Eicosanoids biological activity

Dietary fat serves several important nutritional functions. It is the source of essential fatty acids. Members of the n-6 and n-3 (also known as the co-6 and co-3) families of fatty acids are important constituents of cell membranes and serve as precursors of eicosanoids (biologically active compounds such as prostaglandins, thromboxanes, prostacyclins, and leukotrienes). Fat also serves as a carrier for the fat-soluble vitamins, and it is important source of energy. In addition, it has important culinary properties and contributes to the palatability of food. 

The organization of Part Two is according to structural type. The first section, Chapter Seven, is concerned with the synthesis of macrocyclic compounds. Syntheses of a number of heterocyclic target structures appear in Chapter Eight. Sesquiterpenoids and polycyclic higher isoprenoids are dealt with in Chapters Nine and Ten, respectively. The remainder of Part Two describes syntheses of prostanoids (Chapter Eleven) and biologically active acyclic polyenes including leukotrienes and other eicosanoids (Chapter Twelve). 

Fogh, K., Herlin, T. and Kr balle, K. (1989). Eicosanoids in acute and chronic psoriatic lesions leukotriene B4, but not 12-hydroxyeicosatetraenoic acid is present in biologically active amounts in acute lesions. J. Invest. Dermatol. 92, 837-841. 

Table 8.3 Biologic Activities Associated with the Eicosanoids...

Figure 12.16. Omega-3 fatty acids and their relevance to prostaglandin metabolism, a Omega-3 nnsatnrated fatty acids are derived from linoleic acid by a special desatnrase fonnd in plants bnt not in mammals. They are particnlarly common in cold-waterfish. b The different nnmbers and positions of donble bonds persist in the eicosanoids derived from different fatty acid precnrsors, giving rise to different homologons derivatives. This is shown here for prostaglandin E. c Biological activity of the eicosanoids derived from eicosapentanoic acid (EPA).

The eicosanoids, a group of biologically active lipids that includes the prostaglandins and leukotrienes (Section 29.6) Vioxx, Bextra, and Celebrex—novel anti-inflammatory drugs (Section 29.6)... 

The eicosanoids are a group of biologically active compounds containing 20 carbon atoms derived from arachidonic acid. The prostaglandins (Section 19.6) and the leukotrienes (Section 9.16) are two types of eicosanoids. Two others are the thromboxanes and prostacyclins. 

Each eicosanoid is associated with specific types of biological activity (Table 29.4). In some cases, the effects oppose one another. For example, thromboxanes are vasoconstrictors that trigger blood platelet aggregation, whereas prostacyclins are vasodilators that inhibit platelet aggregation. The levels of these two eicosanoids must be in the right balance for cells to function properly. 

Eicosanoids (Section 29.6) A group of biologically active compounds containing 20 carbon atoms derived from arachidonic acid. 

The fatty acid alkyl chain is susceptible to oxidation both at double bonds and adjacent allylic carbons. Eree-radical and photooxidation at aUylic carbons are responsible for deterioration of unsaturated oils and fats, resulting in rancid flavors and reduced nutritional quality, but they are also used deliberately to polymerize drying oils. Oxidation of double bonds is used in oleochemical production either to cleave the alkyl chain or to introduce additional functionality along the chain. Enzyme catalyzed oxidation is the initial step in the production of eicosanoids and jasmonates (biologically active metabolites in animals and plants respectively) but is not discussed further here. 

Mitochondria are the site of ROS production during ischemia. Arachidonic acid, eNOS, NADPH oxidase and xanthine oxidase are sources of reactive oxygen species at reperfusion. Cytochrome P450 monooxygenases (CYPs) have also been implicated. CYP catalyzes arachidonic acid oxidation to a variety of biologically active eicosanoids and generates reactive oxygen species.1 3... 

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