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Krutzek F, Donat CK, Ullrich M, Stadlbauer S. Design, Synthesis, and Biological Evaluation of Small-Molecule-Based Radioligands with Improved Pharmacokinetic Properties for Imaging of Programmed Death Ligand 1. J Med Chem 2023; 66:15894-15915. [PMID: 38038981 PMCID: PMC10726354 DOI: 10.1021/acs.jmedchem.3c01355] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 11/11/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023]
Abstract
Small molecules offer some advantages for developing positron emission tomography (PET) tracers and are therefore a promising approach for imaging and therapy monitoring of programmed death ligand 1 (PD-L1) positive tumors. Here, we report six biphenyl PD-L1 radioligands using the NODA-GA-chelator for efficient copper-64 complexation. These radioligands contain varying numbers of sulfonic and/or phosphonic acid groups, serving as hydrophilizing units to lower the log D7.4 value down to -4.28. The binding affinities of compounds were evaluated using saturation binding and a real-time binding assay, with a highest binding affinity of 21 nM. Small-animal PET imaging revealed vastly different pharmacokinetic profiles depending on the quantity and type of hydrophilizing units. Of the investigated radioligands, [64Cu]Cu-3 showed the most favorable kinetics in vitro. This was also found in vivo, with a predominantly renal clearance and a specific uptake in the PD-L1-overexpressing tumor. With further modifications, this compound could be a promising candidate for the imaging of PD-L1 in the clinical setting.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Cornelius K. Donat
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Sven Stadlbauer
- Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Radiopharmaceutical
Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- Faculty
of Chemistry and Food Chemistry, School of Science, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
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2
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Krutzek F, Donat CK, Stadlbauer S. Exploring Hydrophilic PD-L1 Radiotracers Utilizing Phosphonic Acids: Insights into Unforeseen Pharmacokinetics. Int J Mol Sci 2023; 24:15088. [PMID: 37894769 PMCID: PMC10606431 DOI: 10.3390/ijms242015088] [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: 09/14/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/29/2023] Open
Abstract
Immune checkpoint inhibitor therapy targeting the PD-1/PD-L1 axis in cancer patients, is a promising oncological treatment. However, the number of non-responders remains high, causing a burden for the patient and the healthcare system. Consequently, a diagnostic tool to predict treatment outcomes would help with patient stratification. Molecular imaging provides said diagnostic tool by offering a whole-body quantitative assessment of PD-L1 expression, hence supporting therapy decisions. Four PD-L1 radioligand candidates containing a linker-chelator system for radiometalation, along with three hydrophilizing units-one sulfonic and two phosphonic acids-were synthesized. After labeling with 64Cu, log D7.4 values of less than -3.03 were determined and proteolytic stability confirmed over 94% intact compound after 48 h. Binding affinity was determined using two different assays, revealing high affinities up to 13 nM. µPET/CT imaging was performed in tumor-bearing mice to investigate PD-L1-specific tumor uptake and the pharmacokinetic profile of radioligands. These results yielded an unexpected in vivo distribution, such as low tumor uptake in PD-L1 positive tumors, high liver uptake, and accumulation in bone/bone marrow and potentially synovial spaces. These effects are likely caused by Ca2+-affinity and/or binding to macrophages. Despite phosphonic acids providing high water solubility, their incorporation must be carefully considered to avoid compromising the pharmacokinetic behavior of radioligands.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
| | - Cornelius K. Donat
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
| | - Sven Stadlbauer
- Helmholtz Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Medicinal Radiochemistry, Bautzner Landstraße 400, 01328 Dresden, Germany; (F.K.); (C.K.D.)
- School of Science, Faculty of Chemistry and Food Chemistry, Technical University Dresden, 01069 Dresden, Germany
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3
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Krutzek F, Donat CK, Ullrich M, Zarschler K, Ludik MC, Feldmann A, Loureiro LR, Kopka K, Stadlbauer S. Design and Biological Evaluation of Small-Molecule PET-Tracers for Imaging of Programmed Death Ligand 1. Cancers (Basel) 2023; 15:cancers15092638. [PMID: 37174103 PMCID: PMC10177516 DOI: 10.3390/cancers15092638] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/18/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
Noninvasive molecular imaging of the PD-1/PD-L1 immune checkpoint is of high clinical relevance for patient stratification and therapy monitoring in cancer patients. Here we report nine small-molecule PD-L1 radiotracers with solubilizing sulfonic acids and a linker-chelator system, designed by molecular docking experiments and synthesized according to a new, convergent synthetic strategy. Binding affinities were determined both in cellular saturation and real-time binding assay (LigandTracer), revealing dissociation constants in the single digit nanomolar range. Incubation in human serum and liver microsomes proved in vitro stability of these compounds. Small animal PET/CT imaging, in mice bearing PD-L1 overexpressing and PD-L1 negative tumors, showed moderate to low uptake. All compounds were cleared primarily through the hepatobiliary excretion route and showed a long circulation time. The latter was attributed to strong blood albumin binding effects, discovered during our binding experiments. Taken together, these compounds are a promising starting point for further development of a new class of PD-L1 targeting radiotracers.
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Affiliation(s)
- Fabian Krutzek
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Cornelius K Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Martin Ullrich
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Kristof Zarschler
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Marie-Charlotte Ludik
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Anja Feldmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Liliana R Loureiro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
- German Cancer Consortium (DKTK), Partner Site Dresden, Fetscherstraße 74, 01307 Dresden, Germany
- National Center for Tumor Diseases (NCT) Dresden, University Hospital Carl Gustav Carus, Fetscherstraße 74, 01307 Dresden, Germany
| | - Sven Stadlbauer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstraße 400, 01328 Dresden, Germany
- School of Science, Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, Mommsenstraße 4, 01069 Dresden, Germany
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4
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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.
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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
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5
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Wongso H, Hendra R, Nugraha AS, Ritawidya R, Saptiama I, Kusumaningrum CE. Microbial metabolites diversity and their potential as molecular template for the discovery of new fluorescent and radiopharmaceutical probes. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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6
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Huang Y, He Z, Manyande A, Feng M, Xiang H. Nerve regeneration in transplanted organs and tracer imaging studies: A review. Front Bioeng Biotechnol 2022; 10:966138. [PMID: 36051591 PMCID: PMC9424764 DOI: 10.3389/fbioe.2022.966138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/21/2022] [Indexed: 11/13/2022] Open
Abstract
The technique of organ transplantation is well established and after transplantation the patient might be faced with the problem of nerve regeneration of the transplanted organ. Transplanted organs are innervated by the sympathetic, parasympathetic, and visceral sensory plexuses, but there is a lack of clarity regarding the neural influences on the heart, liver and kidneys and the mechanisms of their innervation. Although there has been considerable recent work exploring the potential mechanisms of nerve regeneration in organ transplantation, there remains much that is unknown about the heterogeneity and individual variability in the reinnervation of organ transplantation. The widespread availability of radioactive nerve tracers has also made a significant contribution to organ transplantation and has helped to investigate nerve recovery after transplantation, as well as providing a direction for future organ transplantation research. In this review we focused on neural tracer imaging techniques in humans and provide some conceptual insights into theories that can effectively support our choice of radionuclide tracers. This also facilitates the development of nuclear medicine techniques and promotes the development of modern medical technologies and computer tools. We described the knowledge of neural regeneration after heart transplantation, liver transplantation and kidney transplantation and apply them to various imaging techniques to quantify the uptake of radionuclide tracers to assess the prognosis of organ transplantation. We noted that the aim of this review is both to provide clinicians and nuclear medicine researchers with theories and insights into nerve regeneration in organ transplantation and to advance imaging techniques and radiotracers as a major step forward in clinical research. Moreover, we aimed to further promote the clinical and research applications of imaging techniques and provide clinicians and research technology developers with the theory and knowledge of the nerve.
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Affiliation(s)
- Yan Huang
- Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Department of Interventional Therapy, the First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Zhigang He
- Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Anne Manyande
- School of Human and Social Sciences, University of West London, London, United Kingdom
| | - Maohui Feng
- Department of Gastrointestinal Surgery, Wuhan Peritoneal Cancer Clinical Medical Research Center, Zhongnan Hospital of Wuhan University, Hubei Key Laboratory of Tumor Biological Behaviors and Hubei Cancer Clinical Study Center, Wuhan, Hubei, China
- *Correspondence: Maohui Feng, ; Hongbing Xiang,
| | - Hongbing Xiang
- Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- *Correspondence: Maohui Feng, ; Hongbing Xiang,
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7
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Lindemann M, Dukic-Stefanovic S, Hinz S, Deuther-Conrad W, Teodoro R, Juhl C, Steinbach J, Brust P, Müller CE, Wenzel B. Synthesis of Novel Fluorinated Xanthine Derivatives with High Adenosine A 2B Receptor Binding Affinity. Pharmaceuticals (Basel) 2021; 14:ph14050485. [PMID: 34069548 PMCID: PMC8161391 DOI: 10.3390/ph14050485] [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: 04/20/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 12/12/2022] Open
Abstract
The G protein-coupled adenosine A2B receptor is suggested to be involved in various pathological processes accompanied by increased levels of adenosine as found in inflammation, hypoxia, and cancer. Therefore, the adenosine A2B receptor is currently in focus as a novel target for cancer therapy as well as for noninvasive molecular imaging via positron emission tomography (PET). Aiming at the development of a radiotracer labeled with the PET radionuclide fluorine-18 for imaging the adenosine A2B receptor in brain tumors, one of the most potent and selective antagonists, the xanthine derivative PSB-603, was selected as a lead compound. As initial biodistribution studies in mice revealed a negligible brain uptake of [3H]PSB-603 (SUV3min: 0.2), structural modifications were performed to optimize the physicochemical properties regarding blood–brain barrier penetration. Two novel fluorinated derivatives bearing a 2-fluoropyridine (5) moiety and a 4-fluoro-piperidine (6) moiety were synthesized, and their affinity towards the four adenosine receptor subtypes was determined in competition binding assays. Both compounds showed high affinity towards the adenosine A2B receptor (Ki (5) = 9.97 ± 0.86 nM; Ki (6) = 12.3 ± 3.6 nM) with moderate selectivity versus the other adenosine receptor subtypes.
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Affiliation(s)
- Marcel Lindemann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
- Correspondence:
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
- ROTOP Pharmaka GmbH, 01328 Dresden, Germany;
| | - Sonja Hinz
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, 53121 Bonn, Germany; (S.H.); (C.E.M.)
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
| | | | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
| | - Christa E. Müller
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical & Medicinal Chemistry, University of Bonn, 53121 Bonn, Germany; (S.H.); (C.E.M.)
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, 04318 Leipzig, Germany; (S.D.-S.); (W.D.-C.); (R.T.); (J.S.); (P.B.); (B.W.)
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8
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Sun J, Chen J, Kumata K, Xiao Z, Rong J, Haider A, Shao T, Wang L, Xu H, Zhang MR, Liang SH. Imaging the trace amine-associated receptor 1 by positron emission tomography. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.153007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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9
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Agha H, McCurdy CR. In vitro and in vivo sigma 1 receptor imaging studies in different disease states. RSC Med Chem 2021; 12:154-177. [PMID: 34046607 PMCID: PMC8127618 DOI: 10.1039/d0md00186d] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/02/2020] [Indexed: 12/11/2022] Open
Abstract
The sigma receptor system has been classified into two distinct subtypes, sigma 1 (σ1R) and sigma 2 (σ2R). Sigma 1 receptors (σ1Rs) are involved in many neurodegenerative diseases and different central nervous system disorders such as Alzheimer's disease, Parkinson's disease, schizophrenia, and drug addiction, and pain. This makes them attractive targets for developing radioligands as tools to gain a better understanding of disease pathophysiology and clinical diagnosis. Over the years, several σ1R radioligands have been developed to image the changes in σ1R distribution and density providing insights into their role in disease development. Moreover, the involvement of both σ1Rs and σ2Rs with cancer make these ligands, especially those that are σ2R selective, great tools for imaging different types of tumors. This review will discuss the principles of molecular imaging using PET and SPECT, known σ1R radioligands and their applications for labelling σ1Rs under different disease conditions. Furthermore, this review will highlight σ1R radioligands that have demonstrated considerable potential as biomarkers, and an opportunity to fulfill the ultimate goal of better healthcare outcomes and improving human health.
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Affiliation(s)
- Hebaalla Agha
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida Gainesville FL 32610 USA +(352) 273 7705 +1 (352) 294 8691
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida Gainesville FL 32610 USA +(352) 273 7705 +1 (352) 294 8691
- UF Translational Drug Development Core, University of Florida Gainesville FL 32610 USA
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10
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Lai TH, Schröder S, Toussaint M, Dukić-Stefanović S, Kranz M, Ludwig FA, Fischer S, Steinbach J, Deuther-Conrad W, Brust P, Moldovan RP. Development of 18F-Labeled Radiotracers for PET Imaging of the Adenosine A 2A Receptor: Synthesis, Radiolabeling and Preliminary Biological Evaluation. Int J Mol Sci 2021; 22:ijms22052285. [PMID: 33669003 PMCID: PMC7956753 DOI: 10.3390/ijms22052285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/21/2021] [Accepted: 02/22/2021] [Indexed: 12/19/2022] Open
Abstract
The adenosine A2A receptor (A2AR) represents a potential therapeutic target for neurodegenerative diseases. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor changes of receptor density and/or occupancy during the A2AR-tailored therapy, we designed a library of fluorinated analogs based on a recently published lead compound (PPY). Among those, the highly affine 4-fluorobenzyl derivate (PPY1; Ki(hA2AR) = 5.3 nM) and the 2-fluorobenzyl derivate (PPY2; Ki(hA2AR) = 2.1 nM) were chosen for 18F-labeling via an alcohol-enhanced copper-mediated procedure starting from the corresponding boronic acid pinacol ester precursors. Investigations of the metabolic stability of [18F]PPY1 and [18F]PPY2 in CD-1 mice by radio-HPLC analysis revealed parent fractions of more than 76% of total activity in the brain. Specific binding of [18F]PPY2 on mice brain slices was demonstrated by in vitro autoradiography. In vivo PET/magnetic resonance imaging (MRI) studies in CD-1 mice revealed a reasonable high initial brain uptake for both radiotracers, followed by a fast clearance.
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Affiliation(s)
- Thu Hang Lai
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
- Correspondence: (T.H.L.); (R.-P.M.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4634 (R.-P.M.)
| | - Susann Schröder
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Sladjana Dukić-Stefanović
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- PET Imaging Center, University Hospital of North Norway (UNN), 9009 Tromsø, Norway
- Nuclear Medicine and Radiation Biology Research Group, The Arctic University of Norway, 9009 Tromsø, Norway
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., Dresden 01328, Germany;
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (M.T.); (S.D.-S.); (M.K.); (F.-A.L.); (S.F.); (J.S.); (W.D.-C.); (P.B.)
- Correspondence: (T.H.L.); (R.-P.M.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4634 (R.-P.M.)
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11
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Goud NS, Ghouse MS, Nagaraju C, Bharath RD, Alvala M, Kumar P. Automated Radiosynthesis and Molecular Docking Studies of Coumarin-Triazole Hybrid with fluorine-18: A feasibility study. Curr Radiopharm 2021; 15:40-49. [PMID: 33511934 DOI: 10.2174/1874471014666210129141221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/20/2020] [Accepted: 11/22/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND Fluorine-18 is one of the promising radiotracers that can report target specific information related to its physiology to understand the disease status through PET modality. In current study, the radiochemical synthesis, purification and molecular docking studies of fluorine-18 (18F) radiolabeled coumarin-triazole hybrid have been performed. OBJECTIVE To develop target specific fluorine-18 radiotracer for the diagnosis in oncology. METHODS GE Tracer-lab FX2N module with few modifications in the line connections was used for the radiosynthesis and purification of target molecule [18F]SG-2, 4-((2,6-dimethylmorpholino) methyl)-7-((1-(4-(fluoro-18F) benzyl)-1H-1,2,3-triazol-4-yl) oxy)-2H-chromen-2-one, through the nucleophilic radiofluorination mechanism. The radiochemical purity was measured by HPLC, and TLC analytical methods. The kryptofix levels were also evaluated by using TLC method. The residual solvents like DMF, ethanol was measured using GC. The Schrödinger drug discovery suite 2018 was used to study the protein and ligand interactions. RESULTS The quality control parameters revealed the purity, chemical identity, and limits of residual solvents. The radiochemical purity was 95.5 ± 2.3 %, and dimethyl formamide solvent limit was 89 ± 3 ppm. The molecular docking results had suggested that the cold target molecule has made strong electronic interactions and showed the possible pharmacokinetic (ADME) properties with galectin-1 protein. Overall, these results showed that [18F]SG-2 radiolabeling with 18F radionuclide was feasible, and support of molecular docking studies suggest possible interactions with Galectin-1. CONCLUSION we reported feasibility study for labeling coumarin-triazole hybrid with fluorine-18 through aromatic nucleophilic fluorination reaction (SNAr).
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NI & IR), National Institute of Mental Health and Neuro Sciences (NIMHANS). India
| | - Mahammad S Ghouse
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad-500037. India
| | - Chandana Nagaraju
- Department of Neuroimaging and Interventional Radiology (NI & IR), National Institute of Mental Health and Neuro Sciences (NIMHANS). India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NI & IR), National Institute of Mental Health and Neuro Sciences (NIMHANS). India
| | - Mallika Alvala
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Hyderabad-500037. India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NI & IR), National Institute of Mental Health and Neuro Sciences (NIMHANS). India
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12
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Lai TH, Toussaint M, Teodoro R, Dukić-Stefanović S, Kranz M, Deuther-Conrad W, Moldovan RP, Brust P. Synthesis and Biological Evaluation of a Novel 18F-Labeled Radiotracer for PET Imaging of the Adenosine A 2A Receptor. Int J Mol Sci 2021; 22:ijms22031182. [PMID: 33504051 PMCID: PMC7865263 DOI: 10.3390/ijms22031182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/14/2021] [Accepted: 01/18/2021] [Indexed: 02/06/2023] Open
Abstract
The adenosine A2A receptor (A2AR) has emerged as a potential non-dopaminergic target for the treatment of Parkinson’s disease and, thus, the non-invasive imaging with positron emission tomography (PET) is of utmost importance to monitor the receptor expression and occupancy during an A2AR-tailored therapy. Aiming at the development of a PET radiotracer, we herein report the design of a series of novel fluorinated analogs (TOZ1-TOZ7) based on the structure of the A2AR antagonist tozadenant, and the preclinical evaluation of [18F]TOZ1. Autoradiography proved A2AR-specific in vitro binding of [18F]TOZ1 to striatum of mouse and pig brain. Investigations of the metabolic stability in mice revealed parent fractions of more than 76% and 92% of total activity in plasma and brain samples, respectively. Dynamic PET/magnetic resonance imaging (MRI) studies in mice revealed a brain uptake but no A2AR-specific in vivo binding.
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Affiliation(s)
- Thu Hang Lai
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., 01328 Dresden, Germany
- Correspondence: (T.H.L.); (M.T.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4616 (M.T.)
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
- Correspondence: (T.H.L.); (M.T.); Tel.: +49-341-234-179-4635 (T.H.L.); +49-341-234-179-4616 (M.T.)
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
| | - Sladjana Dukić-Stefanović
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
- PET Imaging Center, University Hospital of North Norway (UNN), 9009 Tromsø, Norway
- Nuclear Medicine and Radiation Biology Research Group, The Arctic University of Norway, 9009 Tromsø, Norway
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (S.D.-S.); (M.K.); (W.D.-C.); (R.-P.M.); (P.B.)
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13
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Shaw RC, Tamagnan GD, Tavares AAS. Rapidly (and Successfully) Translating Novel Brain Radiotracers From Animal Research Into Clinical Use. Front Neurosci 2020; 14:871. [PMID: 33117115 PMCID: PMC7559529 DOI: 10.3389/fnins.2020.00871] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 07/27/2020] [Indexed: 12/26/2022] Open
Abstract
The advent of preclinical research scanners for in vivo imaging of small animals has added confidence into the multi-step decision-making process of radiotracer discovery and development. Furthermore, it has expanded the utility of imaging techniques available to dissect clinical questions, fostering a cyclic interaction between the clinical and the preclinical worlds. Significant efforts from medicinal chemistry have also made available several high-affinity and selective compounds amenable for radiolabeling, that target different receptors, transporters and enzymes in vivo. This substantially increased the range of applications of molecular imaging using positron emission tomography (PET) or single photon emission computed tomography (SPECT). However, the process of developing novel radiotracers for in vivo imaging of the human brain is a multi-step process that has several inherent pitfalls and technical difficulties, which often hampers the successful translation of novel imaging agents from preclinical research into clinical use. In this paper, the process of radiotracer development and its relevance in brain research is discussed; as well as, its pitfalls, technical challenges and future promises. Examples of successful and unsuccessful translation of brain radiotracers will be presented.
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Affiliation(s)
- Robert C. Shaw
- BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Edinburgh Imaging, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Adriana Alexandre S. Tavares
- BHF Centre for Cardiovascular Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Edinburgh Imaging, University of Edinburgh, Edinburgh, United Kingdom
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14
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Goud NS, Joshi RK, Bharath RD, Kumar P. Fluorine-18: A radionuclide with diverse range of radiochemistry and synthesis strategies for target based PET diagnosis. Eur J Med Chem 2020; 187:111979. [DOI: 10.1016/j.ejmech.2019.111979] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/16/2019] [Accepted: 12/16/2019] [Indexed: 12/25/2022]
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15
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Ermert J, Benešová M, Hugenberg V, Gupta V, Spahn I, Pietzsch HJ, Liolios C, Kopka K. Radiopharmaceutical Sciences. Clin Nucl Med 2020. [DOI: 10.1007/978-3-030-39457-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Radiosynthesis and Biological Investigation of a Novel Fluorine-18 Labeled Benzoimidazotriazine- Based Radioligand for the Imaging of Phosphodiesterase 2A with Positron Emission Tomography. Molecules 2019; 24:molecules24224149. [PMID: 31731831 PMCID: PMC6891464 DOI: 10.3390/molecules24224149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 11/12/2019] [Indexed: 12/17/2022] Open
Abstract
A specific radioligand for the imaging of cyclic nucleotide phosphodiesterase 2A (PDE2A) via positron emission tomography (PET) would be helpful for research on the physiology and disease-related changes in the expression of this enzyme in the brain. In this report, the radiosynthesis of a novel PDE2A radioligand and the subsequent biological evaluation were described. Our prospective compound 1-(2-chloro-5-methoxy phenyl)-8-(2-fluoropyridin-4-yl)-3- methylbenzo[e]imidazo[5,1-c][1,2,4]triazine, benzoimidazotriazine (BIT1) (IC50 PDE2A = 3.33 nM; 16-fold selectivity over PDE10A) was fluorine-18 labeled via aromatic nucleophilic substitution of the corresponding nitro precursor using the K[18F]F-K2.2.2-carbonate complex system. The new radioligand [18F]BIT1 was obtained with a high radiochemical yield (54 ± 2%, n = 3), a high radiochemical purity (≥99%), and high molar activities (155–175 GBq/μmol, n = 3). In vitro autoradiography on pig brain cryosections exhibited a heterogeneous spatial distribution of [18F]BIT1 corresponding to the known pattern of expression of PDE2A. The investigation of in vivo metabolism of [18F]BIT1 in a mouse revealed sufficient metabolic stability. PET studies in mouse exhibited a moderate brain uptake of [18F]BIT1 with a maximum standardized uptake value of ~0.7 at 5 min p.i. However, in vivo blocking studies revealed a non-target specific binding of [18F]BIT1. Therefore, further structural modifications are needed to improve target selectivity.
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17
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Ludwig FA, Fischer S, Houska R, Hoepping A, Deuther-Conrad W, Schepmann D, Patt M, Meyer PM, Hesse S, Becker GA, Zientek FR, Steinbach J, Wünsch B, Sabri O, Brust P. In vitro and in vivo Human Metabolism of ( S)-[ 18F]Fluspidine - A Radioligand for Imaging σ 1 Receptors With Positron Emission Tomography (PET). Front Pharmacol 2019; 10:534. [PMID: 31263411 PMCID: PMC6585474 DOI: 10.3389/fphar.2019.00534] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/29/2019] [Indexed: 12/26/2022] Open
Abstract
(S)-[18F]fluspidine ((S)-[18F]1) has recently been explored for positron emission tomography (PET) imaging of sigma-1 receptors in humans. In the current report, we have used plasma samples of healthy volunteers to investigate the radiometabolites of (S)-[18F]1 and elucidate their structures with LC-MS/MS. For the latter purpose additional in vitro studies were conducted by incubation of (S)-[18F]1 and (S)-1 with human liver microsomes (HLM). In vitro metabolites were characterized by interpretation of MS/MS fragmentation patterns from collision-induced dissociation or by use of reference compounds. Thereby, structures of corresponding radio-HPLC-detected radiometabolites, both in vitro and in vivo (human), could be identified. By incubation with HLM, mainly debenzylation and hydroxylation occurred, beside further mono- and di-oxygenations. The product hydroxylated at the fluoroethyl side chain was glucuronidated. Plasma samples (10, 20, 30 min p.i., n = 5-6), obtained from human subjects receiving 250–300 MBq (S)-[18F]1 showed 97.2, 95.4, and 91.0% of unchanged radioligand, respectively. In urine samples (90 min p.i.) the fraction of unchanged radioligand was only 2.6% and three major radiometabolites were detected. The one with the highest percentage, also found in plasma, matched the glucuronide formed in vitro. Only a small amount of debenzylated metabolite was detected. In conclusion, our metabolic study, in particular the high fractions of unchanged radioligand in plasma, confirms the suitability of (S)-[18F]1 as PET radioligand for sigma-1 receptor imaging.
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Affiliation(s)
- Friedrich-Alexander Ludwig
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Steffen Fischer
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Richard Houska
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | | | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Dirk Schepmann
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Marianne Patt
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Philipp M Meyer
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Swen Hesse
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany.,Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University, Leipzig, Germany
| | | | - Franziska Ruth Zientek
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany.,Integrated Research and Treatment Center (IFB) Adiposity Diseases, Leipzig University, Leipzig, Germany
| | - Jörg Steinbach
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
| | - Bernhard Wünsch
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Osama Sabri
- Department of Nuclear Medicine, Leipzig University, Leipzig, Germany
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Leipzig, Germany
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18
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Lee SJ, Makaravage KJ, Brooks AF, Scott PJH, Sanford MS. Copper-Mediated Aminoquinoline-Directed Radiofluorination of Aromatic C-H Bonds with K 18 F. Angew Chem Int Ed Engl 2019; 58:3119-3122. [PMID: 30605563 DOI: 10.1002/anie.201812701] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Indexed: 02/05/2023]
Abstract
A Cu-mediated ortho-C-H radiofluorination of aromatic carboxylic acids that are protected as 8-aminoquinoline benzamides is described. The method uses K18 F and is compatible with a wide range of functional groups. The reaction is showcased in the high specific activity automated synthesis of the RARβ2 agonist [18 F]AC261066.
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Affiliation(s)
- So Jeong Lee
- Department of Radiology, University of Michigan, 1301 Catherine St, Ann Arbor, MI, 48109, USA
| | - Katarina J Makaravage
- Department of Chemistry, The University of Michigan, 930 North University Ave, Ann Arbor, MI, 48109, USA
| | - Allen F Brooks
- Department of Radiology, University of Michigan, 1301 Catherine St, Ann Arbor, MI, 48109, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan, 1301 Catherine St, Ann Arbor, MI, 48109, USA
| | - Melanie S Sanford
- Department of Chemistry, The University of Michigan, 930 North University Ave, Ann Arbor, MI, 48109, USA
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19
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Lee SJ, Makaravage KJ, Brooks AF, Scott PJH, Sanford MS. Copper‐Mediated Aminoquinoline‐Directed Radiofluorination of Aromatic C−H Bonds with K
18
F. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201812701] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- So Jeong Lee
- Department of Radiology University of Michigan 1301 Catherine St Ann Arbor MI 48109 USA
| | - Katarina J. Makaravage
- Department of Chemistry The University of Michigan 930 North University Ave Ann Arbor MI 48109 USA
| | - Allen F. Brooks
- Department of Radiology University of Michigan 1301 Catherine St Ann Arbor MI 48109 USA
| | - Peter J. H. Scott
- Department of Radiology University of Michigan 1301 Catherine St Ann Arbor MI 48109 USA
| | - Melanie S. Sanford
- Department of Chemistry The University of Michigan 930 North University Ave Ann Arbor MI 48109 USA
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20
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Moldovan RP, Wenzel B, Teodoro R, Neumann W, Dukic-Stefanovic S, Kraus W, Rong P, Deuther-Conrad W, Hey-Hawkins E, Krügel U, Brust P. Studies towards the development of a PET radiotracer for imaging of the P2Y 1 receptors in the brain: synthesis, 18F-labeling and preliminary biological evaluation. Eur J Med Chem 2019; 165:142-159. [PMID: 30665144 DOI: 10.1016/j.ejmech.2019.01.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/20/2018] [Accepted: 01/04/2019] [Indexed: 12/14/2022]
Abstract
Purine nucleotides such as ATP and ADP are important extracellular signaling molecules in almost all tissues activating various subtypes of purinoreceptors. In the brain, the P2Y1 receptor (P2Y1R) subtype mediates trophic functions like differentiation and proliferation, and modulates fast synaptic transmission, both suggested to be affected in diseases of the central nervous system. Research on P2Y1R is limited because suitable brain-penetrating P2Y1R-selective tracers are not yet available. Here, we describe the first efforts to develop an 18F-labeled PET tracer based on the structure of the highly affine and selective, non-nucleotidic P2Y1R allosteric modulator 1-(2-[2-(tert-butyl)phenoxy]pyridin-3-yl)-3-[4-(trifluoromethoxy)phenyl]urea (7). A small series of fluorinated compounds was developed by systematic modification of the p-(trifluoromethoxy)phenyl, the urea and the 2-pyridyl subunits of the lead compound 7. Additionally, the p-(trifluoromethoxy)phenyl subunit was substituted by carborane, a boron-rich cluster with potential applicability in boron neutron capture therapy (BNCT). By functional assays, the new fluorinated derivative 1-{2-[2-(tert-butyl)phenoxy]pyridin-3-yl}-3-[4-(2-fluoroethyl)phenyl]urea (18) was identified with a high P2Y1R antagonistic potency (IC50 = 10 nM). Compound [18F]18 was radiosynthesized by using tetra-n-butyl ammonium [18F]fluoride with high radiochemical purity, radiochemical yield and molar activities. Investigation of brain homogenates using hydrophilic interaction chromatography (HILIC) revealed [18F]fluoride as major radiometabolite. Although [18F]18 showed fast in vivo metabolization, the high potency and unique allosteric binding mode makes this class of compounds interesting for further optimizations and investigation of the theranostic potential as PET tracer and BNCT agent.
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Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany.
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Wilma Neumann
- Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103, Leipzig, Germany
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Werner Kraus
- BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Str. 11, 12489, Berlin, Germany
| | - Peijing Rong
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, 100700, Beijing, China
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
| | - Evamarie Hey-Hawkins
- Institute of Inorganic Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103, Leipzig, Germany
| | - Ute Krügel
- Rudolf Boehm Institute of Pharmacology and Toxicology, Medical Faculty, Universität Leipzig, 04107, Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, 04318, Leipzig, Germany
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21
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Lindemann M, Hinz S, Deuther-Conrad W, Namasivayam V, Dukic-Stefanovic S, Teodoro R, Toussaint M, Kranz M, Juhl C, Steinbach J, Brust P, Müller CE, Wenzel B. Radiosynthesis and in vivo evaluation of a fluorine-18 labeled pyrazine based radioligand for PET imaging of the adenosine A 2B receptor. Bioorg Med Chem 2018; 26:4650-4663. [PMID: 30104122 DOI: 10.1016/j.bmc.2018.07.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 02/07/2023]
Abstract
On the basis of a pyrazine core structure, three new adenosine A2B receptor ligands (7a-c) were synthesized containing a 2-fluoropyridine moiety suitable for 18F-labeling. Compound 7a was docked into a homology model of the A2B receptor based on X-ray structures of the related A2A receptor, and its interactions with the adenosine binding site were rationalized. Binding affinity data were determined at the four human adenosine receptor subtypes. Despite a rather low selectivity regarding the A1 receptor, 7a was radiolabeled as the most suitable candidate (Ki(A2B) = 4.24 nM) in order to perform in vivo studies in mice with the aim to estimate fundamental pharmacokinetic characteristics of the compound class. Organ distribution studies and a single PET study demonstrated brain uptake of [18F]7a with a standardized uptake value (SUV) of ≈1 at 5 min post injection followed by a fast wash out. Metabolism studies of [18F]7a in mice revealed the formation of a blood-brain barrier penetrable radiometabolite, which could be structurally identified. The results of this study provide an important basis for the design of new derivatives with improved binding properties and metabolic stability in vivo.
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Affiliation(s)
- Marcel Lindemann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Sonja Hinz
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Vigneshwaran Namasivayam
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | | | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | | | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany
| | - Christa E Müller
- Pharma Center Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Leipzig, Germany.
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Yue X, Dhavale DD, Li J, Luo Z, Liu J, Yang H, Mach RH, Kotzbauer PT, Tu Z. Design, synthesis, and in vitro evaluation of quinolinyl analogues for α-synuclein aggregation. Bioorg Med Chem Lett 2018; 28:1011-1019. [PMID: 29482941 PMCID: PMC5870887 DOI: 10.1016/j.bmcl.2018.02.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 02/09/2018] [Accepted: 02/14/2018] [Indexed: 12/19/2022]
Abstract
Here we report the synthesis and in vitro evaluation of 25 new quinolinyl analogues for α-synuclein aggregates. Three lead compounds were subsequently labeled with carbon-11 or fluorine-18 to directly assess their potency in a direct radioactive competitive binding assay ng both α-synuclein fibrils and tissue homogenates from Alzheimer's disease (AD) cases. The modest binding affinities of these three radioligands toward α-synuclein were comparable with results from the Thioflavin T fluorescence assay. However, all three ligand also showed modest binding affinity to the AD homogenates and lack selectivity for α-synuclein. The structure-activity relationship data from these 25 analogues will provide useful information for design and synthesis of new compounds for imaging α-synuclein aggregation.
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Affiliation(s)
- Xuyi Yue
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Dhruva D Dhavale
- Department of Neurology, Washington University School of Medicine, St Louis, MO, United States
| | - Junfeng Li
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Zonghua Luo
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Jialu Liu
- Department of Neurology, Washington University School of Medicine, St Louis, MO, United States
| | - Hao Yang
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States
| | - Robert H Mach
- Department of Radiology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
| | - Paul T Kotzbauer
- Department of Neurology, Washington University School of Medicine, St Louis, MO, United States
| | - Zhude Tu
- Department of Radiology, Washington University School of Medicine, St Louis, MO, United States.
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Kniess T, Laube M, Steinbach J. “Hydrous 18 F-fluoroethylation” – Leaving off the azeotropic drying. Appl Radiat Isot 2017; 127:260-268. [DOI: 10.1016/j.apradiso.2017.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 06/07/2017] [Accepted: 06/12/2017] [Indexed: 12/16/2022]
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Potential of α7 nicotinic acetylcholine receptor PET imaging in atherosclerosis. Methods 2017; 130:90-104. [PMID: 28602809 DOI: 10.1016/j.ymeth.2017.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/02/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
Atherosclerotic events are usually acute and often strike otherwise asymptomatic patients. Although multiple clinical risk factors have been associated with atherosclerosis, as of yet no further individual prediction can be made as to who will suffer from its consequences based on biomarker analysis or traditional imaging methods like CT, MRI or angiography. Previously, non-invasive imaging with 18F-fluorodeoxyglucose (18F-FDG) PET was shown to potentially fill this niche as it offers high sensitive detection of metabolic processes associated with inflammatory changes in atherosclerotic plaques. However, 18F-FDG PET imaging of arterial vessels suffers from non-specificity and has still to be proven to reliably identify vulnerable plaques, carrying a high risk of rupture. Therefore, it may be regarded only as a secondary marker for monitoring treatment effects and it does not offer alternative treatment options or direct insight in treatment mechanisms. In this review, an overview is given of the current status and the potential of PET imaging of inflammation and angiogenesis in atherosclerosis in general and special emphasis is given to imaging of α7 nicotinic acetylcholine receptors (α7 nAChRs). Due to the gaps that still exist in our understanding of atherogenesis and the limitations of the available PET tracers, the search continues for a more specific radioligand, able to differentiate between stable atherosclerosis and plaques prone to rupture. The potential role of the α7 nAChR as imaging marker for plaque vulnerability is explored. Today, strong evidence exists that nAChRs are involved in the atherosclerotic disease process. They are suggested to mediate the deleterious effects of the major tobacco component, nicotine, a nAChR agonist. Mainly based on in vitro data, α7 nAChR stimulation might increase plaque burden via increased neovascularization. However, in animal studies, α7 nAChR manipulation appears to reduce plaque size due to its inhibitory effects on inflammatory cells. Thus, reliable identification of α7 nAChRs by in vivo imaging is crucial to investigate the exact role of α7 nAChR in atherosclerosis before any therapeutic approach in the human setting can be justified. In this review, we discuss the first experience with α7 nAChR PET tracers and developmental considerations regarding the "optimal" PET tracer to image vascular nAChRs.
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Chaturvedi S, Kaul A, Hazari PP, Mishra AK. Mapping neuroreceptors with metal-labeled radiopharmaceuticals. MEDCHEMCOMM 2017; 8:855-870. [PMID: 30108802 PMCID: PMC6072260 DOI: 10.1039/c6md00610h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 02/07/2017] [Indexed: 01/27/2023]
Abstract
The growing epidemiological and economic burden of neurological diseases on society is tremendous. A correct and timely diagnosis can help in lowering the burden and improving the life quality of both the diseased person and the caretaker. Imaging of the brain (neuroimaging) using CT, MRI, and nuclear imaging methods can provide anatomical and functional information. Neuroreceptors are central to neurotransmission and neuromodulation in the CNS. In vivo imaging of receptors in the brain provides powerful tools for the functional study of the central nervous system (CNS) in normal or diseased states. Presently, PET imaging using non-metallic radiotracers dominates the imaging of neuroreceptors. Metal-based probes for SPECT and PET can be economical and logistically easier to use without compromising the information. This review focuses on the development of metallic radiotracers for (99mTc) SPECT and (68Ga) PET along with future directions based on the metallic probes developed for other imaging modalities namely MRI.
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Affiliation(s)
- S Chaturvedi
- Division of Cyclotron and Radiopharmaceutical Sciences , Institute of Nuclear Medicine and Allied Sciences , Brig. S.K. Mazumder Road , Delhi 110054 , India . ; ; ; Tel: +91 11 23095117
| | - A Kaul
- Division of Cyclotron and Radiopharmaceutical Sciences , Institute of Nuclear Medicine and Allied Sciences , Brig. S.K. Mazumder Road , Delhi 110054 , India . ; ; ; Tel: +91 11 23095117
| | - Puja P Hazari
- Division of Cyclotron and Radiopharmaceutical Sciences , Institute of Nuclear Medicine and Allied Sciences , Brig. S.K. Mazumder Road , Delhi 110054 , India . ; ; ; Tel: +91 11 23095117
| | - Anil K Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences , Institute of Nuclear Medicine and Allied Sciences , Brig. S.K. Mazumder Road , Delhi 110054 , India . ; ; ; Tel: +91 11 23095117
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26
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Moldovan RP, Els-Heindl S, Worm DJ, Kniess T, Kluge M, Beck-Sickinger AG, Deuther-Conrad W, Krügel U, Brust P. Development of Fluorinated Non-Peptidic Ghrelin Receptor Ligands for Potential Use in Molecular Imaging. Int J Mol Sci 2017; 18:ijms18040768. [PMID: 28379199 PMCID: PMC5412352 DOI: 10.3390/ijms18040768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/23/2017] [Accepted: 03/31/2017] [Indexed: 12/19/2022] Open
Abstract
The ghrelin receptor (GhrR) is a widely investigated target in several diseases. However, the current knowledge of its role and distribution in the brain is limited. Recently, the small and non-peptidic compound (S)-6-(4-bromo-2-fluorophenoxy)-3-((1-isopropylpiperidin-3-yl)methyl)-2-methylpyrido[3,2-d]pyrimidin-4(3H)-one ((S)-9) has been described as a GhrR ligand with high binding affinity. Here, we describe the synthesis of fluorinated derivatives, the in vitro evaluation of their potency as partial agonists and selectivity at GhrRs, and their physicochemical properties. These results identified compounds (S)-9, (R)-9, and (S)-16 as suitable parent molecules for 18F-labeled positron emission tomography (PET) radiotracers to enable future investigation of GhrR in the brain.
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Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Sylvia Els-Heindl
- Institute of Biochemistry, Universität Leipzig, 04103 Leipzig, Germany.
| | - Dennis J Worm
- Institute of Biochemistry, Universität Leipzig, 04103 Leipzig, Germany.
| | - Torsten Kniess
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Michael Kluge
- Department of Psychiatry, Universität Leipzig, 04103 Leipzig, Germany.
| | | | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
| | - Ute Krügel
- Rudolf Boehm Institute of Pharmacology and Toxicology, Medical Faculty, Universität Leipzig, 04107 Leipzig, Germany.
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf e. V., Institute of Radiopharmaceutical Cancer Research, 04318 Leipzig, Germany.
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Moldovan RP, Deuther-Conrad W, Horti AG, Brust P. Synthesis and Preliminary Biological Evaluation of Indol-3-yl-oxoacetamides as Potent Cannabinoid Receptor Type 2 Ligands. Molecules 2017; 22:molecules22010077. [PMID: 28054997 PMCID: PMC6155603 DOI: 10.3390/molecules22010077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/22/2016] [Accepted: 12/22/2016] [Indexed: 11/22/2022] Open
Abstract
A small series of indol-3-yl-oxoacetamides was synthesized starting from the literature known N-(adamantan-1-yl)-2-(5-(furan-2-yl)-1-pentyl-1H-indol-3-yl)-2-oxoacetamide (5) by substituting the 1-pentyl-1H-indole subunit. Our preliminary biological evaluation showed that the fluorinated derivative 8 is a potent and selective CB2 ligand with Ki = 6.2 nM.
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Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstr. 15, 04318 Leipzig, Germany.
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstr. 15, 04318 Leipzig, Germany.
| | - Andrew G Horti
- Johns Hopkins School of Medicine, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Baltimore, MD 21287, USA.
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research, Permoserstr. 15, 04318 Leipzig, Germany.
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Lever SZ, Fan KH, Lever JR. Tactics for preclinical validation of receptor-binding radiotracers. Nucl Med Biol 2017; 44:4-30. [PMID: 27755986 PMCID: PMC5161541 DOI: 10.1016/j.nucmedbio.2016.08.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Revised: 08/24/2016] [Accepted: 08/24/2016] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Aspects of radiopharmaceutical development are illustrated through preclinical studies of [125I]-(E)-1-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-BF-PE-PIPZE), a radioligand for sigma-1 (σ1) receptors, coupled with examples from the recent literature. Findings are compared to those previously observed for [125I]-(E)-1-(2-(2,3-dimethoxy-5-yl)ethyl)-4-(iodoallyl)piperazine ([125I]-E-IA-DM-PE-PIPZE). METHODS Syntheses of E-IA-BF-PE-PIPZE and [125I]-E-IA-BF-PE-PIPZE were accomplished by standard methods. In vitro receptor binding studies and autoradiography were performed, and binding potential was predicted. Measurements of lipophilicity and protein binding were obtained. In vivo studies were conducted in mice to evaluate radioligand stability, as well as specific binding to σ1 sites in brain, brain regions and peripheral organs in the presence and absence of potential blockers. RESULTS E-IA-BF-PE-PIPZE exhibited high affinity and selectivity for σ1 receptors (Ki = 0.43 ± 0.03 nM, σ2/σ1 = 173). [125I]-E-IA-BF-PE-PIPZE was prepared in good yield and purity, with high specific activity. Radioligand binding provided dissociation (koff) and association (kon) rate constants, along with a measured Kd of 0.24 ± 0.01 nM and Bmax of 472 ± 13 fmol/mg protein. The radioligand proved suitable for quantitative autoradiography in vitro using brain sections. Moderate lipophilicity, Log D7.4 2.69 ± 0.28, was determined, and protein binding was 71 ± 0.3%. In vivo, high initial whole brain uptake, >6% injected dose/g, cleared slowly over 24 h. Specific binding represented 75% to 93% of total binding from 15 min to 24 h. Findings were confirmed and extended by regional brain biodistribution. Radiometabolites were not observed in brain (1%). CONCLUSIONS Substitution of dihydrobenzofuranylethyl for dimethoxyphenethyl increased radioligand affinity for σ1 receptors by 16-fold. While high specific binding to σ1 receptors was observed for both radioligands in vivo, [125I]-E-IA-BF-PE-PIPZE displayed much slower clearance kinetics than [125I]-E-IA-DM-PE-PIPZE. Thus, minor structural modifications of σ1 receptor radioligands lead to major differences in binding properties in vitro and in vivo.
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Affiliation(s)
- Susan Z Lever
- Department of Chemistry, University of Missouri, Columbia, MO, USA; University of Missouri Research Reactor Center, Columbia, MO, USA.
| | - Kuo-Hsien Fan
- Department of Chemistry, University of Missouri, Columbia, MO, USA
| | - John R Lever
- Department of Radiology, University of Missouri, Columbia, MO, USA; Research Service, Harry S. Truman Memorial Veterans' Hospital, Columbia, MO, USA.
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Weber F, Brust P, Laurini E, Pricl S, Wünsch B. Fluorinated PET Tracers for Molecular Imaging of σ 1 Receptors in the Central Nervous System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 964:31-48. [PMID: 28315263 DOI: 10.1007/978-3-319-50174-1_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
At first the role of σ1 receptors in various neurological, psychiatric and neurodegenerative disorders is discussed. In the second part, the principle of positron emission tomography (PET ) is described and the known fluorinated PET tracers for labeling of σ1 receptors are presented. The third part focuses on fluoroalkyl substituted spirocyclic PET tracers, which represent the most promising class of fluorinated PET tracers reported so far. The homologous fluoroalkyl derivatives 12-15 show high σ1 affinity (K i = 0.59-1.4 nM) and high selectivity over the σ2 subtype (408-1331-fold). The enantiomers of the fluoroethyl derivative fluspidine 13 were prepared and pharmacologically characterized. Whereas the (S)-configured enantiomer (S)-13 (K i = 2.3 nM) is 4-fold less active than the (R)-enantiomer (R)-13 (K i = 0.57 nM), (S)-13 is metabolically more stable. The interactions of (S)-13 and (R)-13 with the σ1 receptor were analyzed at the molecular level using the 3D homology model. In an automated radiosynthesis [18F](S)-13 and [18F](R)-13 were prepared by nucleophilic substitution of the tosylates (S)-17 and (R)-17 with K[18F]F in high radiochemical yield, high radiochemical purity and short reaction time. Application of both enantiomers [18F](S)-13 and [18F](R)-13 to mice and piglets led to fast uptake into the brain, but [18F](R)-13 did not show washout from the brain indicating a quasi-irreversible binding. Both radiotracers [18F](S)-13 and [18F](R)-13 were able to label regions in the mouse and piglet brain with high σ1 receptor density. The specific binding of the enantiomeric tracers [18F](S)-13 and [18F](R)-13 could be replaced by the selective σ1 ligand SA4503.
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Affiliation(s)
- Frauke Weber
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Permoserstraße 15, D-04318, Leipzig, Germany
| | - Erik Laurini
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste, Via Valerio 6, 34127, Trieste, Italy
| | - Sabrina Pricl
- Molecular Simulations Engineering (MOSE) Laboratory, Department of Engineering and Architecture (DEA), University of Trieste, Via Valerio 6, 34127, Trieste, Italy
- National Interuniversity Consortium for Material Science and Technology (INSTM), Research Unit MOSE-DEA, University of Trieste, Via Valerio 6, 32127, Trieste, Italy
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstraße 48, D-48149, Münster, Germany.
- Cells-in-Motion Cluster of Excellence (EXC 1003 - CiM), University Münster, Münster, Germany.
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LC-MS Supported Studies on the in Vitro Metabolism of both Enantiomers of Flubatine and the in Vivo Metabolism of (+)-[(18)F]Flubatine-A Positron Emission Tomography Radioligand for Imaging α4β2 Nicotinic Acetylcholine Receptors. Molecules 2016; 21:molecules21091200. [PMID: 27617996 PMCID: PMC6273452 DOI: 10.3390/molecules21091200] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 12/27/2022] Open
Abstract
Both enantiomers of [18F]flubatine are promising radioligands for neuroimaging of α4β2 nicotinic acetylcholine receptors (nAChRs) by positron emission tomography (PET). To support clinical studies in patients with early Alzheimer’s disease, a detailed examination of the metabolism in vitro and in vivo has been performed. (+)- and (−)-flubatine, respectively, were incubated with liver microsomes from mouse and human in the presence of NADPH (β-nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt). Phase I in vitro metabolites were detected and their structures elucidated by LC-MS/MS (liquid chromatography-tandem mass spectrometry). Selected metabolite candidates were synthesized and investigated for structural confirmation. Besides a high level of in vitro stability, the microsomal incubations revealed some species differences as well as enantiomer discrimination with regard to the formation of monohydroxylated products, which was identified as the main metabolic pathway in this assay. Furthermore, after injection of 250 MBq (+)-[18F]flubatine (specific activity > 350 GBq/μmol) into mouse, samples were prepared from brain, liver, plasma, and urine after 30 min and investigated by radio-HPLC (high performance liquid chromatography with radioactivity detection). For structure elucidation of the radiometabolites of (+)-[18F]flubatine formed in vivo, identical chromatographic conditions were applied to LC-MS/MS and radio-HPLC to compare samples obtained in vitro and in vivo. By this correlation approach, we assigned three of four main in vivo radiometabolites to products that are exclusively C- or N-hydroxylated at the azabicyclic ring system of the parent molecule.
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Novel Radioligands for Cyclic Nucleotide Phosphodiesterase Imaging with Positron Emission Tomography: An Update on Developments Since 2012. Molecules 2016; 21:molecules21050650. [PMID: 27213312 PMCID: PMC6273803 DOI: 10.3390/molecules21050650] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 05/09/2016] [Accepted: 05/10/2016] [Indexed: 12/19/2022] Open
Abstract
Cyclic nucleotide phosphodiesterases (PDEs) are a class of intracellular enzymes that inactivate the secondary messenger molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Thus, PDEs regulate the signaling cascades mediated by these cyclic nucleotides and affect fundamental intracellular processes. Pharmacological inhibition of PDE activity is a promising strategy for treatment of several diseases. However, the role of the different PDEs in related pathologies is not completely clarified yet. PDE-specific radioligands enable non-invasive visualization and quantification of these enzymes by positron emission tomography (PET) in vivo and provide an important translational tool for elucidation of the relationship between altered expression of PDEs and pathophysiological effects as well as (pre-)clinical evaluation of novel PDE inhibitors developed as therapeutics. Herein we present an overview of novel PDE radioligands for PET published since 2012.
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Abstract
During the past years, non-neuronal vascular nicotinic acetylcholine receptors (nAChRs) increasingly have gained interest in cardiovascular research, as they are known to mediate the deleterious effects of nicotine and nitrosamines, components of tobacco smoke, on the vasculature. Because smoking is a major risk factor for the development of atherosclerosis, it is obvious that understanding the pathophysiologic role of nAChRs in the atherosclerotic disease process, as well as in the development of new diagnostic and therapeutic nAChR-related options, has become more important. Accordingly, we briefly summarize the pathophysiologic role of vascular nAChRs in the atherosclerotic disease process. We also provide an overview of currently available nAChR positron emission tomography (PET) tracers and their performance in the noninvasive imaging of vascular nAChRs, as well as potential nAChR PET tracers that might be an option for vascular nAChR PET imaging in the future.
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Affiliation(s)
- Matthias Bauwens
- Department of Nuclear Medicine, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands
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Wenzel B, Mollitor J, Deuther-Conrad W, Dukic-Stefanovic S, Kranz M, Vraka C, Teodoro R, Günther R, Donat CK, Ludwig FA, Fischer S, Smits R, Wadsak W, Mitterhauser M, Steinbach J, Hoepping A, Brust P. Development of a Novel Nonpeptidic 18F-Labeled Radiotracer for in Vivo Imaging of Oxytocin Receptors with Positron Emission Tomography. J Med Chem 2016; 59:1800-17. [DOI: 10.1021/acs.jmedchem.5b01080] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Jan Mollitor
- ABX Advanced Biochemical Compounds GmbH, 01454 Radeberg, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Sladjana Dukic-Stefanovic
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Chrysoula Vraka
- Radiopharmacy
and Experimental Nuclear Medicine, Division of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna, Austria
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Robert Günther
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Cornelius K. Donat
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | - Rene Smits
- ABX Advanced Biochemical Compounds GmbH, 01454 Radeberg, Germany
| | - Wolfgang Wadsak
- Radiopharmacy
and Experimental Nuclear Medicine, Division of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna, Austria
| | - Markus Mitterhauser
- Radiopharmacy
and Experimental Nuclear Medicine, Division of Nuclear Medicine, Medical University of Vienna, A-1090 Vienna, Austria
| | - Jörg Steinbach
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
| | | | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Department of Neuroradiopharmaceuticals,, Permoserstr. 15, 04318 Leipzig, Germany
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Pike VW. Considerations in the Development of Reversibly Binding PET Radioligands for Brain Imaging. Curr Med Chem 2016; 23:1818-69. [PMID: 27087244 PMCID: PMC5579844 DOI: 10.2174/0929867323666160418114826] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 04/04/2016] [Accepted: 04/15/2016] [Indexed: 12/17/2022]
Abstract
The development of reversibly binding radioligands for imaging brain proteins in vivo, such as enzymes, neurotransmitter transporters, receptors and ion channels, with positron emission tomography (PET) is keenly sought for biomedical studies of neuropsychiatric disorders and for drug discovery and development, but is recognized as being highly challenging at the medicinal chemistry level. This article aims to compile and discuss the main considerations to be taken into account by chemists embarking on programs of radioligand development for PET imaging of brain protein targets.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Rm. B3C346A, 10 Center Drive, Bethesda, MD 20892, USA.
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Development of highly potent phosphodiesterase 10A (PDE10A) inhibitors: Synthesis and in vitro evaluation of 1,8-dipyridinyl- and 1-pyridinyl-substituted imidazo[1,5-a]quinoxalines. Eur J Med Chem 2015; 107:97-108. [PMID: 26562545 DOI: 10.1016/j.ejmech.2015.10.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/13/2015] [Accepted: 10/14/2015] [Indexed: 12/12/2022]
Abstract
Herein we report the synthesis of fluorinated inhibitors of phosphodiesterase 10A (PDE10A) which can be used potentially as lead structure for the development of a (18)F-labeled PDE10A imaging agent for positron emission tomography. The use of ortho-fluoropyridines as residues could potentially enable the introduction of (18)F through nucleophilic substitution for radiolabeling purposes. 2-Fluoropyridines are introduced by a Suzuki coupling at different positions of the molecule. The reference compounds, 1,8-dipyridinylimidazo[1,5-a]quinoxalines and 1-pyridinylimidazo[1,5-a]quinoxalines, show inhibitory potencies at best in the subnanomolar range and selectivity factors greater than 38 against other PDE's. 1,8-Dipyridinylimidazo[1,5-a]quinoxalines are more potent inhibitors than 1-pyridinylimidazo[1,5-a]quinoxalines. Using 2-fluoro-3-pyridinyl as residue provided the most potent inhibitors 16 (IC50 = 0.12 nM), 17 (IC50 = 0.048 nM) and 32 (IC50 = 0.037 nM).
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Wodtke R, Ruiz-Gómez G, Kuchar M, Pisabarro MT, Novotná P, Urbanová M, Steinbach J, Pietzsch J, Löser R. Cyclopeptides containing the DEKS motif as conformationally restricted collagen telopeptide analogues: synthesis and conformational analysis. Org Biomol Chem 2015; 13:1878-96. [PMID: 25503999 DOI: 10.1039/c4ob02348j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The collagen telopeptides play an important role for lysyl oxidase-mediated crosslinking, a process which is deregulated during tumour progression. The DEKS motif which is located within the N-terminal telopeptide of the α1 chain of type I collagen has been suggested to adopt a βI-turn conformation upon docking to its triple-helical receptor domain, which seems to be critical for lysyl oxidase-catalysed deamination and subsequent crosslinking by Schiff-base formation. Herein, the design and synthesis of cyclic peptides which constrain the DEKS sequence in a β-turn conformation will be described. Lysine-side chain attachment to 2-chlorotrityl chloride-modified polystyrene resin followed by microwave-assisted solid-phase peptide synthesis and on-resin cyclisation allowed for an efficient access to head-to-tail cyclised DEKS-derived cyclic penta- and hexapeptides. An N(ε)-(4-fluorobenzoyl)lysine residue was included in the cyclopeptides to allow their potential radiolabelling with fluorine-18 for PET imaging of lysyl oxidase. Conformational analysis by (1)H NMR and chiroptical (electronic and vibrational CD) spectroscopy together with MD simulations demonstrated that the concomitant incorporation of a D-proline and an additional lysine for potential radiolabel attachment accounts for a reliable induction of the desired βI-turn structure in the DEKS motif in both DMSO and water as solvents. The stabilised conformation of the cyclohexapeptide is further reflected by its resistance to trypsin-mediated degradation. In addition, the deaminated analogue containing allysine in place of lysine has been synthesised via the corresponding ε-hydroxynorleucine containing cyclohexapeptide. Both ε-hydroxynorleucine and allysine containing cyclic hexapeptides have been subjected to conformational analysis in the same manner as the lysine-based parent structure. Thus, both a conformationally restricted lysyl oxidase substrate and product have been synthetically accessed, which will enable their potential use for molecular imaging of these important enzymes.
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Affiliation(s)
- Robert Wodtke
- Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany.
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Barthel C, Sorger D, Deuther-Conrad W, Scheunemann M, Schweiger S, Jäckel P, Roghani A, Steinbach J, Schüürmann G, Sabri O, Brust P, Wenzel B. New systematically modified vesamicol analogs and their affinity and selectivity for the vesicular acetylcholine transporter – A critical examination of the lead structure. Eur J Med Chem 2015; 100:50-67. [DOI: 10.1016/j.ejmech.2015.05.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 12/14/2022]
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Löser R, Pietzsch J. Cysteine cathepsins: their role in tumor progression and recent trends in the development of imaging probes. Front Chem 2015; 3:37. [PMID: 26157794 PMCID: PMC4477214 DOI: 10.3389/fchem.2015.00037] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 05/29/2015] [Indexed: 12/16/2022] Open
Abstract
Papain-like cysteine proteases bear an enormous potential as drug discovery targets for both infectious and systemic human diseases. The considerable progress in this field over the last two decades has also raised interest in the visualization of these enzymes in their native context, especially with regard to tumor imaging. After a short introduction to structure and general functions of human cysteine cathepsins, we highlight their importance for drug discovery and development and provide a critical update on the current state of knowledge toward their involvement in tumor progression, with a special emphasis on their role in therapy response. In accordance with a radiopharmaceutical point of view, the main focus of this review article will be the discussion of recently developed fluorescence and radiotracer-based imaging agents together with related molecular probes.
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Affiliation(s)
- Reik Löser
- Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf Dresden, Germany ; Department of Chemistry and Food Chemistry, Technische Universität Dresden Dresden, Germany
| | - Jens Pietzsch
- Department of Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf Dresden, Germany ; Department of Chemistry and Food Chemistry, Technische Universität Dresden Dresden, Germany
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Schröder S, Wenzel B, Deuther-Conrad W, Teodoro R, Egerland U, Kranz M, Scheunemann M, Höfgen N, Steinbach J, Brust P. Synthesis, 18F-Radiolabelling and Biological Characterization of Novel Fluoroalkylated Triazine Derivatives for in Vivo Imaging of Phosphodiesterase 2A in Brain via Positron Emission Tomography. Molecules 2015; 20:9591-615. [PMID: 26016549 PMCID: PMC6272448 DOI: 10.3390/molecules20069591] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/04/2015] [Accepted: 05/18/2015] [Indexed: 12/31/2022] Open
Abstract
Phosphodiesterase 2A (PDE2A) is highly and specifically expressed in particular brain regions that are affected by neurological disorders and in certain tumors. Development of a specific PDE2A radioligand would enable molecular imaging of the PDE2A protein via positron emission tomography (PET). Herein we report on the syntheses of three novel fluoroalkylated triazine derivatives (TA2–4) and on the evaluation of their effect on the enzymatic activity of human PDE2A. The most potent PDE2A inhibitors were 18F-radiolabelled ([18F]TA3 and [18F]TA4) and investigated regarding their potential as PET radioligands for imaging of PDE2A in mouse brain. In vitro autoradiography on rat brain displayed region-specific distribution of [18F]TA3 and [18F]TA4, which is consistent with the expression pattern of PDE2A protein. Metabolism studies of both [18F]TA3 and [18F]TA4 in mice showed a significant accumulation of two major radiometabolites of each radioligand in brain as investigated by micellar radio-chromatography. Small-animal PET/MR studies in mice using [18F]TA3 revealed a constantly increasing uptake of activity in the non-target region cerebellum, which may be caused by the accumulation of brain penetrating radiometabolites. Hence, [18F]TA3 and [18F]TA4 are exclusively suitable for in vitro investigation of PDE2A. Nevertheless, further structural modification of these promising radioligands might result in metabolically stable derivatives.
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Affiliation(s)
- Susann Schröder
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Barbara Wenzel
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Rodrigo Teodoro
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Ute Egerland
- BioCrea GmbH, Meissner Str. 191, Radebeul 01445, Germany.
| | - Mathias Kranz
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Matthias Scheunemann
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Norbert Höfgen
- BioCrea GmbH, Meissner Str. 191, Radebeul 01445, Germany.
| | - Jörg Steinbach
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Permoserstraße 15, Leipzig 04318, Germany.
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Recent advances in parametric neuroreceptor mapping with dynamic PET: basic concepts and graphical analyses. Neurosci Bull 2014; 30:733-54. [PMID: 25260795 DOI: 10.1007/s12264-014-1465-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 08/15/2014] [Indexed: 10/24/2022] Open
Abstract
Tracer kinetic modeling in dynamic positron emission tomography (PET) has been widely used to investigate the characteristic distribution patterns or dysfunctions of neuroreceptors in brain diseases. Its practical goal has progressed from regional data quantification to parametric mapping that produces images of kinetic-model parameters by fully exploiting the spatiotemporal information in dynamic PET data. Graphical analysis (GA) is a major parametric mapping technique that is independent on any compartmental model configuration, robust to noise, and computationally efficient. In this paper, we provide an overview of recent advances in the parametric mapping of neuroreceptor binding based on GA methods. The associated basic concepts in tracer kinetic modeling are presented, including commonly-used compartment models and major parameters of interest. Technical details of GA approaches for reversible and irreversible radioligands are described, considering both plasma input and reference tissue input models. Their statistical properties are discussed in view of parametric imaging.
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Neuro-molecular imaging. Neurosci Bull 2014; 30:711-2. [PMID: 25260794 DOI: 10.1007/s12264-014-1474-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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