A2A Receptor Ligands: Past, Present and Future Trends

The adenosine A2A receptor is a member of the G protein-coupled receptor family and mediates multiple physiological effects of adenosine, both at the central nervous system and at peripheral tissues. Increasing evidence relates the A2A receptor with several pathological conditions such as neurodegenerative disorders, inflammation, pharmacological stress, and wound healing renewing the interest in A2A receptor agonists and antagonists as promising leads for drugs. However some of them initially tested in clinical trials presented several side effects, short half-life, lower solubility, and in some cases a lack of effects, perhaps attributable to receptor desensitization or to low receptor density in the targeted tissue. For these reasons it is evident that additional rational chemical modifications of the existing A2A receptor ligands to improve their affinity/selectivity and bioavailability as well as further studies to get new template for A2AAR ligands are necessary. The purpose of this review is to analyze and summarize the past and the present aspects related to the medicinal chemistry of A2A receptor ligands. Moreover their current and possible therapeutic applications have been also highlighted