A2A Adenosine Receptor Agonists and their Potential Therapeutic Applications. An Update

Background: Adenosine is an endogenous purine nucleoside, which mediates a variety of important biological processes and diseases, such as vasodilation, inflammation, cancer, wound healing, ischemia reperfusion injury, Parkinson disease, infectious diseases, and other CNS disorders. Particularly important are the A2A receptors that have been expressed in the lung, liver, heart, cardiovascular tissues, leukocytes, neutrophils, and endothelial cells. This review provides an update of the latest A2A receptor agonists developed in the period 2005-2017, their selectivity regarding other adenosine receptors and their potential therapeutic applications. Methods: I have conducted an extensive search from the most common bibliographic databases for critically review the most recent works on the A2A receptor agonists and their therapeutic applications in inflammation, asthma and chronic obstructive pulmonary disease, myocardial perfusion imaging, sepsis, rheumatoid arthritis, and wound healing, among others. Results: In the last decade, a great deal of effort has been devoted to develop adenosine receptor agonists and antagonists for treatment of a number of diseases. Thus, for A2A receptor agonists more than 130 papers and reviews have been found, many of them highlighting the usefulness of these compounds in the field. Conclusions: Although so far many of the A2A receptor agonists have failed in clinical trials due to their side effects, some of them have been approved for protection against cardiac ischemia-reperfusion injury and anemia. The recently reported crystal structure of the human A2A receptor in complex with the agonist UK-432097 is a fundamental keystone for the development of new and selective A2A ligands with new therapeutic applications.