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[(18)F]FMeNER-D2: A systematic in vitro analysis of radio-metabolism. Nucl Med Biol 2016; 43:490-5. [PMID: 27236284 DOI: 10.1016/j.nucmedbio.2016.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 11/23/2022]
Abstract
INTRODUCTION The norepinephrine transporter (NET) presents an important target for therapy and diagnosis of ADHD and other neurodegenerative and psychiatric diseases. Thus, PET is the diagnostic method of choice, using radiolabeled NET-ligands derived from reboxetine. So far, [(18)F]FMeNER-D2 showed best pharmacokinetic and -dynamic properties. However, the disadvantage of reboxetine derived PET tracers is their high metabolic cleavage-resulting in impeding signals in the PET scans, which hamper a proper quantification of the NET in cortical areas. METHODS Metabolic stability testing was performed in vitro using a plethora of human and murine enzymes. RESULTS No metabolism was observed using monoamine oxidase A and B or catechol-O-methyl transferase. Incubation of [(18)F]FMeNER-D2 with CYP450-enzymes, predominantly located in the liver, led to a significant and fast metabolism of the tracer. Moreover, the arising three radiometabolites were found to be more polar than [(18)F]FMeNER-D2. Surprisingly, definitely no formation of free [(18)F]fluoride was observed. CONCLUSION According to our in vitro data, the interfering uptake in cortical regions might be attributed to these emerging radiometabolites but does not reflect bonding in bone due to defluorination. Further research on these radiometabolites is necessary to elucidate the in vivo situation. This might include an analysis of human blood samples after injection of [(18)F]FMeNER-D2, to enable a better correction of the PET-input function.
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Synthesis, radiosynthesis and first in vitro evaluation of novel PET-tracers for the dopamine transporter: [11C]IPCIT and [18F]FE@IPCIT. Bioorg Med Chem 2013; 21:7562-9. [DOI: 10.1016/j.bmc.2013.10.046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 10/17/2013] [Accepted: 10/29/2013] [Indexed: 11/24/2022]
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Philippe C, Nics L, Zeilinger M, Schirmer E, Spreitzer H, Karanikas G, Lanzenberger R, Viernstein H, Wadsak W, Mitterhauser M. Preparation and First Preclinical Evaluation of [(18)F]FE@SNAP: A Potential PET Tracer for the Melanin-Concentrating Hormone Receptor-1 (MCHR1). Sci Pharm 2013; 81:625-39. [PMID: 24106662 PMCID: PMC3791928 DOI: 10.3797/scipharm.1306-02] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/01/2013] [Indexed: 02/06/2023] Open
Abstract
The melanin-concentrating hormone (MCH) system is a new target for the treatment of human disorders. Since the knowledge of the MCH system’s involvement in a variety of pathologies (obesity, diabetes, and deregulation of metabolic feedback mechanism) is based on in vitro or preclinical studies, a suitable positron emission tomography (PET) tracer needs to be developed. We herein present the preparation and first preclinical evaluation of [18F]FE@SNAP – a new PET tracer for MCH receptor-1 (MCHR1). The synthesis was performed using a microfluidic device. Preclinical evaluation included binding affinity, plasma stability, plasma free fraction, stability against the cytochrome P-450 (CYP450) system using liver microsomes, stability against carboxyl-esterase, and methods to assess the penetration of the blood-brain barrier (BBB) such as logD analysis and immobilized artificial membrane (IAM) chromatography. Levels at 374 ± 202 MBq [18F]FE@SNAP were obtained after purification. The obtained Kd value of [18F]FE@SNAP was 2.9 nM. [18F]FE@SNAP evinced high stability against carboxylesterase, CYP450 enzymes, and in human plasma. LogD (3.83) and IAM chromatography results (Pm=0.51) were in the same range as for known BBB-penetrating compounds. The synthesis of [18F]FE@SNAP was reliable and successful. Due to high binding affinity and stability, [18F]FE@SNAP is a promising tracer for MCHR1.
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Affiliation(s)
- Cécile Philippe
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria. ; Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
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Löser R, Fischer S, Hiller A, Köckerling M, Funke U, Maisonial A, Brust P, Steinbach J. Use of 3-[(18)F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides. Beilstein J Org Chem 2013; 9:1002-11. [PMID: 23766817 PMCID: PMC3678395 DOI: 10.3762/bjoc.9.115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 04/26/2013] [Indexed: 11/23/2022] Open
Abstract
3-[(18)F]Fluoropropanesulfonyl chloride, a recently proposed prosthetic agent for fluorine-18 labelling, was prepared in a two-step radiosynthesis via 3-[(18)F]fluoropropyl thiocyanate as an intermediate. Two benzenesulfonate-based radiolabelling precursors were prepared by various routes. Comparing the reactivities of 3-thiocyanatopropyl nosylate and the corresponding tosylate towards [(18)F]fluoride the former proved to be superior accounting for labelling yields of up to 85%. Conditions for a reliable transformation of 3-[(18)F]fluoropropyl thiocyanate to the corresponding sulfonyl chloride with the potential for automation have been identified. The reaction of 3-[(18)F]fluoropropanesulfonyl chloride with eight different aliphatic and aromatic amines was investigated and the identity of the resulting (18)F-labelled sulfonamides was confirmed chromatographically by comparison with their nonradioactive counterparts. Even for weakly nucleophilic amines such as 4-nitroaniline the desired radiolabelled sulfonamides were accessible in satisfactory yields owing to systematic variation of the reaction conditions. With respect to the application of the (18)F-fluoropropansulfonyl group to the labelling of compounds relevant as imaging agents for positron emission tomography (PET), the stability of N-(4-fluorophenyl)-3-fluoropropanesulfonamide against degradation catalysed by carboxylesterase was investigated and compared to that of the analogous fluoroacetamide.
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Affiliation(s)
- Reik Löser
- Institute of Radiopharmaceutical Cancer Research (formerly Institute of Radiopharmacy), Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany ; Department of Chemistry and Food Chemistry, Technical University of Dresden, Bergstraße 66c, 01062 Dresden, Germany
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Philippe C, Ungersboeck J, Schirmer E, Zdravkovic M, Nics L, Zeilinger M, Shanab K, Lanzenberger R, Karanikas G, Spreitzer H, Viernstein H, Mitterhauser M, Wadsak W. [¹⁸F]FE@SNAP-A new PET tracer for the melanin concentrating hormone receptor 1 (MCHR1): microfluidic and vessel-based approaches. Bioorg Med Chem 2012; 20:5936-40. [PMID: 22921745 PMCID: PMC3460236 DOI: 10.1016/j.bmc.2012.07.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/23/2012] [Accepted: 07/23/2012] [Indexed: 11/30/2022]
Abstract
Changes in the expression of the melanin concentrating hormone receptor 1 (MCHR1) are involved in a variety of pathologies, especially obesity and anxiety disorders. To monitor these pathologies in-vivo positron emission tomography (PET) is a suitable method. After the successful radiosynthesis of [(11)C]SNAP-7941-the first PET-Tracer for the MCHR1, we aimed to synthesize its [(18)F]fluoroethylated analogue: [(18)F]FE@SNAP. Therefore, microfluidic and vessel-based approaches were tested. [(18)F]fluoroethylation was conducted via various [(18)F]fluoroalkylated synthons and direct [(18)F]fluorination. Only the direct [(18)F]fluorination of a tosylated precursor using a flow-through microreactor was successful, affording [(18)F]FE@SNAP in 44.3 ± 2.6%.
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Affiliation(s)
- Cécile Philippe
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna 1090, Austria
| | - Johanna Ungersboeck
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
- Department of Inorganic Chemistry, University of Vienna, 1090 Vienna, Austria
| | - Eva Schirmer
- Department of Drug and Natural Product Synthesis, University of Vienna, Vienna 1090, Austria
| | - Milica Zdravkovic
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna 1090, Austria
| | - Lukas Nics
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
- Department of Nutritional Sciences, University of Vienna, Vienna 1090, Austria
| | - Markus Zeilinger
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
| | - Karem Shanab
- Department of Drug and Natural Product Synthesis, University of Vienna, Vienna 1090, Austria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, 1090 Vienna, Austria
| | - Georgios Karanikas
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
| | - Helmut Spreitzer
- Department of Drug and Natural Product Synthesis, University of Vienna, Vienna 1090, Austria
| | - Helmut Viernstein
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna 1090, Austria
| | - Markus Mitterhauser
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
- Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Vienna 1090, Austria
- Hospital Pharmacy of the General Hospital of Vienna, 1090 Vienna, Austria
| | - Wolfgang Wadsak
- Radiochemistry and Biomarker Development Unit, Department of Nuclear Medicine, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
- Department of Inorganic Chemistry, University of Vienna, 1090 Vienna, Austria
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