Novel Reversible-Binding PET Ligands for Imaging Monoacylglycerol Lipase Based on the Piperazinyl Azetidine Scaffold
Jian Rong, Wakana Mori, Xiaotian Xia, Michael A. Schafroth, Chunyu Zhao, Richard Van, Tomoteru Yamasaki, Jiahui Chen, Zhiwei Xiao, Ahmed Haider, Daisuke Ogasawara, Atsuto Hiraishi, Tuo Shao, Yiding Zhang, Zhen Chen, Fuwen Pang, Kuan Hu, Lin Xie, Masayuki Fujinaga, Katsushi Kumata, Yuancheng Gou, Yang Fang, Shuyin Gu, Huiyi Wei, Liang Bao, Hao Xu, Thomas Collier, Yihan Shao, Richard E. Carson, Benjamin F. Cravatt, Lu Wang, Ming‐Rong Zhang, Steven H. Liang
Abstract
Monoacylglycerol lipase (MAGL) is a 33 kDa serine protease primarily responsible for hydrolyzing 2-arachidonoylglycerol into the proinflammatory eicosanoid precursor arachidonic acid in the central nervous system. Inhibition of MAGL constitutes an attractive therapeutic concept for treating psychiatric disorders and neurodegenerative diseases. Herein, we present the design and synthesis of multiple reversible MAGL inhibitor candidates based on a piperazinyl azetidine scaffold. Compounds 10 and 15 were identified as the best-performing reversible MAGL inhibitors by pharmacological evaluations, thus channeling their radiolabeling with fluorine-18 in high radiochemical yields and favorable molar activity. Furthermore, evaluation of [18F]10 and [18F]15 ([18F]MAGL-2102) by autoradiography and positron emission tomography (PET) imaging in rodents and nonhuman primates demonstrated favorable brain uptakes, heterogeneous radioactivity distribution, good specific binding, and adequate brain kinetics, and [18F]15 demonstrated a better performance. In conclusion, [18F]15 was found to be a suitable PET radioligand for the visualization of MAGL, harboring potential for the successful translation into humans.