Synthesis, evaluation and metabolic studies of radiotracers containing a 4-(4-[18F]-fluorobenzyl)piperidin-1-yl moiety for the PET imaging of NR2B NMDA receptors
In this study, novel specific PET radioligands containing the 4-(4-fluorobenzyl)piperidine moiety and selectively antagonistic for the NR2B subunit containing NMDA receptors were developed. Two antagonists, RGH-896 (1a) and 4-(4-fluorobenzyl)piperidinyl-1-methyl-2-benzimidazol-5-ol (2a), belonging t...
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Published in | European journal of medicinal chemistry Vol. 46; no. 6; pp. 2295 - 2309 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier Masson SAS
01.06.2011
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | In this study, novel specific PET radioligands containing the 4-(4-fluorobenzyl)piperidine moiety and selectively antagonistic for the NR2B subunit containing NMDA receptors were developed. Two antagonists, RGH-896 (1a) and 4-(4-fluorobenzyl)piperidinyl-1-methyl-2-benzimidazol-5-ol (2a), belonging to two different structural families, were radiolabeled by an aromatic nucleophilic radiofluorination followed by a reduction of the para-position carbonyl function. Radiotracers [18F]1a, [18F]2a or the pattern 4-(4-[18F]-fluorobenzyl)piperidine ([18F]6) demonstrated an identical in vivo behavior with high accumulation of radioactivity in bone and cartilage which would suggest a radiodefluorination of the radiotracers. The identification of metabolites from 6 by LC-MS-MS confirmed the significant degree of defluorination as a result of the in vivo hydroxylation in the benzyl ring. In conclusion, [18F]1a or [18F]2a are not suitable for imaging the NR2B NMDA receptors due to their poor brain penetration. We also argue for a cautious use of the radiolabeled pattern, 4-(4-[18F]-fluorobenzyl)piperidine, to develop PET radiotracers.
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► Fluorinated antagonists for the NR2B subunit of the NMDA receptors were developed. ► Two PET radiotracers containing the 4-(4-[18F]fluorobenzyl)piperidine moiety were synthesized. ► The in vivo evaluation by PET imaging demonstrated radiodefluorination. ► Metabolism of the 4-(4-[18F]fluorobenzyl)piperidine was studied by LC-MS. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0223-5234 1768-3254 |
DOI: | 10.1016/j.ejmech.2011.03.013 |