Figure 1.

Structures of the major endocannabinoids identified to date; most are based on the 20-carbon fatty acid, arachidonic acid though palmitoylethanolamide (the activity of which as an endocannabinoid is controversial) and the CB₁ cannabinoid and TRPV1 agonist, oleamide, are exceptions with shorter chain lengths. The most frequently studied is anandamide (an agonist at CB₁ and CB₂ receptors as well as TRPV1 channels), which with 2-arachidonoylglycerol (an agonist at both CB₁ and CB₂ receptors with generally higher efficacy than anandamide¹¹) is found to occur in many tissues of the cardiovascular system, including the heart and blood cells (especially platelets and monocytes). 12-S-hydroxyanandamide, which activates CB₁ receptors, is synthesized by 12-lipoxygenase from anandamide taken up by platelets.²¹ Since 12-S-hydroxyanandamide is not a substrate for fatty acid amide hydrolase, then conversion of anandamide to this oxygenated derivative might have the effect of prolonging signaling due to anandamide synthesis.