Synthesis and<i>in vitro</i>evaluation of<sup>18</sup>F-labelled di- and tri(ethylene glycol) metomidate esters
作者:Maria Erlandsson、Håkan Hall、Bengt Långström
DOI:10.1002/jlcr.1597
日期:2009.6.15
By replacing the alkyl chain in a metomidate ester with 18F-labelled di- or tri(ethylene glycol) chains, two 18F-labelled PET tracers, i.e. 2-(2-[18F]fluoroethoxy)ethyl 1-[(1R)-1-phenylethyl]-1H-imidazole-5-carboxylate (1) and 2-[2-(2-[18F]fluoroethoxy)ethoxy]ethyl 1-[(1R)-1-phenylethyl]-1H-imidazole-5-carboxylate (2), were synthesized. Two precursors, 2-(2-bromoethoxy)ethyl 1-[(1R)-1-phenylethyl]-1H-imidazole-5-carboxylate and 2-[2-(2-chloroethoxy)ethoxy]ethyl 1-[(1R)-1-phenylethyl]-1H-imidazole-5-carboxylate, were prepared and used in one-step nucleophilic [18F]fluorination reactions using conventional and microwave heating. Organ distribution, frozen section autoradiography and metabolite analysis were performed. The decay-corrected radiochemical yields of 1 and 2 were 26±8 and 23±8%, respectively, when they were prepared using conventional heating. By performing microwave heating, the reaction time could be decreased and the yields of analogues 1 and 2 could be increased to 57±12 and 51±18%, respectively. Organ distribution studies in the rat showed considerable uptake in the lungs, adrenals and liver. Both compounds bound with low nonspecific binding (1: approx. 20–30%; 2: 2.9% or lower) to tissue from pig and human normal and pathologic adrenals. Metabolite analyses were performed in rats after 5 and 30 min for tracer 1 (20±6 and 2±1%) and tracer 2 (27±5 and 6±4%). Both compounds are interesting candidates for the detection of different types of adrenal disorders. Copyright © 2009 John Wiley & Sons, Ltd.
通过将咪达唑仑酯中的烷基链替换为18F标记的二或三(乙二醇)链,合成了两种18F标记的PET示踪剂,即2-(2-[18F]氟乙氧基)乙基1-[(1R)-1-苯乙基]-1H-咪唑-5-羧酸酯(1)和2-[2-(2-[18F]氟乙氧基)乙氧基]乙基1-[(1R)-1-苯乙基]-1H-咪唑-5-羧酸酯(2)。两种前体,2-(2-溴乙氧基)乙基1-[(1R)-1-苯乙基]-1H-咪唑-5-羧酸酯和2-[2-(2-氯乙氧基)乙氧基]乙基1-[(1R)-1-苯乙基]-1H-咪唑-5-羧酸酯,通过传统和微波加热条件下的一步亲核[18F]氟化反应进行制备。进行了组织分布、冷冻切片放射自显影和代谢物分析。使用传统加热制备时,1和2的衰变校正放射化学产率分别为26±8%和23±8%。通过微波加热,反应时间可以缩短,类似物1和2的产率可以分别提高到57±12%和51±18%。在大鼠的器官分布研究显示在肺、肾上腺和肝脏中有明显的摄取。两种化合物在猪和人类正常及病理性肾上腺组织中结合,非特异性结合较低(1:约20–30%;2:2.9%或更低)。在注射示踪剂1和2后5和30分钟,大鼠中的代谢物分析分别为(示踪剂1:20±6%和2±1%;示踪剂2:27±5%和6±4%)。这两种化合物是检测不同类型肾上腺疾病的潜在候选物。
版权©2009 John Wiley & Sons, Ltd.