Mécanisme moléculaire de l'effet protecteur de la vitamine E dans l'athérosclérose

2002 ◽  
Vol 80 (7) ◽  
pp. 662-669 ◽  
Author(s):  
Abdelouahed Khalil
Keyword(s):  
Lipid Peroxidation ◽  
Vitamin E ◽  
Vascular Diseases ◽  
Epidemiologic Studies ◽  
Low Density Lipoproteins ◽  
Alpha Tocopherol ◽  
Low Density ◽  
Prooxidant Effect

Oxidation of low-density lipoproteins constitutes the first step of a very complex process leading to atherosclerosis. Vitamin E, and principally alpha-tocopherol, is considered as the principal inhibitor of lipid peroxidation. Some studies showed the beneficial role of vitamin E in the prevention and reduction of atherosclerosis and its associated pathologies. However, other in vitro studies advance a prooxidant role of vitamin E. The results of the epidemiologic studies are difficult to generalize without taking account of the clinical randomized tests. In this work, we reviewed the principal studies devoted to the role of vitamin E and discussed the assumption of a prooxidant effect of this molecule.Key words: vitamin E, low-density lipoproteins (LDL), lipid peroxidation, cardio-vascular diseases.

Increased Lipid Peroxidation in Serum and Low-Density Lipoproteins Associated with Aging in Humans

2002 ◽  
Vol 72 (5) ◽  
pp. 315-320 ◽  
Author(s):  
Jale Balkan ◽  
Öznur Kanbagli ◽  
Güldal Mehmetçik ◽  
Ümit Mutlu-Türkoglu ◽  
Gülçin Aykaç-Toker ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Vitamin E ◽  
Ldl Cholesterol ◽  
Serum Vitamin ◽  
Lipid Peroxide ◽  
Low Density Lipoproteins ◽  
Elderly Subjects ◽  
Low Density ◽  
Diene Conjugates ◽  
Diene Conjugate

This study was carried out in 140 healthy subjects who were divided into three subgroups of age: young (21–40 years), mature (41–60 years), and elderly ( 61–85 years) to investigate lipid peroxides and the antioxidant system in serum and low-density lipoproteins (LDL). Serum levels of cholesterol and LDL-cholesterol increased with age. The elderly group was found to have higher polyunsaturated fatty acid (PUFA) levels, thiobarbituric acid reactive substances (TBARS), diene conjugates, and lower cholesterol-adjusted vitamin E levels and antioxidant activity (AOA) as compared to the young group. No age-related difference was detected in serum vitamin C levels. Age correlated positively with serum cholesterol, LDL-cholesterol, PUFA, TBARS, diene conjugates, and negatively with cholesterol-adjusted vitamin E levels and AOA. In addition, endogenous LDL diene conjugate levels and the susceptibility of LDL to copper-induced lipid peroxidation increased in elderly subjects as compared with young subjects. In addition, positive correlations were detected between age and LDL endogenous diene conjugate levels and TBARS formation after copper incubation. However, the susceptibility of whole serum to copper-induced lipid peroxidation did not change in young and elderly subjects. Our results show that endogenous lipid peroxide levels in serum and LDL, and the susceptibility of LDL to copper-induced oxidation, increased with aging in humans.

scholarly journals Vitamin E in human low-density lipoprotein. When and how this antioxidant becomes a pro-oxidant

1992 ◽  
Vol 288 (2) ◽  
pp. 341-344 ◽  
Author(s):  
V W Bowry ◽  
K U Ingold ◽  
R Stocker
Keyword(s):  
Lipid Peroxidation ◽  
Vitamin E ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Peroxyl Radicals ◽  
Careful Examination ◽  
Early Event ◽  
Low Density ◽  
Tocopheroxyl Radical

Uptake of oxidatively modified low-density lipoprotein (LDL) by cells in the arterial wall is believed to be an important early event in the development of atherosclerosis. Because vitamin E is the major antioxidant present in human lipoproteins, it has received much attention as a suppressor of LDL lipid oxidation and as an epidemiological marker for ischaemic heart disease. However, a careful examination of lipid peroxidation in LDL induced by a steady flux of aqueous peroxyl radicals has demonstrated that, following consumption of endogenous ubiquinol-10, the rate of peroxidation (i) declines as vitamin E is consumed, (ii) is faster in the presence of vitamin E than following its complete consumption, (iii) is substantially accelerated by enrichment of the vitamin in LDL, either in vitro or by diet, and (iv) is virtually independent of the applied radical flux. We propose that perodixation is propagated within lipoprotein particles by reaction of the vitamin E radical (i.e. alpha-tocopheroxyl radical) with polyunsaturated fatty acid moieties in the lipid. This lipid peroxidation mechanism, which can readily be rationalized by the known chemistry of the alpha-tocopheroxyl radical and by the radical-isolating properties of fine emulsions such as LDL, explains how reagents which reduce the alpha-tocopheroxyl radical (i.e. vitamin C and ubiquinol-10) strongly inhibit lipid peroxidation in vitamin E-containing LDL.

Metallothionein response to stress in rats: role in free radical scavenging

1988 ◽  
Vol 255 (4) ◽  
pp. E518-E524 ◽  
Author(s):  
J. Hidalgo ◽  
L. Campmany ◽  
M. Borras ◽  
J. S. Garvey ◽  
A. Armario
Keyword(s):  
Lipid Peroxidation ◽  
Vitamin E ◽  
Liver Lipid ◽  
Radical Scavenging ◽  
Antioxidant Vitamin ◽  
Response To Stress ◽  
Liver Lipid Peroxidation

The possibility that liver metallothionein (MT) can function as an antioxidant in vivo has been studied in the rat. It was found that the stress of food and water deprivation with or without physical immobilization consistently increased liver lipid peroxidation (LLP), suggesting that liver MT induction by stress might be related to the stress-induced LLP. This was supported by results with the lipid peroxidation promoter dimethyl sulfoxide (DMSO) and the natural antioxidant vitamin E. Whereas DMSO administration increased LLP levels in basal and stress situations, vitamin E decreased them. Liver MT levels were increased by DMSO in basal and stress situations, whereas they were decreased by vitamin E during stress. These in vivo results are consistent with an antioxidant role of liver MT suggested by previous in vitro results. However, liver MT preinduction by Zn treatment did not result in a lower MT response to stress. Instead a positive synergistic effect between Zn and stress appeared to be present. This result indicates that the mechanism of action of MT as antioxidant remains unclear.

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