2-AG has been isolated from porcine brain, and has been characterized as the natural endocannabinoid ligand for the CB1 receptor.{4614,5306} Incubation of 2-AG with COX-2 and specific PGH2 isomerases in cell cultures and isolated enzyme preparations results in prostaglandin glycerol ester formation.{11045} The biosynthesis of PGH, PGD, PGE, PGF, and TXA-2-glyceryl ester compounds have all been documented. In RAW 264.7 cells, PGD2-2-glyceryl ester is the main COX metabolite.{11045} The 2-glyceryl ester moiety equilibrates rapidly (within minutes) with the more stable 1-glyceryl ester, producing a 10:90 mixture of the 1- and 2-glyceryl esters in typical aqueous media. While the stability and metabolism of these PG products have been investigated, little is known about their intrinsic biological activity.{10555}