Radiosynthesis and preliminary biological evaluation of a new (18)F-labeled triethylene glycol derivative of triphenylphosphonium.

Delocalized lipophilic cations such as [(18)F]fluorobenzyltriphenylphosphonium ([(18)F]FBnTP) can accumulate in mitochondria and have been used in myocardial perfusion imaging (MPI). In this study, we established a simplified method for [(18)F]FBnTP synthesis using triphenylphosphine hydrobromide (PPh3 •HBr) without preparing an intermediate that contains benzyl bromide structure. Applying this new method, we synthesized and evaluated a novel (18)F-labeled PEGylated BnTP derivative ([(18)F]FPEGBnTP). In vitro cellular uptake study demonstrated that [(18)F]FPEGBnTP accumulated in cells in proportion to the relative intensity of mitochondrial membrane potential. Biodistribution study revealed that the heart : liver uptake ratio of [(18)F]FPEGBnTP (4.00 at 60 min) was superior to that of [(18)F]FBnTP (1.50 at 60 min). However, [(18)F]FPEGBnTP showed slow blood clearance and high radioactivity uptake in bone at 120-min post-injection. These results imply the possibility of [(18)F]FPEGBnTP being used as a MPI agent. However, there is a need of further structural optimization and flow-dependent uptake study.