Lawler C P, Gilmore J H, Mooney D H, Mayleben M A, Atashi J R, Mileson B E, Wyrick S D, Mailman R B
Brain and Development Research Center, University of North Carolina School of Medicine, Chapel Hill 27599.
J Neurosci Methods. 1993 Aug;49(1-2):141-53. doi: 10.1016/0165-0270(93)90118-b.
The radiosynthesis of (1R)-(+)-1-phenyl-3-methyl-7-[125I]iodo-8-hydroxy- 2,3,4,5-tetrahydro-1H-3-benzazepine (commonly referred to as SCH23982) and its use as a high affinity D1 dopamine antagonist ligand have been reported previously. We now provide a simple and inexpensive protocol for the rapid and efficient synthesis of this radioligand based on the Cloramine-T-catalyzed reaction between the commercially available precursor (R)-(+)-1-phenyl-3-methyl- 8-hydroxy-2,3,4,5-tetrahydro-1H-3-benzazepine and carrier-free sodium [125I]iodide. [125I]SCH23982 is separated rapidly (within 20 min) from the precursor and reaction byproducts (e.g., chlorinated precursor, SCH23390) by reverse-phase HPLC on a C-8 column. The major iodinated product has been identified as SCH23982 based on co-chromatography with authentic SCH23982, UV spectral characteristics, and biological activity. The chromatographic effluent containing the active product is adsorbed on a C-18 Sep-Pak cartridge to remove mobile-phase constituents and permit it to be eluted and diluted to the desired concentration; this technique is used also for periodic repurification. Our synthesis protocol results in final purified product that incorporates ca. 50% of the initial 125I (tested using starting quantities of 1-10 mCi Na125I); the final product has a specific activity of ca. 2500 +/- 350 Ci/mmol. Data from in vitro receptor autoradiographic and homogenate studies with this radioligand are consistent with previously reported values in terms of expected receptor distribution, affinity, and density (KD of 1.0 nM, Bmax of 1400 fmol/mg protein in rat striatal membranes).
(1R)-(+)-1-苯基-3-甲基-7-[¹²⁵I]碘代-8-羟基-2,3,4,5-四氢-1H-3-苯并氮杂卓（通常称为SCH23982）的放射性合成及其作为高亲和力D1多巴胺拮抗剂配体的用途先前已有报道。我们现在提供一种简单且廉价的方案，用于基于市售前体(R)-(+)-1-苯基-3-甲基-8-羟基-2,3,4,5-四氢-1H-3-苯并氮杂卓与无载体碘化钠[¹²⁵I]之间的氯胺-T催化反应快速高效地合成这种放射性配体。[¹²⁵I]SCH23982通过在C-8柱上的反相高效液相色谱法在前体和反应副产物（例如氯化前体、SCH23390）中快速（20分钟内）分离。基于与真实的SCH23982的共色谱分析、紫外光谱特征和生物活性，主要碘化产物已被鉴定为SCH23982。含有活性产物的色谱流出物吸附在C-18 Sep-Pak柱上以去除流动相成分，并允许其被洗脱并稀释至所需浓度；该技术也用于定期再纯化。我们的合成方案得到的最终纯化产物包含约50%的初始¹²⁵I（使用1 - 10 mCi Na¹²⁵I的起始量进行测试）；最终产物的比活度约为2500±350 Ci/mmol。使用该放射性配体进行的体外受体放射自显影和匀浆研究数据在预期的受体分布、亲和力和密度方面（大鼠纹状体膜中KD为1.0 nM，Bmax为1400 fmol/mg蛋白质）与先前报道的值一致。
