Single-Step High-Yield Radiosynthesis and Evaluation of a Sensitive 18F-Labeled Ligand for Imaging Brain Peripheral Benzodiazepine Receptors with PET.

[摘要]：Elevated levels of peripheral benzodiazepine receptors (PBR) are assocd. with activated microglia in their response to inflammation. Hence, PBR imaging in vivo is valuable for investigating brain inflammatory conditions. Sensitive, easily prepd., and readily available radioligands for imaging with positron emission tomog. (PET) are desirable for this purpose. We describe a new 18F-labeled PBR radioligand, namely [18F]N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline [I (X = 18F)] (II). II was produced easily through a single and highly efficient step, the reaction of [18F]fluoride ion with the corresponding bromo precursor. Ligand I (X = F) exhibited high affinity for PBR in vitro. PET showed that II was avidly taken into monkey brain and gave a high ratio of PBR-specific to nonspecific binding. II was devoid of defluorination in rat and monkey and gave predominantly polar radiometabolite(s). In rat, a low level radiometabolite of intermediate lipophilicity was identified as [18F]2-fluoro-N-(2-phenoxyphenyl)acetamide (III). II is a promising radioligand for future imaging of PBR in living human brain.

[全文传递流程]：

一般上传文献全文的时限在1个工作日内