Prostaglandins, thromboxanes and leukotrienes

Eicosanoid (Section 27.4) A lipid derived biologically from 5,8.11,14-eicosatetraenoic acid, or arachidonic acid. Prostaglandins, thromboxanes and leukotrienes are examples. 

J. E. Pike and D. R. Morton Jr., Advances in Prostaglandin, Thromboxane and Leukotriene Research, Raven Press, New York, 1985. 

Neutrophils are also a source of mediators (PAFs, prostaglandins, thromboxanes, and leukotrienes) that contribute to BHR and airway inflammation. 

The omega (<0) numbering system is also used for unsaturated fatty acids. The co-family describes the position of the last double bond relative to the end of the chain. The omega designation identifies the major precursor fatty add, e.g., arachidonic add is formed from linoleic acid (co-6 family). Arachidonic acid is itself an important precursor for prostaglandins, thromboxanes, and leukotrienes. 

Prostaglandins, thromboxanes, and leukotrienes (the eicosanoids), derived from arachidonate, are extremely potent hormones. 

M. Narisada, M. Ohtani, F. Watanabe, K. Uchida, H. Arita, M. Doteuchi, M. Ueda, K. Hanasaki, H. Kakushi, K. Otani, S. Hara and M. Nakajima, Advances in Prostaglandin, Thromboxane and Leukotriene Research, 19, 659 (1989). 

The prostaglandins, thromboxanes, and leukotrienes have been shown to have a variety of effects on virtually every major physiologic system. Studies have indicated that these compounds can influence cardio-... 

PRIMARY PHYSIOLOGIC EFFECTS OF THE MAJOR CLASSES OF PROSTAGLANDINS, THROMBOXANES, AND LEUKOTRIENES ... 

Eicosanoids The general term for the group of 20-carbon fatty acids that includes the prostaglandins, thromboxanes, and leukotrienes. These substances are involved in mediating inflammation and other pathologic responses. 

Feverfew has been used as an anti-inflammatory agent to treat rheumatoid arthritis. In vitro inhibition of prostaglandin, thromboxane, and leukotriene B4 synthesis as well as cytokine (TNF- and IL-1) expression have been reported. 

N Hamanaka, T Seko, T Miyazaki, A Kawasaki. Rational design of thromboxane A2 antagonists. Adv Prostaglandin, Thromboxane and Leukotriene Res 21 359— 362, 1990. 

Cells that synthesize prostaglandins, thromboxanes, and leukotrienes. 

Palmitic acid (C16 saturated) is the most common fatty acid in living things. Oleic acid (C g mono-unsaturated) is the major fatty acid in olive oil. Arachidonic acid (C20 tctra-unsaturated) is a rare fatty acid, which is the precursor of the very important prostaglandins, thromboxanes, and leukotrienes, of which more later. 

Eicosanoid mediators are derived from araehidonie aeid (eieosatetraenoie) and related poly-unsaturated fatty aeids, sueh as aeid eieosapentanoic acid. These fatty acids are mainly found as constituents of phospholipids in cellular membranes (Figure 12. la), and it is from there that they are mobilized for eicosanoid mediator synthesis. The major classes of eicosanoids are prostaglandins, thromboxanes, and leukotrienes. Eicosanoids are very widespread in the mammalian organism - most cells synthesize them. 

Linoleic acid and the family of fatty acids derived from it are called the omega-6 fatty acids (Figure 9.96). This is because the number of carbons from the methyl end to the first double bond is six. Linoleic acid is used to make arachidonic acid (20 4co6), a fatty acid essential for the synthesis of various hormones. These hormones are the prostaglandins, thromboxanes, and leukotrienes. These three classes... 

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