Synthesis, resolution, and: In vitro evaluation of three vesicular acetylcholine transporter ligands and evaluation of the lead fluorine-18 radioligand in a nonhuman primate

Xuyi Yue, Hongjun Jin, Hui Liu, Zonghua Luo, Xiang Zhang, Kota Kaneshige, Hubert P. Flores, Joel S. Perlmutter, Stanley M. Parsons and Zhude Tu: 2017 Organic and Biomolecular Chemistry Volume 15, Issue 24, 2017, Pages 5197-5209 Read More

Abstract

The vesicular acetylcholine transporter (VAChT) is a reliable biomarker for assessing cholinergic dysfunction associated with dementia. We recently reported three new potent and selective carbon-11 labeled VAChT radiotracers. Herein, we report the resolution with a Chiralcel OD column of three additional fluorine containing VAChT ligands in which a fluoroethoxy or fluoroethylamino moiety was substituted for the methoxy group. An in vitro competitive binding assay showed that (-)-7 had high potency for VAChT (Ki-VAChT = 0.31 ± 0.03 nM) and excellent selectivity for VAChT versus σ receptors (Ki-σ1 = 1870 ± 250 nM, Ki-σ2 = 5480 ± 140 nM). Three different radiolabeling approaches were explored; the radiosynthesis of (-)-[18F]7 was successfully accomplished via a stepwise two-pot, three-step method with moderate yield (11 ± 2%) and high radiochemical purity (>98%). PET imaging studies in a nonhuman primate indicated that (-)-[18F]7 rapidly entered the brain and accumulated in the VAChT-enriched striatum. The uptake of (-)-[18F]7 in the target striatal area peaked at 10 min and displayed improved clearance kinetics compared to the VAChT tracer [18F]VAT, which has been approved by the Food and Drug Administration (FDA) for first-in-man studies. These studies justify further investigation of (-)-[18F]7 and exploration of the structure-activity relationships of these fluoroethoxy and fluoroethylamino analogs. © 2017 The Royal Society of Chemistry.

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Posted on July 28, 2017
Posted in: HPAN, Neurodegeneration, Publications Authors: