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摘要
3-Methyl-1-phenyl-2-pyrazolin-5-one (edaravone, 1), known as a potent free radical scavenger, has been developed as a medical drug for the treatment of acute cerebral infarction. With the aim of developing radiotracers for imaging free radicals in vivo, 1-(3'-[I-125]iodophenyl)-3-methy-2-pyrazolin-5-one (I-125-2) was synthesized by two methods, via isotopic exchange and interhalogen exchange under solvent-free conditions, in which iodo- and bromo-derivatives were used as labeling precursors, respectively. After HPLC purification, I-125-2 was obtained in modest isolated radiochemical yields (ca. 20%) with high radiochemical purities by both methods. The former gave specific activities of 0.2-0.6 kBq/mu mol, whereas the latter approach achieved specific activities of more than 0.14 GBq/mu mol. On attempting to prepare an injectable formulation for I-125-2 with high specific activity, its radiochemical purities dropped to about 60-70%. Unlabeled analog 2 was found to have lipophilic and antioxidant properties similar to edaravone. Intravenous injection of I-125-2 with low specific radioactivity into normal mice showed signs of distribution profiles similar to reported results for C-14-labeled edaravone in normal rats.
- 出版日期2010-8
