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Discovery of a High Affinity Adenosine A1/A3 Receptor Antagonist with a Novel 7-Amino-pyrazolo[3,4-d]pyridazine Scaffold.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Suchankova, Anna 
Stampelou, Margarita 
Koutsouki, Klontiana 
Pousias, Athanasios 
Dhingra, Lakshiv 

Abstract

Here we describe the design and synthesis of pyrazolo[3,4-d]pyridazines as adenosine receptor (AR) ligands. We demonstrate that the introduction of a 3-phenyl group, together with a 7-benzylamino and 1-methyl group at the pyrazolopyridazine scaffold, generated the antagonist compound 10b, which displayed 21 nM affinity and a residence time of ∼60 min, for the human A1R, 55 nM affinity and a residence time of ∼73 min, for the human A3R and 1.7 μΜ affinity for the human A2BR while not being toxic. Strikingly, the 2-methyl analog of 10b, 15b, had no significant affinity. Docking calculations and molecular dynamics simulations of the ligands inside the orthosteric binding area suggested that the 2-methyl group in 15b hinders the formation of hydrogen bonding interactions with N6.55 which are considered critical for the stabilization inside the orthosteric binding cavity. We, therefore, demonstrate that 10a is a novel scaffold for the development of high affinity AR ligands. From the mutagenesis experiments the biggest effect was observed for the Y2717.46A mutation which caused an ∼10-fold reduction in the binding affinity of 10b.

Description

Keywords

Adenosine A(1) receptor, adenosine A(3) receptor, adenosine A(2B )receptor, antagonist, binding kinetics, BRET, cAMP, cytotoxicity, molecular dynamics, mutagenesis, residence time

Journal Title

ACS Med Chem Lett

Conference Name

Journal ISSN

1948-5875
1948-5875

Volume Title

13

Publisher

American Chemical Society (ACS)
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/M00015X/2)