N6-functionalized congeners of adenosine with high potency at A2-adenosine receptors: potential ligands for affinity chromatography.

Adenosine analogues substituted at N6 with spacer arms designed for attachment to soluble macromolecules or to solid supports for affinity chromatography are agonists at the A2-adenosine receptor that mediates coronary vasodilation in the dog. The most active analogues had spacer arms terminating in -NH2, -NHCH3 or in a biotin residue. Comparisons of coronary vasoactivity with affinity for brain A1 adenosine receptors identified one biotin-containing analogue as relatively selective for coronary A2 receptors. The complex of this analogue with avidin retained coronary vasoactivity.