Radiosynthesis of a Novel 11C‐Labeled Derivative of 4’‐O‐Methylhonokiol and Its Preliminary Evaluation in an LPS Rat Model of Neuroinflammation

Cyclooxygenase type 2 (COX‐2) is an attractive biomarker for the visualization of neuroinflammation processes by positron emission tomography (PET). Neolignan 4’‐O‐methylhonokiol (MH) is known to have high anti‐inflammatory activity and inhibits the expression of COX‐2. We synthesized 4′‐[11C]methoxy‐5‐propyl‐1,1′‐biphenyl‐2‐ol ([11C]MPbP), a compound based on the MH structure and labeled with carbon‐11 (T1/2=20.4 min) and studied its distribution in rats treated with lipopolysaccharide (LPS). It was shown that the new ligand has significant inhibitory activity against COX‐2 (IC50=0.14 μM) and sufficient lipophilicity (logD7.4=2.46±0.12) for penetration the blood brain barrier (BBB). [11C]MPbP was obtained by 11C‐methylation using [11C]CH3I with decay‐corrected radiochemical yield of 20% based on [11C]CH3I with molar activity 10–15 GBq/μmol, high radiochemical purity (> 99%) and low level of chemical impurities (