title: Determination of cholesterol oxidation products in human plasma by isotope dilution-mass spectrometry.
abstract: A method based on isotope dilution-mass spectrometry was developed for the determination of nine cholesterol oxidation products in human plasma. The cholesterol oxidation products determined were cholest-5-ene-3 beta,7 alpha-diol, cholest-5-ene-3 beta,7 beta-diol (7 alpha- and 7 beta-hydroxycholesterol, respectively), 3 beta-hydroxycholest-5-en-7-one(7-oxocholesterol),5,6 alpha-epoxy-5 alpha- cholestan-3 beta-ol (cholesterol-5 alpha,6 alpha-epoxide),5,6 beta-epoxy-5 beta-cholestan-3 beta-ol (cholesterol-5 beta,6 beta-epoxide), (cholesterol-5 beta,6 beta-epoxide), cholestane-3 beta,5 alpha,6 beta-triol, cholest-5-ene-3 beta,24-diol (24-hydroxycholesterol), cholest-5-ene-3 beta,25-diol (25-hydroxycholesterol), and cholest-5-ene-3 beta,27-diol (27-hydroxycholesterol). A corresponding deuterium-labeled internal standard, containing 3 to 6 deuterium atoms, was synthesized for each cholesterol oxidation product except 5 beta,6 beta-epoxycholesterol which was determined using the internal standard for 5 alpha,6 alpha-epoxycholesterol. Plasma from 31 healthy volunteers was analyzed by the new method and 27-, 24-, and 7 alpha-hydroxycholesterol were the most abundant cholesterol oxidation products (mean values 154, 64, and 43 ng/ml, respectively). The other oxysterols determined were present in concentrations lower than 30 ng/ml. Males had higher 27-hydroxycholesterol concentrations in plasma than females. The 5,6-oxygenated products were present mainly unesterified while the other oxidation products were mostly in esterified form.
authors.affiliation: Department of Medical Laboratory Sciences and Technology, Karolinska Institute, Huddinge University Hospital, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Dzeletovic
authors.forename: O
authors.initials: O
authors.lastname: Breuer
authors.forename: E
authors.initials: E
authors.lastname: Lund
authors.forename: U
authors.initials: U
authors.lastname: Diczfalusy
mesh_terms: D002784:Cholesterol / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood* / Q000138:chemical synthesis; D003903:Deuterium; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D006868:Hydrolysis; D007553:Isotope Labeling / Q000379:methods; D008297:Male; D010084:Oxidation-Reduction; D011865:Radioisotope Dilution Technique; D012016:Reference Values; D012680:Sensitivity and Specificity; D013261:Sterols / Q000097:blood*
chemical_list: D013261:Sterols; D002784:Cholesterol; D003903:Deuterium