Abstract
Dual modulation of adenosine A(2A) and A(3) receptors (ARs) is an emerging strategy for disorders involving receptor interplay. We designed and synthesized truncated 4'-thioadenosines bearing a C2-NH-R linker to enable dual A(2A)/A(3) AR engagement. Structure-activity trends showed that aryl amine analogues tended to display affinity toward both A(2A) and A(3) receptors, whereas aliphatic ones were inactive at both receptors. Ortho substitution in aryl amine analogues consistently enhanced binding affinity relative to meta or para substitution. Lead 4q (σ-morpholinophenyl) exhibited high affinity for hA(2A)AR and hA(3)AR (K (i) = 15.0 ± 1.2 nM; 4.5 ± 0.5 nM). Computational modeling supported orthosteric binding at both receptors, and cAMP assays revealed inverse agonism at hA(2A)AR (-19%) and antagonism at hA(3)AR (69% inhibition of the NECA response). These findings suggest that the C2-NH-R-modified, truncated 4'-thioadenosine as a compact scaffold for A(2A)/A(3) binding and highlight 4q as a dual ligand that may contribute to future AR ligand research.