[Lipophilic derivatives of caffeic acid as lipoxygenase inhibitors with antioxidant properties].

We have prepared two lipophilic derivatives of caffeic acid at the carboxylic function--caffeic acid phenethyl ester, an active component of propolis, and N,N'-dicyclohexyl-O-(3,4-dihydroxycinnamoyl)-isourea. Both substances inhibit barley 5-lipoxygenase and soybean 15-lipoxygenase at micromolar concentrations. The inhibition is uncompetitive, dose-dependent and reversible. The caffeic acid derivatives also exhibit antioxidant properties and at a concentration 5-10 microM completely block the production of the reactive oxygen species in human neutrophils and in the cell-free xanthine/xanthine oxidase system.