Pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine Derivatives: Potent and Selective A2A Adenosine Antagonists
摘要:
A series of pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine derivatives (10a-o,q,r), bearing alkyl and aralkyl chains on positions 7 and 8, were synthesized in the attempt to obtain potent and selective antagonists for the A(2A) adenosine receptor subtype. The compounds were tested in binding and functional assays to evaluate their potency for the A(2A) compared with the A(1) adenosine receptor subtype. In binding studies in rat brain membranes, most of the compounds showed affinity for A(2A) receptors in the low nanomolar range with a different degree of A(2A) versus A(1) selectivity. Comparison of N-7 (10a-d,h-o)- and N-8 (10e-g)-substituted pyrazolo derivatives indicates that N-7 substitution decreases the A(1) affinity with the concomitant increase of A(2A) selectivity. Specifically, the introduction of a 3-phenylpropyl group at pyrazolo nitrogen in position 7 (101) increased significantly the A(2A) selectivity, being 210-fold, while the A(2A) receptor affinity remained high (K-i = 2.4 nM). With regards to the affinity for A(2A) receptors, also the compound 10n, bearing in the 7-position a beta-morpholin-4-ylethyl group, deserves attention (K-i = 5.6 nM) even though the A(2A) selectivity (84-fold) was not as high as that of 101. Conversely, the compound 10m (N-7-4-phenylbutyl derivative) showed a remarkable selectivity (A(1)/A(2A) ratio = 129) associated with lower A(2A) affinity (K-i = 21 nM). In functional studies, most of the compounds examined reversed 5'-(N-ethylcarbamoyl)adenosine-induced inhibition of rabbit platelet aggregation inhibition which is a biological response mediated by the A(2A) receptor subtype. The compounds are potent and selective A(2A) antagonists which can be useful to elucidate the pathophysiological role of this adenosine receptor subtype. These compounds deserve to be further developed to assess their potential for treatment of neurodegenerative disorders such as Parkinson's disease.
Pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine Derivatives: Potent and Selective A2A Adenosine Antagonists
摘要:
A series of pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine derivatives (10a-o,q,r), bearing alkyl and aralkyl chains on positions 7 and 8, were synthesized in the attempt to obtain potent and selective antagonists for the A(2A) adenosine receptor subtype. The compounds were tested in binding and functional assays to evaluate their potency for the A(2A) compared with the A(1) adenosine receptor subtype. In binding studies in rat brain membranes, most of the compounds showed affinity for A(2A) receptors in the low nanomolar range with a different degree of A(2A) versus A(1) selectivity. Comparison of N-7 (10a-d,h-o)- and N-8 (10e-g)-substituted pyrazolo derivatives indicates that N-7 substitution decreases the A(1) affinity with the concomitant increase of A(2A) selectivity. Specifically, the introduction of a 3-phenylpropyl group at pyrazolo nitrogen in position 7 (101) increased significantly the A(2A) selectivity, being 210-fold, while the A(2A) receptor affinity remained high (K-i = 2.4 nM). With regards to the affinity for A(2A) receptors, also the compound 10n, bearing in the 7-position a beta-morpholin-4-ylethyl group, deserves attention (K-i = 5.6 nM) even though the A(2A) selectivity (84-fold) was not as high as that of 101. Conversely, the compound 10m (N-7-4-phenylbutyl derivative) showed a remarkable selectivity (A(1)/A(2A) ratio = 129) associated with lower A(2A) affinity (K-i = 21 nM). In functional studies, most of the compounds examined reversed 5'-(N-ethylcarbamoyl)adenosine-induced inhibition of rabbit platelet aggregation inhibition which is a biological response mediated by the A(2A) receptor subtype. The compounds are potent and selective A(2A) antagonists which can be useful to elucidate the pathophysiological role of this adenosine receptor subtype. These compounds deserve to be further developed to assess their potential for treatment of neurodegenerative disorders such as Parkinson's disease.
Pyrazolo[4,3-<i>e</i>]1,2,4-triazolo[1,5-<i>c</i>]pyrimidine Derivatives as Highly Potent and Selective Human A<sub>3</sub> Adenosine Receptor Antagonists: Influence of the Chain at the N<sup>8</sup> Pyrazole Nitrogen
作者:Pier Giovanni Baraldi、Barbara Cacciari、Romeo Romagnoli、Giampiero Spalluto、Stefano Moro、Karl-Norbert Klotz、Edward Leung、Katia Varani、Stefania Gessi、Stefania Merighi、Pier Andrea Borea
DOI:10.1021/jm001047y
日期:2000.12.1
IB-MECA was measured in membranes of CHO cells stably transfected with the human A(3) receptor. The new compounds are among the most potent and selective A(3) antagonists so far described. The derivatives with higher affinity at human A(3) adenosine receptors proved to be antagonists, in the cAMP assay, capable of inhibiting the effect of IB-MECA with IC(50) values in the nanomolar range, with a trend strictly
The compounds of the following formula:
1
wherein R, R
2
, R
3
and A have the meanings given in the specification, are endowed with selective A
3
adenosine receptor antagonist activity. These compounds can be used in a pharmaceutical composition to treat disorders caused by excessive activation of the A
3
receptor, or can be used in a diagnostic application to determine the relative binding of other compounds to the A
3
receptor. The compounds can be labeled, for example with fluorescent or radiolabels, and the labels used in vivo or in vitro to determine the presence of tumor cells which possess a high concentration of adenosine A
3
receptors.
The compounds of the following formula:
wherein R, R
2
, R
3
and A have the meanings given in the specification, are endowed with selective A
3
adenosine receptor antagonist activity. These compounds can be used in a pharmaceutical composition to treat disorders caused by excessive activation of the A
3
receptor, or can be used in a diagnostic application to determine the relative binding of other compounds to the A
3
receptor. The compounds can be labeled, for example with fluorescent or radiolabels, and the labels used in vivo or in vitro to determine the presence of tumor cells which possess a high concentration of adenosine A
3
receptors.
Pyrazolo[4,3-<i>e</i>]-1,2,4-triazolo[1,5-<i>c</i>]pyrimidine Derivatives as Highly Potent and Selective Human A<sub>3</sub> Adenosine Receptor Antagonists
作者:Pier Giovanni Baraldi、Barbara Cacciari、Romeo Romagnoli、Giampiero Spalluto、Karl-Norbert Klotz、Edward Leung、Katia Varani、Stefania Gessi、Stefania Merighi、Pier Andrea Borea