New, non-adenosine, high-potency agonists for the human adenosine A2B receptor with an improved selectivity profile compared to the reference agonist n-ethylcarboxamidoadenosine

The adenosine A(2B) receptor is the least well characterized of the four known adenosine receptor subtypes because of the absence of potent, selective agonists. Here, we present five non-adenosine agonists. Among them, 2-amino-4-(4-hydroxyphenyl)-6-(1H-imidazol-2-ylmethylsulfanyl)pyridine-3,5.-dicarbonitrile, 17, LUF5834, is a high-efficacy partial agonist with EC50 = 12 nM and 45-fold selectivity over the adenosine A(3) receptor but lacking selectivity versus the A, and A(2A) subtypes. Compound 18, LUF5835, the 3-hydroxyphenyl analogue, is a full agonist with EC50 = 10 nM.