Isoprostanes

Article By:

FitzGerald, Garret A. Department of Pharmacology, Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania.

Rokach, Joshua Claude Pepper Institute and Department of Chemistry, Florida Institute of Technology, Melbourne, Florida.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.800800

A class of natural prostaglandin-like products. The isoprostanes (iPs) are isomeric with another class of natural products, the prostaglandins. The prostaglandins are the result of enzymatic oxygenation of polyunsaturated fatty acids (PUFAs), in particular arachidonic acid (AA). In contrast, the iPs are formed in vivo by a nonenzymatic, free-radical oxygenation of arachidonic acid. This important distinction in the mode of formation of the iPs is responsible for a more complex mixture of iPs being generated in vivo. For example, whereas the endoperoxide prostaglandin G₂ (PGG₂) is formed by the cyclooxygenase enzymes (COX1 and COX2), four classes of iPs are formed as a result of the free-radical oxygenation of arachidonic acid (Fig. 1), with each class containing 16 iPs for a total of 64 individual iP molecules. The discovery of iPs is important for two reasons: (1) group III iPs are incidental ligands for the prostaglandin receptors; hence they possess biological activity; (2) iPs are the product of oxidative stress. Their measurements have been shown to be a predictor of the onset and severity of inflammatory diseases such as Alzheimer's disease and atherosclerosis. See also: Alzheimer's disease; Circulation disorders; Eicosanoids; Free radical

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