Formation of Novel Isoprostane-Like Compounds from Docosahexaenoic Acid
Isoprostanes (IsoPs) are prostaglandin (PG)-like compounds that are formed non-enzymatically in vivo by free radical-induced peroxidation of arachidonic acid.1 Formation of these compounds proceeds through bicyclic endoperoxide intermediates resembling PGH2. The endoperoxide intermediates are then reduced to PGF2-like compounds termed F2-IsoPS or undergo rearrangement to form D-ring and E-ring IsoPs (D2/E2-IsoPs)2 and thromboxane-like compounds (isothromboxanes).3 Unlike cyclooxygenase derived PGs in which arachidonic acid must first be released from phospholipids prior to oxygenation, IsoPs are formed completely in situ esterified in lipids and are subsequently released by a phospholipase(s) A2.4 Since the identification of these compounds, we have accumulated a large body of evidence showing that quantification of IsoPs provides an accurate measure of lipid peroxidation in vitro and in vivo.5,6 Further, at least three of these compounds possess biological activity1,2,7 and thus may mediate some of the adverse effects associated with oxidant stress.
KeywordsHydroxyl Retina Prostaglandin Kato Tetrachloride
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