title: Isoquinoline and quinazoline urea analogues as antagonists for the human adenosine A(3) receptor.
abstract: Isoquinoline and quinazoline urea derivatives were found to bind to human adenosine A(3) receptors. Series of N-phenyl-N'-quinazolin-4-ylurea derivatives and N-phenyl-N'-isoquinolin-1-ylurea derivatives were synthesized and tested in radioligand binding assays on their adenosine receptor affinities. A structure-affinity analysis indicated that on the 2-position of the quinazoline ring or the equivalent 3-position of the isoquinoline ring a phenyl or heteroaryl substituent increased the adenosine A(3) receptor affinity in comparison to unsubstituted or aliphatic derivatives. Furthermore, the structure-affinity relationship of substituted phenylurea analogues was investigated. Substituents such as electron-withdrawing or electron-donating groups were introduced at different positions of the benzene ring to probe electronic and positional effects of substitution. Substitution on the 3- or 4-position of the phenyl ring decreased the adenosine A(3) receptor affinity. Substitution at position 2 with an electron-donating substituent, such as methyl or methoxy, increased human adenosine A(3) receptor affinity, whereas substitution on the 2-position with an electron-withdrawing substituent did not influence affinity. Combination of the optimal substituents in the two series had an additive effect, which led to the potent human adenosine A(3) receptor antagonist N-(2-methoxyphenyl)-N'-(2-(3-pyridyl)quinazolin-4-yl)urea (VUF5574, 10a) showing a K(i) value of 4 nM and being at least 2500-fold selective vs A(1) and A(2A) receptors. Compound 10a competitively antagonized the effect of an agonist in a functional A(3) receptor assay, i.e., inhibition of cAMP production in cells expressing the human adenosine A(3) receptor; a pA(2) value of 8.1 was derived from a Schild plot. In conclusion, compound 10a is a potent and selective human adenosine A(3) receptor antagonist and might be a useful tool in further characterization of the human A(3) receptor.
authors.affiliation: Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Department of Pharmacochemistry, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. muylwyk@chem.vu.nl
authors.forename: J E
authors.initials: JE
authors.lastname: van Muijlwijk-Koezen
authors.forename: H
authors.initials: H
authors.lastname: Timmerman
authors.forename: H
authors.initials: H
authors.lastname: van der Goot
authors.forename: W M
authors.initials: WM
authors.lastname: Menge
authors.forename: J
authors.initials: J
authors.lastname: Frijtag Von Drabbe Künzel
authors.forename: M
authors.initials: M
authors.lastname: de Groote
authors.forename: A P
authors.initials: AP
authors.lastname: IJzerman
mesh_terms: D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D006224:Cricetinae; D006801:Humans; D007546:Isoquinolines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D058915:Purinergic P1 Receptor Antagonists; D011799:Quinazolines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D051381:Rats; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D007546:Isoquinolines; D058915:Purinergic P1 Receptor Antagonists; D011799:Quinazolines; D043684:Receptor, Adenosine A3; D018047:Receptors, Purinergic P1