posted on 2021-06-14, 07:14authored byPhuc N.
H. Trinh, Daniel J. W. Chong, Katie Leach, Stephen J. Hill, Joel D. A. Tyndall, Lauren T. May, Andrea J. Vernall, Karen J. Gregory
Adenosine
receptors are attractive therapeutic targets for multiple
conditions, including ischemia-reperfusion injury and neuropathic
pain. Adenosine receptor drug discovery efforts would be facilitated
by the development of appropriate tools to assist in target validation
and direct receptor visualization in different native environments.
We report the development of the first bifunctional (chemoreactive
and clickable) ligands for the adenosine A1 receptor (A1R) and adenosine A3 receptor (A3R) based
on an orthosteric antagonist xanthine-based scaffold and on an existing
structure–activity relationship. Bifunctional ligands were
functional antagonists with nanomolar affinity and irreversible binding
at the A1R and A3R. In-depth pharmacological
profiling of these bifunctional ligands showed moderate selectivity
over A2A and A2B adenosine receptors. Once bound
to the receptor, ligands were successfully “clicked”
with a cyanine-5 fluorophore containing the complementary “click”
partner, enabling receptor detection. These bifunctional ligands are
expected to aid in the understanding of A1R and A3R localization and trafficking in native cells and living systems.