Biologically Active Linear Metabolites of Arachidonic Acid—The First Endogenous Ligand of the Cannabinoid Receptor

Despite their simple construction the metabolites of arachidonic acid (1) are very important in the regulation of elementary biological processes such as the immune response and the receptor-mediated signal transduction in the nervous system. The first naturally occurring ligand of the cannabinoid receptor, which plays a role in the control of movement and the perception of pain, was isolated recently from porcine brain. This N-(2-hydroxyethyl)amide derivative of 1 binds to the receptor. Attempts to identify other arachidonic acid derivatives as ligands specific to this receptor have failed so far.