Synthesis and biological activity of trisubstituted adenines as A(2A) adenosine receptor antagonists

The discovery of new drugs for the treatment of neurodegenerative disorders, such as Parkinson's disease, has become an attractive field of research. Due to the regulation of D2 receptor activity by A2 A adenosine receptor, potent and selective ligands of A2 A subtype could be useful tools to study neurodegenerative disorders. A series of 2,8-disubstituted-9-ethyladenine derivatives was synthesized and tested in binding affinity assay at human adenosine receptors. New compounds showed good affinity and selectivity at A2 A receptor versus the other subtypes. The introduction of a bromine atom in 8-position increased the affinity of these compounds, leading to ligands with Ki in the nanomolar range.