(S-^(18)F-氟代甲基)-L-半胱氨酸的半自动化合成及其初步炎症PET显像

Semi-automated synthesis and preliminary inflammation PET study of(S-[^(18)F]-fluoromethyl)-L-cysteine

改进现有合成模块,研究(S-^(18)F-氟代甲基)-L-半胱氨酸(^(18)F-MCYS)的自动化合成工艺,并对无菌炎症模型进行正电子发射断层(PET)显像。以CH_2Br_2为前体,经氟化反应制备甲基化试剂^(18)F-CH_2Br,后者与溶解在二甲基亚砜(DMSO)中的L-半胱氨酸充分反应,用Sep-Pak C18小柱分离纯化,得到^(18)F-MCYS注射液。^(18)F-MCYS的未校正放化产率为(10.0±3.0)%(n=4,按^(18)F计算),放化纯度>95%,放化合成时间35 min。^(18)F-MCYS可被炎症组织高度摄取,但不稳定,不适于PET显像研究。

Semi-automated synthesis of （S-[18F]-fluoromethyl）-L-cysteine （18F-MCYS） was achieved with the modified commercial synthesizer and PET imaging of aseptic inflammatory mice was performed with 18F-MCYS. 18FCH2Br as 18F-fluoromethylation agent was prepared by 18F-fluorination of dibromomethane. 18F-MCYS was obtained from the reaction of 18FCH2Br with L-cysteine dissolved in dimethyl sulfoxide （DMSO） and purification on the solid-phase extraction cartridges. Without correction, the radiochemical yield of 18F-MCYS was （10.0±3.0）% （n=4, based on 18F-）, the radiochemical purity of 18F-MCYS was more than 95%, and the total synthesis time was about 35 min. It was found that 18F-MCYS had high uptake in the inflammatory tissues, but 18F-MCYS was unstable. Thus, 18F-MCYS is not a potential PET tracer for amino acid imaging and it is necessary for us to develop a novel stable 18F-labelled cysteine.