Eicosanoid Formation and Regulation of Phospholipase A2
The oxygenated derivatives of arachidonic acid that are biologically active are defined as eicosanoids (Needleman et al., 1986). Among the eicosanoids are prostaglandins, including prostacyclin, thromboxanes, leukotrienes, and various hydroxy acids (Fig. 1). The eicosanoid precursor, arachidonic acid, is esterified in the 2-position of several phospholipids, and it must be hydrolyzed before the eicosanoids can be synthesized (Fig. 1). The liberated arachidonic acid can be enzymatically oxygenated by a membrane-bound cyclooxygenase, a microsomal cytochrome p450 or a cytosolic lipoxygenase with the formation of unstable intermediate products (Fig.1). These intermediate products include endoperoxides for prostaglandin production and epoxides and hydroperoxides for leukotriene and hydroxy acid formation (Fig 1). The type of arachidonate oxygenation is characteristic of the enzymes that each cell contains.
KeywordsProstaglandin Glucocorticoid Thrombin PGE2 Hydroperoxide
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- Lapetina, E. G., 1984, Phospholipases, in: “Annual Reports Medicinal Chemistry,” 19: 213.Google Scholar
- Lapetina, E. G., 1986, Inositide-dependent and -independent mechanisms in platelet activation, in: “Phosphoinositides and Receptor Mechanisms,” J. W. Putney, Jr., ed., p. 271, Alan R. Liss, Inc., New York.Google Scholar
- Samuelsson, B., 1981, Prostaglandins, thromboxanes, and leukotrienes: Formation and biological roles, in: “The Harvey Lectures,” Series 75, Academic Press, New York, NY, 1: 40.Google Scholar