Novel 1,3-dipropyl-8-(1-heteroarylmethyl-1H-pyrazol-4-yl)-xanthine derivatives as high affinity and selective A2B adenosine receptor antagonists

A series of new 1,3-dipropyl-8-(1-heteroarylmethyl-1H-pyrazol-4-yl)-xanthine derivatives as A2B-AdoR antagonists have been synthesized and evaluated for their binding affinities for the A2B, A1, A2A, and A3-AdoRs. 8-(1-((3-phenyl-1,2,4-oxadiazol-5-yl)methyl)-1H-pyrazol-4-yl)-1,3-dipropyl-1H-purine-2,6(3H,7H)-dione (4) displayed high affinity (Ki = 1 nM) and selectivity for the A2B-AdoR versus A1, A2A, and A3-AdoRs (A1/A2B, A2A/A2B, and A3/A2B selectivity ratios of 370, 1100, and 480, respectively). The synthesis and SAR of this novel class of compounds are presented herein.