INHIBITION OF ENDOTHELIAL CELL-MEDIATED OXIDATION OF LOW-DENSITY-LIPOPROTEIN BY ROSEMARY AND PLANT PHENOLICS

Plant-derived phenolic compounds possess antioxidant activity that may be applicable to such diverse areas as human health and the preservat ion of food lipids. The potential antioxidant activities of a variety of plant phenolics were investigated using human aortic endothelial ce lls (HAEC) to mediate the oxidation of low-density lipoprotein(LDL). C arnosic acid, carnosol, and rosmarinic acid, present in rosemary extra ct, and thymol, carvacrol, and zingerone, present in thyme, origanum, and ginger, were individually incubated with HAEC and LDL for 12 h. Th e extent of oxidation was determined spectrophotometrically by measuri ng absorbance (at 234 nn) of conjugated dienes. All antioxidants produ ced dose-dependent inhibition of LDL oxidation. Their relative antioxi dant activities decreased in the order carnosol > carnosic acid approx imate to rosmarinic acid >>> thymol > carvacrol > zingerone. The antio xidant activity of these plant phenolics in the HAEC system suggests t hat they may have potential benefits in human health.