Exploring human adenosine A3 receptor complementarity and activity for adenosine analogues modified in the ribose and purine moiety

In this paper we investigated the influence on affinity, selectivity and intrinsic activity upon modification of the adenosine agonist scaffold at the 3- and 5'-positions of the ribofuranosyl moiety and the 2- and N-6-positions of the purine base. This resulted in the synthesis of various analogues, that is, 3-12 and 24-33, with good hA(3)AR selectivity and moderate-to-high affinities (as in 32, K-i = 27 nM). Interesting was the ability to tune the intrinsic activity depending on the substituent introduced at the 3'-position. (C) 2004 Elsevier Ltd. All rights reserved.