A variety of cells release and oxygenate arachidonic acid during their interaction with specific stimuli. In its nonesterified form, arachidonic acid may be subjected to oxygenation by either the cyclooxygenase or lipoxygenase pathways. The lipoxygenase pathways of mammalian tissues (i. e., 5-, 12-, or 15-) (Hamberg, 1984) transform arachidonate into a number of biologically potent compounds, which include several mono- and dihydroxyeicosatetraenoic acids. For example, via the 5-lipoxygenase pathway, arachidonic acid is converted to 5(5)-hydroperoxy-6,8,ll,14-eicosatetraenoic acid (5-HPETE), which may be further transformed into leuko-trienes (Borgeat et al., 1976; Borgeat and Samuelsson, 1979). Leukotrienes, particularly LTB4 and LTC4, are believed to serve as mediators in both immediate hypersensitivity reactions and inflammation (Samuelsson, 1983). In fact, leukotriene B4 serves as a complete secretagogue in human neutrophils, stimulating aggregation, mobilization of Ca2+, degranulation, and the generation of active oxygen species within seconds of its addition (Serhan et al., 1982).
KeywordsArachidonic Acid Human Leukocyte Human Neutrophil Superoxide Anion Generation Ethyl Acetate Fraction
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