– PSB 0777 ammonium hydrate is a potent and selective adenosine A2A receptor full agonist, with K i values of 44.4 nM for rat A2A receptors and 360 nM for human A2A receptors. For rat and human A1 receptors, it has significantly lower affinity, with K i values of ≥10000 nM and 541 nM, respectively. The compound exhibits poor brain penetration and is not orally absorbable. It is of interest in research related to inflammatory bowel disease (IBD) [1] [2] [3].