6-[¹⁸F]Fluoro-Dehydroascorbic Acid:Synthesis and Tissue Distribution in Mice

Abstract

6-Deoxy-6-[¹⁸F]fluoro-L-threo-2,3-hexodiulosonic acid γ-lactone(6-[¹⁸F]fluoro-dehydroascorbic acid, ¹⁸F-FDHA)was synthesized by oxidation of 6-deoxy-6-[¹⁸F]fluoro-L-ascorbic acid(¹⁸F-DFA)with Br₂, a route that is analogous to the original synthesis of FDHA, in order to develop a radiotracer for nuclear medical imaging. Tissue biodistribution of ¹⁸F-FDHA in fibrosarcoma-bearing mice showed a low accumulation of radioactivity in the brain, with both substantial in vivo defluorination and low tumoral uptake levels. Several organs of mice unfed for 24h showed a more significant increase in radioactivity postinjection of ¹⁸F-FDHA than did fed mice. Co-injection with 2-deoxyglucose of ¹⁸F-FDHA did not significantly alter brain and tumor uptake, as confirmed by tissue-to-blood ratios, and as compared to control experiments. Thus, ¹⁸F-FDHA does not exhibit desirable properties as a brain-targeting imaging agent for ascorbic acid bioactivity.