1
|
Humpert S, Schneider D, Bier D, Schulze A, Neumaier F, Neumaier B, Holschbach M. 8-Bicycloalkyl-CPFPX derivatives as potent and selective tools for in vivo imaging of the A 1 adenosine receptor. Eur J Med Chem 2024; 271:116380. [PMID: 38615410 DOI: 10.1016/j.ejmech.2024.116380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 03/19/2024] [Accepted: 04/01/2024] [Indexed: 04/16/2024]
Abstract
Imaging of the A1 adenosine receptor (A1R) by positron emission tomography (PET) with 8-cyclopentyl-3-(3-[18F]fluoropropyl)-1-propyl-xanthine ([18F]CPFPX) has been widely used in preclinical and clinical studies. However, this radioligand suffers from rapid peripheral metabolism and subsequent accumulation of radiometabolites in the vascular compartment. In the present work, we prepared four derivatives of CPFPX by replacement of the cyclopentyl group with norbornane moieties. These derivatives were evaluated by competition binding studies, microsomal stability assays and LC-MS analysis of microsomal metabolites. In addition, the 18F-labeled isotopologue of 8-(1-norbornyl)-3-(3-fluoropropyl)-1-propylxanthine (1-NBX) as the most promising candidate was prepared by radiofluorination of the corresponding tosylate precursor and the resulting radioligand ([18F]1-NBX) was evaluated by permeability assays with Caco-2 cells and in vitro autoradiography in rat brain slices. Our results demonstrate that 1-NBX exhibits significantly improved A1R affinity and selectivity when compared to CPFPX and that it does not give rise to lipophilic metabolites expected to cross the blood-brain-barrier in microsomal assays. Furthermore, [18F]1-NBX showed a high passive permeability (Pc = 6.9 ± 2.9 × 10-5 cm/s) and in vitro autoradiography with this radioligand resulted in a distribution pattern matching A1R expression in the brain. Moreover, a low degree of non-specific binding (5%) was observed. Taken together, these findings identify [18F]1-NBX as a promising candidate for further preclinical evaluation as potential PET tracer for A1R imaging.
Collapse
Affiliation(s)
- Swen Humpert
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Daniela Schneider
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Dirk Bier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Annette Schulze
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| | - Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany; Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany; Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany; Max Planck Institute for Metabolism Research, Gleueler Straße 50, 50931, Cologne, Germany.
| | - Marcus Holschbach
- Forschungszentrum Jülich GmbH, Institute of Neurosciences and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428, Jülich, Germany
| |
Collapse
|
2
|
Species Differences in Microsomal Metabolism of Xanthine-Derived A 1 Adenosine Receptor Ligands. Pharmaceuticals (Basel) 2021; 14:ph14030277. [PMID: 33803861 PMCID: PMC8003343 DOI: 10.3390/ph14030277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/10/2021] [Accepted: 03/15/2021] [Indexed: 11/17/2022] Open
Abstract
Tracer development for positron emission tomography (PET) requires thorough evaluation of pharmacokinetics, metabolism, and dosimetry of candidate radioligands in preclinical animal studies. Since variations in pharmacokinetics and metabolism of a compound occur in different species, careful selection of a suitable model species is mandatory to obtain valid data. This study focuses on species differences in the in vitro metabolism of three xanthine-derived ligands for the A1 adenosine receptor (A1AR), which, in their 18F-labeled form, can be used to image A1AR via PET. In vitro intrinsic clearance and metabolite profiles of 8-cyclopentyl-3-(3-fluoropropyl)-1-propylxanthine (CPFPX), an established A1AR-ligand, and two novel analogs, 8-cyclobutyl-3-(3-fluoropropyl)-1-propylxanthine (CBX) and 3-(3-fluoropropyl)-8-(1-methylcyclobutyl)-1-propylxanthine (MCBX), were determined in liver microsomes from humans and preclinical animal species. Molecular mechanisms leading to significant differences between human and animal metabolite profiles were also examined. The results revealed significant species differences regarding qualitative and quantitative aspects of microsomal metabolism. None of the tested animal species fully matched human microsomal metabolism of the three A1AR ligands. In conclusion, preclinical evaluation of xanthine-derived A1AR ligands should employ at least two animal species, preferably rodent and dog, to predict in vivo behavior in humans. Surprisingly, rhesus macaques appear unsuitable due to large differences in metabolic activity towards the test compounds.
Collapse
|
3
|
Mekheimer RA, Hayallah AM, Moustafa MS, Al-Mousawi SM, Abd-Elmonem M, Mostafa SM, Abo Elsoud FA, Sadek KU. Microwave-assisted reactions: Efficient and versatile one-step synthesis of 8-substituted xanthines and substituted pyrimidopteridine-2,4,6,8-tetraones under controlled microwave heating. GREEN PROCESSING AND SYNTHESIS 2021; 10:201-207. [DOI: 10.1515/gps-2021-0014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Abstract
We report herein a simple and efficient one-step synthesis of 8-substituted xanthines and substituted pyrimidopteridine-2,4,6,8-tetraones via reaction of 1,3-dimethyl-5,6-diaminouracil 1 with activated double bond systems 2 assisted by controlled microwave irradiation. The obtained heterocycles are privileged biologically relevant scaffolds.
Collapse
Affiliation(s)
| | - Alaa M. Hayallah
- Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Deraya University , Minia , Egypt
- Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Assiut University , Assiut 71526 , Egypt
| | - Moustafa Sherief Moustafa
- Department of Chemistry, Faculty of Science, Kuwait University , P. O. Box 12613 , Safat 13060 , Kuwait
| | - Saleh Mohammed Al-Mousawi
- Department of Chemistry, Faculty of Science, Kuwait University , P. O. Box 12613 , Safat 13060 , Kuwait
| | - Mohamed Abd-Elmonem
- Chemistry Department, Faculty of Science, Minia University , Minia 61519 , Egypt
| | - Sara M. Mostafa
- Chemistry Department, Faculty of Science, Minia University , Minia 61519 , Egypt
| | - Fatma A. Abo Elsoud
- Pharmaceutical Organic Chemistry Department, Faculty of Pharmacy, Deraya University , Minia , Egypt
| | - Kamal Usef Sadek
- Chemistry Department, Faculty of Science, Minia University , Minia 61519 , Egypt
| |
Collapse
|