Development of 18F-Labeled Radiotracers for PET Imaging of the Adenosine A2A Receptor: Synthesis, Radiolabeling and Preliminary Biological Evaluation

Autor: Thu Hang Lai, Susann Schröder, Magali Toussaint, Sladjana Dukić-Stefanović, Mathias Kranz, Friedrich-Alexander Ludwig, Steffen Fischer, Jörg Steinbach, Winnie Deuther-Conrad, Peter Brust, Rareş-Petru Moldovan
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: International Journal of Molecular Sciences, Vol 22, Iss 5, p 2285 (2021)
Druh dokumentu: article
ISSN: 1422-0067
1661-6596
DOI: 10.3390/ijms22052285
Popis: The adenosine A2A receptor (A2AR) represents a potential therapeutic target for neurodegenerative diseases. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor changes of receptor density and/or occupancy during the A2AR-tailored therapy, we designed a library of fluorinated analogs based on a recently published lead compound (PPY). Among those, the highly affine 4-fluorobenzyl derivate (PPY1; Ki(hA2AR) = 5.3 nM) and the 2-fluorobenzyl derivate (PPY2; Ki(hA2AR) = 2.1 nM) were chosen for 18F-labeling via an alcohol-enhanced copper-mediated procedure starting from the corresponding boronic acid pinacol ester precursors. Investigations of the metabolic stability of [18F]PPY1 and [18F]PPY2 in CD-1 mice by radio-HPLC analysis revealed parent fractions of more than 76% of total activity in the brain. Specific binding of [18F]PPY2 on mice brain slices was demonstrated by in vitro autoradiography. In vivo PET/magnetic resonance imaging (MRI) studies in CD-1 mice revealed a reasonable high initial brain uptake for both radiotracers, followed by a fast clearance.
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