Effect of natural polyphenol compounds on oxidative modification of low-density lipoproteins

: The effect of polyphenols (PP) from Alchimilia vulgaris L. and Rosa majalis Herrm. on oxidative modification of low density lipoproteins (LDL) was studied in the cultured peritoneal macrophages and in unicellular medium in the presence of Cu2+. The experiments on cultured macrophages indicated that PP (10-50 micrograms/ml) reduced the lipid peroxidation products, measured as thiobarbituric acid reactive substances, by as much as 40-77% and decreased the macrophage degradation of 125I-LDL by 60-87%. In contract, the addition of alpha-tocopherol (50-100 microM) inhibited by only 40-60% under the same conditions. Oxidation of LDL by macrophages was effectively dose-dependently inhibited by PP (5-500 micrograms/ml), as was Cu(2+)-catalyzed oxidation of LDL. Our data indicate that PP of these plants protect LDL against oxidation and may be used for the prevention and regression of atherosclerosis.