Novel radioiodinated aurones as probes for SPECT imaging of ƒÀ-amyloid plaques
in the brain.
We report a novel series of radioiodinated aurone derivatives as probes for imaging AƒÀ plaques in the brains of patients with Alzheimer's disease (AD) using single photon emission computed tomography (SPECT). In binding experiments in vitro, aurone derivatives showed very good affinity for AƒÀ aggregates (Ki = 1.1 to 3.4 nM). No-carrier-added radioiodinated aurones were successfully prepared through an iododestannylation reaction from the corresponding tributyltin derivatives. In biodistribution experiments using normal mice, aurone derivatives displayed high brain uptake (1.7-4.5% ID/g at 2 min) and rapid clearance from the brain (0.1-0.4% ID/g at 30 min), especially [125I]15. Furthermore, a specific plaque labeling signal was observed in in vitro autoradiography of postmortem AD brain sections using [125I]15. [125I]15 may be a useful SPECT imaging agent for detecting AƒÀ plaques in the brain of AD.