INHIBITION OF LEUKOCYTE LEUKOTRIENE B< sub> 4 PRODUCTION BY AN OLIVE OIL-DERIVED PHENOL IDENTIFIED BY MASS-SPECTROMETRY

We have evaluated the effects of hydroxytyrosol (HT), a potent antioxidant present in olive oil, on the formation of arachidonic acid 5- lipoxygenase metabolites by leukocytes in vitro. HT, a simple phenolic compound, extracted from first-pressure oil, was isolated by HPLC and characterized by gas chromatography/mass spectrometry. HT inhibited in a dose-related manner the production of leukotriene B4 (LTB4) by calcium ionophore-stimulated leukocytes. As expected, similar inhibition was observed for ω-oxidized metabolites of LTB4, namely 20-hydroxy and 20-carboxy- LTB4. The results disclose a new biological activity of olive oil-derived phenols on leukocyte eicosanoid production.