LIPOPHILIC DERIVATIVES OF CAFFEIC ACID AS LIPOXYGENASE INHIBITORS WITH ANTIOXIDANT PROPERTIES

We have prepared two lipophilic derivatives of caffeic acid at the car boxylic function - caffeic acid phenethyl ester, an active component o f propolis, and '-dicyclohexyl-O-(3,4-dihydroxycinnamoyl)-isourea. Bot h substances inhibit barley 5-lipoxygenase and soybean 15-lipoxygenase at micromolar concentrations. The inhibition is uncompetitive;dose-de pendent and reversible. The caffeic acid derivatives also exhibit anti oxidant properties and at a concentration 5 - 10 mu M completely block the production of the reactive oxygen species in human neutrophils an d in the cell-free xanthine/xanthine oxidase system.