2-Phenylpyrazolo[4,3-d]pyrimidin-7-one as a new scaffold to obtain potent and selective human A3 adenosine receptor antagonists: new insights into the receptor-antagonist recognition.

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Lenzi O, Colotta V, Catarzi D, Varano F, Poli D, Filacchioni G, Varani K, Vincenzi F, Borea PA, Paoletta S, Morizzo E, Moro S

2-Phenylpyrazolo[4,3-d]pyrimidin-7-one as a new scaffold to obtain potent and selective human A3 adenosine receptor antagonists: new insights into the receptor-antagonist recognition.

J Med Chem. 2009 Dec 10;52(23):7640-52. doi: 10.1021/jm900718w.

PubMed ID

19743865 [ View in PubMed

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Abstract

A molecular simplification approach of previously reported 2-arylpyrazolo[3,4-c]quinolin-4-ones was applied to design 2-arylpyrazolo[4,3-d]pyrimidin-7-one derivatives as new human A(3) adenosine receptor antagonists. Substituents with different lipophilicity and steric hindrance were introduced at the 5-position of the bicyclic scaffold (R(5) = H, Me, Et, Ph, CH(2)Ph) and on the 2-phenyl ring (OMe, Me). Most of the synthesized derivatives were highly potent hA(3) adenosine receptor antagonists, the best being the 2-(4-methoxyphenyl)pyrazolo[4,3-d]pyrimidin-7-one (K(i) = 1.2 nM). The new compounds were also highly selective, being completely devoid of affinity toward hA(1), hA(2A), and hA(2B) adenosine receptors. On the basis of the recently published human A(2A) receptor crystallographic information, we propose a novel receptor-driven hypothesis to explain both A(3) AR affinity and A(3) versus A(2A) selectivity profiles of these new antagonists.

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Binding Properties

Drug	Target	Property	Measurement	pH	Temperature (°C)
4-{2-[(7-amino-2-furan-2-yl[1,2,4]triazolo[1,5-a][1,3,5]triazin-5-yl)amino]ethyl}phenol	Adenosine receptor A2a	Ki (nM)	1.2	N/A	N/A	Details