The synthesis, radiolabeling and in vitro evaluation of new silicon-fluoride acceptor (SiFA) derivatized D2-receptor ligands is reported. The SiFA-technology simplifies the introduction of fluorine-18 into target specific biomolecules for Positron-Emission-Tomography (PET). However, one of the remaining challenges, especially for small molecules such as receptor-ligands, is the bulkiness of the SiFA-moiety. We therefore synthesized four Fallypride SiFA-conjugates derivatized either directly at the benzoic acid ring system (SiFA-DMFP, SiFA-FP, SiFA-DDMFP) or at the butyl-side chain (SiFA-M-FP) and tested their receptor affinities. We found D2-receptor affinities for all compounds in the nanomolar range (Ki(SiFA-DMFP) = 13.6 nM, Ki(SiFA-FP) = 33.0 nM, Ki(SiFA-DDMFP) = 62.7 nM and Ki(SiFA-M-FP) = 4.21 nM). The radiofluorination showed highest yields when 10 nmol of the precursors were reacted with [18F]fluoride/TBAHCO3 in acetonitrile. After a reversed phased cartridge purification the desired products could be isolated as an injectable solution after only 10 min synthesis time with radiochemical yields (RCY) of more than 40% in the case of SiFA-DMFP resulting in specific activities >41 GBq/µmol (>1,100 Ci/mmol). Furthermore, the radiolabeled products were shown to be stable in the injectable solutions, as well as in human plasma, for at least 90 min.
报告了新型
硅-
氟受体(SiFA)衍生 D2 受体
配体的合成、放射性标记和体外评估。SiFA 技术简化了将
氟-18 引入正电子发射断层扫描(PET)靶标特定
生物大分子的过程。然而,SiFA 分子的体积过大仍是一个难题,尤其是对于受体
配体等小分子而言。因此,我们合成了四种直接在
苯甲酸环系统(SiFA-
DMFP、SiFA-FP、SiFA-D
DMFP)或丁基侧链(SiFA-M-FP)上衍生的 FAllypride SiFA-共轭物,并测试了它们的受体亲和力。我们发现所有化合物的 D2 受体亲和力都在纳摩尔范围内(Ki(SiFA-
DMFP) = 13.6 nM、Ki(SiFA-FP) = 33.0 nM、Ki(SiFA-D
DMFP) = 62.7 nM 和 Ki(SiFA-M-FP) = 4.21 nM)。当 10 nmol 的前体与
乙腈中的 [18F]fluoride/T
BAHCO3 反应时,放射性
氟化的产率最高。经过反相滤芯纯化后,仅需 10 分钟的合成时间就能分离出所需产物的注射溶液,SiFA-
DMFP 的放射
化学收率(RCY)超过 40%,比活度大于 41 GBq/µmol(大于 1,100 Ci/mmol)。此外,放射性标记产品在注射液和人体血浆中至少能稳定存在 90 分钟。