Design, synthesis, and biological evaluation of A adenosine receptor antagonists containing pyrrolo[2,3-d]pyrimidin-2-amine skeleton.

A series of novel A adenosine receptor (AR) antagonists containing a pyrrolo[2,3-d]pyrimidin-2-amine skeleton were developed through a bioisosterism strategy based on human A AR structures. The synthesis of all targeted compounds was accomplished, and their inhibitory effectiveness against the A AR was assessed using cAMP assays. Notably, compounds 12a and 18e demonstrated superior inhibitory effects compared to the control compounds AB928 and ZM241385. Competitive radioligand binding experiments confirmed their high binding affinities to the A AR. Molecular docking studies revealed that the pyrrolo[2,3-d]pyrimidin-2-amine core moiety forms two π-π interactions with the aromatic residue Phe168, alongside forming hydrogen bonds with residues Glu169 and Asn253. This information elucidates the rationality of molecular design. Moreover, both compounds 12a and 18e exhibited negligible toxicity towards normal cell lines. Compound 12a also demonstrated favorable stabilities in liver microsomes and acceptable pharmacokinetic profiles in vivo. These findings underscore the promise of compound 12a as a leading candidate for further research and development, highlighting its potential therapeutic applications.