Monoarachidonin, also termed 1-monoarachidonin or 1-arachidonoylglycerol (1-AG), is a polyunsaturated monoglyceride formed by esterifying glycerol with arachidonic acid at the sn-1 position. It plays a niche role in lipid biochemistry as a structural isomer of the endocannabinoid 2-AG and is frequently encountered in signaling studies despite its lower biological potency.
Chemical Structure
Monoarachidonin has the molecular formula C23H38O4 and a molecular weight of 378.6 g/mol. Its structure consists of a glycerol backbone esterified with an arachidonoyl chain (20:4 n-6, cis-5,8,11,14), resulting in an amphiphilic molecule characterized by high lipophilicity (LogP ≈ 6.3) and susceptibility to acyl migration and isomerization.
Physical Properties
This compound typically appears as a clear to pale yellow oily liquid with an approximate density of 0.992 g/cm³, a reported boiling point around 509 °C, and a pKa of 13.15. It is slightly soluble in organic solvents such as chloroform and methanol. To minimize oxidative degradation and conversion to the bioactive 2-AG isomer, storage at −20 °C under inert conditions is recommended.
Biological Role
In contrast to 2-arachidonoylglycerol, monoarachidonin exhibits weak agonistic activity toward the CB1 cannabinoid receptor, with an affinity approximately 10- to 100-fold lower. It is commonly generated through spontaneous or enzymatic isomerization, which can complicate quantitative analyses in endocannabinoid research. In addition, 1-AG may serve as a reservoir of arachidonic acid for eicosanoid biosynthesis, thereby potentially influencing inflammatory signaling pathways and cellular lipid metabolism.