Description | 13,14-dihydro-15-keto PGF2a E1 is an isoprostane. The isoprostanes embody a vast family of novel prostaglandin-like lipids that are produced by nonenzymatic peroxidation of arachidonic acid (AA) in response to free radicals and reactive oxygen species. Although free AA is required for the formation of prostaglandins by cyclooxygenases, the isoprostanes can be generated nonenzymatically from esterified AA in membrane phospholipids before being released by a phospholipase(s). Another dissimilarity is that isoprostanes feature side chains that are almost exclusively orientated cis relative to the cyclopentane ring and are therefore distinct from the prostaglandins, which always have side chains in the trans configuration. Nevertheless, isoprostanes are isomeric with prostaglandins and have been given the prefix D-, E-, and F{alpha}- to denote the prostane ring shared with PGD2, PGE2, and PGF2{alpha} respectively. An additional level of complexity is that peroxidation of AA can occur at one of any of four carbon atoms producing regioisomers, the so-called 5-, 12-, 8-, and 15-series isoprostanes, each consisting of eight racemic diastereomers. Thus, a total of 64 isomers can be generated for each of the D-, E-, and F{alpha}-ring isoprostanes. (PMID: 15528403) |