Adenosine, its analogues and conjugates

Adenosine is an endogenous purine nucleoside that plays an important role in many biochemical processes. It acts through the four types of adenosine receptors: A(1), A(2A), A(2B), A(3) which are located i.a. in the immune, nervous, circulatory, respiratory or urinary system. Adenosine is used as an antiarrhythmic agent in the treatment of paroxysmal supraventricular tachycardia. However, due to a very short blood half-time other clinical applications are limited. In order to overcome this obstacle many analogues and conjugates of adenosine with better pharmacokinetic properties have been synthesized. Some of them have been successfully registered as drugs, but there is still a big number of adenosine analogues in clinical trials or preclinical studies. Synthesized compounds demonstrate not only antiarrhytmic, antinociceptive, anti-dibetic, antiphlogistic or antiviral actions but also influence the course of immune diseases, such as rheumatoid arthritis, nephritis, uveitis or endotoxin shock. This article is focused on novel adenosine analogues and conjugates with potential biological properties.