The isoprostanes in biology and medicine

Isoprostanes are a new class of lipids, isomers of the conventional enzymat ically derived prostaglandins, which are produced in vivo primarily by a fr ee radical-catalyzed peroxidation of polyunsaturated fatty acids. F-2-isopr ostanes, isomers of the enzyme-derived prostaglandin F-2 alpha, are the mos t studied species, but analogous isomers of other prostaglandins and leukot rienes have been described. Because of their mechanism of formation, specif ic structural features that distinguish them from other free radical-genera ted products and chemical stability, they can provide a reliable index for the oxidant component of several diseases in vivo. Consistent data suggest that formation of F-2-isoprostanes is altered in a variety of clinical sett ings putatively associated with oxidant stress. Moreover, measurement of F- 2-isoprostanes might provide a sensitive biochemical basis for dose-selecti on in studies of natural and synthetic antioxidants. Finally, some F-2-isop rostanes possess potent biological activities in vitro and in vivo, suggest ing that they may also act as mediators of the cellular effects of oxidativ e stress.