Novel Radioiodinated Aurones as Probes for SPECT Imaging of beta-Amyloid Plaques in the Brain

We report a novel series of radioiodinated aurone derivatives as probes for imaging A beta 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 A beta aggregates (K-i = 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 [I-121]15. Furthermore, a specific plaque labeling signal was observed in in vitro autoradiography of postmortem AD brain sections using [I-121]15. [I-121]15 may be a useful SPECT imaging agent for detecting A beta plaques in the brain of AD.