title: Preparation and mass spectrometry of 14 pure and 18O(2)-labeled oxidation products from the phytosterols beta-sitosterol and stigmasterol.
abstract: To lower cholesterol, phytosterols are currently introduced as food additives, where they may become oxidized. In addition, specific biological effects of oxyphytosterols are suggested by the recent molecular clarification of the phytosterol storage disease as a dysfunctional mutation of an active sterol reexporter potentially regulated by oxidized phytosterols. We therefore studied the hydroxybenzotriazole-mediated PbO(2)-driven oxidation of phytosterols and compared it to the oxidation of cholesterol. We prepared, identified, and purified standards of 14 oxidation products of two major phytosterols. The gas chromatographic mass spectrometric characteristics of the 7alpha- and 7beta-hydroxy-, 5alpha,6alpha-epoxy, 5beta,6beta-epoxy, 7keto-, 3beta,5alpha,6beta-trihydroxy-, 3keto-, and 7-dehydro-derivatives of beta-sitosterol and stigmasterol are presented. The method also provided a convenient access to prepare 18O-labeled oxyphytosterols of high chemical and isotopic purity and can easily be extended to further phytosterols and -stanols. This enables the gas chromatography-mass spectrometry analysis of oxyphytosterols and the study of their biological effects.
authors.affiliation: Institute for Prophylaxis of Cardiovascular Diseases, University of Munich, Pettenkofer Str. 9, 80336 Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Johannes
authors.forename: Reinhard L
authors.initials: RL
authors.lastname: Lorenz
mesh_terms: D006415:Hematoporphyrins / Q000737:chemistry; D007553:Isotope Labeling; D007854:Lead / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D010083:Oxidants, Photochemical / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010103:Oxygen Isotopes / Q000737:chemistry*; D010840:Phytosterols / Q000737:chemistry*; D012855:Sitosterols / Q000737:chemistry* / Q000302:isolation & purification; D013265:Stigmasterol / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification; D014230:Triazoles / Q000737:chemistry
chemical_list: D006415:Hematoporphyrins; D010083:Oxidants, Photochemical; D010087:Oxides; D010103:Oxygen Isotopes; D010840:Phytosterols; D012855:Sitosterols; D014230:Triazoles; D007854:Lead; C047365:lead oxide; C025473:gamma-sitosterol; C012771:benzotriazole; D013265:Stigmasterol