Studies On The Amino Acid Derivatives For Positron Emission Tomography Imaging

2-[¹⁸F]Fluoro-2-deoxyglucose(¹⁸F-FDG)is the most commonly used tracer for positron emission tomography?PET?imaging,but there are some limitations of¹⁸F-FDG due to the low sensitivity and specificity for the detection of certain tumors.To make up for the shortage of ¹⁸F-FDG,¹⁸F-labeled amino acid derivatives have been also employed in tumor imaging with PET in preclinical and clinical studies.Recently,we proposed the hypothesis that the N-(2-[¹⁸F]fluoropropionyl)group of the radiolabeled N-position amino acid derivatives could be considered as an extremely useful pharmacophore model for PET tumor imaging.In proof-of-concept studies,a series of N-substituted ¹⁸F-labeled amino acid derivatives containing2-[¹⁸F]fluoro-propionyl group was developed for PET tumor imaging in this work,such as ¹⁸F-FP-?-L-Glu,¹⁸F-FP-?-D-Glu,¹⁸F-FP-?-Glu,¹⁸F-FPGln and ¹⁸F-FPDopa,this class of the radiotracers demonstrated high tumor to background contrast and favorable pharmacokinetics in vivo.Moreover,Based on the molecular structures of glutamate and glutamine,three new N-substituted ¹⁸F-labeled amino acid derivatives containing2-[¹⁸F]fluorohexylgroupwerealsosynthesized,including¹⁸F-FH-?-L-Glu,¹⁸F-FH-Gln,¹⁸F-FH-?-Glu.Apoptosis is an inherent cellular self-destruction process,which is also involved in the course of numerous diseases.Recent studies have shown that apoptosis plays a significant part in the pathophysiology of pulmonary fibrosis.We hypothesize that accurate PET imaging of apoptosis may be able to provide a novel method for the detection of pulmonary fibrosis.In study,a new radiosynthetic route to prepare2-(3-[¹⁸F]fluoropropyl)-2-methylmalonic acid(¹⁸F-ML-8)was developed,and PET imaging of PF rats was performed at day 21 after instillation of bleomycin?BLM?.PET studies showed that compared with control group,4-to 5-fold greater uptake of¹⁸F-ML-8 in BLM-treated rats was found,which suggested that ¹⁸F-ML-8 as a PET apoptosis tracer could be used for monitoring of pulmonary fibrosis.