1
|
Ueberham L, Gündel D, Kellert M, Deuther-Conrad W, Ludwig FA, Lönnecke P, Kazimir A, Kopka K, Brust P, Moldovan RP, Hey-Hawkins E. Development of the High-Affinity Carborane-Based Cannabinoid Receptor Type 2 PET Ligand [ 18F]LUZ5- d8. J Med Chem 2023; 66:5242-5260. [PMID: 36944112 PMCID: PMC10782483 DOI: 10.1021/acs.jmedchem.3c00195] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Indexed: 03/23/2023]
Abstract
The development of cannabinoid receptor type 2 (CB2R) radioligands for positron emission tomography (PET) imaging was intensively explored. To overcome the low metabolic stability and simultaneously increase the binding affinity of known CB2R radioligands, a carborane moiety was used as a bioisostere. Here we report the synthesis and characterization of carborane-based 1,8-naphthyridinones and thiazoles as novel CB2R ligands. All tested compounds showed low nanomolar CB2R affinity, with (Z)-N-[3-(4-fluorobutyl)-4,5-dimethylthiazole-2(3H)-ylidene]-(1,7-dicarba-closo-dodecaboranyl)-carboxamide (LUZ5) exhibiting the highest affinity (0.8 nM). Compound [18F]LUZ5-d8 was obtained with an automated radiosynthesizer in high radiochemical yield and purity. In vivo evaluation revealed the improved metabolic stability of [18F]LUZ5-d8 compared to that of [18F]JHU94620. PET experiments in rats revealed high uptake in spleen and low uptake in brain. Thus, the introduction of a carborane moiety is an appropriate tool for modifying literature-known CB2R ligands and gaining access to a new class of high-affinity CB2R ligands, while the in vivo pharmacology still needs to be addressed.
Collapse
Affiliation(s)
- Lea Ueberham
- Universität
Leipzig, Faculty of Chemistry
and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany
| | - Daniel Gündel
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
| | - Martin Kellert
- Universität
Leipzig, Faculty of Chemistry
and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
| | - Peter Lönnecke
- Universität
Leipzig, Faculty of Chemistry
and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany
| | - Aleksandr Kazimir
- Universität
Leipzig, Faculty of Chemistry
and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
- Faculty
of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Peter Brust
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
- The
Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, 04318 Leipzig, Germany
| | - Evamarie Hey-Hawkins
- Universität
Leipzig, Faculty of Chemistry
and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany
| |
Collapse
|
3
|
Moldovan RP, Hausmann K, Deuther-Conrad W, Brust P. Development of Highly Affine and Selective Fluorinated Cannabinoid Type 2 Receptor Ligands. ACS Med Chem Lett 2017; 8:566-571. [PMID: 28523112 DOI: 10.1021/acsmedchemlett.7b00129] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 04/28/2017] [Indexed: 11/30/2022] Open
Abstract
Cannabinoid type 2 receptors (CB2 receptors) are involved in various pathological processes, and the visualization of their in vivo availability with positron emission tomography (PET) is of high interest. The study focuses on the introduction of fluorine into the structure of the highly affine and selective CB2 receptor ligand N-(adamantan-1-yl)-5-ethyl-2-methyl-1-phenyl-1H-imidazole-4-carboxamide (5). A novel series of compounds was developed by modifying (i) the adamantane-3-position, (ii) the imidazole-N-phenyl ring, and (iii) the imidazole-2-position, and the impact on the CB2 binding affinity and selectivity toward cannabinoid type 1 receptors (CB1) was evaluated. This study identified compound 15 as one of the most potent (Ki(CB2) = 0.29 nM) and selective (CB1/CB2 > 10000) CB2 receptor ligands discovered so far, eligible for the development of an 18F-labeled PET radiotracer.
Collapse
Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, Leipzig 04318, Germany
| | - Kristin Hausmann
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, Leipzig 04318, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, Leipzig 04318, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, Leipzig 04318, Germany
| |
Collapse
|