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Laube M, Gassner C, Neuber C, Wodtke R, Ullrich M, Haase-Kohn C, Löser R, Köckerling M, Kopka K, Kniess T, Hey-Hawkins E, Pietzsch J. Deuteration versus ethylation - strategies to improve the metabolic fate of an 18F-labeled celecoxib derivative. RSC Adv 2020; 10:38601-38611. [PMID: 35517533 PMCID: PMC9057277 DOI: 10.1039/d0ra04494f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/11/2020] [Indexed: 12/14/2022] Open
Abstract
The inducible isoenzyme cyclooxygenase-2 (COX-2) is closely associated with chemo-/radioresistance and poor prognosis of solid tumors. Therefore, COX-2 represents an attractive target for functional characterization of tumors by positron emission tomography (PET). In this study, the celecoxib derivative 3-([18F]fluoromethyl)-1-[4-(methylsulfonyl)phenyl]-5-(p-tolyl)-1H-pyrazole ([18F]5a) was chosen as a lead compound having a reported high COX-2 inhibitory potency and a potentially low carbonic anhydrase binding tendency. The respective deuterated analog [D2,18F]5a and the fluoroethyl-substituted derivative [18F]5b were selected to study the influence of these modifications with respect to COX inhibition potency in vitro and metabolic stability of the radiolabeled tracers in vivo. COX-2 inhibitory potency was found to be influenced by elongation of the side chain but, as expected, not by deuteration. An automated radiosynthesis comprising 18F-fluorination and purification under comparable conditions provided the radiotracers [18F]5a,b and [D2,18F]5a in good radiochemical yields (RCY) and high radiochemical purity (RCP). Biodistribution and PET studies comparing all three compounds revealed bone accumulation of 18F-activity to be lowest for the ethyl derivative [18F]5b. However, the deuterated analog [D2,18F]5a turned out to be the most stable compound of the three derivatives studied here. Time-dependent degradation of [18F]5a,b and [D2,18F]5a after incubation in murine liver microsomes was in accordance with the data on metabolism in vivo. Furthermore, metabolites were identified based on UPLC-MS/MS. The aim of this study is to investigate the influence of deuteration and elongation on an 18F-labeled COX-2 inhibitor with focus on metabolic stability to develop suitable COX-2 targeting radiotracers.![]()
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Affiliation(s)
- Markus Laube
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Cemena Gassner
- 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 D-01062 Dresden Germany
| | - Christin Neuber
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Robert Wodtke
- 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
| | - Cathleen Haase-Kohn
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Reik Löser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Martin Köckerling
- University of Rostock, Institute of Chemistry, Department of Inorganic Solid State Chemistry Albert-Einstein-Str. 3a D-18059 Rostock Germany
| | - Klaus Kopka
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Torsten Kniess
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research Bautzner Landstrasse 400 01328 Dresden Germany
| | - Evamarie Hey-Hawkins
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry Johannisallee 29 D-04103 Leipzig Germany
| | - Jens Pietzsch
- 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 D-01062 Dresden Germany
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Sthalam VK, Singh AK, Pabbaraja S. An Integrated Continuous Flow Micro-Total Ultrafast Process System (μ-TUFPS) for the Synthesis of Celecoxib and Other Cyclooxygenase Inhibitors. Org Process Res Dev 2019. [DOI: 10.1021/acs.oprd.9b00212] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Vinay Kumar Sthalam
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC) Campus, Ghaziabad 201002, Uttar Pradesh, India
| | - Ajay K. Singh
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - Srihari Pabbaraja
- Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-Human Resource Development Centre (CSIR-HRDC) Campus, Ghaziabad 201002, Uttar Pradesh, India
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Jia L, Miao C, Dong F, Li W, Wang M, Zheng QH, Xu Z. Facile synthesis of carbon-11-labeled sEH/PDE4 dual inhibitors as new potential PET agents for imaging of sEH/PDE4 enzymes in neuroinflammation. Bioorg Med Chem Lett 2019; 29:1654-1659. [PMID: 31047754 DOI: 10.1016/j.bmcl.2019.04.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/15/2019] [Accepted: 04/24/2019] [Indexed: 02/05/2023]
Abstract
To develop PET tracers for imaging of neuroinflammation, new carbon-11-labeled sEH/PDE4 dual inhibitors have been synthesized. The reference standard N-(4-methoxy-2-(trifluoromethyl)benzyl)benzamide (1) and its corresponding desmethylated precursor N-(4-hydroxy-2-(trifluoromethyl)benzyl)benzamide (2) were synthesized from (4-methoxy-2-(trifluoromethyl)phenyl)methanamine and benzoic acid in one and two steps with 84% and 49% overall chemical yield, respectively. The standard N-(4-methoxy-2-(trifluoromethyl)benzyl)-1-propionylpiperidine-4-carboxamide (MPPA, 4) and its precursor N-(4-hydroxy-2-(trifluoromethyl)benzyl)-1-propionylpiperidine-4-carboxamide (5) were synthesized from methyl 4-piperidinecarboxylate, propionyl chloride and (4-methoxy-2-(trifluoromethyl)phenyl)methanamine in two and three steps with 62% and 34% overall chemical yield, respectively. The target tracers N-(4-[11C]methoxy-2-(trifluoromethyl)benzyl)benzamide ([11C]1) and N-(4-[11C]methoxy-2-(trifluoromethyl)benzyl)-1-propionylpiperidine-4-carboxamide ([11C]MPPA, [11C]4) were prepared from their corresponding precursors 2 and 5 with [11C]CH3OTf through O-[11C]methylation and isolated by HPLC combined with SPE in 25-35% radiochemical yield, based on [11C]CO2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the molar activity (AM) at EOB was 370-740 GBq/μmol with a total synthesis time of 35-40-minutes from EOB.
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Affiliation(s)
- Limeng Jia
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China
| | - Caihong Miao
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China
| | - Fugui Dong
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China
| | - Wei Li
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China
| | - Min Wang
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 1345 West 16(th) Street, Room 202, Indianapolis, IN 46202, USA
| | - Qi-Huang Zheng
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 1345 West 16(th) Street, Room 202, Indianapolis, IN 46202, USA.
| | - Zhidong Xu
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of Ministry of Education, College of Chemistry and Environmental Science, Hebei University, Baoding, Hebei 071002, China; College of Chemical & Pharmaceutical Engineering, Key Laboratory of Molecular Chemistry for Medicine of Hebei Province, Hebei University of Science & Technology, Shijiazhuang, Hebei 050018, China; Shijiazhuang Vince Pharmatech Co., Ltd., Shijiazhuang, Hebei 050030, China.
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Abdelgawad MA, Labib MB, Ali WA, Kamel G, Azouz AA, EL-Nahass ELS. Design, synthesis, analgesic, anti-inflammatory activity of novel pyrazolones possessing aminosulfonyl pharmacophore as inhibitors of COX-2/5-LOX enzymes: Histopathological and docking studies. Bioorg Chem 2018; 78:103-114. [DOI: 10.1016/j.bioorg.2018.03.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/27/2018] [Accepted: 03/07/2018] [Indexed: 11/17/2022]
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Stevenson RJ, Azimi I, Flanagan JU, Inserra M, Vetter I, Monteith GR, Denny WA. An SAR study of hydroxy-trifluoromethylpyrazolines as inhibitors of Orai1-mediated store operated Ca 2+ entry in MDA-MB-231 breast cancer cells using a convenient Fluorescence Imaging Plate Reader assay. Bioorg Med Chem 2018; 26:3406-3413. [PMID: 29776832 DOI: 10.1016/j.bmc.2018.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/01/2018] [Accepted: 05/08/2018] [Indexed: 12/30/2022]
Abstract
The proteins Orai1 and STIM1 control store-operated Ca2+ entry (SOCE) into cells. SOCE is important for migration, invasion and metastasis of MDA-MB-231 human triple negative breast cancer (TNBC) cells and has been proposed as a target for cancer drug discovery. Two hit compounds from a medium throughput screen, displayed encouraging inhibition of SOCE in MDA-MB-231 cells, as measured by a Fluorescence Imaging Plate Reader (FLIPR) Ca2+ assay. Following NMR spectroscopic analysis of these hits and reassignment of their structures as 5-hydroxy-5-trifluoromethylpyrazolines, a series of analogues was prepared via thermal condensation reactions between substituted acylhydrazones and trifluoromethyl 1,3-dicarbonyl arenes. Structure-activity relationship (SAR) studies showed that small lipophilic substituents at the 2- and 3-positions of the RHS and 2-, 3- and 4-postions of the LHS terminal benzene rings improved activity, resulting in a novel class of potent and selective inhibitors of SOCE.
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Affiliation(s)
- Ralph J Stevenson
- Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
| | - Iman Azimi
- The School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia; Mater Research Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia; Division of Pharmacy, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Jack U Flanagan
- Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | - Marco Inserra
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland 4072, Australia; School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Irina Vetter
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland 4072, Australia; School of Pharmacy, The University of Queensland, Woolloongabba, Queensland 4102, Australia
| | - Gregory R Monteith
- The School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia; Mater Research Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - William A Denny
- Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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Synthesis of N -(3-(4-[ 11 C]methylpiperazin-1-yl)−1-(5-methylpyridin-2-yl)−1 H -pyrazol-5-yl)pyrazolo[1,5- a ]pyrimidine-3-carboxamide as a new potential PET agent for imaging of IRAK4 enzyme in neuroinflammation. Appl Radiat Isot 2018; 132:6-12. [DOI: 10.1016/j.apradiso.2017.11.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/17/2017] [Accepted: 11/05/2017] [Indexed: 12/19/2022]
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Microwave-Assisted Synthesis of some Novel Azoles and Azolopyrimidines as Antimicrobial Agents. Molecules 2017; 22:molecules22030346. [PMID: 28241500 PMCID: PMC6155381 DOI: 10.3390/molecules22030346] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 02/19/2017] [Accepted: 02/21/2017] [Indexed: 11/27/2022] Open
Abstract
In this study, new derivatives of pyrazole, isoxazole, pyrazolylthiazole, and azolopyrimidine having a thiophene ring were synthesized under microwave irradiation. Their pharmacological activity toward bacteria and fungi inhibition was screened and compared to the references Chloramphenicol and Trimethoprim/sulphamethoxazole. The antimicrobial results of the investigated compounds revealed promising results and some derivatives have activities similar to the references used.
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Simple synthesis of new carbon-11-labeled 1,2,4-triazolo[4,3-a]quinoxalin-1-one derivatives for PET imaging of A₃ adenosine receptor. Appl Radiat Isot 2014; 91:71-8. [PMID: 24908190 DOI: 10.1016/j.apradiso.2014.05.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Revised: 04/29/2014] [Accepted: 05/12/2014] [Indexed: 12/31/2022]
Abstract
The reference standards 4a-b, 6a-b, 7a-c, and desmethylated precursors 9a-b, 10a-b, 8a-c were synthesized from 4-methoxyaniline, ethyl 2-chloro-acetoacetate and substituted benzene-1,2-diamines with 3, 5, 6 steps in 61-67%, 34-41%, 23-31%, and with 4, 6, 7 steps in 49-57%, 28-35%, 20-27% overall chemical yield, respectively. The target tracers [(11)C]4a-b, [(11)C]6a-b, [(11)C]7a-c were synthesized from their corresponding precursors with [(11)C]CH3OTf through O-[(11)C]methylation and isolated by simplified SPE in 40-60% decay corrected radiochemical yields at EOB, with 185-370 GBq/μmol specific activity at EOS.
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Pacelli A, Greenman J, Cawthorne C, Smith G. Imaging COX-2 expression in cancer using PET/SPECT radioligands: current status and future directions. J Labelled Comp Radiopharm 2014; 57:317-22. [PMID: 24470172 DOI: 10.1002/jlcr.3160] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/29/2013] [Indexed: 12/21/2022]
Abstract
The role of cyclooxygenase (COX)-2 as a driving force in early tumourigenesis and the current interest in the combination of COX-2 inhibitors with standard therapy in clinical trials creates an urgent need to establish clinically relevant diagnostic tests for COX-2 expression. Molecular imaging using small-molecule probes radiolabelled for both positron emission tomography (PET) and single photon emission computed tomography (SPECT) offers the potential to meet this need, providing a minimally invasive readout for the whole disease burden. This review summarises current approaches to the radiolabelling of small-molecule COX-2 inhibitors and their analogues for PET and SPECT imaging, and gives an overview of their biological evaluation and likely success of clinical application.
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Affiliation(s)
- A Pacelli
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull, HU6 7RX, UK
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Wu C, Li F, Niu G, Chen X. PET imaging of inflammation biomarkers. Theranostics 2013; 3:448-66. [PMID: 23843893 PMCID: PMC3706689 DOI: 10.7150/thno.6592] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 05/24/2013] [Indexed: 01/04/2023] Open
Abstract
Inflammation plays a significant role in many disease processes. Development in molecular imaging in recent years provides new insight into the diagnosis and treatment evaluation of various inflammatory diseases and diseases involving inflammatory process. Positron emission tomography using (18)F-FDG has been successfully applied in clinical oncology and neurology and in the inflammation realm. In addition to glucose metabolism, a variety of targets for inflammation imaging are being discovered and utilized, some of which are considered superior to FDG for imaging inflammation. This review summarizes the potential inflammation imaging targets and corresponding PET tracers, and the applications of PET in major inflammatory diseases and tumor associated inflammation. Also, the current attempt in differentiating inflammation from tumor using PET is also discussed.
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Laube M, Kniess T, Pietzsch J. Radiolabeled COX-2 inhibitors for non-invasive visualization of COX-2 expression and activity--a critical update. Molecules 2013; 18:6311-55. [PMID: 23760031 PMCID: PMC6269837 DOI: 10.3390/molecules18066311] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 05/16/2013] [Accepted: 05/24/2013] [Indexed: 01/21/2023] Open
Abstract
Cyclooxygenase-2 (COX-2) is a key player in inflammation. Its overexpression is directly associated with various inflammatory diseases and, additionally, with several processes of carcinogenesis. The development of new selective COX-2 inhibitors (COXIBs) for use in cancer treatment is in the focus of the medicinal chemistry research field. For this purpose, a set of methods is available to determine COX-2 expression and activity in vitro and ex vivo but it is still a problem to functionally characterize COX-2 in vivo. This review focusses on imaging agents targeting COX-2 which have been developed for positron emission tomography (PET) and single photon emission computed tomography (SPECT) since 2005. The literature reveals that different radiochemical methods are available to synthesize COXIBs radiolabeled with fluorine-18, carbon-11, and isotopes of radioiodine. Unfortunately, most of the compounds tested did not show sufficient stability in vivo due to de[18F]fluorination or de[11C]methylation or they failed to bind specifically in the target region. So, suitable stability in vivo, matching lipophilicity for the target compartment and both high affinity and selectivity for COX-2 were identified as prominent criteria for radiotracer development. Up to now, it is not clear what approach and which model is the most suited to evaluate COX-2 targeting imaging agents in vivo. However, for proof of principle it has been shown that some radiolabeled compounds can bind specifically in COX-2 overexpressing tissue which gives hope for future work in this field.
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Affiliation(s)
- Markus Laube
- Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany; E-Mails: (T.K.); (J.P.)
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +49-351-260-2810; Fax: +49-351-260-2915
| | - Torsten Kniess
- Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany; E-Mails: (T.K.); (J.P.)
| | - Jens Pietzsch
- Department Radiopharmaceutical and Chemical Biology, Institute of Radiopharmaceutical Cancer Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany; E-Mails: (T.K.); (J.P.)
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany
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Gao M, Yang Q, Wang M, Miller KD, Sledge GW, Zheng QH. Synthesis of radiolabeled protein disulfide isomerase (PDI) inhibitors as new potential PET agents for imaging of the enzyme PDI in neurological disorders and cancer. Appl Radiat Isot 2013; 74:61-9. [DOI: 10.1016/j.apradiso.2013.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2012] [Revised: 11/29/2012] [Accepted: 01/01/2013] [Indexed: 12/28/2022]
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Gao M, Wang M, Miller KD, Zheng QH. Simple synthesis of carbon-11-labeled chromen-4-one derivatives as new potential PET agents for imaging of DNA-dependent protein kinase (DNA-PK) in cancer. Appl Radiat Isot 2012; 70:1558-63. [DOI: 10.1016/j.apradiso.2012.04.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 04/04/2012] [Accepted: 04/19/2012] [Indexed: 12/22/2022]
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