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Factors affecting resistance of low density lipoproteins to oxidation
Author(s) -
Ziouzenkova O.,
Gieseg S. P.,
Ramos P.,
Esterbauer H.
Publication year - 1996
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02637054
Subject(s) - lipidology , clinical chemistry , chemistry , resistance (ecology) , food science , biochemistry , biology , ecology
Abstract Oxidation resistance (OR) of low density lipoproteins (LDL) is frequently determined by the conjugated diene (CD) assay, in which isolated LDL is exposed to Cu 2+ as prooxidant in the range of 1–10 μM. A brief review on major findings obtained with this assay will be given. A consistent observation is that vitamin E supplements or oleic acid‐rich diets increase OR. Oxidation indices measured by the CD assay and effects of antioxidants very significantly depend on the Cu 2+ concentration used for LDL oxidation. For medium and high Cu 2+ concentrations, the relationship between lag time and propagation rate can be described by a simple hyperbolic saturation function, which has the same mathematical form as the Michaelis‐Menten equation. At medium and high Cu 2+ concentrations (0.5 to 5 μM), vitamin E increases lag time in a dose‐dependent manner. The increase is higher for 0.5 μM Cu 2+ as compared to 5 μM. At low Cu 2+ concentrations (0.5 μM or less), the mechanism of LDL oxidation changes. Significant oxidation occurs in a preoxidation phase, which commences shortly after addition of Cu 2+ . Preoxidation is not inhibited by vitamin E. It is concluded that much additional work is needed to validate the importance of oxidation indices derived from CD and similar assays.