Mass spectral characterization of two onion constituents with prostaglandin E-like activity as lipoxygenase metabolites of linoleic acid

N-phenyllinoleamide metabolism by human polymorphonuclear leukocytes

1. N-phenyllinoleamide (NPLA), the anilide of linoleic acid, has been associated with the epidemiology of Toxic Oil Syndrome, but so far data available on its metabolism are scarce. On account of the similarities in chemical structure between linoleic acid and NPLA, the objective here has been to investigate the oxidative metabolism of this xenobiotic by human polymorphonuclear leukocytes. 2. Human polymorphonuclear leukocytes were incubated with 0.1 mM NPLA spiked with NPLA labelled either on the aniline or the fatty acid moieties. The metabolites were separated by high-performance liquid chromatography and individually collected prior to gas chromatography-mass spectrometry analysis. 3. Identification of the metabolites as N-phenyl-9-hydroxy- and N-phenyl-13-hydroxy-10,12-octadecenamide (9-HNPLA and 13-HNPLA) and their corresponding non-amidated metabolites, the 9-hydroxy- and 13-hydroxyoctadecenoic acids (9-HODE and 13-HODE), suggests that NPLA can be metabolized via the same hydroperoxidative processes acting upon linoleic acid. 4. Identification of free aniline as a NPLA metabolite suggests an amidase-like activity with liberation of aniline and the free fatty acid moieties.

Oxidative metabolism of N-phenyllinoleamide by human nasal polyps

N-phenyllinoleamide (NPLA), the anilide of linoleic acid, has been associated with the epidemiology of Toxic Oil Syndrome, but no data are available on its metabolism. On account of the similarity in chemical structure between the linoleic acid and NPLA, the aim of this study has been to investigate the oxidative metabolism of this xenobiotic by the human nasal polyp, a tissue with elevated 15-lipoxygenase activity. For this purpose, tissue homogenates have been incubated for 2 h with NPLA (0.1 mM) spiked with either N-(ring G-3H)PLA (0.2 microCi/ml) or N-P(1-14C)LA (0.05 microCi/ml). Gas chromatographic/mass spectrometric analysis of the high performance liquid radiochromatographic fractions shows that the 9,12,13-trihydroxy, 12,13-epoxy-11-hydroxy and 13-hydroxy NPLA derivatives are the major metabolites. These results revealed that NPLA metabolites are chemical structures related to the linoleic acid derivatives, some of which may show biological activity.