F-18 Stilbenes as PET imaging agents for detecting β-amyloid plaques in the brain

Imaging agents targeting beta-amyloid (A beta) may be useful for diagnosis and treatment of patients with Alzheimer's disease (AD). Compounds 3e and 4e are fluorinated stilbene derivatives displaying high binding affinities for A beta plaques in AD brain homogenates (K-i = 15 +/- 6 and 5.0 +/- 1.2 nM, respectively). In vivo biodistributions of [F-18]3e and [F-18]4e in normal mice exhibited excellent brain penetrations (5.55 and 9.75% dose/g at 2 min), and rapid brain washouts were observed, especially for [F-18]4e (0.72% dose/g at 60 min). They also showed in vivo plaque labeling in APP/PS1 or Tg2576 transgenic mice, animal models for AD. Autoradiography of postmortem AD brain sections and AD homogenate binding studies confirmed the selective and specific binding properties to A beta plaques. In conclusion, the preliminary results strongly suggest that these fluorinated stilbene derivatives, [F-18]3e and [(18F)]4e, are suitable candidates as A beta plaque imaging agents for studying patients with AD.