Synthesis and structure-activity relationships of deazaxanthines: analogs of potent A1- and A2-adenosine receptor antagonists.
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 2-3-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 (Ki = 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.
Grahner
B
B
Eberhard-Karls-Universität Tübingen, Pharmazeutisches Institut, Germany.
Winiwarter
S
S
Lanzner
W
W
Müller
C E
CE
D000818:Animals; D001921:Brain / Q000378:metabolism; D066298:In Vitro Techniques; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014970:Xanthines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*
D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014970:Xanthines