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Antioxidant/Prooxidant Effects of Dietary Non‐Flavonoid Phenols on the Cu 2+ ‐Induced Oxidation of Human Low‐Density Lipoprotein (LDL)
Author(s) -
Briante Raffaella,
Febbraio Ferdinando,
Nucci Roberto
Publication year - 2004
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200490130
Subject(s) - hydroxytyrosol , chemistry , oleuropein , phenols , antioxidant , low density lipoprotein , flavonoid , olea , rutin , lipid peroxidation , lipoprotein , quercetin , food science , lipid oxidation , ferric reducing ability of plasma , biochemistry , polyphenol , cholesterol , botany , antioxidant capacity , biology
A central role in the oxidative development of atherosclerotic lesions has been ascribed to the peroxidation of plasma low‐density lipoprotein (LDL). Dietary supplementation with virgin olive oils increases the total plasma antioxidant status and the resistance of low‐density lipoprotein to ex vivo oxidation. We have studied the effects of some dietary non‐flavonoid phenols from Olea europaea L., both in purified form or in complex mixtures obtained by biotransformation of olive leaf extracts, on the LDL oxidation induced by Cu 2+ ions. Cu 2+ ‐Induced LDL oxidation is inhibited by oleuropein and hydroxytyrosol in the initiation phase of the reaction at concentrations of phenols higher than that of Cu 2+ ions. Interestingly, at lower concentration, both phenols anticipated the initiation process of LDL oxidation, thus exerting prooxidant capacities. Although similar effects are already described for flavonoids, such as quercetin, rutin, and apigenin, it is the first time that a prooxidant effect of dietary non‐flavonoid phenols, such as oleuropein and hydroxytyrosol, on the LDL oxidation is reported. Our results show that a net effect of oleuropein and hydroxytyrosol on Cu 2+ ‐induced LDL peroxidation is determined by a balance of their pro‐ and antioxidant capacities. It is worth to underline that, during Cu 2+ ‐induced LDL oxidation in the presence of bioreactor eluates, we have evidence of a sinergistic effect among phenolic compounds that enhance their antioxidant capacities so avoiding the prooxidant effects.