Development of high-affinity fluorinated ligands for cannabinoid subtype 2 receptor, and in vitro evaluation of a radioactive tracer for imaging.

The development of neurodegenerative diseases is associated with cerebral inflammation, which activates resident immune cells of the central nervous system (CNS), namely microglial cells that show an up-regulation of the cannabinoid subtype 2 receptor (CBR) expression. Therefore our work aimed to design and synthesize a radiotracer for the detection of CBR expression by positron emission tomography (PET) allowing an early diagnosis of neurodegenerative diseases. For the development of such a PET tracer, N-alkyl-substituted indole-3-yl-tetramethylcyclopropylketones served as lead structures due to their high CBR potency and selectivity, allowing radiolabeling on the N-alkyl chain.