Synthesis, biological activity and molecular modelling of new trisubstituted 8-azaadenines with high affinity for A1 adenosine receptors
摘要:
We describe here the synthesis and biological activity of new 8-azaadenines bearing both a phenyl group on C(2) and a 9-benzyl group substituted in the ortho position with a Cl or a F atom or a CF3 group, to verify the synergistic effect of a combination of these substitution patterns on binding with the A(1) adenosine receptors. In position N-6 aliphatic and cycloaliphatic substituents were chosen which had been shown to bind well with the A(1) receptors. Because of the high lipophilicity of these kinds of molecules, we also introduced a hydroxyalkyl substituent in the same position. The compounds obtained generally showed a very good affinity and selectivity for A(1) receptors. Some of the compounds showed K-i in the nanomolar range, one even in the subnanomolar range (0.6 nM). Molecular docking calculations were performed in order to evaluate the interaction energies between the bovine A(1) receptor model and the selected ligands, and then to correlate these energies with biological activities of the ligands as obtained from the experiments. Molecular docking analysis suggests different binding modes towards A(1) receptors that are plausible for these ligands. (c) 2006 Elsevier Masson SAS. All rights reserved.
2,9-Disubstituted-N6-(arylcarbamoyl)-8-azaadenines as new selective A3 adenosine receptor antagonists: Synthesis, biochemical and molecular modelling studies
摘要:
A number of N-6-(N-arylcarbamoyl)-2-substituted-9-benzyl-8-azaadenines, obtained by a modification of the synthetic scheme used to prepare selective A(1) ligands, by only three or two steps, are described. At first we prepared a series of 2-phenyl-9-benzyl-8-azaadenines having as N-6 substituent a variously substituted N-phenylcarbamoyl group. Some of these derivatives demonstrated good affinity towards the A(3) subtype but low selectivity. Compounds having p-CF3, p-F and p-OCH3, as substituents on the phenylcarbamoyl group were selected as lead compounds for the second part of this study. Without modifying the N-6 substituent, which would assure A(3) affinity, we varied the 9 and 2 positions on these molecules to enhance selectivity. Some compounds having a p-methyl group on the 2-phenyl substituent showed a very good affinity and selectivity for the A(3) subtype, revealing the first class of A(3) adenosine receptor selective antagonists with a bicyclic structure strictly correlated to the adenine nucleus. The molecular modelling work, carried out using the DOCK program, supplied two models which may be useful for a better understanding of the binding modes. Both models highlighted the preferred interacting tautomeric forms of the antagonists for human A(1) and A(3) receptors. (c) 2005 Elsevier Ltd. All rights reserved.