Synthesis and structure-activity relationships of deazaxanthines: Analogs of potent A1- and A2-adenosine receptor antagonists

Article abstract of DOI:10.1021/jm00036a019

A set of 22 9-deazaxanthines (pyrrolo[3,2-d]pyrimidine-2,4-diones) and three 7-deazaxanthines (pyrrolo[2,3-d]pyrimidine-2,4-diones) with various substituents in the 1-, 3-, 7- or 9-, and 8-positions was synthesized and investigated in A1 and A2a adenosine receptor binding assays at rat brain cortical membranes and rat brain striatal membranes, respectively. 9- Deazaxanthines showed structure-activity relationships that were similar to those of xanthines. They were about equipotent to the corresponding xanthines at A2a adenosine receptors. 9-Deazaxanthines were generally at least 1-3- fold more potent than xanthines at A1 receptors and therefore exhibited higher A1 selectivities compared to the xanthines. 1,3-Dimethyl-8-(2- naphthyl)-9-deazaxanthine (19e) showed high affinity (K(i) = 26 nM) and selectivity for A1 adenosine receptors. A hydroxyl function at N7 of 9- deazaxanthines was unfavorable for A1 and A2a receptor binding. 7- Deazaxanthines were considerably less potent compared to xanthines and to 9- deazaxanthines at both receptor subtypes.