Targeting adenosine receptors with coumarins: Synthesis and binding activities of amide and carbamate derivatives

Abstract

Objectives With the aim of finding the structural features governing binding activity and selectivity against adenosine receptors (ARs), several 3-subtituted coumarins with amide (compounds 3-6) and carbamate (7-9) functions were synthesized. To study its possible influence on the binding activity and selectivity, a hydroxyl substituent was also introduced at position 4 of the coumarin moiety. Methods A new series of coumarins (3-9) were synthesized and evaluated by radioligand binding studies towards ARs. Key findings None of the 4-hydroxy derivatives (4, 8 and 9) showed binding affinity for any of the ARs. None of the compounds interacted with the hA2B AR (Ki > 100 000 nm). Compounds 3, 5, 6 and 7 had different activity profiles with dissimilar binding affinity and selectivity towards human A1, A 2A and A3 ARs. Conclusions The most remarkable derivative is compound 7, which presents the best affinity and selectivity for the A 3 adenosine receptor (Ki = 5500 nm). © 2012 Royal Pharmaceutical Society.