Formation of prostaglandins E2 and D2 via the isoprostane pathway: a mechanism for the generation of bioactive prostaglandins independent of cyclooxygenase.

It has heretofore been assumed that the cyclooxygenases (COXs) are solely responsible for peostaglandin (PG) synthesis in vivo. An important structural feature of PGH2 formed by COX is the trans-configuration of side chains relative to the prostane ring. Previously, we reported that a series of PG-like compounds termed isoprostanes (IsoPs) are formed in vivo in humans from the free radical-catalyzed peroxidation of arachidonate independent of COX.