Different mechanisms are progressively recruited to promote Cu(II) reduction by isolated human low-density lipoprotein undergoing oxidation

Perugini, C.; Seccia, M.; Bagnati, Marco; Cau, C.; Albano, Emanuele; Bellomo, Giorgio

doi:10.1016/s0891-5849(98)00075-6

Cited by 23 publications

(20 citation statements)

References 28 publications

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“…In the presence of pre‐existing traces of hydroperoxides (LOOH), Cu 2+ and Cu + may be either reduced or oxidized, generating hydroperoxyl (LOO·) or alkoxyl (LO·) radicals that in turn can trigger the LPO propagation phase. It is currently admitted that Cu 2+ reduction to Cu + is required for triggering LPO in LDL [50], but the exact nature of the involved reductants in LDL, such as pre‐existing LOOH, tryptophan residues or even α‐tocopherol, is still questioned [51–59]. Their progressive involvement has been suggested by Perugini et al .…”

Section: Discussionmentioning

confidence: 99%

Anti‐ and pro‐oxidant effects of quercetin in copper‐induced low density lipoprotein oxidation

Filipe

Haigle

Silva

et al. 2004

European Journal of Biochemistry

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We recently reported that, depending on its concentration, urate is either a pro- or an antioxidant in Cu(2+)-induced low-density lipoprotein (LDL) oxidation. We also previously demonstrated an antioxidant synergy between urate and some flavonoids in the Cu(2+)-induced oxidation of diluted serum. As a result, the effect of the flavonoid quercetin on the Cu(2+)-induced oxidation of isolated LDL has been studied either in the presence or absence of urate. We demonstrate that, like urate, quercetin alone, at low concentration, exhibits a pro-oxidant activity. The pro-oxidant behavior depends on the Cu(2+) concentration but it is not observed at high Cu(2+) concentration. When compared with urate, the switch between the pro- and the antioxidant activities occurs at much lower quercetin concentrations. As for urate, the pro-oxidant character of quercetin is related to its ability to reduce Cu(2+) with the formation of semioxidized quercetin and Cu(+) with an expected yield larger than that obtained with urate owing to a more favorable redox potential. It is also shown that the pro-oxidant activity of urate can be inhibited by quercetin. An electron transfer between quercetin and semioxidized urate leading to the repair of urate could account for this observation as suggested by recently published pulse radiolysis data. It is anticipated that the interactions between quercetin-Cu(2+)-LDL and urate, which are tightly controlled by their respective concentration, determine the balance between the pro- and antioxidant behaviors. Moreover, as already observed with other antioxidants, it is demonstrated that quercetin alone behaves as a pro-oxidant towards preoxidized LDL.

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Section: Discussionmentioning

confidence: 99%

Anti‐ and pro‐oxidant effects of quercetin in copper‐induced low density lipoprotein oxidation

Filipe

Haigle

Silva

et al. 2004

European Journal of Biochemistry

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“…Perigini et al . [46] demonstrated that these different mechanisms are progressively recruited to promote Cu 2+ reduction. Although not demonstrated, the involvement of has been suggested [49], according to the reaction:…”

Section: Discussionmentioning

confidence: 99%

Anti‐ and pro‐oxidant effects of urate in copper‐induced low‐density lipoprotein oxidation

Filipe

Haigle

Freitas

et al. 2002

European Journal of Biochemistry

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We reported earlier that urate may behave as a prooxidant in Cu 2+ -induced oxidation of diluted plasma. Thus, its effect on Cu 2+ -induced oxidation of isolated low-density lipoprotein (LDL) was investigated by monitoring the formation of malondialdehyde and conjugated dienes and the consumption of urate and carotenoids. We show that urate is antioxidant at high concentration but pro-oxidant at low concentration. Depending on Cu 2+ concentration, the switch between the pro-and antioxidant behavior of urate occurs at different urate concentrations. At high Cu 2+ concentration, in the presence of urate, superoxide dismutase and ferricytochrome c protect LDL from oxidation but no protection is observed at low Cu 2+ concentration. The use of Cu 2+ or Cu + chelators demonstrates that both copper redox states are required. We suggest that two mechanisms occur depending on the Cu 2+ concentration. Urate may reduce Cu 2+ to Cu + , which in turn contributes to O Á À 2 formation. The Cu 2+ reduction is likely to produce the urate radical (UH AE-). It is proposed that at high Cu 2+ concentration, the reaction of UH AE-radical with O Á À 2 generates products or intermediates, which trigger LDL oxidation. At low Cu 2+ concentration, we suggest that the Cu + ions formed reduce lipid hydroperoxides to alkoxyl radicals, thereby facilitating the peroxidizing chain reaction. It is anticipated that these two mechanisms are the consequence of complex LDL-urate-Cu 2+ interactions. It is also shown that urate is pro-oxidant towards slightly preoxidized LDL, whatever its concentration. We reiterate the conclusion that the use of antioxidants may be a two-edged sword.

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“…Human LDLs were isolated from EDTA fasting plasma samples using density gradient sequential ultracentrifugation and desalting by gel permeation chromatography (Perugini et al, 1998). Samples were collected from healthy volunteers (10 men, 20-30 years) who were not using vitamin supplements (Havel et al, 1955).…”

Section: Spectrophotometric Equilibrium Measurementsmentioning

confidence: 99%

Biological activities of Prunella vulgaris extract

Psotová

Kolář

Soušek

et al. 2003

Phytotherapy Research

163

122

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The organic fraction (OF; 25.7% w/w of rosmarinic acid) of Prunella vulgaris (total extract) was found to exhibit the following: scavenging activity on diphenylpicrylhydrazyl radical (DPPH), inhibition of in vitro human LDL Cu(II)-mediated oxidation, protection of rat mitochondria and rat hepatocytes exposed to either tert-butyl hydroperoxide, or to Cu(II) and Fe(III) ions. OF also showed a potential to inhibit rat erythrocyte haemolysis and it reduced the production of LTB(4) in bovine PMNL generated by the 5-lipoxygenase pathway. Other observations included antiproliferative effects against HaCaT cells and mouse epidermal fibroblasts and a moderate OF antimicrobial activity on gram-positive bacteria. Rosmarinic, caffeic and 3-(3,4-dihydroxyphenyl)lactic acids exhibited less potent activity than the plant extract in all bioassays. The antioxidative, antimicrobial, together with antiviral effects offer good prospects for the medicinal applications of P. vulgaris.

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Different mechanisms are progressively recruited to promote Cu(II) reduction by isolated human low-density lipoprotein undergoing oxidation

Cited by 23 publications

References 28 publications

Anti‐ and pro‐oxidant effects of quercetin in copper‐induced low density lipoprotein oxidation

Anti‐ and pro‐oxidant effects of quercetin in copper‐induced low density lipoprotein oxidation

Anti‐ and pro‐oxidant effects of urate in copper‐induced low‐density lipoprotein oxidation

Biological activities of Prunella vulgaris extract

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