Radiolabeled bioactive benzoheterocycles for imaging β-amyloid plaques in Alzheimer's disease

Alzheimer's disease (AD) is a debilitating neurodegenerative dementia that involves substantial neuronal loss. Extracellular deposition of neurotoxic β-amyloid (Aβ) plaques in the brain has been recognized as the central histological characteristic of AD. In the past decade, precise detection of the Aβ plaques at preclinical AD with positron emission tomography (PET) or single photon emission computed tomography (SPECT) has achieved continued development. A big category of Aβ imaging agents was benzoheterocycles which derived from Thioflavin-T (ThT), a traditional amyloid binding dye. This review summarizes the past and current status of radioactive benzoheterocycles designed to selectively bind to Aβ plaques. Separate sections discuss the chemical synthesis, in vitro and in vivo investigations of radiolabeled benzothiazole, benzoxazole, benzofuran, benzothiophene, indole, imidazopyridine and quinoxaline analogs to act as PET/SPECT candidates for imaging Aβ plaques.