title: Ozonation of cholesterol in the presence of ethanol: identification of a cytotoxic ethoxyhydroperoxide molecule.
abstract: Cholesterol ozonation was carried out in ethanol-containing aqueous or nonaqueous solvent, and the ozonized products were analyzed by chemiluminescence detection-HPLC with on-line electrospray MS (HPLC-CL-MS) and characterized on the basis of NMR and FABMS. After the ozonolysis of cholesterol in water/ethanol (aqueous system) as well as in chloroform/ethanol (nonaqueous system), a unique ethoxyhydroperoxide molecule (7alpha-ethoxy-3beta-hydroxy-5alpha-B-homo-6-oxacholestane-5-hydroperoxide, termed "7alpha-ethoxy-5-OOH") appeared as main ozonation product. In addition to structural analysis, we confirmed the remarkable cytotoxicity of 7alpha-ethoxy-5-OOH toward human lung adenocarcinoma A549 cells and found that its cytotoxicity is superior to that of the commonly known autoxidized cholesterol (3beta-hydroxycholest-5-ene-7-one). Hence, 7alpha-ethoxy-5-OOH is a toxic molecule of primary importance, arising during cholesterol ozonation in the presence of ethanol.
authors.affiliation: Food & Biodynamic Chemistry Laboratory, Graduate School of Life Science and Agriculture, Tohoku University, Sendai, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Tagiri-Endo
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sugawara
authors.forename: Kaori
authors.initials: K
authors.lastname: Ono
authors.forename: Teruo
authors.initials: T
authors.lastname: Miyazawa
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D002776:Cholestanes / Q000633:toxicity*; D002784:Cholesterol / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D006801:Humans; D008054:Lipid Peroxides / Q000633:toxicity; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*
chemical_list: C496266:7alpha-ethoxy-3beta-hydroxy-5alpha-B-homo-6-oxacholestane-5-hydroperoxide; D002776:Cholestanes; D008054:Lipid Peroxides; D000431:Ethanol; D010126:Ozone; D002784:Cholesterol