A dual fluorinated and iodinated radiotracer for PET and SPECT imaging of â└-amyloid plaques in the brain.
We report a fluorinated and iodinated radiotracer as a probe for PET/SPECT to detect of â└-amyloid (Aâ└) plaques in the brain of patients with Alzheimerüfs disease (AD). We successfully designed and synthesized the fluorinated and iodinated aurone derivative (3) and its radiolabels ([125I]3 and [18F]3). In binding experiments in vitro, 3 showed high affinity for Aâ└ aggregates (Ki = 6.81 nM). In brain sections of AD model mice, 3 intensely stained Aâ└ plaques. Furthermore, a specific plaque labeling signal was observed on the autoradiography of postmortem AD brain sections using [125I]3. In biodistribution experiments using normal mice, [125I]3 and [18F]3 displayed good uptake into and a rapid washout from the brain, properties highly desirable for Aâ└ imaging agents. These results suggest that 3 may function as a PET/SPECT dual imaging agent for detecting Aâ└ plaques in AD brains.