Development of [18F]-labeled pyrazolo[4,3-e ]-1,2,4-triazolo[1, 5-c ]pyrimidine (SCH442416) analogs for the imaging of cerebral adenosine A 2A receptors with positron emission tomography

Shivashankar Khanapur, Soumen Paul, Anup Shah, Suresh Vatakuti, Michel J.B. Koole, Rolf Zijlma, Rudi A.J.O. Dierckx, Gert Luurtsema, Prabha Garg, Aren Van Waarde, Philip H. Elsinga

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21 Citations (Scopus)


Cerebral adenosine A2A receptors (A2ARs) are attractive therapeutic targets for the treatment of neurodegenerative and psychiatric disorders. We developed high affinity and selective compound 8 (SCH442416) analogs as in vivo probes for A2ARs using PET. We observed the A2AR-mediated accumulation of [18F] fluoropropyl ([18F]-10b) and [18F]fluoroethyl ([ 18F]-10a) derivatives of 8 in the brain. The striatum was clearly visualized in PET and in vitro autoradiography images of control animals and was no longer visible after pretreatment with the A2AR subtype-selective antagonist KW6002. In vitro and in vivo metabolite analyses indicated the presence of hydrophilic (radio)metabolite(s), which are not expected to cross the blood-brain-barrier. [18F]-10b and [18F]-10a showed comparable striatum-to-cerebellum ratios (4.6 at 25 and 37 min post injection, respectively) and reversible binding in rat brains. We concluded that these compounds performed equally well, but their kinetics were slightly different. These molecules are potential tools for mapping cerebral A2ARs with PET.

Original languageEnglish
Pages (from-to)6765-6780
Number of pages16
JournalJournal of Medicinal Chemistry
Issue number15
Publication statusPublished - 14 Aug 2014
Externally publishedYes

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