[18F]FMDAA1106 and [18F]FEDAA1106: two positron-Emitter labeled ligands for peripheral benzodiazepine receptor (PBR)

We synthesized and evaluated N-(5-fluoro-2-phenoxyphenyl)-N-(2-[18F]fluoromethyl-5-methoxybenzyl)acetamide ([18F]-FMDAA1106) and N-(5-fluoro-2-phenoxyphenyl)-N-(2-[18F]fluoroethyl-5-methoxybenzyl)acetamide ([18F]FEDAA1106) as two potent radioligands for peripheral benzodiazepine receptors (PBR). [18F]FMDAA1106 and [18F]FEDAA1106 were respectively synthesized by fluoroalkylation of the desmethyl precursor DAA1123 with [18F]FCH2I and [18F]FCH2CH2Br. Ex vivo autoradiograms of [18F]FMDAA1106 and [18F]FEDAA1106 binding sites in the rat brains revealed that a high radioactivity was present in the olfactory bulb, the highest PBR density region in the brain.