1
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Chisholm TS, Hunter CA. A closer look at amyloid ligands, and what they tell us about protein aggregates. Chem Soc Rev 2024; 53:1354-1374. [PMID: 38116736 DOI: 10.1039/d3cs00518f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
The accumulation of amyloid fibrils is characteristic of neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease. Detecting these fibrils with fluorescent or radiolabelled ligands is one strategy for diagnosing and better understanding these diseases. A vast number of amyloid-binding ligands have been reported in the literature as a result. To obtain a better understanding of how amyloid ligands bind, we have compiled a database of 3457 experimental dissociation constants for 2076 unique amyloid-binding ligands. These ligands target Aβ, tau, or αSyn fibrils, as well as relevant biological samples including AD brain homogenates. From this database significant variation in the reported dissociation constants of ligands was found, possibly due to differences in the morphology of the fibrils being studied. Ligands were also found to bind to Aβ(1-40) and Aβ(1-42) fibrils with similar affinities, whereas a greater difference was found for binding to Aβ and tau or αSyn fibrils. Next, the binding of ligands to fibrils was shown to be largely limited by the hydrophobic effect. Some Aβ ligands do not fit into this hydrophobicity-limited model, suggesting that polar interactions can play an important role when binding to this target. Finally several binding site models were outlined for amyloid fibrils that describe what ligands target what binding sites. These models provide a foundation for interpreting and designing site-specific binding assays.
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Affiliation(s)
- Timothy S Chisholm
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1 EW, UK.
| | - Christopher A Hunter
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1 EW, UK.
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2
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Kim MH, Jung WJ, Jeong HJ, Lee K, Kil HS, Chung WS, Nam KR, Lee YJ, Lee KC, Lim SM, Chi DY. Off‐target screening of amyloid‐beta plaque targeting [
18
F
]florapronol ([
18
F
]
FC119S
) in postmortem Alzheimer's disease tissues. B KOREAN CHEM SOC 2022. [DOI: 10.1002/bkcs.12532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Min Hwan Kim
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
| | - Woon Jung Jung
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
| | - Hyeon Jin Jeong
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
| | - Kyongkyu Lee
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
| | - Hee Seup Kil
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
| | - Wee Sup Chung
- Division of Applied RI Korea Institute of Radiological & Medical Sciences Nowon‐gu, Seoul Republic of Korea
| | - Kyung Rok Nam
- Division of Applied RI Korea Institute of Radiological & Medical Sciences Nowon‐gu, Seoul Republic of Korea
| | - Yong Jin Lee
- Division of Applied RI Korea Institute of Radiological & Medical Sciences Nowon‐gu, Seoul Republic of Korea
| | - Kyo Chul Lee
- Division of Applied RI Korea Institute of Radiological & Medical Sciences Nowon‐gu, Seoul Republic of Korea
| | - Sang Moo Lim
- Department of Nuclear Medicine Korea Institute of Radiological & Medical Sciences Nowon‐gu, Seoul Republic of Korea
| | - Dae Yoon Chi
- Research Institute of Radiopharmaceuticals FutureChem Co., Ltd. Seongdong‐gu, Seoul Republic of Korea
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3
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Ferris T, Carroll L, Jenner S, Aboagye EO. Use of radioiodine in nuclear medicine-A brief overview. J Labelled Comp Radiopharm 2021; 64:92-108. [PMID: 33091159 DOI: 10.1002/jlcr.3891] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/06/2020] [Accepted: 10/11/2020] [Indexed: 12/15/2022]
Abstract
Radioiodines have a long history in nuclear medicine. Herein, we discuss the production, properties and applications of these versatile iodine-based imaging and theragnostic agents. There are 38 isotopes of iodine (I) including one stable form (127 I). The most common radionuclides used in medical imaging and treatment, including Iodine-123 (123 I), Iodine-124 (124 I), Iodine-125 (125 I) and Iodine-131 (131 I), are discussed in this review.
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Affiliation(s)
- Trevor Ferris
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London White City Campus, London, UK
| | - Laurence Carroll
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
| | | | - Eric O Aboagye
- Comprehensive Cancer Imaging Centre, Department of Surgery and Cancer, Imperial College, Hammersmith Campus, London, UK
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4
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Jia J, Zhang L, Song J, Dai J, Cui M. Discovery of Diphenoxy Derivatives with Flexible Linkers as Ligands for β-Amyloid Plaques. Mol Pharm 2020; 17:4089-4100. [PMID: 32845647 DOI: 10.1021/acs.molpharmaceut.0c00537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The highly rigid and planar scaffolds with π-conjugated systems have been widely considered to be indispensable for β-amyloid (Aβ) binding ligands. In this study, a library of diphenoxy compounds with different types of more flexible linkers as Aβ ligands were synthesized and evaluated. Most of them displayed good affinity (Ki < 100 nM) for Aβ1-42 aggregates, and some ligands even showed values of Ki less than 10 nM. Structure-activity relationship analysis revealed that modification on the linkers or substituents tolerated great flexibility, which challenged the long-held belief that rigid and planar structures are exclusively favored for Aβ binding. Three ligands were labeled by iodine-125, and they exhibited good properties in vitro and in vivo, which further supported that this flexible scaffold was potential and promising for the development of Aβ imaging agents.
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Affiliation(s)
- Jianhua Jia
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.,Department of Radiological Medicine and Oncology, College of Basic Medicine, Chongqing Medical University, Chongqing 400016, P. R. China
| | - Longfei Zhang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jia Song
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jiapei Dai
- Wuhan Institute for Neuroscience and Neuroengineering, South-Central University for Nationalities, Wuhan 430074, P. R. China
| | - Mengchao Cui
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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5
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Okumura Y, Maya Y, Onishi T, Shoyama Y, Izawa A, Nakamura D, Tanifuji S, Tanaka A, Arano Y, Matsumoto H. Design, Synthesis, and Preliminary Evaluation of SPECT Probes for Imaging β-Amyloid in Alzheimer's Disease Affected Brain. ACS Chem Neurosci 2018; 9:1503-1514. [PMID: 29580057 DOI: 10.1021/acschemneuro.8b00064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In this study, we synthesized of a series of 2-phenyl- and 2-pyridyl-imidazo[1,2- a]pyridine derivatives and examine their suitability as novel probes for single-photon emission computed tomography (SPECT)-based imaging of β-amyloid (Aβ). Among the 11 evaluated compounds, 10 showed moderate affinity to Aβ(1-42) aggregates, exhibiting half-maximal inhibitory concentrations (IC50) of 14.7 ± 6.07-87.6 ± 39.8 nM. In vitro autoradiography indicated that 123I-labeled triazole-substituted derivatives displayed highly selective binding to Aβ plaques in the hippocampal region of Alzheimer's disease (AD)-affected brain. Moreover, biodistribution studies performed on normal rats demonstrated that all 123I-labeled probes featured high initial uptake into the brain followed by a rapid washout and were thus well suited for imaging Aβ plaques, with the highest selectivity observed for a 1 H-1,2,3-triazole-substituted 2-pyridyl-imidazopyridine derivative, [123I]ABC577. This compound showed good kinetics in rat brain as well as moderate in vivo stability in rats and is thus a promising SPECT imaging probe for AD in clinical settings.
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Affiliation(s)
- Yuki Okumura
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
- Department of Molecular Imaging and Radiotherapy, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Yoshifumi Maya
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Takako Onishi
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Yoshinari Shoyama
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Akihiro Izawa
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Daisaku Nakamura
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Shigeyuki Tanifuji
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Akihiro Tanaka
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
| | - Yasushi Arano
- Department of Molecular Imaging and Radiotherapy, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Hiroki Matsumoto
- Research Centre, Nihon Medi-Physics Co., Ltd., 3-1, Kitasode, Sodegaura City, Chiba 299-0266, Japan
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6
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Sloan NL, Luthra SK, McRobbie G, Pimlott SL, Sutherland A. A one-pot radioiodination of aryl amines via stable diazonium salts: preparation of 125I-imaging agents. Chem Commun (Camb) 2018; 53:11008-11011. [PMID: 28849815 DOI: 10.1039/c7cc06211g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An operationally simple, one-pot, two-step tandem procedure that allows the incorporation of radioactive iodine into aryl amines via stable diazonium salts is described. The mild conditions are tolerant of various functional groups and substitution patterns, allowing late-stage, rapid access to a wide range of 125I-labelled aryl compounds and SPECT radiotracers.
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Affiliation(s)
- Nikki L Sloan
- WestCHEM, School of Chemistry, The Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, UK.
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7
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Sloan N, Luthra SK, McRobbie G, Pimlott SL, Sutherland A. Late stage iodination of biologically active agents using a one-pot process from aryl amines. RSC Adv 2017. [DOI: 10.1039/c7ra11860k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A tandem process has been developed for the general preparation of aryl iodide compounds from anilines that is also applicable for the late-stage iodination of biologically active agents.
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Affiliation(s)
- Nikki L. Sloan
- WestCHEM
- School of Chemistry
- The Joseph Black Building
- University of Glasgow
- Glasgow G12 8QQ
| | | | | | - Sally L. Pimlott
- West of Scotland PET Centre
- Greater Glasgow and Clyde NHS Trust
- Glasgow G12 0YN
- UK
| | - Andrew Sutherland
- WestCHEM
- School of Chemistry
- The Joseph Black Building
- University of Glasgow
- Glasgow G12 8QQ
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8
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Jia J, Song J, Dai J, Liu B, Cui M. Optically Pure Diphenoxy Derivatives as More Flexible Probes for β-Amyloid Plaques. ACS Chem Neurosci 2016; 7:1275-82. [PMID: 27337293 DOI: 10.1021/acschemneuro.6b00155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The highly rigid and planar scaffold with π-conjugated systems has been widely considered to be indispensable for Aβ binding probes. However, the flexible benzyloxybenzene derivative [(125)I]BOB-4 represents an excellent lead candidate for targeting Aβ in AD brains. Based on that, we designed two pairs of more flexible and optically pure diphenoxy derivatives with a chiral center as novel Aβ probes. These compounds possessed high affinity (Ki = 15.8-45.0 nM) for Aβ1-42 aggregates, and (R)-enantiomers showed slightly better binding ability than (S)-enantiomers. In addition, the competition binding assay implied that the optically pure diphenoxy derivatives with more flexible geometry shared the same binding site as IMPY, a classical rigid and planar Aβ probe. For (125)I-radiolabeled enantiomers, (S)-[(125)I]5 and (R)-[(125)I]5, specific plaque labeling on brain sections of Tg mice and AD patients were observed in in vitro autoradiography, persuasively proving the excellent affinity of the probes. In biodistribution, (S)-[(125)I]5 and (R)-[(125)I]5 with relatively low lipophilicity exhibited moderate initial brain uptake (4.37% and 3.72% ID/g at 2 min, respectively) and extremely fast washout from normal mice brain (brain2min/brain60min = 19.0 and 17.7, respectively). In summary, the separate enantiomers displayed similar properties in vitro and in vivo, and (S/R)-[(123)I]5 may be potential SPECT probes for recognizing Aβ plaques in AD brains.
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Affiliation(s)
- Jianhua Jia
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jia Song
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Jiapei Dai
- Wuhan
Institute for Neuroscience and Neuroengineering, South-Central University for Nationalities, Wuhan 430074, P. R. China
| | - Boli Liu
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Mengchao Cui
- Key
Laboratory of Radiopharmaceuticals, Ministry of Education, College
of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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9
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Amyloid imaging: Past, present and future perspectives. Ageing Res Rev 2016; 30:95-106. [PMID: 26827784 DOI: 10.1016/j.arr.2016.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/21/2016] [Accepted: 01/22/2016] [Indexed: 11/23/2022]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, and tau neurofibrillary tangles, along dendritic and synaptic loss and reactive gliosis. Functional and molecular neuroimaging techniques such as positron emission tomography (PET) using functional and molecular tracers, in conjuction with other Aβ and tau biomarkers in CSF, are proving valuable in the differential diagnosis of AD, as well as in establishing disease prognosis. With the advent of new therapeutic strategies, there has been an increasing application of these techniques for the determination of Aβ burden in vivo in the patient selection, evaluation of target engagement and assessment of the efficacy of therapeutic approaches aimed at reducing Aβ in the brain.
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10
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Jollymore-Hughes CT, Pottie IR, Martin E, Rosenberry TL, Darvesh S. Development of acetophenone ligands as potential neuroimaging agents for cholinesterases. Bioorg Med Chem 2016; 24:5270-5279. [PMID: 27637382 DOI: 10.1016/j.bmc.2016.08.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/22/2016] [Accepted: 08/26/2016] [Indexed: 10/21/2022]
Abstract
Association of cholinesterase with β-amyloid plaques and tau neurofibrillary tangles in Alzheimer's disease offers an opportunity to detect disease pathology during life. Achieving this requires development of radiolabelled cholinesterase ligands with high enzyme affinity. Various fluorinated acetophenone derivatives bind to acetylcholinesterase with high affinity, including 2,2,2-trifluoro-1-(3-dimethylaminophenyl)ethanone (1) and 1-(3-tert-butylphenyl)-2,2,2-trifluoroethanone (2). Such compounds also offer potential for incorporation of radioactive fluorine (18F) for Positron Emission Tomography (PET) imaging of cholinesterases in association with Alzheimer's disease pathology in the living brain. Here we describe the synthesis of two meta-substituted chlorodifluoroacetophenones using a Weinreb amide strategy and their rapid conversion to the corresponding trifluoro derivatives through nucleophilic substitution by fluoride ion, in a reaction amenable to incorporating 18F for PET imaging. In vitro kinetic analysis indicates tight binding of the trifluoro derivatives to cholinesterases. Compound 1 has a Ki value of 7nM for acetylcholinesterase and 1300nM for butyrylcholinesterase while for compound 2 these values are 0.4nM and 26nM, respectively. Tight binding of these compounds to cholinesterase encourages their development for PET imaging detection of cholinesterase associated with Alzheimer's disease pathology.
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Affiliation(s)
| | - Ian R Pottie
- Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada; Department of Chemistry, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Earl Martin
- Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada
| | | | - Sultan Darvesh
- Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Chemistry, Mount Saint Vincent University, Halifax, Nova Scotia, Canada; Department of Medicine (Neurology and Geriatric Medicine), Dalhousie University, Halifax, Nova Scotia, Canada.
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11
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Racys DT, Sharif SAI, Pimlott SL, Sutherland A. Silver(I)-Catalyzed Iodination of Arenes: Tuning the Lewis Acidity of N-Iodosuccinimide Activation. J Org Chem 2016; 81:772-80. [PMID: 26795534 DOI: 10.1021/acs.joc.5b02761] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A mild and rapid method for the iodination of arenes that utilizes silver(I) triflimide as a catalyst for activation of N-iodosuccinimide has been developed. The transformation was found to be general for a wide range of anisole, aniline, acetanilide, and phenol derivatives and allowed the late-stage iodination of biologically active compounds such as PIMBA, a SPECT imaging agent of breast cancer, and (-)-IBZM, a dopamine D2 receptor antagonist. The method was also modified for the radioiodination of arenes using a one-pot procedure involving the in situ generation of [(125)I]-N-iodosuccinimide followed by the silver(I)-catalyzed iodination.
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Affiliation(s)
- Daugirdas T Racys
- WestCHEM, School of Chemistry, The Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Salaheddin A I Sharif
- WestCHEM, School of Chemistry, The Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Sally L Pimlott
- West of Scotland PET Centre, Greater Glasgow and Clyde NHS Trust, Glasgow G12 0YN, United Kingdom
| | - Andrew Sutherland
- WestCHEM, School of Chemistry, The Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
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12
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Liao M, Zhao Y, Huang L, Cheng B, Huang K. Isoliquiritigenin and liquiritin from Glycyrrhiza uralensis inhibit α-synuclein amyloid formation. RSC Adv 2016. [DOI: 10.1039/c6ra17770k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bioactive isoliquiritigenin and liquiritin inhibit α-synuclein aggregation and extend the life span of theC. elegansmodel of Parkinson's disease.
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Affiliation(s)
- Mingyan Liao
- Tongji School of Pharmacy
- Huazhong University of Science and Technology
- Wuhan
- China
| | - Yudan Zhao
- Tongji School of Pharmacy
- Huazhong University of Science and Technology
- Wuhan
- China
| | - Lizi Huang
- Tongji School of Pharmacy
- Huazhong University of Science and Technology
- Wuhan
- China
| | - Biao Cheng
- The Department of Pharmacy
- The Central Hospital of Wuhan
- Wuhan
- China
| | - Kun Huang
- Tongji School of Pharmacy
- Huazhong University of Science and Technology
- Wuhan
- China
- Center for Biomedicine Research
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13
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Watanabe H, Ono M, Iikuni S, Kimura H, Okamoto Y, Ihara M, Saji H. Synthesis and biological evaluation of 123I-labeled pyridyl benzoxazole derivatives: novel β-amyloid imaging probes for single-photon emission computed tomography. RSC Adv 2015. [DOI: 10.1039/c4ra10742j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The result in the present study suggested that [123I]9 may be a potential SPECT probe for imaging β-amyloid plaques in the brains of patient with Alzheimer's disease.
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Affiliation(s)
- Hiroyuki Watanabe
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Masahiro Ono
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Shimpei Iikuni
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Hiroyuki Kimura
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Yoko Okamoto
- Department of Pathology
- National Cerebral and Cardiovascular Center
- Suita
- Japan
| | - Masafumi Ihara
- Department of Stroke and Cerebrovascular Diseases
- National Cerebral and Cardiovascular Center
- Suita
- Japan
| | - Hideo Saji
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
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14
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Ono M, Saji H. Recent advances in molecular imaging probes for β-amyloid plaques. MEDCHEMCOMM 2015. [DOI: 10.1039/c4md00365a] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review recent advances in our development of molecular imaging probes for PET, SPECT, and optical imaging for in vivo detection of β-amyloid plaques in the brain.
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Affiliation(s)
- Masahiro Ono
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Hideo Saji
- Department of Patho-Functional Bioanalysis
- Graduate School of Pharmaceutical Sciences
- Kyoto University
- Kyoto 606-8501
- Japan
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15
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Yang Y, Cui M. Radiolabeled bioactive benzoheterocycles for imaging β-amyloid plaques in Alzheimer's disease. Eur J Med Chem 2014; 87:703-21. [DOI: 10.1016/j.ejmech.2014.10.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/29/2014] [Accepted: 10/04/2014] [Indexed: 01/30/2023]
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16
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Wang X, Cui M, Jia J, Liu B. (99m)Tc-labeled-2-arylbenzoxazole derivatives as potential Aβ imaging probes for single-photon emission computed tomography. Eur J Med Chem 2014; 89:331-9. [PMID: 25462249 DOI: 10.1016/j.ejmech.2014.10.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 10/13/2014] [Accepted: 10/14/2014] [Indexed: 11/18/2022]
Abstract
Four neutral (99m)Tc/Re-labeled 2-arylbenzoxazole derivatives conjugated to bis (aminoethanethiol) (BAT) chelating ligand via a short propoxy spacer were synthesized and evaluated. In vitro binding assay showed that they displayed binding affinities to Aβ1-42 aggregates (Ki = 15.86-393.18 nM). In vitro autoradiography studies further confirmed the high and specific binding of [(99m)Tc]20 to β-amyloid plaques on brain sections of transgenic mice. Biodistribution study of [(99m)Tc]17-20 in normal mice displayed moderate initial brain uptake (0.96-1.55%ID/g at 2 min), and fast washed out from the brain (0.14-0.40%ID/g at 60 min), especially for [(99m)Tc]20 with a brain2min/brain60min ratio of 8.86. Taken together, these preliminary data suggested that [(99m)Tc]20 may be a potential imaging probe for detecting amyloid plaques in the brain.
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Affiliation(s)
- Xuedan Wang
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Mengchao Cui
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China.
| | - Jianhua Jia
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
| | - Boli Liu
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
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17
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Gadolinium-based contrast agents targeted to amyloid aggregates for the early diagnosis of Alzheimer's disease by MRI. Eur J Med Chem 2014; 87:843-61. [PMID: 25440885 DOI: 10.1016/j.ejmech.2014.10.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 09/16/2014] [Accepted: 10/07/2014] [Indexed: 12/14/2022]
Abstract
While important efforts were made in the development of positron emission tomography (PET) tracers for the in vivo molecular diagnosis of Alzheimer's disease, very few investigations to develop magnetic resonance imaging (MRI) probes were performed. Here, a new generation of Gd(III)-based contrast agents (CAs) is proposed to detect the amyloid β-protein (Aβ) aggregates by MRI, one of the earliest biological hallmarks of the pathology. A building block strategy was used to synthesize a library of 16 CAs to investigate structure-activity relationships (SARs) on physicochemical properties and binding affinity for the Aβ aggregates. Three types of blocks were used to modulate the CA structures: (i) the Gd(III) chelates (Gd(III)-DOTA and Gd(III)-PCTA), (ii) the biovectors (2-arylbenzothiazole, 2-arylbenzoxazole and stilbene derivatives) and (iii) the linkers (neutrals, positives and negatives with several lengths). These investigations revealed unexpected SARs and a difficulty of these probes to cross the blood-brain barrier (BBB). General insights for the development of Gd(III)-based CAs to detect the Aβ aggregates are described.
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Eckroat TJ, Mayhoub AS, Garneau-Tsodikova S. Amyloid-β probes: Review of structure-activity and brain-kinetics relationships. Beilstein J Org Chem 2013; 9:1012-44. [PMID: 23766818 PMCID: PMC3678428 DOI: 10.3762/bjoc.9.116] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2013] [Accepted: 04/30/2013] [Indexed: 11/30/2022] Open
Abstract
The number of people suffering from Alzheimer's disease (AD) is expected to increase dramatically in the coming years, placing a huge burden on society. Current treatments for AD leave much to be desired, and numerous research efforts around the globe are focused on developing improved therapeutics. In addition, current diagnostic tools for AD rely largely on subjective cognitive assessment rather than on identification of pathophysiological changes associated with disease onset and progression. These facts have led to numerous efforts to develop chemical probes to detect pathophysiological hallmarks of AD, such as amyloid-β plaques, for diagnosis and monitoring of therapeutic efficacy. This review provides a survey of chemical probes developed to date for AD with emphasis on synthetic methodologies and structure-activity relationships with regards to affinity for target and brain kinetics. Several probes discussed herein show particularly promising results and will be of immense value moving forward in the fight against AD.
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Affiliation(s)
- Todd J Eckroat
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone Street, Lexington, KY, 40536-0596, United States
- Life Sciences Institute and Department of Medicinal Chemistry, University of Michigan, 210 Washtenaw Ave, Ann Arbor, MI, 48109-2216, United States
| | - Abdelrahman S Mayhoub
- Life Sciences Institute and Department of Medicinal Chemistry, University of Michigan, 210 Washtenaw Ave, Ann Arbor, MI, 48109-2216, United States
| | - Sylvie Garneau-Tsodikova
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone Street, Lexington, KY, 40536-0596, United States
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19
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Rodríguez-Rodríguez C, Telpoukhovskaia M, Orvig C. The art of building multifunctional metal-binding agents from basic molecular scaffolds for the potential application in neurodegenerative diseases. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2012.03.008] [Citation(s) in RCA: 126] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Wang X, Cui M, Yu P, Li Z, Yang Y, Jia H, Liu B. Synthesis and biological evaluation of novel technetium-99m labeled phenylbenzoxazole derivatives as potential imaging probes for β-amyloid plaques in brain. Bioorg Med Chem Lett 2012; 22:4327-31. [DOI: 10.1016/j.bmcl.2012.05.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 11/28/2022]
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21
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Cui M, Ono M, Kimura H, Ueda M, Nakamoto Y, Togashi K, Okamoto Y, Ihara M, Takahashi R, Liu B, Saji H. Novel 18F-Labeled Benzoxazole Derivatives as Potential Positron Emission Tomography Probes for Imaging of Cerebral β-Amyloid Plaques in Alzheimer’s Disease. J Med Chem 2012; 55:9136-45. [DOI: 10.1021/jm300251n] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Mengchao Cui
- Department of Patho-Functional
Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University,
46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
- Key Laboratory of Radiopharmaceuticals,
Ministry of Education, College of Chemistry, Beijing Normal University,
Beijing 100875, PR China
| | - Masahiro Ono
- Department of Patho-Functional
Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University,
46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hiroyuki Kimura
- Department of Patho-Functional
Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University,
46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Masashi Ueda
- Department of Patho-Functional
Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University,
46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
- Department of Diagnostic Imaging
and Nuclear Medicine, Graduate School of Medicine, Kyoto University,
54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yuji Nakamoto
- Department of Diagnostic Imaging
and Nuclear Medicine, Graduate School of Medicine, Kyoto University,
54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Kaori Togashi
- Department of Diagnostic Imaging
and Nuclear Medicine, Graduate School of Medicine, Kyoto University,
54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Yoko Okamoto
- Department of Neurology, Graduate
School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku,
Kyoto 606-8507, Japan
| | - Masafumi Ihara
- Department of Neurology, Graduate
School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku,
Kyoto 606-8507, Japan
| | - Ryosuke Takahashi
- Department of Neurology, Graduate
School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku,
Kyoto 606-8507, Japan
| | - Boli Liu
- Key Laboratory of Radiopharmaceuticals,
Ministry of Education, College of Chemistry, Beijing Normal University,
Beijing 100875, PR China
| | - Hideo Saji
- Department of Patho-Functional
Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University,
46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
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22
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Iordanescu G, Venkatasubramanian PN, Wyrwicz AM. Automatic segmentation of amyloid plaques in MR images using unsupervised support vector machines. Magn Reson Med 2012; 67:1794-802. [PMID: 22189675 PMCID: PMC3311764 DOI: 10.1002/mrm.23138] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 06/30/2011] [Accepted: 07/13/2011] [Indexed: 11/06/2022]
Abstract
Deposition of the β-amyloid peptide (Aβ) is an important pathological hallmark of Alzheimer's disease (AD). However, reliable quantification of amyloid plaques in both human and animal brains remains a challenge. We present here a novel automatic plaque segmentation algorithm based on the intrinsic MR signal characteristics of plaques. This algorithm identifies plaque candidates in MR data by using watershed transform, which extracts regions with low intensities completely surrounded by higher intensity neighbors. These candidates are classified as plaque or nonplaque by an unsupervised learning method using features derived from the MR data intensity. The algorithm performance is validated by comparison with histology. We also demonstrate the algorithm's ability to detect age-related changes in plaque load ex vivo in amyloid precursor protein (APP) transgenic mice that coexpress five familial AD mutations (5xFAD mice). To our knowledge, this study represents the first quantitative method for characterizing amyloid plaques in MRI data. The proposed method can be used to describe the spatiotemporal progression of amyloid deposition, which is necessary for understanding the evolution of plaque pathology in mouse models of Alzheimer's disease and to evaluate the efficacy of emergent amyloid-targeting therapies in preclinical trials.
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Affiliation(s)
- Gheorghe Iordanescu
- Center for Basic MR Research, NorthShore University HealthSystem, Evanston, Illinois 60201, USA.
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23
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Swahn BM, Sandell J, Pyring D, Bergh M, Jeppsson F, Juréus A, Neelissen J, Johnström P, Schou M, Svensson S. Synthesis and evaluation of pyridylbenzofuran, pyridylbenzothiazole and pyridylbenzoxazole derivatives as ¹⁸F-PET imaging agents for β-amyloid plaques. Bioorg Med Chem Lett 2012; 22:4332-7. [PMID: 22647721 DOI: 10.1016/j.bmcl.2012.05.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/02/2012] [Accepted: 05/03/2012] [Indexed: 11/25/2022]
Abstract
The synthesis and SAR of new β-amyloid binding agents are reported. Evaluation of important properties for achieving good signal-to-background ratio is described. Compounds 27, 33, and 36 displayed desirable lipophilic and pharmacokinetic properties. Compound 27 was further evaluated with autoradiographic studies in vitro on human brain tissue and in vivo in Tg2576 mice. Compound 27 showed an increased signal-to-background ratio compared to flutemetamol 4, indicating its suitability as PET ligand for β-amyloid deposits in AD patients. The preparation of the corresponding (18)F-labeled PET radioligand of compound 27 is presented.
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Affiliation(s)
- Britt-Marie Swahn
- Department of Medicinal Chemistry, AstraZeneca R&D Södertälje, S-151 85 Södertälje, Sweden.
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24
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Common benzothiazole and benzoxazole fluorescent DNA intercalators for studying Alzheimer Aβ1-42 and prion amyloid peptides. Biotechniques 2012; 52:000113873. [DOI: 10.2144/000113873] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/04/2012] [Indexed: 11/23/2022] Open
Abstract
Amyloids are fibrillar protein aggregates associated with a number of neurodegenerative pathologies including Alzheimer and Creutzfeldt—Jakob disease. The study of amyloids is usually based on fluorescence with the dye thioflavin-T. Although a number of amyloid binding compounds have been synthesized, many are nonfluorescent or not readily available for research use. Here we report on a class of commercial benzothiazole/benzoxazole containing fluorescent DNA intercalators from Invitrogen that possess the ability to bind amyloid Aβ1-42 peptide and hamster prion. These dyes fluoresce from 500–750 nm and are available as dimers or monomers. We demonstrate that these dyes can be used as acceptors for thioflavin-T fluorescence resonance energy transfer as well as reporter groups for binding studies with Congo red and chrysamine G. As more potential therapeutic compounds for these diseases are generated, there is a need for simple and inexpensive methods to monitor their interactions with amyloids. The fluorescent dyes reported here are readily available and can be used as tools for biochemical studies of amyloid structures and in vitro screening of potential therapeutics.
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25
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Lee I, Choe YS, Choi JY, Lee KH, Kim BT. Synthesis and evaluation of ¹⁸F-labeled styryltriazole and resveratrol derivatives for β-amyloid plaque imaging. J Med Chem 2012; 55:883-92. [PMID: 22236086 DOI: 10.1021/jm201400q] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In the present study, a styryltriazole and four resveratrol derivatives were synthesized as candidates for β-amyloid (Aβ) plaque imaging. On the basis of their binding affinities to Aβ(1-42) aggregates, the styryltriazole (1, K(i) = 12.8 nM) and one resveratrol derivative (5, K(i) = 0.49 nM) were labeled with (18)F. In normal mice, tissue distribution of [(18)F]5 showed good initial brain uptake (3.26% ID/g at 2 min) but slow wash-out from brains (2-to-60 min uptake ratio: 2.9). Furthermore, it underwent in vivo metabolic defluorination (1.88% ID/g at 2 min and 9.73% ID/g at 60 min). In contrast, [(18)F]1 displayed high initial brain uptake (5.38% ID/g at 2 min) with rapid wash-out from brains (0.52% ID/g at 60 min; 2-to-60 min uptake ratio: 10.3). These results indicate that [(18)F]1 has in vivo kinetics comparable to PET radiopharmaceuticals currently under commercial development, demonstrating that [(18)F]1 is a desirable PET radioligand for Aβ plaque imaging.
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Affiliation(s)
- Iljung Lee
- Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Kangnam-ku, Seoul 135-710, Korea
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26
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Ribeiro Morais G, Paulo A, Santos I. A Synthetic Overview of Radiolabeled Compounds for β‐Amyloid Targeting. European J Org Chem 2011. [DOI: 10.1002/ejoc.201101449] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Goreti Ribeiro Morais
- Group of Radiopharmaceutical Sciences, Institute Tecnologic and Nuclear, Estrada Nacional 10, 2686‐953 Sacavém, Portugal
| | - António Paulo
- Group of Radiopharmaceutical Sciences, Institute Tecnologic and Nuclear, Estrada Nacional 10, 2686‐953 Sacavém, Portugal
| | - Isabel Santos
- Group of Radiopharmaceutical Sciences, Institute Tecnologic and Nuclear, Estrada Nacional 10, 2686‐953 Sacavém, Portugal
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27
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Abstract
Alzheimer's disease (AD) is a common neurodegenerative disorder characterized by the deposition of amyloids in the brain. One prominent form of amyloid is composed of repeating units of the amyloid-β (Aβ) peptide. Over the past decade, it has become clear that these Aβ amyloids are not homogeneous; rather, they are composed of a series of structures varying in their overall size and shape and the number of Aβ peptides they contain. Recent theories suggest that these different amyloid conformations may play distinct roles in disease, although their relative contributions are still being discovered. Here, we review how chemical probes, such as Congo red, thioflavin T and their derivatives, have been powerful tools for the better understanding of amyloid structure and function. Moreover, we discuss how design and deployment of conformationally selective probes might be used to test emerging models of AD.
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Affiliation(s)
- Ashley A Reinke
- Department of Biological Chemistry, Pathology and the Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109-2216, USA
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28
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SPECT Imaging Agents for Detecting Cerebral β-Amyloid Plaques. INTERNATIONAL JOURNAL OF MOLECULAR IMAGING 2011; 2011:543267. [PMID: 21603239 PMCID: PMC3094870 DOI: 10.1155/2011/543267] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 11/06/2010] [Accepted: 01/24/2011] [Indexed: 11/17/2022]
Abstract
The development of radiotracers for use in vivo to image β-amyloid (Aβ) plaques in cases of Alzheimer's disease (AD) is an important, active area of research. The presence of Aβ aggregates in the brain is generally accepted as a hallmark of AD. Since the only definitive diagnosis of AD is by postmortem staining of affected brain tissue, the development of techniques which enable one to image Aβ plaques in vivo has been strongly desired. Furthermore, the quantitative evaluation of Aβ plaques in the brain could facilitate evaluation of the efficacy of antiamyloid therapies currently under development. This paper reviews the current situation in the development of agents for SPECT-based imaging of Aβ plaques in Alzheimer's brains.
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29
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Cui M, Ono M, Kimura H, Kawashima H, Liu BL, Saji H. Radioiodinated benzimidazole derivatives as single photon emission computed tomography probes for imaging of β-amyloid plaques in Alzheimer's disease. Nucl Med Biol 2011; 38:313-20. [DOI: 10.1016/j.nucmedbio.2010.09.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 09/16/2010] [Accepted: 09/28/2010] [Indexed: 10/18/2022]
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30
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Kumar N, Tiwari AK, Kakkar D, Saini N, Chand M, Mishra AK. Design, Synthesis, and Fluorescence Lifetime Study of Benzothiazole Derivatives for Imaging of Amyloids. Cancer Biother Radiopharm 2010; 25:571-5. [DOI: 10.1089/cbr.2010.0794] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Nitin Kumar
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
- Department of Chemistry, D.A.V. (PG) College, CCS University, Muzaffarnager, Uttar Pradesh, India
| | - Anjani K. Tiwari
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Dipti Kakkar
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Nisha Saini
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Mukesh Chand
- Department of Chemistry, D.A.V. (PG) College, CCS University, Muzaffarnager, Uttar Pradesh, India
| | - Anil K. Mishra
- Division of Cyclotron and Radiopharmaceutical Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
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31
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Abstract
The progressive nature of neurodegeneration suggests an age-dependent process that ultimately leads to synaptic failure and neuronal damage in cortical areas of the brain critical for memory and higher mental functions. The increasing age of the population in developed countries suggests that, if unchecked, these disorders will become increasingly prevalent. In the absence of specific biologic markers, direct pathologic examination of brain tissue still is the only definitive method for establishing a diagnosis of Alzheimer disease (AD) and other types of dementia. Pathologic hallmarks of AD are intracellular neurofibrillary tangles (NFT) and extracellular amyloid plaques. NFT are intraneuronal bundles of paired helical filaments mainly composed of the aggregates of an abnormally phosphorylated form of tau protein; neuritic plaques consist of dense extracellular aggregates of β-amyloid (Aβ), surrounded by reactive gliosis and dystrophic neurites. To date, all available evidence strongly supports the notion that an imbalance between the production and removal of Aβ leading to its progressive accumulation is central to the pathogenesis of AD. A growing understanding of the molecular mechanisms of Aβ formation, degradation, and neurotoxicity is being translated into new therapeutic approaches. Whereas AD is the most common cause of dementia in the elderly, postmortem studies have found dementia with Lewy Bodies and frontotemporal lobe degeneration each to account for about 20% of cases. Molecular neuroimaging techniques such as PET have been used for the in vivo assessment of molecular processes at their sites of action, permitting detection of subtle pathophysiological changes in the brain at asymptomatic stages The development of molecular imaging methods for noninvasively assessing disease-specific traits such as Aβ burden in AD is allowing early diagnosis at presymptomatic stages, more accurate differential diagnosis and, when available, the evaluation and monitoring of disease-modifying therapy.
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Affiliation(s)
- Victor L Villemagne
- Department of Nuclear Medicine and Centre for PET, Austin Health, 145 Studley Road, Heidelberg, Victoria 3084, Australia; The Mental Health Research Institute of Victoria, 135 Oak Street, Parkville, Victoria 3052, Australia; Department of Medicine, Austin Health, Victoria 3084, Australia.
| | - Christopher C Rowe
- Department of Nuclear Medicine and Centre for PET, Austin Health, 145 Studley Road, Heidelberg, Victoria 3084, Australia; Department of Medicine, Austin Health, Victoria 3084, Australia
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32
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Watanabe H, Ono M, Haratake M, Kobashi N, Saji H, Nakayama M. Synthesis and characterization of novel phenylindoles as potential probes for imaging of β-amyloid plaques in the brain. Bioorg Med Chem 2010; 18:4740-6. [PMID: 20605471 DOI: 10.1016/j.bmc.2010.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/01/2010] [Accepted: 05/04/2010] [Indexed: 11/25/2022]
Abstract
We synthesized a novel series of phenylindole (PI) derivatives and evaluated their biological activities as probes for imaging Aβ plaques in vivo. The affinity for Aβ plaques was assessed by an in vitro-binding assay using pre-formed synthetic Aβ aggregates. 2-phenyl-1H-indole (2-PI) derivatives showed high affinity for Aβ42 aggregates with K(i) values ranging from 4 to 32 nM. 2-PI derivatives clearly stained Aβ plaques in an animal model of AD. In biodistribution experiments using normal mice, 2-PI derivatives displayed sufficient uptake for imaging, ranging from 1.1% to 2.6% ID/g. Although additional modifications are necessary to improve uptake by and clearance from the brain, 2-PI derivatives may be useful as a backbone structure to develop novel Aβ imaging agents.
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Affiliation(s)
- Hiroyuki Watanabe
- Department of Hygienic Chemistry, Graduate School of Biomedical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
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Cui MC, Li ZJ, Tang RK, Liu BL. Synthesis and evaluation of novel benzothiazole derivatives based on the bithiophene structure as potential radiotracers for beta-amyloid plaques in Alzheimer's disease. Bioorg Med Chem 2010; 18:2777-84. [PMID: 20211565 DOI: 10.1016/j.bmc.2010.02.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Revised: 02/01/2010] [Accepted: 02/02/2010] [Indexed: 10/19/2022]
Abstract
In this study, six novel benzothiazole derivatives based on the bithiophene structure were developed as potential beta-amyloid probes. In vitro binding studies using Abeta aggregates showed that all of them demonstrated high binding affinities with K(i) values ranged from 0.11 to 4.64nM. In vitro fluorescent staining results showed that these compounds can intensely stained Abeta plaques within brain sections of APP/PS1 transgenic mice, animal model for AD. Two radioiodinated compounds [(125)I]-2-(5'-iodo-2,2'-bithiophen-5-yl)-6-methoxybenzo[d]thiazole [(125)I]10 and [(125)I]-2-(2,2'-bithiophen-5-yl)-6-iodobenzo[d]thiazole [(125)I]13 were successfully prepared through an iododestannylation reaction. Furthermore, in vitro autoradiography of the AD model mice brain sections showed that both [(125)I]10 and [(125)I]13 labeled the Abeta plaques specifically with low background. In vivo biodistribution studies in normal mice indicated that [(125)I]13 exhibited high brain uptake (3.42% ID/g at 2min) and rapid clearance from the brain (0.53% ID/g at 60min), while [(125)I]10 showed lower brain uptake (0.87% ID/g at 2min). In conclusion, these preliminary results of this study suggest that the novel radioiodinated benzothiazole derivative [(125)I]13 may be a candidate as an in vivo imaging agent for detecting beta-amyloid plaques in the brain of AD patients.
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Affiliation(s)
- Meng-Chao Cui
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, PR China
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34
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Ono M. Development of positron-emission tomography/single-photon emission computed tomography imaging probes for in vivo detection of beta-amyloid plaques in Alzheimer's brains. Chem Pharm Bull (Tokyo) 2009; 57:1029-39. [PMID: 19801854 DOI: 10.1248/cpb.57.1029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Currently, the development of radiotracers for in vivo imaging of beta-amyloid plaques in Alzheimer's disease (AD) brains is an important, active area of molecular imaging. Postmortem brains of AD patients reveal neuropathologic features: the presence of beta-amyloid plaques and neurofibrillary tangles, which contain beta-amyloid peptides and highly phosphorylated tau proteins. Increases in the concentration of beta-amyloid in the course of the disease lead to changes in AD brains. Thus, when used in combination with positron-emission tomography/single-photon emission computed tomography (PET/SPECT), beta-amyloid imaging agents could serve as surrogate markers for the early diagnosis and neuropathogenetic studies of AD. Furthermore, quantitative evaluation of beta-amyloid plaques in the brain could facilitate the evaluation of the efficacy of antiamyloid therapies that are currently being investigated. This paper reviews our research on the development of PET/SPECT imaging agents for in vivo detection of beta-amyloid plaques in Alzheimer's brains.
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Affiliation(s)
- Masahiro Ono
- Department of Patho-Functional Bioanalyses, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
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35
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Serdons K, Vanderghinste D, Van Eeckhoudt M, Borghgraef P, Kung H, Van Leuven F, de Groot T, Bormans G, Verbruggen A. Synthesis and evaluation of two fluorine-18 labelled phenylbenzothiazoles as potentialin vivotracers for amyloid plaque imaging. J Labelled Comp Radiopharm 2009. [DOI: 10.1002/jlcr.1662] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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Agdeppa ED, Spilker ME. A review of imaging agent development. AAPS J 2009; 11:286-99. [PMID: 19415506 PMCID: PMC2691464 DOI: 10.1208/s12248-009-9104-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Accepted: 04/01/2009] [Indexed: 12/16/2022] Open
Abstract
This educational review highlights the processes, opportunities, and challenges encountered in the discovery and development of imaging agents, mainly positron emission tomography and single-photon emission computed tomography tracers. While the development of imaging agents parallels the drug development process, unique criteria are needed to identify opportunities for new agents. Imaging agent development has the flexibility to pursue functional or nonfunctional targets as long as they play a role in the specific disease or mechanism of interest and meet imageability requirements. However, their innovation is tempered by relatively small markets for diagnostic imaging agents, intellectual property challenges, radiolabeling constraints, and adequate target concentrations for imaging. At the same time, preclinical imaging is becoming a key translational tool for proof of mechanism and concept studies. Pharmaceutical and imaging industries face a common bottleneck in the form of the limited number of trials one company can possibly perform. However, microdosing and theranostics are evidence that partnerships between pharmaceutical and imaging companies can accelerate clinical translation of tracers and therapeutic interventions. This manuscript will comment on these aspects to provide an educational review of the discovery and development processes for imaging agents.
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Affiliation(s)
- Eric D. Agdeppa
- />Medical, Science, and Technology Office, GE Healthcare, 101 Carnegie Center, Princeton, New Jersey 08540 USA
| | - Mary E. Spilker
- />Pfizer Global Research and Development, 10646 Science Center Drive, San Diego, California 92121 USA
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37
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Small organic probes as amyloid specific ligands - Past and recent molecular scaffolds. FEBS Lett 2009; 583:2593-9. [DOI: 10.1016/j.febslet.2009.04.016] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 04/08/2009] [Accepted: 04/09/2009] [Indexed: 12/29/2022]
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Chang KW, Chen CC, Lee SY, Shen LH, Wang HE. The synthesis and characterization of [(124)I]IMPY, a thioflavin-S derivative, in transgenic mouse models of Alzheimer's disease. Appl Radiat Isot 2009; 67:1397-400. [PMID: 19307132 DOI: 10.1016/j.apradiso.2009.02.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
6-[(124)I]iodo-2-(4'-N,N-dimethylamino)-phenylimidazo[1,2-a]pyridine ([(124)I]IMPY) was synthesized and characterized as a positron-emitting probe to identify Alzheimer's disease in transgenic mouse models. A significant reduction in radioactivity retention in the hippocampus and frontal cortex by co-incubation with nonradioactive IMPY was observed. Highly specific retention of radioactivity in beta-amyloid-rich regions of brain sections was also noted. This study demonstrated that [(124)I]IMPY was a promising probe for the mouse model and may be useful for positron emission tomography to image beta-amyloid plaques in the human brain.
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Affiliation(s)
- K W Chang
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, No. 155, Sect. 2, Li-Nong St., Taipei 112, Taiwan
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Serdons K, Terwinghe C, Vermaelen P, Van Laere K, Kung H, Mortelmans L, Bormans G, Verbruggen A. Synthesis and Evaluation of 18F-Labeled 2-Phenylbenzothiazoles as Positron Emission Tomography Imaging Agents for Amyloid Plaques in Alzheimer’s Disease. J Med Chem 2009; 52:1428-37. [DOI: 10.1021/jm8013376] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kim Serdons
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Christelle Terwinghe
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Peter Vermaelen
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Koen Van Laere
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Hank Kung
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Luc Mortelmans
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Guy Bormans
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
| | - Alfons Verbruggen
- Laboratory for Radiopharmacy, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium, Department of Nuclear Medicine, U. Z. Gasthuisberg, Leuven, Belgium, and Department of Radiology, University of Pennsylvania, Philadelphia
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40
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Hong HS, Maezawa I, Budamagunta M, Rana S, Shi A, Vassar R, Liu R, Lam KS, Cheng RH, Hua DH, Voss JC, Jin LW. Candidate anti-A beta fluorene compounds selected from analogs of amyloid imaging agents. Neurobiol Aging 2008; 31:1690-9. [PMID: 19022536 DOI: 10.1016/j.neurobiolaging.2008.09.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/13/2008] [Accepted: 09/30/2008] [Indexed: 10/21/2022]
Abstract
Alzheimer's disease (AD) is characterized by depositions of beta-amyloid (A beta) aggregates as amyloid in the brain. To facilitate diagnosis of AD by radioligand imaging, several highly specific small-molecule amyloid ligands have been developed. Because amyloid ligands display excellent pharmacokinetics properties and brain bioavailability, and because we have previously shown that some amyloid ligands bind the highly neurotoxic A beta oligomers (A beta O) with high affinities, they may also be valuable candidates for anti-A beta therapies. Here we identified two fluorene compounds from libraries of amyloid ligands, initially based on their ability to block cell death secondary to intracellular A beta O. We found that the lead fluorenes were able to reduce the amyloid burden including the levels of A beta O in cultured neurons and in 5xFAD mice. To explain these in vitro and in vivo effects, we found that the lead fluorenes bind and destabilize A beta O as shown by electron paramagnetic resonance spectroscopy studies, and block the harmful A beta O-synapse interaction. These fluorenes and future derivatives, therefore, have a potential use in AD therapy and research.
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Affiliation(s)
- Hyun-Seok Hong
- M.I.N.D. Institute and Department of Pathology and Laboratory Medicine, University of California Davis Medical Center, 2805 50th Street, Sacramento, CA 95817, USA
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41
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Aβ-binding molecules: Possible application as imaging probes and as anti-aggregation agents. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s11426-008-0075-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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42
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Hausner SH, Alagille D, Koren AO, Amici L, Staley JK, Cosgrove KP, Baldwin RM, Tamagnan GD. Synthesis of 5- and 6-substituted 2-(4-dimethylaminophenyl)-1,3-benzoxazoles and their in vitro and in vivo evaluation as imaging agents for amyloid plaque. Bioorg Med Chem Lett 2008; 19:543-5. [PMID: 19081717 DOI: 10.1016/j.bmcl.2008.05.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 05/07/2008] [Accepted: 05/08/2008] [Indexed: 11/30/2022]
Abstract
A series of novel 5- and 6-substituted 2-(4-dimethylaminophenyl)-1,3-benzoxazoles was synthesized and their potential as imaging probes for Alzheimer's Disease (AD)-related amyloid plaque was evaluated in vitro and in vivo. In vitro binding affinities for Abeta1-40 peptide of several of these compounds were in the low-nanomolar range . The lowest K(i) of 9.3nM was found for N-(2-(4-(dimethylamino)phenyl)-1,3-benzoxazol-5-yl)-4-iodobenzamide (1e). Its (123)I-radiolabeled form ([(123)I]1e) was subsequently prepared by iododestannylation of the corresponding tributylstannyl precursor and evaluated in vivo in a baboon model using SPECT imaging. Contrary to our expectations, 1e did not cross the blood-brain barrier (BBB) to any significant extent.
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Affiliation(s)
- Sven H Hausner
- School of Medicine, Department of Psychiatry and Diagnostic Radiology, Yale University, VACHS, West Haven, CT 06516, USA
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43
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44
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Radiochemistry and Radiopharmacy. Clin Nucl Med 2008. [DOI: 10.1007/978-3-540-28026-2_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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45
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Maezawa I, Hong HS, Liu R, Wu CY, Cheng RH, Kung MP, Kung HF, Lam KS, Oddo S, Laferla FM, Jin LW. Congo red and thioflavin-T analogs detect Abeta oligomers. J Neurochem 2007; 104:457-68. [PMID: 17953662 DOI: 10.1111/j.1471-4159.2007.04972.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Several small molecule ligands for amyloid-beta (Abeta) fibrils deposited in brain have been developed to facilitate radiological diagnosis of Alzheimer's disease (AD). Recently, the build-up of Abeta oligomers (AbetaO) in brain has been recognized as an additional hallmark of AD and may play a more significant role in early stages. Evidence suggests that quantitative assessment of AbetaO would provide a more accurate index of therapeutic effect of drug trials. Therefore, there is an urgent need to develop methods for efficient identification as well as structural analysis of AbetaO. We found that some well established amyloid ligands, analogs of Congo red and thioflavin-T (ThT), bind AbetaO with high affinity and detect AbetaO in vitro and in vivo. Binding studies revealed the presence of binding sites for Congo red- and thioflavin-T-analogs on AbetaO. Furthermore, these ligands can be used for imaging intracellular AbetaO in living cells and animals and as positive contrast agent for ultrastructural imaging of AbetaO, two applications useful for structural analysis of AbetaO in cells. We propose that by improving the binding affinity of current ligands, in vivo imaging of AbetaO is feasible by a 'signal subtraction' procedure. This approach may facilitate the identification of individuals with early AD.
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Affiliation(s)
- Izumi Maezawa
- M.I.N.D. Institute and Department of Pathology, University of California Davis, Sacramento, California 95817, USA
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46
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Li Q, Min J, Ahn YH, Namm J, Kim EM, Lui R, Kim HY, Ji Y, Wu H, Wisniewski T, Chang YT. Styryl-Based Compounds as Potential in vivo Imaging Agents for β-Amyloid Plaques. Chembiochem 2007; 8:1679-87. [PMID: 17705341 DOI: 10.1002/cbic.200700154] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A group of styryl-based neutral compounds has been synthesized in this study for potential use as in vivo imaging agents for beta-amyloid plaques. Of 56 candidates, 14 compounds were found to label beta-amyloid plaques well on Alzheimer's disease (AD) human brain sections in vitro. The binding affinity to beta-amyloid fibrils was then determined by measuring the change in fluorescence intensity. Interestingly, we found that a class of quinaldine-styryl scaffold compounds displays specific binding to beta-amyloid fibrils. A representative compound, STB-8, was used in ex vivo and in vivo imaging experiments on an AD transgenic mouse model and demonstrated excellent blood-brain barrier (BBB) permeability and specific staining of the AD beta-amyloid plaques.
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Affiliation(s)
- Qian Li
- Department of Chemistry, New York University, School of Medicine, New York, NY 11219, USA
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47
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Stephenson KA, Chandra R, Zhuang ZP, Hou C, Oya S, Kung MP, Kung HF. Fluoro-pegylated (FPEG) imaging agents targeting Abeta aggregates. Bioconjug Chem 2007; 18:238-46. [PMID: 17226978 PMCID: PMC2597429 DOI: 10.1021/bc060239q] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel approach of producing positron emission tomography (PET) imaging agents through the formation of bioconjugates based on a pegylation-fluorination strategy resulting in fluoro-pegylated (FPEG) molecules is reported. This approach offers a simple and easy method by which to incorporate 18F in the target molecule without an appreciable increase in the lipophilicity. After 18F labeling, this convenient approach leads to PET imaging probes binding to Abeta aggregates in the brain (an important factor associated with Alzheimer's disease) using the known core structures, such as [2-(4-dimethylaminophenyl)-vinyl]-benzoxazol (3') or 2-phenylbenzothiazole (4). This approach appears to be effective in some core structures, but it cannot be uniformly applied to all structures.
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Affiliation(s)
- Karin A Stephenson
- Department of Radiology, University of Pennsylvania, 3700 Market Street, Room 305, Philadelphia, Pennsylvania 19104, USA.
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48
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Wu C, Wei J, Gao K, Wang Y. Dibenzothiazoles as novel amyloid-imaging agents. Bioorg Med Chem 2006; 15:2789-96. [PMID: 17293116 DOI: 10.1016/j.bmc.2006.11.022] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Revised: 11/03/2006] [Accepted: 11/13/2006] [Indexed: 11/29/2022]
Abstract
Novel dibenzothiazole derivatives were synthesized and evaluated as amyloid-imaging agents. In vitro quantitative binding studies using AD brain tissue homogenates showed that the dibenzothiazole derivatives displayed high binding affinities with K(i) values in the nanomolar range (6.8-36 nM). These derivatives are relatively lipophilic with partition coefficients (logP oct) in the range of 1.25-3.05. Preliminary structure-activity relationship studies indicated dibenzothiazole derivatives bearing electron-donating groups exhibited higher binding affinities than those bearing electron-withdrawing groups. A lead compound was selected for its high binding affinity and radiolabeled with [(125)I] through direct radioiodination using sodium [(125)I] iodide in the presence of Chloramine T. The radioligand (4-[2,6']dibenzothiazolyl-2'-yl-2-[(125)I]-phenylamine) displayed moderate lipophilicity (logP oct, 2.70), very good brain uptake (3.71+/-0.63% ID/g at 2 min after iv injection in mice), and rapid washout from normal brains (0.78% and 0.43% ID/g at 30 and 60 min, respectively). These studies indicated that lipophilic dibenzothiazole derivatives represent a promising pharmacophore for the development of novel amyloid-imaging agents for potential application in Alzheimer's disease and related neurodegenerative disorders.
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Affiliation(s)
- Chunying Wu
- Department of Chemistry and Radiology, Case Western Reserve University, Cleveland, OH 44106, USA
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49
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Villemagne VL, Ng S, Cappai R, Barnham KJ, Fodero-Tavoletti MT, Rowe CC, Masters CL. La lunga attesa: towards a molecular approach to neuroimaging and therapeutics in Alzheimer's disease. Neuroradiol J 2006; 19:453-74. [PMID: 24351248 DOI: 10.1177/197140090601900406] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2006] [Accepted: 04/08/2006] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are Aβ amyloid plaques, neurofibrillary tangles (NFT), synaptic loss and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography (CT) and magnetic resonance imaging (MRI) is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of AD. Functional neuroimaging techniques such as functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET) and single photon emission computed tomography (SPECT), possibly in conjuction with other related Aβ biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the Aβ amyloid burden in the brain, there is increasing interest in the development of MRI contrast agents and PET and SPECT radioligands that will permit the assessment of Aβ amyloid burden in vivo. - ma dov'è / la lenta processione di stagioni / che fu un'alba infinita e senza strade, / dov'è la lunga attesa e qual è il nome / del vuoto che ci invade. - Eugenio Montale.
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Affiliation(s)
- V L Villemagne
- Department of Nuclear Medicine, Centre for PET, Austin Health; Heidelberg, VIC, Australia - Department of Pathology, The University of Melbourne; VIC, Australia. - The Mental Health Research Institute of Victoria, Parkville; VIC, Australia -
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50
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Chang YS, Jeong JM, Lee YS, Kim HW, Ganesha RB, Kim YJ, Lee DS, Chung JK, Lee MC. Synthesis and evaluation of benzothiophene derivatives as ligands for imaging β-amyloid plaques in Alzheimer's disease. Nucl Med Biol 2006; 33:811-20. [PMID: 16934700 DOI: 10.1016/j.nucmedbio.2006.06.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 06/20/2006] [Accepted: 06/28/2006] [Indexed: 01/27/2023]
Abstract
The imaging of the distribution of beta-amyloid (Abeta) plaques in the brain is becoming an important diagnostic modality in Alzheimer's disease (AD). Here, we synthesized novel benzothiophene derivatives and labeled them with (18)F for the potential diagnostic imaging of AD patients using positron emission tomography. The K(i) values of benzothiophene derivatives were evaluated by competitive binding assay using 2-(3'-[(125)I]iodo-4'-N-methylaminophenyl)benzothiazole as a radioligand and Abeta(1-40) or Abeta(1-42) aggregates as receptors. All synthesized benzothiophene derivatives showed high binding affinities (K(i)=0.28-6.50 nM) to both Abeta(1-40) and Abeta(1-42) aggregates. Binding affinities were increased by O-alkylation or N-alkylation of 2-(4'-hydroxyphenyl)benzothiophene or 2-(4'-aminophenyl)benzothiophene. Biodistribution studies of 2-(4'-O-(2''-[(18)F]fluoroethyl)hydroxyphenyl)benzothiophene ([(18)F]) and 2-(4'-O-(3''-[(18)F]fluoropropyl)hydroxyphenyl)benzothiophene ([(18)F]) in normal mice were performed after intravenous injection through the tail vein. In biodistribution data, [(18)F] and [(18)F] showed high initial brain uptakes at 2 min (5.2+/-0.4% and 3.3+/-0.2% ID/g, respectively), and brain activities washed out to 2.0+/-0.2% and 0.5+/-0.1% ID/g at 4 h, respectively. In conclusion, benzothiophene derivatives showed excellent binding affinities for Abeta aggregates and high initial brain uptakes in normal mice.
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Affiliation(s)
- Young Soo Chang
- Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea
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