)) and human breast carcinoma (MCF-7neo) cells. 67Ga-metalloprobes comprising trans-phenolates showing an overall octahedral geometry and exhibiting uniform spatial distribution of positive charges on their molecular surface show steady-state accumulation in H9c2(2-1) and MCF-7neo cells, and localize in the mitochondria of the cells. Importantly, the surrogate geometrically similar and monocationic metalloprobe counterparts possessing the cis arrangement of phenolates do not show cellular uptake in H9c2(2-1) and MCF-7neo cells. Exploiting their modest fluorescent traits, live cell imaging indicates that trans-isomers of metalloprobes localize within the mitochondria of cells following their penetration, thereby indicating the excellent correlation of radiotracer data and live-cell microscopy results. Overall, these results indicate that the cell uptake profiles of metalloprobes within this class are mediated by the spatial distribution of charges over their molecular surface and hydrophobicity.
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Affiliation(s)
- Jothilingam Sivapackiam
- ICCE Institute , Molecular Imaging Center , Mallinckrodt Institute of Radiology , Washington University School of Medicine , St. Louis , MO 63110 , USA .
| | - Scott E Harpstrite
- ICCE Institute , Molecular Imaging Center , Mallinckrodt Institute of Radiology , Washington University School of Medicine , St. Louis , MO 63110 , USA .
| | - Nigam P Rath
- Department of Chemistry & Biochemistry , University of Missouri , St. Louis , MO 63121 , USA
| | - Vijay Sharma
- ICCE Institute , Molecular Imaging Center , Mallinckrodt Institute of Radiology , Washington University School of Medicine , St. Louis , MO 63110 , USA . .,Department of Neurology , Washington University School of Medicine , St. Louis , MO 63110 , USA.,Department of Biomedical Engineering , School of Engineering & Applied Science , Washington University , St. Louis 63105 , USA
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Beckford FA, Brock A, Gonzalez-Sarrías A, Seeram NP. Cytotoxic gallium complexes containing thiosemicarbazones derived from 9-anthraldehyde: Molecular docking with biomolecules. J Mol Struct 2016; 1121:156-166. [PMID: 27980346 DOI: 10.1016/j.molstruc.2016.05.075] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We have synthesized a trio of gallium complexes bearing 9-anthraldehyde thiosemicarbazones. The complexes were assessed for their anticancer activity and their biophysical reactivity was also investigated. The three complexes displayed good cytotoxic profiles against two human colon cancer cell lines, HCT-116 and Caco-2. The IC50 ranged from 4.7 - 44.1 μM with the complex having an unsubstituted amino group on the thiosemicarbazone being the most active. This particular complex also showed a high therapeutic index. All three complexes bind strongly to DNA via intercalation with binding constants ranging from 7.46 × 104 M-1 to 3.25 × 105 M-1. The strength of the binding cannot be directly related to the level of anticancer activity. The complexes also bind strongly to human serum albumin with binding constants on the order of 104 - 105 M-1 as well. The complexes act as chemical nucleases as evidenced by their ability to cleave pBR322 plasmid DNA. The binding constants along with the cleavage results may suggest that the extent of DNA interaction is not directly correlated with anticancer activity. The results of docking studies with DNA, ribonucleotide reductase and human serum albumin, however showed that the complex with the best biological activity had the largest binding constant to DNA.
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Affiliation(s)
| | - Alyssa Brock
- Science Division, Lyon College, Batesville, AR 72501, USA
| | - Antonio Gonzalez-Sarrías
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Navindra P Seeram
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
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9
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A gallium(III) Schiff base-curcumin complex that binds to amyloid-β plaques. J Inorg Biochem 2016; 162:274-279. [PMID: 26988571 DOI: 10.1016/j.jinorgbio.2016.02.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 02/18/2016] [Accepted: 02/25/2016] [Indexed: 01/20/2023]
Abstract
Gallium-68 is a positron-emitting isotope that can be used in positron-emission tomography imaging agents. Alzheimer's disease is associated with the formation of plaques in the brain primarily comprised of aggregates of a 42 amino acid protein called amyloid-β. With the goal of synthesising charge neutral, low molecular weight, lipophilic gallium complexes with the potential to cross the blood-brain barrier and bind to Aβ plaques we have used an ancillary tetradentate N2O2 Schiff base ligand and the β-diketone curcumin as a bidentate ligand to give a six-coordinate Ga3+ complex. The tetradentate Schiff base ligand adopts the cis-β configuration with deprotonated curcumin acting as a bidentate ligand. The complex binds to amyloid-β plaques in human brain tissue and it is possible that extension of this chemistry to positron-emitting gallium-68 could provide useful imaging agents for Alzheimer's disease.
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10
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Ramogida CF, Schindler D, Schneider C, Tan YK, Huh S, Ferreira CL, Adam MJ, Orvig C. Synthesis and characterization of lipophilic cationic Ga(iii) complexes based on the H2CHXdedpa and H2dedpa ligands and their 67/68Ga radiolabeling studies. RSC Adv 2016. [DOI: 10.1039/c6ra24070d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Novel lipophilic H2dedpa or H2CHXdedpa analogues have been synthesized, characterized, and radiolabeled with 67/68Ga3+ in 10 minutes at ambient temperature.
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Affiliation(s)
- C. F. Ramogida
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
| | - D. Schindler
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
| | - C. Schneider
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
| | - Y. L. K. Tan
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
| | - S. Huh
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
| | | | - M. J. Adam
- Life Sciences Division
- TRIUMF
- Vancouver
- Canada V6T 2A3
| | - C. Orvig
- Medicinal Inorganic Chemistry Group
- Department of Chemistry
- University of British Columbia
- Vancouver
- Canada V6T 1Z1
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Sharma V, Sivapackiam J, Harpstrite SE, Prior JL, Gu H, Rath NP, Piwnica-Worms D. A generator-produced gallium-68 radiopharmaceutical for PET imaging of myocardial perfusion. PLoS One 2014; 9:e109361. [PMID: 25353349 PMCID: PMC4212944 DOI: 10.1371/journal.pone.0109361] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 08/31/2014] [Indexed: 11/19/2022] Open
Abstract
Lipophilic cationic technetium-99m-complexes are widely used for myocardial perfusion imaging (MPI). However, inherent uncertainties in the supply chain of molybdenum-99, the parent isotope required for manufacturing 99Mo/99mTc generators, intensifies the need for discovery of novel MPI agents incorporating alternative radionuclides. Recently, germanium/gallium (Ge/Ga) generators capable of producing high quality 68Ga, an isotope with excellent emission characteristics for clinical PET imaging, have emerged. Herein, we report a novel 68Ga-complex identified through mechanism-based cell screening that holds promise as a generator-produced radiopharmaceutical for PET MPI.
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Affiliation(s)
- Vijay Sharma
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail: (VS); (DPW)
| | - Jothilingam Sivapackiam
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Scott E. Harpstrite
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Julie L. Prior
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Hannah Gu
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Nigam P. Rath
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, Missouri, United States of America
| | - David Piwnica-Worms
- BRIGHT Institute, Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Departments of Cell Biology and Physiology and Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail: (VS); (DPW)
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Thews O, Zimny M, Eppard E, Piel M, Bausbacher N, Nagel V, Rösch F. In Vitro and In Vivo Structure–Property Relationship of 68Ga-Labeled Schiff Base Derivatives for Functional Myocardial PET Imaging. Mol Imaging Biol 2014; 16:802-12. [DOI: 10.1007/s11307-014-0750-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
Radiometals comprise many useful radioactive isotopes of various metallic elements. When properly harnessed, these have valuable emission properties that can be used for diagnostic imaging techniques, such as single photon emission computed tomography (SPECT, e.g.(67)Ga, (99m)Tc, (111)In, (177)Lu) and positron emission tomography (PET, e.g.(68)Ga, (64)Cu, (44)Sc, (86)Y, (89)Zr), as well as therapeutic applications (e.g.(47)Sc, (114m)In, (177)Lu, (90)Y, (212/213)Bi, (212)Pb, (225)Ac, (186/188)Re). A fundamental critical component of a radiometal-based radiopharmaceutical is the chelator, the ligand system that binds the radiometal ion in a tight stable coordination complex so that it can be properly directed to a desirable molecular target in vivo. This article is a guide for selecting the optimal match between chelator and radiometal for use in these systems. The article briefly introduces a selection of relevant and high impact radiometals, and their potential utility to the fields of radiochemistry, nuclear medicine, and molecular imaging. A description of radiometal-based radiopharmaceuticals is provided, and several key design considerations are discussed. The experimental methods by which chelators are assessed for their suitability with a variety of radiometal ions is explained, and a large selection of the most common and most promising chelators are evaluated and discussed for their potential use with a variety of radiometals. Comprehensive tables have been assembled to provide a convenient and accessible overview of the field of radiometal chelating agents.
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Affiliation(s)
- Eric W Price
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, CanadaV6T 1Z1.
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Evaluation of 68Ga-labeled tracers for PET imaging of myocardial perfusion in pigs. Nucl Med Biol 2012; 39:715-23. [DOI: 10.1016/j.nucmedbio.2011.11.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 10/27/2011] [Accepted: 11/08/2011] [Indexed: 11/19/2022]
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Cutler CS, Sisay N, Cantorias M, Galazzi F, Quinn TP, Smith CJ. Development of PET molecular targeting agents with gallium-68. RADIOCHIM ACTA 2011. [DOI: 10.1524/ract.2011.1887] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The utilization of positron emission tomography (PET) is increasing due to its superior imaging quality and its ability to be used for in vivo quantification. Radionuclides that decay by positron emission can be attached to the same chelators used for radiotherapy applications in diagnosis and staging. One such isotope is 68Ga (T
1/2 = 68 min), which can be obtained from a long-lived generator by decay of the parent 68Ge (T
1/2 = 270.8 d). The availability of 68Ga from a generator plus its ability to be stably incorporated with a variety of chelates hold promise for expanding PET utilization to facilities unable to afford their own cyclotron. In collaboration with researchers at the University of Missouri, we have developed and evaluated peptides that target the melanocortin-1 receptor and the gastrin-releasing peptide (GRP) receptor for peptide guided imaging and the rapy. The melanocortin-1 receptor is an attractive target for peptide guided melanoma imaging and therapy. The limited number of receptors per cell, approximately 900–5000, requires high specific activity radiolabeled peptide ligands to prevent target saturation and ensure optimal cellular uptake. GRP receptors are over-expressed by a variety of human cancers such as breast, lung, pancreatic and prostate tumors, and due to bombesin's toxicity, it is necessary to label it in high specific activity. Results are presented on NOTA and DOTA bifunctionalized α-MSH and bombesin peptides, highlighting the differences in specific activity, preparation time and in vivo characteristics.
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Mendes F, Paulo A, Santos I. Metalloprobes for functional monitoring of tumour multidrug resistance by nuclear imaging. Dalton Trans 2011; 40:5377-93. [DOI: 10.1039/c0dt01275k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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(68)Ga-labeled radiopharmaceuticals for positron emission tomography. Nucl Med Mol Imaging 2010; 44:233-40. [PMID: 24899958 DOI: 10.1007/s13139-010-0056-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022] Open
Abstract
(68)Ga is a promising emerging radionuclide for positron emission tomography (PET). It is produced using a (68)Ge/(68)Ga-generator, and thus, would enable the cyclotron-independent distribution of PET. However, new (68)Ga-labeled radiopharmaceuticals that can replace (18)F-labeled agents like [(18)F]fluorodeoxyglucose (FDG) are needed. Most of the (68)Ga-labeled derivatives currently used are peptide agents, but the developments of other agents, such as amino acid derivatives, nitroimidazole derivatives, and glycosylated human serum albumin, are being actively pursued in many laboratories. Thus, appearance of new (68)Ga-labeled radiopharmaceuticals with high impact are expected in the near future. Here, we present an overview of (68)Ga-labeled agents in terms of their clinical significances and relevances to the management of certain tumors, and pertinent pre-clinical developments.
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Sivapackiam J, Harpstrite SE, Prior JL, Gu H, Rath NP, Sharma V. Synthesis, molecular structure, and validation of metalloprobes for assessment of MDR1 P-glycoprotein-mediated functional transport. Dalton Trans 2010; 39:5842-50. [PMID: 20505882 DOI: 10.1039/c002361b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
UNLABELLED The human genome is known to consist of 49 ATP-binding cassette (ABC) transporter genes. Among these ABC proteins, overexpression of multidrug resistance (MDR1) P-glycoprotein (Pgp/ABCB1) is the best characterized barrier to successful chemotherapeutic treatments, impacts pharmacokinetics of numerous recognized drugs, and is also quickly emerging as an important target in the development of neurodegenerative diseases. Therefore, there exists an urgent need to seek radiopharmaceuticals, incorporated with generator-produced radionuclides to assist their widespread deployment, for noninvasive assessment of Pgp-mediated functional transport activity in vivo. METHODS gallium(III) complexes (5a and 5b) possessing octahedral geometry were synthesized, analytically characterized, and evaluated for their potential to serve as probes of Pgp-mediated functional transport activity in cellulo and in vivo. While unlabeled compounds (5a and 5b) were examined via cell cytotoxicity assays, the (67)Ga-labeled counterparts (6a and 6b) were evaluated via cell transport studies and quantitative biodistribution studies in mdr1a/1b((-/-)) gene-deleted mice and their wild-type (WT) counterparts. RESULTS cytotoxicity data of 5a and 5b displayed profiles modified by the expression of Pgp in drug-resistant cells. (67)Ga-metalloprobes (6a and 6b) showed high accumulation in human epidermal carcinoma drug-sensitive KB-3-1 cells (Pgp-), human breast carcinoma MCF-7 (Pgp-) cells; an inhibitor (LY335979, 1 microM) induced accumulation in multidrug resistant (MDR, Pgp+) KB-8-5, KB-8-5-11 cells, and stably transfected MCF-7/MDR1 cells, thus demonstrating their ability to interrogate Pgp-mediated functional transport activity in cellulo. In mdr1a/1b((-/-)) gene-deleted mice, the (67)Ga-metalloprobe (6b) showed 8-fold greater brain uptake and retention compared with WT counterparts and no significant difference in blood pharmacokinetics. CONCLUSION molecular imaging of the functional transport activity of MDR1 Pgp (ABCB1) with (67/68)Ga-metalloprobes could enable non-invasive monitoring of the blood-brain barrier, tumors, and tissues in vivo.
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Affiliation(s)
- Jothilingam Sivapackiam
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, Box 8225, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA
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Wadas TJ, Wong EH, Weisman GR, Anderson CJ. Coordinating radiometals of copper, gallium, indium, yttrium, and zirconium for PET and SPECT imaging of disease. Chem Rev 2010; 110:2858-902. [PMID: 20415480 PMCID: PMC2874951 DOI: 10.1021/cr900325h] [Citation(s) in RCA: 681] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Thaddeus J Wadas
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, 510 S. Kingshighway Blvd., Campus Box 8225 St. Louis, Missouri 63110, USA.
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Yang BY, Jeong JM, Kim YJ, Choi JY, Lee YS, Lee DS, Chung JK, Lee MC. Formulation of 68Ga BAPEN kit for myocardial positron emission tomography imaging and biodistribution study. Nucl Med Biol 2010; 37:149-55. [DOI: 10.1016/j.nucmedbio.2009.10.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Revised: 10/07/2009] [Accepted: 10/23/2009] [Indexed: 11/15/2022]
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Sivapackiam J, Gammon ST, Harpstrite SE, Sharma V. Targeted chemotherapy in drug-resistant tumors, noninvasive imaging of P-glycoprotein-mediated functional transport in cancer, and emerging role of Pgp in neurodegenerative diseases. Methods Mol Biol 2010; 596:141-81. [PMID: 19949924 DOI: 10.1007/978-1-60761-416-6_8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Multidrug resistance (MDR) mediated by overexpression of P-glycoprotein (Pgp) is one of the best characterized transporter-mediated barriers to successful chemotherapy in cancer patients and is also a rapidly emerging target in the progression of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Therefore, strategies capable of delivering chemotherapeutic agents into drug-resistant tumors and targeted radiopharmaceuticals acting as ultrasensitive molecular imaging probes for detecting functional Pgp expression in vivo could be expected to play a vital role in systemic biology as personalized medicine gains momentum in the twenty-first century. While targeted therapy could be expected to deliver optimal doses of chemotherapeutic drugs into the desired targets, the interrogation of Pgp-mediated transport activity in vivo via noninvasive imaging techniques (SPECT and PET) would be beneficial in stratification of patient populations likely to benefit from a given therapeutic treatment, thereby assisting management of drug resistance in cancer and treatment of neurodegenerative diseases. Both strategies could play a vital role in advancement of personalized treatments in cancer and neurodegenerative diseases. Via this tutorial, authors make an attempt in outlining these strategies and discuss their strengths and weaknesses.
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Affiliation(s)
- Jothilingam Sivapackiam
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO, USA
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Hsiao YM, Mathias CJ, Wey SP, Fanwick PE, Green MA. Synthesis and biodistribution of lipophilic and monocationic gallium radiopharmaceuticals derived from N,N'-bis(3-aminopropyl)-N,N'-dimethylethylenediamine: potential agents for PET myocardial imaging with 68Ga. Nucl Med Biol 2009; 36:39-45. [PMID: 19181267 DOI: 10.1016/j.nucmedbio.2008.10.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 09/18/2008] [Accepted: 10/21/2008] [Indexed: 11/26/2022]
Abstract
INTRODUCTION In locations that lack nearby cyclotron facilities for radionuclide production, generator-based (68)Ga radiopharmaceuticals might have clinical utility for positron emission tomography (PET) studies of myocardial perfusion and other physiological processes. METHODS The lipophilic and monocationic (67)Ga-labeled gallium chelates of five novel hexadentate bis(salicylaldimine) ligands the bis(salicylaldimine), bis(3-methoxysalicylaldimine), bis(4-methoxysalicylaldimine), bis(6-meth,oxysalicylaldimine), and bis(4,6-dimethoxysalicylaldimine) of N,N'-bis(3-aminopropyl)-N,N'-dimethylethylenediamine (BAPDMEN), were prepared. The structure of the unlabeled [Ga(4-MeOsal)(2)BAPDMEN](+)PF(6)(-) salt was determined by X-ray crystallography, and the biodistribution of each of the (67)Ga-labeled gallium chelates was determined in rats following intravenous administration and compared with the biodistribution of [(86)Rb]rubidium chloride. RESULTS The [Ga(4-MeOsal)(2)BAPDMEN](+)PF(6)(-) complex exhibited the expected pseudo-octahedral N(4)O(2)(2-) coordination sphere about the Ga(3+) center with a trans disposition of the phenolate oxygen atoms. All five (67)Ga radiopharmaceuticals were found to afford the desired myocardial retention of the radiogallium. The [(67/68)Ga][Ga(3-MeOsal)(2)BAPDMEN](1+) radiopharmaceutical appears to have the best properties for myocardial imaging, exhibiting 2% of the injected dose in the heart 1 min and 2 h postinjection and very high heart/nontarget ratios (heart/blood ratios of 7.6+/-1.0 and 54+/-10 at 1 and 120 min, respectively; heart/liver ratios of 1.8+/-0.4 and 39+/-3 at 1 and 120 min, respectively). CONCLUSIONS Most of these new agents, particularly [(67/68)Ga][Ga(3-MeOsal)(2)BAPDMEN](1+), would appear superior to previously reported bis(salicylaldimine) ligands of N,N'-bis(3-aminopropyl)ethylenediamine as candidates for PET imaging of the heart with (68)Ga.
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Affiliation(s)
- Yui-May Hsiao
- Department of Industrial and Physical Pharmacy, Purdue University, West Lafayette, IN 47907, USA
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Design considerations towards simultaneously radiolabeled and fluorescent imaging probes incorporating metallic species. ADVANCES IN INORGANIC CHEMISTRY 2009. [DOI: 10.1016/s0898-8838(09)00203-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Plössl K, Chandra R, Qu W, Lieberman BP, Kung MP, Zhou R, Huang B, Kung HF. A novel gallium bisaminothiolate complex as a myocardial perfusion imaging agent. Nucl Med Biol 2007; 35:83-90. [PMID: 18158947 DOI: 10.1016/j.nucmedbio.2007.08.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2007] [Revised: 08/09/2007] [Accepted: 08/11/2007] [Indexed: 11/15/2022]
Abstract
The development of new myocardial perfusion imaging agents for positron emission tomography (PET) may improve the resolution and quantitation of changes in regional myocardial perfusion measurement. It is known that a (68)Ge/(68)Ga generator can provide a convenient source of PET tracers because of the long physical half-life of (68)Ge (271 days). A new ligand, 7,8-dithia-16,24-diaza-trispiro[5.2.5.2.5.3]pentacosa-15,24-diene, which consists of a N(2)S(2)-chelating core incorporated into three cyclohexyl rings, was prepared. To test feasibility and potential utility, the N(2)S(2) ligand was successfully labeled and tested with (67)Ga (half-life=3.26 day; gamma=93.3, 184.6 and 300.2 keV), which showed >92% radiochemical purity. The corresponding "cold" Ga complex was synthesized, and its structure containing a pyramidal N(2)S(2) chloride core was elucidated with X-ray crystallography. In vivo biodistribution of this novel (67)Ga complex, evaluated in normal rats, exhibited excellent heart uptake and retention, with 2.1% and 0.9% initial dose/organ at 2 and 60 min, respectively, after an intravenous injection. Autoradiography was performed in normal rats and in rats that had the left anterior descending coronary artery permanently ligated surgically. Autoradiography showed an even uptake of activity in the normal heart, and there was a distinctively lower uptake in the damaged side of the surgically modified heart. In conclusion, the new N(2)S(2) ligand was readily prepared and labeled with radioactive (67)Ga. Biodistribution in rats revealed high initial heart uptake and relatively high retention reflecting regional myocardial perfusion.
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Affiliation(s)
- Karl Plössl
- Department of Radiology, University of Pennsylvania, Philadelphia, PA 19104, USA
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Harpstrite SE, Prior J, Rath NP, Sharma V. Metalloprobes: synthesis, characterization, and potency of a novel gallium(III) complex in human epidermal carcinoma cells. J Inorg Biochem 2007; 101:1347-53. [PMID: 17617464 PMCID: PMC4349512 DOI: 10.1016/j.jinorgbio.2007.04.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 04/17/2007] [Accepted: 04/20/2007] [Indexed: 12/20/2022]
Abstract
Multidrug resistance (MDR) mediated by overexpression of the MDR1 gene product, P-glycoprotein (Pgp), represents one of the best characterized barriers to chemotherapeutic treatment in cancer and may be a pivotal factor in progression of Alzheimer's disease (AD). Thus, agents capable of probing Pgp-mediated transport could be beneficial in biomedical imaging. Herein, we synthesized and structurally characterized a gallium(III) complex (5) of the naphthol-Schiff base ligand. The crystal structure revealed octahedral geometry for the metallodrug. Cytotoxicity profiles of 5 were evaluated in KB-3-1 (Pgp-) and KB-8-5 (Pgp+) human epidermal carcinoma cell lines. Compared with an LC(50) (the half-maximal cytotoxic concentration) value of 1.93 microM in drug-sensitive (Pgp-) cells, the gallium(III) complex 5 demonstrated an LC(50) value>100 microM in drug-resistant (Pgp+) cells, thus indicating that 5 was recognized by the Pgp as its substrate, thereby extruded from the cells and sequestered away from their cytotoxic targets. Radiolabeled analogues of 5 could be beneficial in noninvasive imaging of Pgp-mediated transport in vivo.
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Affiliation(s)
- Scott E. Harpstrite
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO 63110
| | - Julie Prior
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO 63110
| | - Nigam P. Rath
- Department of Chemistry & Biochemistry, University of Missouri, St. Louis, MO 63121
| | - Vijay Sharma
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO 63110
- Correspondence: Vijay Sharma, Ph.D., Mallinckrodt Institute of Radiology, Washington University Medical School, Box 8225, 510 S. Kingshighway Blvd., St. Louis, MO 63110, Tele: 314-362-9358; Fax: 314-362-0152,
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Piwnica-Worms D, Kesarwala AH, Pichler A, Prior JL, Sharma V. Single photon emission computed tomography and positron emission tomography imaging of multi-drug resistant P-glycoprotein--monitoring a transport activity important in cancer, blood-brain barrier function and Alzheimer's disease. Neuroimaging Clin N Am 2007; 16:575-89, viii. [PMID: 17148020 DOI: 10.1016/j.nic.2006.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Overexpression of multi-drug resistant P-glycoprotein (Pgp) remains an important barrier to successful chemotherapy in cancer patients and impacts the pharmacokinetics of many important drugs. Pgp is also expressed on the luminal surface of brain capillary endothelial cells wherein Pgp functionally comprises a major component of the blood-brain barrier by limiting central nervous system penetration of various therapeutic agents. In addition, Pgp in brain capillary endothelial cells removes amyloid-beta from the brain. Several single photon emission computed tomography and positron emission tomography radiopharmaceutical have been shown to be transported by Pgp, thereby enabling the noninvasive interrogation of Pgp-mediated transport activity in vivo. Therefore, molecular imaging of Pgp activity may enable noninvasive dynamic monitoring of multi-drug resistance in cancer, guide therapeutic choices in cancer chemotherapy, and identify transporter deficiencies of the blood-brain barrier in Alzheimer's disease.
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Affiliation(s)
- David Piwnica-Worms
- Washington University Medical School, 510 South Kingshighway Boulevard, Box 8225, St. Louis, MO 63110, USA.
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Sharma V. Radiopharmaceuticals for assessment of multidrug resistance P-glycoprotein-mediated drug transport activity. Bioconjug Chem 2005; 15:1464-74. [PMID: 15546216 DOI: 10.1021/bc0498469] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Multidrug resistance (MDR) mediated by overexpression of MDR1 P-glycoprotein (Pgp) is one of the best characterized transporter-mediated barriers to successful chemotherapy in cancer patients. Thus, noninvasive interrogation of Pgp-mediated transport activity in vivo would be beneficial in guiding therapeutic choices. Both small organic medicinals as well as metal complexes characterized as transport substrates for Pgp are amenable to incorporation of PET or SPECT radionuclides and may enable noninvasive imaging of Pgp in cancer patients. Toward this objective, clinically approved agents, exemplified by (99m)Tc-Sestamibi and (99m)Tetrofosmin, have already shown promise for the functional evaluation of Pgp-mediated transport activity in human tumors in vivo. In addition, selected agents from an upcoming class of substituted Schiff-base gallium(III) complexes containing an N(4)O(2) donor core in their organic scaffold and capable of generating both SPECT and PET radiopharmaceuticals have also been shown to be promising for noninvasive assessment of Pgp activity in vitro and in vivo.
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Affiliation(s)
- Vijay Sharma
- Molecular Imaging Center, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, Missouri 63110, USA.
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Yoo J, Reichert DE, Welch MJ. Comparative in vivo behavior studies of cyclen-based copper-64 complexes: regioselective synthesis, X-ray structure, radiochemistry, log P, and biodistribution. J Med Chem 2005; 47:6625-37. [PMID: 15588098 DOI: 10.1021/jm0496990] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The in vivo behavior of copper(II)-cyclen complexes was modified via substitution of the parent ligand with two different substituents, 4-tert-butylbenzyl and acetate. This was achieved by using same synthetic strategy (regioselective protection/first alkylation/deprotection/second alkylation) to give nine cyclen derivatives. The X-ray structure of [Cu(2c)Cl]+ (2c = 1-(4-tert-butylbenzyl)-1,4,7,10-tetraazacyclododecane) showed that the chlorine ion from the reaction mixture occupied the remaining apical position of a square pyramidal coordination environment of these Cu-cyclen complexes. Eight out of nine compounds were labeled with 64Cu in high radiochemical purity. log P measurements showed that the lipophilicities of the copper complexes were increased dramatically by attaching hydrophobic substituents on the nitrogen atoms of cyclen. Conversely, as the number of acetate groups increased, the lipophilicity was decreased. The biodistribution of Cu-cyclen complexes was found to be influenced mostly by the overall charge of the complexes rather than their lipophilicity. Positively charged (+2) complexes showed high blood retention at early time points with sluggish clearance from liver by 24 h. The attachment of even one acetate group onto cyclen accelerated blood and liver clearance dramatically compared to +2 charged Cu(II) complexes. Neutral trans-substituted Cu-4 showed the best clearance and lowest retention of doses from all organs most time, followed by -1 charged complex Cu-2. Trans-substituted complexes structure isomers Cu-3 and Cu-4 showed better clearance and lower retention from all organs than their cis-counterparts Cu-5 and Cu-6.
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Affiliation(s)
- Jeongsoo Yoo
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, Campus Box 8225, 510 South Kingshighway Boulevard, St. Louis, Missouri 63110, USA
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Ocheskey JA, Harpstrite SE, Oksman A, Goldberg DE, Sharma V. Metalloantimalarials: synthesis and characterization of a novel agent possessing activity against Plasmodium falciparum. Chem Commun (Camb) 2005:1622-4. [PMID: 15770280 DOI: 10.1039/b415771k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis, characterization, and antimalarial potency of an amine-phenol complex of gallium(III), [{1,12-bis(2-hydroxy-3-methoxy-5-(quinolin-3-yl)-benzyl)-1,5,8,12-tetraazadodecane}-gallium(III)]+, [Ga-3-M-5-Quadd]+ (7) is described; a novel agent that targets Plasmodium falciparum strains.
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Affiliation(s)
- Joseph A Ocheskey
- Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO, USA
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Ocheskey JA, Polyakov VR, Harpstrite SE, Oksman A, Goldberg DE, Piwnica-Worms D, Sharma V. Synthesis, characterization, and molecular structure of a gallium(III) complex of an amine-phenol ligand with activity against chloroquine-sensitive Plasmodium falciparum strains. J Inorg Biochem 2003; 93:265-70. [PMID: 12576290 DOI: 10.1016/s0162-0134(02)00592-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Emergence of chloroquine-resistant Plasmodium falciparum strains necessitates discovery of novel antimalarial drugs, especially if the agents can be synthesized from commercially available, inexpensive precursors via short synthetic routes. While exploring structure-activity relationships, we found a gallium(III) complex, [(1,12-bis(2-hydroxy-5-methoxybenzyl)-1,5,8,12-tetraazadodecane)-gallium(III)](+) [Ga-5-Madd](+), 1, that possessed antimalarial efficacy. Like previously reported complexes, the crystal structure of 1 revealed gallium(III) in a symmetrical octahedral environment surrounded by four secondary amine nitrogen atoms in equatorial plane and two axial oxygen atoms. In contrast to a previously reported complex, [Ga-3-Madd](+), this novel metallo-antimalarial 1 possessed modest efficacy against chloroquine-sensitive HB3 Plasmodium lines. Thus, slight variation in the positions of methoxy functionalities on the aromatic rings of the organic scaffold dramatically altered specificity thereby suggesting a targeted (e.g., transporter- or receptor-mediated) rather than non-specific (e.g., pH or other gradient-mediated) mechanism of action for these agents.
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Affiliation(s)
- Joseph A Ocheskey
- Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO 63110, USA
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Sharma V, Dahlheimer J, Piwnica-Worms D. Novel gallium(III) complexes as potential pet imaging agents for probing multidrug resistance (MDR1) P-glycoprotein (PGP) transport activity: Effect of MDR reversal agents. J Labelled Comp Radiopharm 2001. [DOI: 10.1002/jlcr.2580440126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sharma V, Beatty A, Wey SP, Dahlheimer J, Pica CM, Crankshaw CL, Bass L, Green MA, Welch MJ, Piwnica-Worms D. Novel gallium(III) complexes transported by MDR1 P-glycoprotein: potential PET imaging agents for probing P-glycoprotein-mediated transport activity in vivo. CHEMISTRY & BIOLOGY 2000; 7:335-43. [PMID: 10801474 DOI: 10.1016/s1074-5521(00)00111-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Multidrug resistance (MDR) mediated by expression of MDR1 P-glycoprotein (Pgp) represents one of the best characterized barriers to chemotherapy in cancer patients. Positron emission tomography (PET) agents for analysis of Pgp-mediated drug transport activity in vivo would enable noninvasive assessment of chemotherapeutic regimens and MDR gene therapy. RESULTS Candidate Schiff-base phenolic gallium(III) complexes were synthesized from their heptadentate precursors and gallium(III)acetylacetonate. Crystal structures demonstrated a hexacoordinated central gallium with overall trans-pseudo-octahedral geometry. Radiolabeled (67)Ga-complexes were obtained in high purity and screened in drug-sensitive (Pgp(-)) and MDR (Pgp(+)) tumor cells. Compared with control, lead compound 6. demonstrated antagonist-reversible 55-fold lower accumulation in Pgp-expressing MDR cells. Futhermore, compared with wild-type control, quantitative pharmacokinetic analysis showed markedly increased penetration and retention of 6. in brain and liver tissues of mdr1a/b((-/-)) gene disrupted mice, correctly mapping Pgp-mediated transport activity at the capillary blood-brain barrier and hepatocellular biliary cannalicular surface in vivo. CONCLUSIONS These results indicate that gallium(III) complex 6. is recognized by MDR1 Pgp as an avid transport substrate, thereby providing a useful scaffold to generate (68)Ga radiopharmaceuticals for molecular imaging of Pgp transport activity in tumors and tissues in vivo using PET.
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Affiliation(s)
- V Sharma
- Department of Molecular Biology and Pharmacology, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, MO 63110, USA
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Sharma V, Piwnica-Worms D. Metal complexes for therapy and diagnosis of drug resistance. Chem Rev 1999; 99:2545-60. [PMID: 11749491 DOI: 10.1021/cr980429x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- V Sharma
- Laboratory of Molecular Radiopharmacology, Mallinckrodt Institute of Radiology, and Department of Molecular Biology and Pharmacology, Washington University Medical School, St. Louis, Missouri
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Anderson CJ, Welch MJ. Radiometal-labeled agents (non-technetium) for diagnostic imaging. Chem Rev 1999; 99:2219-34. [PMID: 11749480 DOI: 10.1021/cr980451q] [Citation(s) in RCA: 383] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C J Anderson
- Mallinckrodt Institute of Radiology, Washington University School of Medicine 510 S. Kingshighway, Campus Box 8225 St. Louis, Missouri 63110
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Cutler CS, Giron MC, Reichert DE, Snyder AZ, Herrero P, Anderson CJ, Quarless DA, Koch SA, Welch MJ. Evaluation of gallium-68 tris(2-mercaptobenzyl)amine: a complex with brain and myocardial uptake. Nucl Med Biol 1999; 26:305-16. [PMID: 10363802 DOI: 10.1016/s0969-8051(98)00108-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Previous research into development of a gallium-radiolabeled agent that crosses the blood-brain barrier has met with limited success. In this study, we focused our attention on a Ga(III) complex of a 4-coordinate amine trithiolate tripod ligand, tris(2-mercaptobenzyl) amine (S3N). The Ga(III) S3N complex is small, neutral, and lipophilic, meeting the requirements for a potential brain imaging agent. The Ga-68 complex was easily formed with a radiochemical purity of >95%. In vitro stability of the Ga-S3N complex, determined in rat serum incubated at 37 degrees C, was greater than 95% intact at 2 h by silica gel and reversed-phase radio-thin layer chromatography. Biodistribution studies conducted in female Sprague-Dawley rats showed the complex cleared rapidly from the blood with initial high liver uptake followed by rapid washout. Significant uptake was observed in the brain, with brain:blood ratios increasing from 0.11 at 2 min postinjection to 3.8 at 60 min postinjection. Uptake was also observed in the heart going from a heart:blood ratio of 2.3 at 2 min postinjection to 11 at 60 min postinjection. Molecular mechanics were used to determine the coordination number, and demonstrated that the Ga(III) complex prefers to be 4-coordinate. Imaging studies with 68Ga-S3N in a Nemestrina macaque showed significant brain uptake, similar to other lipophilic agents. The extraction of 68Ga-S3N into the brains of both rodents and primates, higher than any 68Ga agent reported in the literature, suggests that this compound may have potential as a brain imaging agent for positron emission tomography.
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Affiliation(s)
- C S Cutler
- The Edward Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Polyakov VR, Sharma V, Crankshaw CL, Piwnica-Worms D. Synthesis, Molecular Structure, and Properties of a Neutral Schiff Base Phenolic Complex of Magnesium. Inorg Chem 1998; 37:4740-4742. [PMID: 11670631 DOI: 10.1021/ic971466u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Valery R. Polyakov
- Laboratory of Molecular Radiopharmacology, Departments of Radiology and Molecular Biology and Pharmacology, Washington University Medical School, St. Louis, Missouri 63110
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Packard AB, Kronauge JF, Day PJ, Treves ST. Synthesis and biodistribution of 64Cu-labeled monocationic diiminedioxime copper(II) complexes. Nucl Med Biol 1998; 25:531-7. [PMID: 9751419 DOI: 10.1016/s0969-8051(98)00029-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Monocationic copper(II) complexes of three derivatives of the diiminedioxime ligand 2,10-dioximino-3,9-dimethyl-4,8-diazaundeca-3,8-diene were labeled with 64Cu in high radiochemical yield, and the biodistribution of the complexes was measured in mice. The concentration of the complexes in the heart was low, but the partition coefficients of the complexes are less than optimal for a myocardial perfusion agent. All three complexes are resistant to reduction by glutathione in vitro. This suggests that more lipophilic derivatives of these compounds merit further investigation as possible myocardial perfusion agents.
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Affiliation(s)
- A B Packard
- Division of Nuclear Medicine, Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Jones-Wilson TM, Deal KA, Anderson CJ, McCarthy DW, Kovacs Z, Motekaitis RJ, Sherry AD, Martell AE, Welch MJ. The in vivo behavior of copper-64-labeled azamacrocyclic complexes. Nucl Med Biol 1998; 25:523-30. [PMID: 9751418 DOI: 10.1016/s0969-8051(98)00017-1] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The use of copper radioisotopes in imaging and therapy applications has created a greater need for bifunctional chelates (BFCs) for complexing copper radioisotopes to biomolecules. It has been demonstrated that the charge and lipophilicity of the Cu-BFC complex has a significant effect on the in vivo behavior of the radiolabeled Cu-BFC-biomolecule conjugate. To evaluate the effects of charge, stability, and macrocyclic backbone size on the biological behavior of 64Cu complexes, a series of macrocyclic 64Cu complexes have been prepared, and the biodistributions of these agents were evaluated in normal Sprague-Dawley rats. Two macrocyclic backbones, dodecane and tetradecane, were evaluated; cyclen, DOTA, and DO2A were dodecane backbone derivatives, and cyclam, TETA, and et-cyclam were tetradecane backbone derivatives. The biodistributions of the 64Cu-labeled complexes correlated with differences in the size of the macrocycle backbone and the formal charge of the complex. All compounds showed uptake and clearance through the liver and kidneys; however, the positively charged 64Cu complexes showed significantly higher uptake in both of these organs than did the negatively charged or neutral complexes. 64Cu-TETA, a negatively charged complex with the tetradecane backbone, had the most efficient clearance by 24 hours' postinjection. These data suggest that negatively charged complexes may have more favorable clearance properties when used as BFCs.
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Affiliation(s)
- T M Jones-Wilson
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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40
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Sri-Aran M, Mathias CJ, Lim JK, Green MA. Synthesis and evaluation of a monocationic copper(II) radiopharmaceutical derived from N-(2-pyridylmethyl)-N'-(salicylaldimino)-1,3-propanediamine. Nucl Med Biol 1998; 25:107-10. [PMID: 9468024 DOI: 10.1016/s0969-8051(97)00164-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The monocationic 67Cu complex of N-(2-pyridylmethyl)-N'-(salicylaldimino)-1,3-propanediamine was obtained in high radiochemical purity by reaction of 67Cu2+ with the ligand in ethanol solution. Although this compound exhibited low heart uptake, the desired myocardial retention was observed over the 30 min time period studied in a rat model. Since the octanol/water partition coefficient of [67Cu]Cu(II)-N-(2-pyridylmethyl)-N'-(salicylaldiminato)-1,3- propanediamine] is lower than a value believed to be the optimal myocardial uptake, it is likely that derivatives of this compound with a higher lipophilicity merit further investigation for use in myocardial imaging with copper radioisotopes.
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Affiliation(s)
- M Sri-Aran
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907-1333, USA
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41
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Wang S, Luo J, Lantrip DA, Waters DJ, Mathias CJ, Green MA, Fuchs PL, Low PS. Design and synthesis of [111In]DTPA-folate for use as a tumor-targeted radiopharmaceutical. Bioconjug Chem 1997; 8:673-9. [PMID: 9327130 DOI: 10.1021/bc9701297] [Citation(s) in RCA: 166] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Folate-conjugated metal chelates have been proposed as potential imaging agents for cancers that overexpress folate receptors. In a previous study, folic acid was linked through its gamma-carboxyl group to deferoxamine (DF), and the 67Ga-labeled complex ([67Ga]DF-folate) was examined for in vivo tumor targeting efficiency in athymic mice with a human tumor cell implant. Although superb tumor-to-background contrast was obtained, slow hepatobiliary clearance would compromise imaging of abdominal tumors such as ovarian cancer. In the present study, folic acid was conjugated to an alternative chelator, diethylenetriaminepentaacetic acid (DTPA), via an ethylenediamine spacer. The desired DTPA-folate (gamma) regioisomer was synthesized by two different approaches, purified by reversed phase column chromatography, and characterized mainly by analytical HPLC, mass spectroscopy, and NMR. In cultured tumor cells, uptake of [111In]DTPA-folate (gamma) was found to be specific for folate receptor-bearing cells, and the kinetics of uptake were similar to those of free folate and other folate-conjugated molecules. In the normal rat, intravenously administered [111In]DTPA-folate (gamma) was found to be rapidly excreted into the urine, giving intestinal levels of radiotracer 10-fold lower than those observed with [67Ga]DF-folate (gamma) at 4 h. In a preliminary mouse imaging study, a folate receptor-positive KB cell tumor was readily visualized by gamma scintigraphy 1 h following intravenous administration of [111In]DTPA-folate (gamma).
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Affiliation(s)
- S Wang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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42
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XIIth international symposium on radiopharmaceutical chemistry: Abstracts and programme. J Labelled Comp Radiopharm 1997. [DOI: 10.1002/jlcr.2580400501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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43
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Goldberg DE, Sharma V, Oksman A, Gluzman IY, Wellems TE, Piwnica-Worms D. Probing the chloroquine resistance locus of Plasmodium falciparum with a novel class of multidentate metal(III) coordination complexes. J Biol Chem 1997; 272:6567-72. [PMID: 9045684 DOI: 10.1074/jbc.272.10.6567] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The malaria organism Plasmodium falciparum detoxifies heme released during degradation of host erythrocyte hemoglobin by sequestering it within the parasite digestive vacuole as a polymer called hemozoin. Antimalarial agents such as chloroquine appear to work by interrupting the heme polymerization process, but their efficacy has been impaired by the emergence of drug-resistant organisms. We report here the identification of a new class of antimalarial compounds, hexadentate ethylenediamine-N, N'-bis[propyl(2-hydroxy-(R)-benzylimino)]metal(III) complexes [(R)-ENBPI-M(III)] and a corresponding ((R)-benzylamino)] analog [(R)-ENBPA-M(III)], a group of lipophilic monocationic leads amenable to metallopharmaceutical development. Racemic mixtures of Al(III), Fe(III), or Ga(III) but not In(III) (R)-ENBPI metallo-complexes killed intraerythrocytic malaria parasites in a stage-specific manner, the R = 4,6-dimethoxy-substituted ENBPI Fe(III) complex being most potent (IC50 approximately 1 microM). Inhibiting both chloroquine-sensitive and -resistant parasites, potency of these imino complexes correlated in a free metal-independent manner with their ability to inhibit heme polymerization in vitro. In contrast, the reduced (amino) 3-MeO-ENBPA Ga(III) complex (MR045) was found to be selectively toxic to chloroquine-resistant parasites in a verapamil-insensitive manner. In 21 independent recombinant progeny of a genetic cross, susceptibility to this agent mapped in perfect linkage with the chloroquine resistance phenotype suggesting that a locus for 3-MeO-ENBPA Ga(III) susceptibility was located on the same 36-kilobase segment of chromosome 7 as the chloroquine resistance determinant. These compounds may be useful as novel probes of chloroquine resistance mechanisms and for antimalarial drug development.
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Affiliation(s)
- D E Goldberg
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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44
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Sharma V, Crankshaw CL, Piwnica-Worms D. Effects of multidrug resistance (MDR1) P-glycoprotein expression levels and coordination metal on the cytotoxic potency of multidentate (N4O2) (ethylenediamine)bis[propyl(R-benzylimino)]metal(III) cations. J Med Chem 1996; 39:3483-90. [PMID: 8784446 DOI: 10.1021/jm950823c] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Enhanced mitochondrial transmembrane potentials in tumor cells have been proposed to confer tumor-selective-targeting properties to modestly lipophilic monocationic compounds. To explore the potential cytotoxic activity of lipophilic cationic metallopharmaceuticals containing a highly flexible hexadentate N4O2 Schiff-base phenolic ligand, we first synthesized precursors H3Mabi (1) and H3DMabi (2) by condensation of an appropriate linear tetraamine with substituted salicylaldehydes. The desired N4O2 ligands, (ethylenediamine)-N,N'-bis[propyl[(2-hydroxy-3-methoxybenzyl)imino]] and (ethylenediamine)-N,N'-bis[propyl[2-hydroxy-4,6-dimethoxybenzyl)-imino]] (R-ENBPI), were obtained by cleavage of the imidazolidine ring, and their corresponding monocationic complexes were produced by reaction with appropriate hydrated salts or acetylacetonates of Al(III), Fe(III), Ga(III), and In(III). All complexes were stable to neutral hydrolysis. In human epidermal carcinoma KB-3-1 cells, cytotoxic potencies of racemic mixtures of these complexes were in the low micromolar range and, for a given ligand, depended on the identity of the coordinating central metal. The active 4,6-dimethoxy-ENBPI complexes were more potent than their 3-methoxy analogs, while the free ligands and metal(III) ions showed little or no cytotoxic activity. Furthermore, in colchicine-selected KB-8-5 multidrug resistant (MDR) cells, modest cellular expression of human MDR1 P-glycoprotein conferred protection from the cytotoxic activities of Al(III), Fe(III), and Ga(III) R-ENBPI complexes indicating that these complexes were recognized as transport substrates by the P-glycoprotein efflux transporter. However, the cytotoxic activities of the corresponding In(III) complexes, while among the lowest in potencies, were also not altered by expression of MDR1 P-glycoprotein. Thus, for the Group III elements, human cells were capable of distinguishing R-ENBPI complexes formed of the same ligands with different metals. Furthermore, selected R-ENBPI metal(III) complexes may be useful as novel anticancer metallopharmaceuticals.
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Affiliation(s)
- V Sharma
- Laboratory of Molecular Radiopharmacology, Mallinckrodt Institute of Radiology, Washington University Medical School, St. Louis, Missouri 63110, USA
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45
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Wong E, Caravan P, Liu S, Rettig SJ, Orvig C. Selectivity of Potentially Hexadentate Amine Phenols for Ga3+ and In3+ in Aqueous Solution,. Inorg Chem 1996. [DOI: 10.1021/ic951019j] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ernest Wong
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - P. Caravan
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Shuang Liu
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Steven J. Rettig
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
| | - Chris Orvig
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
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