Prostaglandin E2-1-glyceryl ester-d5 (PGE2-1-glyceryl ester-d5) contains five deuterium atoms. It is intended for use as an internal standard for the quantification of PGE2-1-glyceryl ester by GC- or LC-mass spectrometry. 2-Arachidonoyl glycerol (2-AG) has been isolated from porcine brain, and has been characterized as the natural endocannabinoid ligand for the central cannabinoid receptor.1,2 Incubation of 2-AG with cyclooxygenase-2 and specific PGH2 isomerases in cell cultures and isolated enzyme preparations results in PG glycerol ester formation.3 The biosynthesis of PGH, PGD, PGE, PGF, and thromboxane A-2-glyceryl ester compounds have all been documented. The 2-glyceryl ester moiety equilibrates rapidly (within minutes) with the more stable 1-glyceryl ester, producing a 10:90 2:1-glyceryl ester mixture in typical aqueous media. While the stability and metabolism of these prostaglandin products has been investigated, little is known about their intrinsic biological activity.4WARNING This product is not for human or veterinary use.