Inhibition of Oxidation of Low Density Lipoprotein by Vitamin E and Related Compounds
作者:
CompoundsRelated,
GotohNaohiro,
NoguchiNoriko,
TsuchiyaJunichi,
MoritaKazwo,
SakaiHirokazu,
ShimasakiHiromjki,
NikiEtsuo,
期刊:
Free Radical Research
(Taylor Available online 1996)
卷期:
Volume 24,
issue 2
页码: 123-134
ISSN:1071-5762
年代: 1996
DOI:10.3109/10715769609088008
出版商: Taylor&Francis
关键词: Lipid peroxidation;low density lipoprotein;vitamin E;antioxidants;free radicals
数据来源: Taylor
摘要:
The oxidation of low density lipoprotein (LDL) was carried out aiming specifically at elucidating the anti-oxidant action ofα-tocopherol. Lipophilic and hydro-philic azo compounds and copper induced the oxidation of LDL similarly to give cholesterol ester and phosphatidylcholine hydroperoxides as major products. The antioxidant potency of a-tocopherol in LDL was much poorer than in homogeneous solution. Doxyl stearic acids were used as spin probe and incorporated in LDL. The rate of reduction of doxyl nitroxide in LDL by ascorbate decreased with increasing distance from the LDL surface. From the competition between the spin probe and a-tocopherol in scavenging radical, it was found that the efficacy of radical scavenging by a-tocopherol became smaller as the radical went deeper into the interior of LDL. On the other hand, 2,2,5,7,8-pentamethyl-6-chromal spared the spin label regardless of the position of nitroxide. The antioxidant activity of chromanols against LDL oxidation increased with decreasing length of isoprenoid side chain at the 2-position. All these results were interpreted by location and low mobility of a-tocopherol in LDL. The tocopherol mediated propagation was observed notably at low rate of radical flux, but this was suppressed by reductant such as ascorbic acid and ubiquinol.
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