Practical Radiosynthesis and Preclinical Neuroimaging of [11C]isradipine, a Calcium Channel Antagonist
作者:Benjamin Rotstein、Steven Liang、Vasily Belov、Eli Livni、Dylan Levine、Ali Bonab、Mikhail Papisov、Roy Perlis、Neil Vasdev
DOI:10.3390/molecules20069550
日期:——
In the interest of developing in vivo positron emission tomography (PET) probes for neuroimaging of calcium channels, we have prepared a carbon-11 isotopologue of a dihydropyridine Ca2+-channel antagonist, isradipine. Desmethyl isradipine (4-(benzo[c][1,2,5]oxadiazol-4-yl)-5-(isopropoxycarbonyl)-2,6-dimethyl-1,4-dihydropyridine -3-carboxylic acid) was reacted with [11C]CH3I in the presence of tetrabutylammonium hydroxide in DMF in an HPLC injector loop to produce the radiotracer in a good yield (6 ± 3% uncorrected radiochemical yield) and high specific activity (143 ± 90 GBq·µmol−1 at end-of-synthesis). PET imaging of normal rats revealed rapid brain uptake at baseline (0.37 ± 0.08% ID/cc (percent of injected dose per cubic centimeter) at peak, 15–60 s), which was followed by fast washout. After pretreatment with isradipine (2 mg·kg−1, i.p.), whole brain radioactivity uptake was diminished by 25%–40%. This preliminary study confirms that [11C]isradipine can be synthesized routinely for research studies and is brain penetrating. Further work on Ca2+-channel radiotracer development is planned.
为了开发用于钙通道神经成像的体内正电子发射断层扫描(PET)探针,我们制备了一种二氢吡啶类 Ca2+ 通道拮抗剂--异拉地平的碳-11 同素异形体。去甲基异拉地平(4-(苯并[c][1,2,5]恶二唑-4-基)-5-(异丙氧羰基)-2,6-二甲基-1、4-二氢吡啶-3-羧酸)与[11C]CH3I 在四丁基氢氧化铵存在下于 DMF 中在高效液相色谱注射器环路中发生反应,生成放射性示踪剂,产率高(6 ± 3% 未校正放射化学产率),比活度高(合成结束时为 143 ± 90 GBq-µmol-1)。正常大鼠的 PET 成像显示,基线时脑摄取迅速(峰值时为 0.37 ± 0.08%ID/cc(每立方厘米注射剂量的百分比),15-60 秒),随后快速冲洗。在使用异拉地平(2 mg-kg-1,静脉注射)进行预处理后,全脑放射性摄取减少了 25%-40%。这项初步研究证实,[11C]异拉地平可以常规合成用于研究,而且具有脑穿透性。我们计划进一步开发 Ca2+ 通道放射性示踪剂。