The synthesis of new adenosine A3 selective ligands containing bioisosteric isoxazoles

The synthesis and purinergic receptor binding of novel adenosine A3 ligands is described. Many selective A3 receptor agonists e.g. N-(3-iodobenzyl)adenosine-5′-methyluronamide (IB-MECA) contain a 4′-ribosylalkylamide moiety. We found that this amide and other 4′-functional groups could be replaced with an isosteric isoxazole, and the target molecules retained potent binding to the recombinant human A3 receptor.