N(6)-SUBSTITUTED 2-PHENYL-9-BENZYL-8-AZAADENINES - AFFINITY FOR ADENOSINE A(1)-RECEPTOR AND A(2)-RECEPTOR - A COMPARISON WITH 2-N-BUTYL ANALOGOUS DERIVATIVES .5.

The title compounds were prepared to evaluate their affinity towards a denosine A1 and A2 receptors. Some 2-phenyl-N(6)-substituted-8-azadeni nes showed good binding properties and good A1 selectivity. The biolog ical results allow us to confirm the presence in A1 receptors of a thi rd lipophilic pocket, able to receive the substituent on N(9), and to evince increased affinity when a phenyl group on C(2) substitutes an n -butyl group. These affinity differences between analogous 2-n-butyl a nd 2-phenyl derivatives indicate that they arrange themselves within A 1 receptors in a similar manner and suggest that this receptor is able to arrange 8-azaadenines, bearing three lipophilic substituents, in t wo different ways.