The significance of 2-furyl ring substitution with a 2-(para-substituted) aryl group in a new series of pyrazolo-triazolo-pyrimidines as potent and highly selective hA3 adenosine receptor antagonists: new insights into structure affinity relathionship and receptor antagonist recognition.

Among the heterocyclic structures identified as potent human A3 (hA3) adenosine receptor’s antagonists, we have demonstrated that the new pyrazolo-triazolo-pyrimidines, bearing an aryl group in replacement of the C2-furyl ring, not only confer a good pharmacological profile (with significantly enhanced selectivity against other adenosine receptor subytpes) but also overcome the metabolic transformation of the furan ring into toxic intermediates.