KF-26777 explained

KF-26777 is a drug which acts as a potent and selective antagonist for the adenosine A₃ receptor, with sub-nanomolar affinity (A₃ Ki=0.2nM) and high selectivity over the other three adenosine receptor subtypes.^[1] Simple xanthine derivatives such as caffeine and DPCPX have generally low affinity for the A₃ subtype and must be extended by expanding the ring system and adding an aromatic group to give high A₃ affinity and selectivity.^[2]

Notes and References

1. Saki M, Tsumuki H, Nonaka H, Shimada J, Ichimura M . KF26777 (2-(4-bromophenyl)-7,8-dihydro-4-propyl-1H-imidazo[2,1-i]purin-5(4H)-one dihydrochloride), a new potent and selective adenosine A3 receptor antagonist . European Journal of Pharmacology . 444 . 3 . 133–41 . May 2002 . 12063073 . 10.1016/S0014-2999(02)01662-X.
2. Baraldi PG, Tabrizi MA, Gessi S, Borea PA . Adenosine receptor antagonists: translating medicinal chemistry and pharmacology into clinical utility . Chemical Reviews . 108 . 1 . 238–63 . January 2008 . 18181659 . 10.1021/cr0682195 .