The inhibition by quercetin and ganhuangenin on oxidatively modified low density lipoprotein

Oxidatively modified low-density lipoproteins (ox-LDL) have been strongly implicated in the pathogenesis of atherosclerosis. Both in vivo and in vitro experiments have shown that antioxidant treatment can attenuate oxidative damage from LDL. The aim of this study was to establish whether the ox-LDL induced by in vitro incubation can be inhibited by two well-known natural antioxidants, quercetin and ganhuangenin. In our study, oxidation was quantitatively assessed in the presence and absence of these antioxidants by measuring lipid oxidation products and lipid peroxide generation. When non-oxidized, native LDL was incubated in the presence of 20 mM Cu2+, LDL modifications were found to proceed in a time-dependent manner. Our results further showed both quercetin and ganhuangenin inhibited the oxidative modification of LDL, as evidenced by the reduced thiobarbituric acid reactive substances (TBARS), phosphatidylcholine hydroperoxides (PCOOH) production, and ox-LDL fluorescence intensity. Based on these data, we concluded that both quercetin and ganhuangenin have the ability to effectively suppress in vitro LDL oxidation, thereby providing additional evidence for their potential beneficial use as antiatherogenic agents. © 1998 John Wiley & Sons, Ltd.