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Liu Z, Sun Y, Liu T. Recent Advances in Synthetic Methodologies to Form C-18F Bonds. Front Chem 2022; 10:883866. [PMID: 35494631 PMCID: PMC9047704 DOI: 10.3389/fchem.2022.883866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/14/2022] [Indexed: 11/13/2022] Open
Abstract
Positron emission tomography (PET) is an important technique for the early diagnosis of disease. Due to the specific physical and chemical properties of Fluorine-18, this important isotope is widely used in PET for labelling and molecular imaging, and its introduction into medicine molecules could produce PET tracers. Developing with the development of organic synthetic methodologies, the introduction of Fluorine-18 into drug molecules efficiently and rapidly under mild conditions, and the formation of C-18F chemical bonds, has become one of the leading topics in both organic synthetic chemistry and radiochemistry. In this mini-review, we review a series of recent advances in the organic synthesis of C-18F bonds (2015–2021), including non-catalytic radiofluorinations via good leaving functional groups, transition metal-catalyzed radiofluorinations, and photo- or electro-catalytic synthetic radiofluorinations. As a result of the remarkable advancements in this field, organic synthetic methods for forming C-18F bonds are expected to continue growing.
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Affiliation(s)
- Zhiyi Liu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
| | - Yijun Sun
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
| | - Tianfei Liu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin, China
- The Haihe Laboratory of Sustainable Chemical Transformations, Nankai University, Tianjin, China
- Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
- *Correspondence: Tianfei Liu,
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Lee SJ, Morales-Colón MT, Brooks AF, Wright JS, Makaravage KJ, Scott PJH, Sanford MS. S NAr Radiofluorination with In Situ Generated [ 18F]Tetramethylammonium Fluoride. J Org Chem 2021; 86:14121-14130. [PMID: 34505779 DOI: 10.1021/acs.joc.1c01491] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This report describes a method for the nucleophilic radiofluorination of (hetero)aryl chlorides, (hetero)aryl triflates, and nitroarenes using a combination of [18F]KF·K2.2.2 and Me4NHCO3 for the in situ formation of a strongly nucleophilic fluorinating reagent (proposed to be [18F]Me4NF). This method is applied to 24 substrates bearing diverse functional groups, and it generates [18F](hetero)aryl fluoride products in good to excellent radiochemical yields in the presence of ambient air/moisture. The reaction is applied to the preparation of 18F-labeled HQ-415 for potential (pre)clinical use.
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Affiliation(s)
- So Jeong Lee
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States.,Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114,United States
| | - María T Morales-Colón
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Allen F Brooks
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jay S Wright
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Katarina J Makaravage
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Peter J H Scott
- Department of Radiology, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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Ajenjo J, Destro G, Cornelissen B, Gouverneur V. Closing the gap between 19F and 18F chemistry. EJNMMI Radiopharm Chem 2021; 6:33. [PMID: 34564781 PMCID: PMC8464544 DOI: 10.1186/s41181-021-00143-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/03/2021] [Indexed: 11/10/2022] Open
Abstract
Positron emission tomography (PET) has become an invaluable tool for drug discovery and diagnosis. The positron-emitting radionuclide fluorine-18 is frequently used in PET radiopharmaceuticals due to its advantageous characteristics; hence, methods streamlining access to 18F-labelled radiotracers can make a direct impact in medicine. For many years, access to 18F-labelled radiotracers was limited by the paucity of methodologies available, and the poor diversity of precursors amenable to 18F-incorporation. During the last two decades, 18F-radiochemistry has progressed at a fast pace with the appearance of numerous methodologies for late-stage 18F-incorporation onto complex molecules from a range of readily available precursors including those that do not require pre-functionalisation. Key to these advances is the inclusion of new activation modes to facilitate 18F-incorporation. Specifically, new advances in late-stage 19F-fluorination under transition metal catalysis, photoredox catalysis, and organocatalysis combined with the availability of novel 18F-labelled fluorination reagents have enabled the invention of novel processes for 18F-incorporation onto complex (bio)molecules. This review describes these major breakthroughs with a focus on methodologies for C-18F bond formation. This reinvigorated interest in 18F-radiochemistry that we have witnessed in recent years has made a direct impact on 19F-chemistry with many laboratories refocusing their efforts on the development of methods using nucleophilic fluoride instead of fluorination reagents derived from molecular fluorine gas.
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Affiliation(s)
- Javier Ajenjo
- Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Gianluca Destro
- Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, OX3 7DQ, UK
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK
| | - Bart Cornelissen
- Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, OX3 7DQ, UK
| | - Véronique Gouverneur
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3TA, UK.
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4
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Ascorbic acid analogue 6-Deoxy-6-[ 18F] fluoro-L-ascorbic acid as a tracer for identifying human colorectal cancer with SVCT2 overexpression. Transl Oncol 2021; 14:101055. [PMID: 33677235 PMCID: PMC8046958 DOI: 10.1016/j.tranon.2021.101055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/26/2021] [Accepted: 02/22/2021] [Indexed: 01/05/2023] Open
Abstract
6-Deoxy-6-[18F]fluoro-L-ascorbic Acid (18F-DFA) was successfully prepared and biological evaluated. Cancer cells with high expression of SVCT2 have higher AA uptake than cancer cells with low expression of SVCT2. 18F-DFA PET imaging showed cancer cells with high expression of SVCT2 had higher 18F-DFA accumulation after tumorigenesis in mice. The first time (to our knowledge), PET imaging directly verified the high accumulation of AA in adrenal gland.
L-ascorbic acid (AA) was reported to have an anti-cancer effect over 40 years. In recent years, several ongoing clinical trials are exploring the safety and efficacy of intravenous high-dose AA for cancer treatment. The lack of appropriate imaging modality limits the identification of potentially suitable patients for AA treatment. This study focuses on identifying AA-sensitive tumor cells using molecular imaging. 6-Deoxy-6-[18F] fluoro-L-ascorbic Acid (18F-DFA), a structural analog of AA, was synthesized and labeled to visualize the metabolism of AA in vivo. Colorectal cancer (CRC) cell lines with high and low expression of sodium-dependent vitamin C transporters 2 (SVCT2) were used for a series of cellular uptake tests. PET imaging was performed on xenograft tumor-bearing mice. More AA uptake was observed in CRC cells with high SVCT2 expression than in cells with low SVCT2 expression. The substrate (unlabeled AA) can competitively inhibit the 18F-DFA tracer uptake by CRC cells. The biodistribution of 18F-DFA in mice showed high radioactivity was seen in organs such as adrenal glands, kidneys, and liver that were known to have high concentrations of AA. Both PET imaging and tissue distribution showed that cancer cells with high SVCT2 expression enhanced the accumulation of 18F-DFA in mice after tumor formation. Immunohistochemistry was used to verify the corresponding results. As a radiotracer, 18F-DFA can provide powerful imaging information to identify tumor with high affinity of AA, and SVCT2 can be a potential biomarker in this process.
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Deng X, Rong J, Wang L, Vasdev N, Zhang L, Josephson L, Liang SH. Chemistry for Positron Emission Tomography: Recent Advances in 11 C-, 18 F-, 13 N-, and 15 O-Labeling Reactions. Angew Chem Int Ed Engl 2019; 58:2580-2605. [PMID: 30054961 PMCID: PMC6405341 DOI: 10.1002/anie.201805501] [Citation(s) in RCA: 201] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Indexed: 01/07/2023]
Abstract
Positron emission tomography (PET) is a molecular imaging technology that provides quantitative information about function and metabolism in biological processes in vivo for disease diagnosis and therapy assessment. The broad application and rapid advances of PET has led to an increased demand for new radiochemical methods to synthesize highly specific molecules bearing positron-emitting radionuclides. This Review provides an overview of commonly used labeling reactions through examples of clinically relevant PET tracers and highlights the most recent developments and breakthroughs over the past decade, with a focus on 11 C, 18 F, 13 N, and 15 O.
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Affiliation(s)
- Xiaoyun Deng
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Lu Wang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Lei Zhang
- Medicine Design, Pfizer Inc., Cambridge, MA, 02139, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, USA
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6
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Deng X, Rong J, Wang L, Vasdev N, Zhang L, Josephson L, Liang SH. Chemie der Positronenemissionstomographie: Aktuelle Fortschritte bei
11
C‐,
18
F‐,
13
N‐ und
15
O‐Markierungsreaktionen. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201805501] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Xiaoyun Deng
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
| | - Jian Rong
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
| | - Lu Wang
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
| | - Lei Zhang
- Medicine DesignPfizer Inc. Cambridge MA 02139 USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular ImagingMassachusetts General Hospital & Department of RadiologyHarvard Medical School Boston MA 02114 USA
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7
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Vatsadze SZ, Eremina OE, Veselova IA, Kalmykov SN, Nenajdenko VG. 18F-Labelled catecholamine type radiopharmaceuticals in the diagnosis of neurodegenerative diseases and neuroendocrine tumours: approaches to synthesis and development prospects. RUSSIAN CHEMICAL REVIEWS 2018. [DOI: 10.1070/rcr4752] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Preshlock S, Tredwell M, Gouverneur V. (18)F-Labeling of Arenes and Heteroarenes for Applications in Positron Emission Tomography. Chem Rev 2016; 116:719-66. [PMID: 26751274 DOI: 10.1021/acs.chemrev.5b00493] [Citation(s) in RCA: 477] [Impact Index Per Article: 59.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Diverse radiochemistry is an essential component of nuclear medicine; this includes imaging techniques such as positron emission tomography (PET). As such, PET can track diseases at an early stage of development, help patient care planning through personalized medicine and support drug discovery programs. Fluorine-18 is the most frequently used radioisotope in PET radiopharmaceuticals for both clinical and preclinical research. Its physical and nuclear characteristics (97% β(+) decay, 109.8 min half-life, 635 keV positron energy) and high specific activity make it an attractive nuclide for labeling and molecular imaging. Arenes and heteroarenes are privileged candidates for (18)F-incorporation as they are metabolically robust and therefore widely used by medicinal chemists and radiochemists alike. For many years, the range of (hetero)arenes amenable to (18)F-fluorination was limited by the lack of chemically diverse precursors, and of radiochemical methods allowing (18)F-incorporation in high selectivity and efficiency (radiochemical yield and purity, specific activity, and radio-scalability). The appearance of late-stage fluorination reactions catalyzed by transition metal or small organic molecules (organocatalysis) has encouraged much research on the use of these activation manifolds for (18)F-fluorination. In this piece, we review all of the reactions known to date to install the (18)F substituent and other key (18)F-motifs (e.g., CF3, CHF2, OCF3, SCF3, OCHF2) of medicinal relevance onto (hetero)arenes. The field has changed significantly in the past five years, and the current trend suggests that the radiochemical space available for PET applications will expand rapidly in the near future.
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Affiliation(s)
- Sean Preshlock
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Matthew Tredwell
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford , Oxford OX1 3TA, United Kingdom
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10
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Abstract
Molecular imaging has witnessed an upsurge in growth, with positron emission tomography leading the way. This trend has encouraged numerous synthetic chemists to enter the field of (18) F-radiochemistry and provide generic solutions to address the well-recognized challenges of late-stage fluorination. This Minireview focuses on recent developments in the (18)F-labeling of aromatic substrates.
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Affiliation(s)
- Matthew Tredwell
- Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, UK.
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Mu L, Fischer CR, Holland JP, Becaud J, Schubiger PA, Schibli R, Ametamey SM, Graham K, Stellfeld T, Dinkelborg LM, Lehmann L. 18F-Radiolabeling of Aromatic Compounds Using Triarylsulfonium Salts. European J Org Chem 2012. [DOI: 10.1002/ejoc.201101730] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Maeda M, Tatsuki Y, Fukumura T, Kojima M. Synthesis of 5-fluoroalkyl-5-methyloxazolidine-2,4-diones and their 18F-labeled analogs as potential indicators of tissue pH. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580270508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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A new synthesis of 2-deoxy-2-[18f]fluoro-D-galactose using [18f]fluoride ion. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580250705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Haradahira T, Maeda M, Kojima M. Alternative synthesis of no-carrier-added 2-deoxy-2-[18F]fluoro-D-glucose using [18F] fluoride ion. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580250504] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Karramkam M, Hinnen F, Bramoullé Y, Jubeau S, Dollé F. Ortho-[18F]Fluoronitrobenzenes by no-carrier-added nucleophilic aromatic substitution with K[18F]F-K222-A comparative study. J Labelled Comp Radiopharm 2002. [DOI: 10.1002/jlcr.628] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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16
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Yamamoto F, Aoki M, Furusawa Y, Ando K, Kuwabara Y, Masuda K, Sasaki S, Maeda M. Synthesis and evaluation of 4-bromo-1-(3-[18F]fluoropropyl)-2-nitroimidazole with a low energy LUMO orbital designed as brain hypoxia-targeting imaging agent. Biol Pharm Bull 2002; 25:616-21. [PMID: 12033502 DOI: 10.1248/bpb.25.616] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In order to develop new imaging markers for brain hypoxia, 4-bromo-1-(3-fluoropropyl)-2-nitroimidazole (4-BrFPN) was designed based on molecular orbital calculations, synthesized and labeled with fluorine-18 as a lipophilic nitroimidazole analog with a lower energy LUMO orbital than those for fluoromisonidazole (FMISO) and 1-(3-fluoropropyl)-2-nitroimidazole (FPN). In an in vitro radiosensitization study, the sensitizer enhancement ratio for 4-BrFPN was found to be 1.65 at a I mM concentration, in comparison to 1.81 for FMISO. The preparation of 18F-labeled 4-BrFPN (4-Br18FPN) was achieved by [18F]fluoride ion displacement reaction of the tosylate precursor, in a reasonable radiochemical yield (33%, not corrected for decay). Metabolites in tumor and muscle extracts from methylcholanthrene-induced fibrosarcoma mice, as well as the tissue distribution of 4-Br18FPN in normal rats, were studied. The initial uptake into rat brain of 4-Br18FPN was significantly higher relative to 18F-labeled FMISO (18FMISO), followed by a rapid washout from the brain. The tumor uptake of 4-Br18FPN was somewhat enhanced compared to those obtained with 18FMISO and 18F-labeled FPN (18FPN), but with lower tumor localization than 18FMISO. Analyses of tumor and muscle extracts showed metabolites remaining base line on the radio-TLC plates, and they were produced to a greater extent in tumor than muscle. The use of two drugs which increase hypoxic cell fraction in tumor, hydralazine or nitro-L-arginine, produced a significant increase in tumor levels of 4-Br18FPN, suggestive of a hypoxic mechanism of accumulation. The results imply that lowering of the LUMO energy of a molecule alone is not sufficient to improve its biodistribution properties for better imaging of regions of hypoxia.
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Affiliation(s)
- Fumihiko Yamamoto
- Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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17
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Nagatsugi F, Sasaki S, Maeda M. 8-[18F]fluorooctanoic acid and its beta-substituted derivatives as potential agents for cerebral fatty acid studies: synthesis and biodistribution. Nucl Med Biol 1994; 21:809-17. [PMID: 9234330 DOI: 10.1016/0969-8051(94)90160-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fluorine-18 labeled analogs of 8-fluorooctanoic acid and its structurally modified derivatives with methyl or gem-dimethyl branching or with oxygen substitution at the C3 position were prepared using nucleophilic substitution of the tosylate precursors by [18F]fluoride ion, for evaluation as tracers for cerebral fatty acid metabolism. Tissue distribution studies in rats showed low brain uptakes of these 18F-labeled fatty acid analogs with poor brain-to-blood ratios of activity. The oxygen-substituted analog did not show any significant accumulation of radioactivity in most tissues. The initial brain uptake of activity after injection of ethyl 8-[18F]fluorooctanoate and its free acid remained virtually unchanged over an extended time period, beta-Monomethyl and beta-gem-dimethyl branched analogs had similar brain uptake at the early time period, but they showed rapid clearance of activity from the brain. TLC analysis showed no incorporation of 8-[18F]fluorooctanoic acid and its beta-dimethyl analogs into brain lipids. It was also shown in the metabolite analysis that the labeled metabolites produced from 8-[18F]fluorooctanoic acid are found in blood, and that they could enter the brain to a significant degree. On the contrary, such radioactive metabolites could not be found in the brain in the experiment with the beta-gem-dimethyl branched analog. Thus, the present studies showed that retention of radioactivity in the brain with 8-[18F]fluorooctanoic acid derivatives is mainly attributable to their radioactive metabolites, and that the rapid clearance of beta-branched analogs from the brain is due to the lack of availability as substrates in the cerebral fatty acid metabolism.
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Affiliation(s)
- F Nagatsugi
- Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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18
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19
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Garg PK, Garg S, Zalutsky MR. Synthesis and preliminary evaluation of para- and meta-[18F]fluorobenzylguanidine. Nucl Med Biol 1994; 21:97-103. [PMID: 9234270 DOI: 10.1016/0969-8051(94)90135-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
meta-[18F]Fluorobenzylguanidine ([18F]MFBG) and para-[18F]fluorobenzylguanidine ([18F]PFBG) were synthesized in three steps beginning with a fluoro for nitro exchange reaction on 3- and 4-nitrobenzonitrile, respectively. Overall radiochemical yields were 10-15% for [18F]MFBG and 50-55% for [18F]PFBG in a total synthesis time of 60 min. However, impurities interfered with the binding of the product to target cells. A new route was adopted for the synthesis of [18F]PFBG using 4-nitrilophenyl trimethylammonium trifluoromethanesulfonate (Q.S.) as the starting material. In addition to shortening the overall synthesis time by 10 min, this precursor also eliminated problems associated with the presence of small amounts of starting material in the preparation. In vitro binding of [18F]PFBG prepared by the Q.S. method to SK-N-SH, human neuroblastoma cells was 26.5 +/- 1.1%, compared to 16.9 +/- 1.6% when the nitro precursor was used. Selective uptake of both 18F-labeled isomers in the heart and adrenal was seen in mice. At 4 h, adrenal and heart uptake of [18F]PFBG prepared using Q.S. was 20.3 +/- 4.8 and 5.9 +/- 0.8% ID/g respectively, compared to 23.8 +/- 5.0 and 10.5 +/- 1.7% ID/g for [18F]MFBG. Based on the 5-fold higher radiochemical yields obtained with [18F]PFBG, this isomer would appear to be the more practical choice; however, in vitro and in vivo results suggest that [18F]MFBG exhibits greater similarities to MIBG.
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Affiliation(s)
- P K Garg
- Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA
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20
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Orita K, Sasaki S, Maeda M, Hashimoto A, Nishikawa T, Yugami T, Umezu K. Synthesis and evaluation of 1-(1-[5-(2'-[18F]fluoroethyl)-2-thienyl]-cyclohexyl)piperidine as a potential in vivo radioligand for the NMDA receptor-channel complex. Nucl Med Biol 1993; 20:865-73. [PMID: 8241999 DOI: 10.1016/0969-8051(93)90153-l] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
1-(1-[5-(2'-[18F]Fluoroethyl)-2-thienyl]cyclohexyl)piperidine (18FE-TCP) was prepared as a fluorine-substituted analogue of the potent NMDA receptor channel blocker, 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP), by the mesylate displacement with [18F]fluoride ion with isolated radiochemical yields of 6-12%, and the synthesis time including a two step HPLC purification was 120 min. The regional distribution in rat brain after i.v. injection of 18FE-TCP was heterogeneous and similar to the known distribution of phencyclidine recognition sites, with hippocampus-cerebellum, striatum-cerebellum and cerebral cortex-cerebellum concentration ratios of 2.08, 1.7 and 1.54, respectively, 15 min post-injection. Furthermore, this localized regional cerebral distribution was blocked by co-injection with the unlabelled FE-TCP or pretreatment with cis-2-hydroxymethyl-r-1-(N-piperidyl)-1-(2-thienyl)cyclohexane, with the greatest reductions seen in the hippocampus followed by the striatum and cerebral cortex. However, relatively low receptor binding affinity and high non-specific binding due to its high lipophilicity suggest that 18FE-TCP may not be a suitable radioligand for in vivo PET investigations of the NMDA receptor-channel complex.
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Affiliation(s)
- K Orita
- Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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21
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Yamamoto F, Sasaki S, Maeda M. Positron labeled antioxidants: synthesis and tissue biodistribution of 6-deoxy-6-[18F]fluoro-L-ascorbic acid. INTERNATIONAL JOURNAL OF RADIATION APPLICATIONS AND INSTRUMENTATION. PART A, APPLIED RADIATION AND ISOTOPES 1992; 43:633-9. [PMID: 1325422 DOI: 10.1016/0883-2889(92)90032-a] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A one-pot synthesis of 6-deoxy-6-[18F]fluoro-L-ascorbic acid (18F-DFA) has been developed via nucleophilic displacement of a cyclic sulfate with no-carrier-added [18F]fluoride ion. Isolated radiochemical yields of around 15% were obtained with radiochemical purity of over 99% after overall synthesis time of 90 min. Tissue distribution studies with 18F-DFA in rats showed high uptake of radioactivity in the adrenals, kidneys, liver and small intestine--organs known to have high concentrations of L-ascorbic acid. The slow and low uptake of radioactivity in the brain was observed between 10 and 120 min after i.v. injection. In vivo behavior of 18F-DFA in mice bearing 3-methylcholanthrene-induced fibrosarcoma demonstrated its ability to accumulate in the tumor.
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Affiliation(s)
- F Yamamoto
- Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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Maeda M, Tsukiyama S, Fukumura T, Orita K, Kojima M. Positron labeled analogs of TCP: Synthesis of 1−[4−[18F]fluoromethyl-1−(2-thienyl)cyclohexyl]piperidine. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0883-2889(91)90163-u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Affiliation(s)
- T Tsuchiya
- Institute of Bioorganic Chemistry, Kawasaki, Japan
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Kvaternik H, Angelberger P, Buchtela K. Reactor-produced (18F)fluoride in the synthesis of NCA 2-(18F)fluoro-2-deoxy-D-glucose. J Labelled Comp Radiopharm 1989. [DOI: 10.1002/jlcr.25802601195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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