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Effects of Glucose and α‐Tocopherol on Low‐Density Lipoprotein Oxidation and Glycation
Author(s) -
CHANG CHUNJEN,
HSIEH RONGHONG,
WANG HUIFANG,
CHIN MEIYUN,
HUANG SHIHYI
Publication year - 2005
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1338.052
Subject(s) - tbars , glycation , chemistry , thiobarbituric acid , incubation , low density lipoprotein , medicine , endocrinology , malondialdehyde , lipid peroxidation , tocopherol , lipoprotein , antioxidant , biochemistry , cholesterol , vitamin e , receptor
A bstract : Glycation of blood proteins is considered to be a major contributor to hyperglycemic complications in diabetes mellitus patients. In this study, we demonstrate the efficacy of α‐tocopherol in reducing low‐density lipoprotein (LDL) oxidation and glycation in vitro . Native LDL isolated from healthy subjects was exposed to various concentrations of glucose and malondialdehyde (MDA) with or without α‐tocopherol enrichment for 7 days in sealed vacuum ampoules. The degree of glycation, copper‐induced lag time, content of thiobarbituric acid‐reactive substances (TBARS), and α‐tocopherol levels in LDL were then assessed. LDL lag time was significantly reduced with high levels of glucose and MDA. α‐Tocopherol enrichment dramatically inhibited the oxidation of LDL in the lag‐time assay. However, the length of incubation time was inversely related to the LDL lag time. Longer incubation time resulted in shorter LDL lag time, with or without α‐tocopherol enrichment. The level of TBARS associated with LDL oxidation was highest in native, MDA‐supplemented, and high‐glucose samples. The α‐tocopherol levels were inversely related to glucose levels and incubation times. In conclusion, high‐glucose concentrations heightened the oxidative susceptibility of LDL. α‐Tocopherol enrichment reduced this trend and prevented LDL from undergoing architectural modification.