title: Synthesis, biological activity and molecular modelling studies of tricyclic alkylimidazo-, pyrimido- and diazepinopurinediones.
abstract: Syntheses and biological activities of imidazo-, pyrimido- and diazepino[2,1-f]purinediones containing N-alkyl substituents (with straight, branched or unsaturated chains) are described. Tricyclic derivatives were synthesized by the cyclization of 8-bromo-substituted 7-(2-bromoethyl)-, 7-(3-chloropropyl)- or 7-(4-bromobutyl)-theophylline with primary amines under various conditions. Compound 22 with an ethenyl substituent was synthesized by dehydrohalogenation of 9-(2-bromoethyl)-1,3-dimethyltetrahydropyrimido[2,1-f]purinedione. The obtained derivatives (5-35) were initially evaluated for their affinity at rat A1 and A2A adenosine receptors (AR), showing moderate affinity for both adenosine receptor subtypes. The best ligands were diazepinopurinedione 28 (K i = 0.28 μM) with fivefold A2A selectivity and the non-selective A1/A2A AR ligand pyrimidopurinedione 35 (K i A1 = 0.28 μM and K i A2A = 0.30 μM). The compounds were also evaluated for their affinity at human A1, A2A, A2B and A3 ARs. All of the obtained compounds were docked to the A2A AR X-ray structure in complex with the xanthine-based, potent adenosine receptor antagonist-XAC. The likely interactions of imidazo-, pyrimido- and diazepino[2,1-f]purinediones with the residues forming the A2A binding pocket were discussed. Furthermore, the new compounds were tested in vivo as anticonvulsants in maximal electroshock, subcutaneous pentylenetetrazole (ScMet) and TOX tests in mice (i.p.). Pyrimidopurinediones showed anticonvulsant activity mainly in the ScMet test. The best derivative was compound 11, showing 100 % protection at a dose of 100 mg/kg without symptoms of neurotoxicity. Compounds 6, 7, 8 and 14 with short substituents showed neurotoxicity and caused death. In rat tests (p.o.), 9 was characterized by a high protection index (>13.3). AR affinity did not apparently correlate with the antiepileptic potency of the compounds.
authors.affiliation: Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688, Kraków, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Drabczyńska
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Karcz
authors.forename: Ewa
authors.initials: E
authors.lastname: Szymańska
authors.forename: Meryem
authors.initials: M
authors.lastname: Köse
authors.forename: Christa E
authors.initials: CE
authors.lastname: Müller
authors.forename: Minka
authors.initials: M
authors.lastname: Paskaleva
authors.forename: Janina
authors.initials: J
authors.lastname: Karolak-Wojciechowska
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Handzlik
authors.forename: Olga
authors.initials: O
authors.lastname: Yuzlenko
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kieć-Kononowicz
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D051379:Mice; D008958:Models, Molecular; D011869:Radioligand Assay; D051381:Rats; D018047:Receptors, Purinergic P1; D013329:Structure-Activity Relationship; D014970:Xanthines / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000927:Anticonvulsants; D008024:Ligands; D018047:Receptors, Purinergic P1; D014970:Xanthines
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