One-step radiosynthesis of [18F]LBT-999: a selective radioligand for the visualization of the dopamine transporter with PET
作者:Frédéric Dollé、Julie Helfenbein、Françoise Hinnen、Sylvie Mavel、Zoïa Mincheva、Wadad Saba、Marie-Anne Schöllhorn-Peyronneau、Heric Valette、Lucette Garreau、Sylvie Chalon、Christer Halldin、Jean-Claude Madelmont、Jean-Bernard Deloye、Michel Bottlaender、Joël Le Gailliard、Denis Guilloteau、Patrick Emond
DOI:10.1002/jlcr.1412
日期:2007.7
LBT-999 (8-((E)-4-fluoro-but-2-enyl)-3-beta-p-tolyl-8-aza-bicyclo[3.2.1]octane-2-beta-carboxylicacid methyl ester) is a recently developed cocaine derivative belonging to a new generation of highly selective dopamine transporter (DAT) ligands (KD: 9 nM for the DAT and IC50 > 1000 nM for the serotonin and norepinephrine transporter). Initial fluorine-18-labelling of LBT-999 was based on the robust and reliable two-step radiochemical pathway often reported for such tropane derivatives, involving first the preparation of (E)-1-[18F]fluoro-4-tosyloxybut-2-ene followed by a N-alkylation reaction with the appropriate nor-tropane moiety. In the present work, a simple one-step fluorine-18-labelling of LBT-999 is reported, based on a chlorine-for-fluorine nucleophilic aliphatic substitution, facilitating as expected both automation and final high-performance liquid chromatography (HPLC) purification. The process involves: (A) reaction of K[18F]F–Kryptofix®222 with the chlorinated precursor (3.5–4.5 mg) at 165°C for 10 min in DMSO (0.6 mL) followed by (B) C-18 PrepSep cartridge pre-purification and finally (C) semi-preparative HPLC purification on a Waters Symmetry® C-18. Typically, 3.70–5.92 GBq of [18F]LBT-999 (> 95% chemically and radiochemically pure) could be obtained with specific radioactivities ranging from 37 to 111 GBq/µmol within 85–90 min (HPLC purification and Sep-Pak-based formulation included), starting from a 37.0 GBq [18F]fluoride batch (overall radiochemical yields: 10–16%, non-decay-corrected). Copyright © 2007 John Wiley & Sons, Ltd.
LBT-999(8-((E)-4-氟-丁-2-烯基)-3-β-对甲苯基-8-氮杂双环[3.2.1]辛烷-2-β-羧酸甲酯)是最近开发的一种可卡因衍生物,属于新一代高选择性多巴胺转运体(DAT)配体(DAT 的 KD:9 nM,5-羟色胺和去甲肾上腺素转运体的 IC50 > 1000 nM)。LBT-999 最初的氟-18 标记是基于此类托烷衍生物经常报道的稳健可靠的两步放射化学途径,首先制备 (E)-1-[18F]氟-4-tosyloxybut-2-ene,然后与适当的正托烷分子进行 N- 烷基化反应。本研究报告了一种简单的一步法氟-18 标记 LBT-999,该方法基于氯对氟的亲核脂肪族取代,有助于实现自动化和最终的高效液相色谱(HPLC)纯化。该过程包括:(A) K[18F]F-Kryptofix®222 与氯化前体(3.5-4.5 毫克)在 165°C 下于 DMSO(0.6 毫升)中反应 10 分钟,然后 (B) C-18 PrepSep 滤芯预纯化,最后 (C) 在 Waters Symmetry® C-18 上进行半制备型 HPLC 纯化。通常情况下,从 37.0 GBq [18F]氟化物批次开始,在 85-90 分钟内可获得 3.70-5.92 GBq [18F]LBT-999(化学纯度和放射化学纯度大于 95%),特定放射性活度范围为 37-111 GBq/µmol(包括 HPLC 纯化和基于 Sep-Pak 的配方)(总体放射化学收率:10-16%,非衰变校正)。Copyright © 2007 John Wiley & Sons, Ltd. All Rights Reserved.