Chemoselective pre-conjugate radiohalogenation of unprotected mono- and multimeric peptides via oxime formation
Chemoselective pre-conjugate radiohalogenation of unprotected mono- and multimeric peptides via oxime formation
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DOI：
10.1524/ract.92.4.317.35591
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发表时间：
2004-01-01
影响因子：
1.8
通讯作者：
Wester, HJ
中科院分区：
文献类型：
--
作者：
Poethko, T;Schottelius, M;Wester, HJ
作为我们正在进行的开发用于临床PET成像的新（18）F标记肽的努力的一部分。研究并优化了一种新的两步（18）F标记方法，该方法基于未保护的氨氧基官能化肽与（18）F标记醛之间的化学选择性肟化反应。4-甲酰基-N，N，N-三甲基苯胺三氟甲磺酸盐的重结晶，并通过放射性HPLC或强阳离子交换/反相柱系统进行纯化。采用固相肽合成法合成了氨基氧乙酸（Aoa）修饰的模型肽LEF-NH（2）（Leu-Glu-Phe-NH（2））和含RGD的单、二、四聚体环肽。研究了用Aoa修饰的未保护肽形成N（4-[（18）F]氟亚苄基）肟（[（18）F]FBOA）的放射化学产率。优化的反应条件（60 ℃，0.5 mM肽，15 min，水溶液，pH 2.5）导致所研究的所有未保护肽的70%-90%缀合产率。在与氨基酸混合物的竞争实验中证明了化学选择性。携带M21黑色素瘤的小鼠中的生物分布显示在系列c（RGDfE）HEG-Dpr-[（18）F]FBOA <（c（RGDfE）HEG）（2）K-Dpr-[（18）F]FBOA <（（c（RGDfE）HEG）（2）K）（2）K-Dpr-[（18）F]FBOA中改善的肿瘤摄取和排泄行为。两小时注射完整的c（RGDfE）HEG-K-Dpr[（18）F]FBOA在血液、肝、肾和肿瘤中的分数> 90%，表明肟键的体内稳定性高。用（（c（RGDfE）HEG）（2）-K）（2）-K-Dpr-[（18）F]FBOA进行的初步PET研究显示了小鼠M21黑色素瘤的良好成像。这种方法也适用于其他放射性同位素（例如一般的放射性卤化），因此将提供广泛的应用领域。
As part of our ongoing efforts in the development of new (18)F-labeled peptides for clinical PET imaging. a new two-step (18)F-labeling methodology based on the chemoselective oxime formation between an unprotected aminooxy-functionalized peptide and a (18)F-labeled aldehyde was investigated and optimized.4-[(18)F]Fluorobenzaldehyde ([(18)F]FB-CHO) was prepared by direct n.c.a. fluorination of 4-formyl-N,N,N-trimethylanilimum triflate and purified by radio-HPLC or a strong-cation-exchance/reverse phase cartridge system. The aminooxyacetic acid (Aoa) modified model peptide LEF-NH(2) (Leu-Glu-Phe-NH(2)) and monomeric, dimeric and tetrameric RGD-containing cyclopeptides were synthesized by solid phase peptide synthesis. Radiochemical yields of N(4-[(18)F]fluorobenzylidene)-oxime-formation ([(18)F]FBOA) with the Aoa-modified unprotected peptides were investigated. Optimized reaction conditions (60degreesC, 0.5 mM peptide, 15 min, aqueous solution, pH 2.5) resulted in 70%-90% conjugation yields for all unprotected peptides studied. Chemoselectivity was demonstrated in competition experiments with amino acid mixtures. Biodistribution in M21 melanoma bearing mice showed improved tumor uptake and excretion behaviour in the series c(RGDfE)HEG-Dpr-[(18)F]FBOA < (c(RGDfE)HEG)(2)K-Dpr-[(18)F]FBOA < ((c(RGDfE)HEG)(2)K)(2)K-Dpr-[(18)F]FBOA. Two hours p.i. the fraction of intact c(RGDfE)HEG-K-Dpr[(18)F]FBOA in blood, liver, kidney and tumor was > 90%, indicating high in vivo stability of the oxime linkage. Initial PET studies with ((c(RGDfE)HEG)(2)-K)(2)-K-Dpr-[(18) F]FBOA showed excellent imaging of M21-melanomas in mice.In conclusion, the new two-step chemoselective (18)F-labeling fulfills all requirements for large scale syntheses C of peptides in clinical routine. This methodology is also adaptable to other radioisotopes (e.g. radiohalogenation in General) and will thus offer a broad field of application.