title: Analysis of oxysterols by electrospray tandem mass spectrometry.
abstract: Oxysterols are oxygenated derivatives of cholesterol. They are intermediates in cholesterol excretion pathways and may also be regarded as transport forms of cholesterol. The introduction of additional hydroxyl groups to the cholesterol skeleton facilitates the flux of oxysterols across the blood brain barrier, and oxysterols have been implicated in mediating a number of cholesterol-induced metabolic effects. Oxysterols are difficult to analyze by atmospheric pressure ionization mass spectrometry on account of the absence of basic or acidic functional groups in their structures. In this communication, we report a method for the derivatization and analysis of oxysterols by electrospray mass spectrometry. Oxysterols with a 3beta-hydroxy-Delta5 structure were converted by cholesterol oxidase to 3-oxo-Delta4 steroids and then derivatized with the Girard P reagent to give Girard P hydrazones, which were subsequently analyzed by tandem mass spectrometry. The improvement in sensitivity for the analysis of 25-hydroxycholesterol upon oxidation and derivatization was over 1000.
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, London, United Kingdom.
authors.forename: William J
authors.initials: WJ
authors.lastname: Griffiths
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Gunvor
authors.initials: G
authors.lastname: Alvelius
authors.forename: Suya
authors.initials: S
authors.lastname: Liu
authors.forename: Karl
authors.initials: K
authors.lastname: Bodin
authors.forename: Jan
authors.initials: J
authors.lastname: Sjövall
mesh_terms: D002789:Cholesterol Oxidase / Q000737:chemistry*; D006835:Hydrazones / Q000032:analysis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013261:Sterols / Q000032:analysis* / Q000737:chemistry*
chemical_list: D006835:Hydrazones; D013261:Sterols; D002789:Cholesterol Oxidase