Cholesterol autoxidation in phospholipid membrane bilayers

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · Lipids; (United States)

DOI:https://doi.org/10.1007/BF02533940· OSTI ID:5757493

Sevanian, A; McLeod, L L

Lipid peroxidation in unilamellar liposomes of known cholesterol-phospholipid composition was monitored under conditions of autoxidation or as induced by a superoxide radical generating system, gamma-irradiation or cumene hydroperoxide. Formation of cholesterol oxidation products was indexed to the level of lipid peroxidation. The major cholesterol oxidation products identified were 7-keto-cholesterol, isomeric cholesterol 5,6-epoxides, isomeric 7-hydroperoxides and isomeric 3,7-cholestane diols. Other commonly encountered products included 3,5-cholestadiene-7-one and cholestane-3 beta, 5 alpha, 6 beta-triol. Superoxide-dependent peroxidation required iron and produced a gradual increase in 7-keto-cholesterol and cholesterol epoxides. Cholesterol oxidation was greatest in liposomes containing high proportions of unsaturated phospholipid to cholesterol (4:1 molar ratio), intermediate with low phospholipid to cholesterol ratios (2:1) and least in liposomes prepared with dipalmitoylphosphatidylcholine and cholesterol. This relationship held regardless of the oxidizing conditions used. Cumene hydroperoxide-dependent lipid peroxidation and/or more prolonged oxidations with other oxidizing systems yielded a variety of products where cholesterol-5 beta,6 beta-epoxide, 7-ketocholesterol and the 7-hydroperoxides were most consistently elevated. Oxyradical initiation of lipid peroxidation produced a pattern of cholesterol oxidation products distinguishable from the pattern derived by cumene hydroperoxide-dependent peroxidation.

• Research Organization: Univ. of Southern California, Los Angeles
• OSTI ID: 5757493
• Journal Information: Lipids; (United States), Journal Name: Lipids; (United States) Vol. 22:9; ISSN LPDSA
• Country of Publication: United States
• Language: English

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560120* -- Radiation Effects on Biochemicals
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
CELL CONSTITUENTS
CELL MEMBRANES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
CHOLESTEROL
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IONIZING RADIATIONS
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ORGANIC PHOSPHORUS COMPOUNDS
ORGANOIDS
OXYGEN COMPOUNDS
PEROXIDES
PHOSPHOLIPIDS
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RADIATION EFFECTS
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RADICALS
STEROIDS
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SUPEROXIDE RADICALS