Novel radioiodinated aurones as probes for SPECT imaging of β-amyloid plaques in the brain.

ABSTRACT
We report a novel series of radioiodinated aurone derivatives as probes for imaging Aβ 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 Aβ 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 [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 Aβ plaques in the brain of AD.