Synthesis and adenosine receptor affinity and potency of 8-alkynyl derivatives of adenosine

Adenosine derivatives bearing different (ar)alkynyl chains at the 8-position were synthesized and tested at human adenosine receptors. Binding studies showed that all compounds possess affinity for the A3 subtype in the high nM range. Moreover, guanosine 5'-O-(3-35S]thio)triphosphate binding assay indicated that the 8-alkynyl adenosines behaved as antagonists of NECA at A3 receptors.