title: De novo analysis of receptor binding affinity data of 8-ethenyl-xanthine antagonists to adenosine A1 and A2a receptors.
abstract: The receptor binding affinity data to adenosine A1 and A2a receptors of a wide series of 8-ethenyl-xanthine derivatives has been analyzed by means of the Free-Wilson model. The analysis of the individual group contributions (aij) shows the importance of the presence of an ethenyl moiety at position 8 on the xanthine ring for obtaining selective A2a antagonists. The different aij values of the substituents for the adenosine. A1 receptor do not correlate with the corresponding ones for the A2a receptor, indicating the possibility to obtain A1 and A2a selective compounds. The presence of aromatic substituents at the 8-ethenyl group, such as 3,5-(OCH3)2-phenyl, permits to obtain strongly A2a selective compounds (affinity ratio of up to 100); moreover, it appears that 8-ethenyl-xanthinic derivatives cannot have high selectivity for the adenosine A1 receptor (affinity ratio < or = 10).
authors.affiliation: Dipartimento di Chimica, Università di Ferrara, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Dalpiaz
authors.forename: S
authors.initials: S
authors.lastname: Gessi
authors.forename: K
authors.initials: K
authors.lastname: Varani
authors.forename: P A
authors.initials: PA
authors.lastname: Borea
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008954:Models, Biological; D011485:Protein Binding; D051381:Rats; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014970:Xanthines / Q000037:antagonists & inhibitors*
chemical_list: D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1; D014970:Xanthines