Purpose: The vesicular acetylcholine transporter (VAChT) is a specific biomarker for imaging presynaptic cholinergic neurons. The syntheses and C-11 labeling of two potent enantiopure VAChT inhibitors are reported here.
Procedures: Two VAChT inhibitors, (±)-2 and (±)-6, were successfully synthesized. A chiral HPLC column was used to resolve the enantiomers from each corresponding racemic mixture for in vitro characterization. The radiosyntheses of (−)-[11C]2 and (−)-[11C]6 from the corresponding desmethyl phenol precursor was accomplished using [11C]methyl iodide or [11C]methyl triflate, respectively.
Results: The synthesis of (−)-[11C]2 was accomplished with 40–50 % radiochemical yield (decay-corrected), SA > 480 GBq/μmol (EOB), and radiochemical purity >99 %. Synthesis of (−)-[11C]6 was accomplished with 5–10 % yield, SA > 140 GBq/μmol (EOB), and radiochemical purity >97 %. The radiosynthesis and dose formulation of each tracer was completed in 55–60 min.
Conclusions: Two potent enantiopure VAChT ligands were synthesized and 11C-labeled with good radiochemical yield and specific activity.
- Alzheimer’s disease
- PET imaging