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Synthesis, biological activity and molecular modelling studies of tricyclic alkylimidazo-, pyrimido- and diazepinopurinediones.

Drabczyńska A, Karcz T, Szymańska E, Köse M, Müller CE, Paskaleva M, Karolak-Wojciechowska J, Handzlik J, Yuzlenko O, Kieć-Kononowicz K - Purinergic Signal. (2013)

Bottom Line: The best derivative was compound 11, showing 100 % protection at a dose of 100 mg/kg without symptoms of neurotoxicity.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688, Kraków, Poland.

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.

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cAMP accumulation studies in CHO cells expressing the human adenosine A2A receptor. The dose–response curves for the NECA-induced stimulation of cAMP accumulation were generated with NECA in the absence or in the presence of two different concentrations of 28 (a) or 35 (b). Graphs from two independent experiments performed in duplicates with mean values ± SEM are shown. Both investigated compounds shifted the concentration–response curve for NECA in a parallel manner to the right, indicating competitive antagonism. Apparent Kb values were as follows: 1,510 ± 20 nM (28) and 1,210 ± 130 nM (35)
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Fig3: cAMP accumulation studies in CHO cells expressing the human adenosine A2A receptor. The dose–response curves for the NECA-induced stimulation of cAMP accumulation were generated with NECA in the absence or in the presence of two different concentrations of 28 (a) or 35 (b). Graphs from two independent experiments performed in duplicates with mean values ± SEM are shown. Both investigated compounds shifted the concentration–response curve for NECA in a parallel manner to the right, indicating competitive antagonism. Apparent Kb values were as follows: 1,510 ± 20 nM (28) and 1,210 ± 130 nM (35)

Mentions: Two of the most potent rat and human A2A receptor ligands (compounds 28 and 35) were investigated for their functional properties using cAMP accumulation assay. They were investigated for their potency to inhibit NECA-induced cAMP accumulation in CHO cells expressing the human A2A receptor (Fig. 3). The compounds clearly behaved as competitive antagonists as the concentration–response curve of NECA was shifted to the right in a parallel fashion in their presence. Kb values determined in living CHO cells expressing the human adenosine A2A receptor were well in accordance with Ki values determined in radioligand binding studies at membrane preparations of the same cell line. Owing to the structural similarity of all compounds in this series, we suppose that they are all antagonists.Fig. 3


Synthesis, biological activity and molecular modelling studies of tricyclic alkylimidazo-, pyrimido- and diazepinopurinediones.

Drabczyńska A, Karcz T, Szymańska E, Köse M, Müller CE, Paskaleva M, Karolak-Wojciechowska J, Handzlik J, Yuzlenko O, Kieć-Kononowicz K - Purinergic Signal. (2013)

cAMP accumulation studies in CHO cells expressing the human adenosine A2A receptor. The dose–response curves for the NECA-induced stimulation of cAMP accumulation were generated with NECA in the absence or in the presence of two different concentrations of 28 (a) or 35 (b). Graphs from two independent experiments performed in duplicates with mean values ± SEM are shown. Both investigated compounds shifted the concentration–response curve for NECA in a parallel manner to the right, indicating competitive antagonism. Apparent Kb values were as follows: 1,510 ± 20 nM (28) and 1,210 ± 130 nM (35)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3757144&req=5

Fig3: cAMP accumulation studies in CHO cells expressing the human adenosine A2A receptor. The dose–response curves for the NECA-induced stimulation of cAMP accumulation were generated with NECA in the absence or in the presence of two different concentrations of 28 (a) or 35 (b). Graphs from two independent experiments performed in duplicates with mean values ± SEM are shown. Both investigated compounds shifted the concentration–response curve for NECA in a parallel manner to the right, indicating competitive antagonism. Apparent Kb values were as follows: 1,510 ± 20 nM (28) and 1,210 ± 130 nM (35)
Mentions: Two of the most potent rat and human A2A receptor ligands (compounds 28 and 35) were investigated for their functional properties using cAMP accumulation assay. They were investigated for their potency to inhibit NECA-induced cAMP accumulation in CHO cells expressing the human A2A receptor (Fig. 3). The compounds clearly behaved as competitive antagonists as the concentration–response curve of NECA was shifted to the right in a parallel fashion in their presence. Kb values determined in living CHO cells expressing the human adenosine A2A receptor were well in accordance with Ki values determined in radioligand binding studies at membrane preparations of the same cell line. Owing to the structural similarity of all compounds in this series, we suppose that they are all antagonists.Fig. 3

Bottom Line: The best derivative was compound 11, showing 100 % protection at a dose of 100 mg/kg without symptoms of neurotoxicity.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, 30-688, Kraków, Poland.

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.

Show MeSH
Related in: MedlinePlus