Development of 2-(2-(3-(4-([18F]Fluoromethoxy- d2)phenyl)-7-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione for Positron-Emission-Tomography Imaging of Phosphodiesterase 10A in the Brain.

Abstract

Phosphodiesterase 10A (PDE10A) is a newly identified therapeutic target for central-nervous-system disorders. 2-(2-(3-(4-([18F]Fluoroethoxy)phenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione ([18F]MNI-659, [18F]5) is a useful positron-emission-tomography (PET) ligand for imaging of PDE10A in the human brain. However, the radiolabeled metabolite of [18F]5 can accumulate in the brain. In this study, using [18F]5 as a lead compound, we designed four new 18F-labeled ligands ([18F]6-9) to find one more suitable than [18F]5. Of these, 2-(2-(3-(4-([18F]fluoromethoxy- d2)phenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione ([18F]9) exhibited high in vitro binding affinity ( Ki = 2.9 nM) to PDE10A and suitable lipophilicity (log D = 2.2). In PET studies, the binding potential (BPND) of [18F]9 (5.8) to PDE10A in the striatum of rat brains was significantly higher than that of [18F]5 (4.6). Furthermore, metabolite analysis showed much lower levels of contamination with radiolabeled metabolites in the brains of rats given [18F]9 than in those given [18F]5. In conclusion, [18F]9 is a useful PET ligand for PDE10A imaging in brain.

• Authors: Wakana Mori, Tomoteru Yamasaki, Masayuki Fujinaga, Masanao Ogawa, Yiding Zhang, Akiko Hatori, Lin Xie, Katsushi Kumata, Hidekatsu Wakizaka, Yusuke Kurihara, Takayuki Ohkubo, Nobuki Nengaki, Ming-Rong Zhang
• Journal: Journal of medicinal chemistry (J Med Chem) Vol. 62 Issue 2 Pg. 688-698 (01 24 2019) ISSN: 1520-4804 [Electronic] United States
• PMID: 30516998 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 2-(2-(3-(4-(2-fluoroethoxy)phenyl)-7-methyl-4-oxo-3,4-dihydroquinazolin-2-yl)ethyl)-4-isopropoxyisoindoline-1,3-dione
• Fluorine Radioisotopes
• Ligands
• Phthalimides
• Quinazolinones
• Radiopharmaceuticals
• PDE10A protein, rat
• Phosphoric Diester Hydrolases
• Fluorine-18

Topics

• Animals
• Brain (diagnostic imaging, metabolism)
• Drug Evaluation, Preclinical
• Fluorine Radioisotopes (chemistry)
• Isotope Labeling
• Ligands
• Male
• Mice
• Phosphoric Diester Hydrolases (chemistry, metabolism)
• Phthalimides (blood, chemistry, metabolism)
• Positron-Emission Tomography
• Protein Binding
• Quinazolinones (blood, chemistry, metabolism)
• Radiopharmaceuticals (chemistry, metabolism)
• Rats
• Rats, Sprague-Dawley
• Tissue Distribution