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Radiolabeling of a high potency cannabinoid subtype‐1 receptor ligand, N ‐(4‐fluoro‐benzyl)‐4‐(3‐(piperidin‐1‐yl)‐indole‐1‐sulfonyl)benzamide (PipISB), with carbon‐11 or fluorine‐18
Author(s) -
Donohue Sean R.,
Halldin Christer,
Schou Magnus,
Hong Jinsoo,
Phebus Lee,
Chernet Eyassu,
Hitchcock Stephen A.,
Gardinier Kevin M.,
Ruley Kevin M.,
Krushinski Joseph H.,
Schaus John,
Pike Victor W.
Publication year - 2008
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.1491
Subject(s) - radiosynthesis , chemistry , benzamide , sulfonyl , indole test , ligand (biochemistry) , bromide , fluoride , pet imaging , nuclear chemistry , stereochemistry , medicinal chemistry , receptor , positron emission tomography , organic chemistry , inorganic chemistry , nuclear medicine , medicine , biochemistry , alkyl
Abstract PipISB [ N ‐(4‐fluoro‐benzyl)‐4‐(3‐(piperidin‐1‐yl)‐indole‐1‐sulfonyl)benzamide, 9] was identified as a selective high potency CB 1 receptor ligand. Here we describe the labeling of 9 with positron‐emitters to provide candidate radioligands for imaging brain CB 1 receptors with positron emission tomography (PET). The radiolabeling of 9 was achieved by two methods, method A with carbon‐11 and method B with fluorine‐18. In method A, [ 11 C]9 was prepared in one step from [ 11 C]carbon monoxide, itself prepared from cyclotron‐produced [ 11 C]carbon dioxide. In method B, [ 18 F]9 was prepared from cyclotron‐produced [ 18 F]fluoride ion in a two‐stage, four‐step synthesis with [ 18 F]4‐fluoro‐benzyl bromide as a labeling agent. The radiosynthesis time for method A was 44 min; decay‐corrected radiochemical yields (RCYs) from [ 11 C]carbon monoxide ranged from 3.1 to 11.6% and specific radioactivities ranged from 21 to 67 GBq/µmol. The radiosynthesis time for method B was 115 min; RCYs from [ 18 F]fluoride ion ranged from 1.5 to 5.6% and specific radioactivities ranged from 200 to 348 GBq/µmol. With these methods, [ 11 C]9 and [ 18 F]9 may be prepared in adequate activity and quality for future evaluation as PET radioligands. Copyright © 2008 John Wiley & Sons, Ltd.