Impact of food polyphenols on oxylipin biosynthesis in human neutrophils
The intake of food polyphenols is associated with beneficial impacts on health. Besides anti-oxidative effects, anti-inflammatory properties have been suggested as molecular modes of action, which may result from modulations of the arachidonic acid (AA) cascade. Here, we investigated the effects of a library of food polyphenols on 5-lipoxygenase (5-LOX) activity in a cell-free assay, and in human neutrophils. Resveratrol, its dimer (ε-viniferin), and its imine analogue (IRA) potently blocked the 5-LOX-mediated LT formation in neutrophils with IC50 values in low μM-range. Among the tested flavonoids only the isoflavone genistein showed potent 5-LOX inhibition in neutrophils (IC50 = 0.4 ± 0.1 μM), however was ineffective on isolated 5-LOX. We exclude an interference with the 5-LOX-activating protein (FLAP) in HEK_5-LOX/±FLAP cells and suggest global effects on intact immune cells. Using LC-MS based targeted oxylipin metabolomics, we analyzed the effects of 5-LOX-inhibiting polyphenols on all branches of the AA cascade in Ca2+-ionophore-challenged neutrophils. While ε-viniferin causes a clear substrate shunt towards the remaining AA cascade enzymes (15-LOX, cyclooxygenase - COX-1/2, cytochrome P450), resveratrol inhibited the COX-1/2 pathway and showed a weak attenuation of 12/15-LOX activity. IRA had no impact on 15-LOX activity, but elevated the formation of COX-derived prostaglandins, having no inhibitory effects on COX-1/2. Overall, we show that food polyphenols have the ability to block 5-LOX activity and the oxylipin pattern is modulated with a remarkable compound/structural specificity. Taken the importance of polyphenols for a healthy diet and their concentration in food supplements into account, this finding justifies further investigation.
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