Effects of exogenous arachidonic, eicosapentaenoic, and docosahexaenoic acids on the generation of 5-lipoxygenase pathway products by ionophore-activated human neutrophils.

Abstract

Exogenous eicosapentaenoic acid (EPA) and docosahexaenoic acid (DCHA) have been compared with exogenous arachidonic acid for their capacity to modulate the oxidative metabolism of mem- brane-derived arachidonic acid by the 5-lipoxygenase pathway in ionophore-activated human neutrophils and for their suitability as parallel substrates in this pathway. The products from specific 14Cor 3H-labeled substrates were isolated by reverse phase high performance liquid chromatography (RP-HPLC) and were identified by elution of radiolabel at the retention times of the appro- priate synthetic standards. Each product was also char- acterized by its ultraviolet (UV) absorption spectrum, and 7-hydroxy-DCHA was defined in addition by analysis of its mass spectrum. The metabolites, 5-hy- droxyeicosatetraenoic acid, leukotriene B4 (LTB4), 6-trans-LTB4 diastereoisomers, 5-hydroxyeicosapentaenoic acid, 6-trans-leukotriene B5 diastereoisomers, leu- kotriene B5 (LTB5), and 7-hydroxy-DCHA were quan- titated by integrated UV absorbance during resolution by RP-HPLC. LTB4 and LTB5 were also quantitated by