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The preparation of 123/125 I‐clioquinol for the study of Aβ protein in Alzheimer's disease
Author(s) -
Papazian V.,
Jackson T.,
Pham T.,
Liu X.,
Greguric I.,
Loc'h C.,
Rowe C.,
Villemagne V.,
Masters C. L.,
Katsifis A.
Publication year - 2005
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.942
Subject(s) - clioquinol , chemistry , iodine 123 , specific activity , radiochemistry , high performance liquid chromatography , chelation , biodistribution , chromatography , nuclear chemistry , pharmacology , nuclear medicine , in vitro , biochemistry , enzyme , organic chemistry , medicine
Clioquinol or 5‐chloro‐7‐iodo‐8‐hydroxyquinoline (CQ) is a lipophilic hydroxyquinoline currently under investigation for the treatment of Alzheimer's disease by targeted copper and zinc chelation. CQ was radiolabelled with no‐carrier‐added iodine‐123/125 to give high specific activity analogs for SPECT imaging and biochemical studies. 123 I‐clioquinol ( 123 I‐CQ) was prepared by direct iodination of the activated hydroxyquinoline using a variety of oxidants. Highest yields (>85%) and purity were obtained when chloramine‐T or iodogen at pH 4–5 was used. Large‐scale radiolabelled 123 I‐CQ was purified by reverse‐phase HPLC using a C‐18 small ‘Rocket®’ column. The radiochemical purity of 123 I‐CQ as assessed by analytical HPLC was 99.1±0.6% ( n = 9) with specific activity higher than 3 GBq/nmol for 123 I‐CQ and 80 MBq/nmol for 125 I‐CQ. The total preparation time was 40 min and starting from 3.7 GBq of iodine‐123, more than 2.5 GBq of formulated 123 I‐CQ as radiopharmaceutical was available for clinical investigations. Using the same method of preparation, 125 I‐CQ was produced in radiochemical and chemical purity higher than 97% with a specific activity of 80 MBq/nmol. Copyright © 2005 John Wiley & Sons, Ltd.