Novel Irreversible Agonists Acting at the A1 Adenosine Receptor.

The A1 adenosine receptor (A1AR) is an important G protein-coupled receptor that regulates a range of physiological functions. Herein we report the discovery of novel irreversible agonists acting at the A1AR, which have the potential to serve as useful research tools for studying receptor structure and function. A series of novel adenosine derivatives bearing electrophilic substituents was synthesized, and four compounds, 8b, 15a, 15b, and 15d, were shown to possess similar potency and efficacy to the reference high efficacy agonist, NECA, in an assay of ERK1/2 phosphorylation assay. Insensitivity to antagonist addition in a real-time, label-free, xCELLigence assay was subsequently used to identify compounds that likely mediated their agonism through an irreversible interaction with the A1AR. Of these compounds, 15b and 15d were more directly validated as irreversible agonists of the A1AR using membrane-based [3H]DPCPX and [35S]GTPγS binding experiments.