Radiosynthesis of [¹¹C]MNS for PET imaging of NLRP3 inflammasome with [¹¹C]nitromethane in one-pot and its evaluation in rat brains

3,4-Methylenedioxy-β-nitrostyrene (MNS) is an inhibitor of NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3) inflammasome. This inflammasome is a potential PET imaging target, because it is involved in the aggregation of amyloid-β and tau proteins in Alzheimer's disease brains. We succeeded in a challenging radio-synthesis of [¹¹C]MNS using nitromethylenating piperonal with [¹¹C]nitromethane (CH₃NO₂) in one pot. We then evaluated this ligand in rat brains. Although [¹¹C]MNS had some moderate brain uptake and quick washout in rat brains, we were unable to detect any presence of specific binding of this ligand to NLRP3 either in vivo or in vitro. Further studies appear needed to develop more suitable radioligands for PET imaging of NLRP3. (author)