Analysis of Oxysterols by Electrospray Tandem Mass Spectrometry

• Published in: Journal of the American Society for Mass Spectrometry Vol. 17; no. 3; pp. 341 - 362
• Main Authors: Griffiths, William J., Wang, Yuqin, Alvelius, Gunvor, Liu, Suya, Bodin, Karl, Sjövall, Jan
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY Elsevier Inc 01-03-2006; Elsevier Science; Springer Nature B.V
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; Brain; Cholesterol; Cholesterol oxidase; Cholesterol Oxidase - chemistry; Electrospraying; Excretion; Functional groups; Fundamental and applied biological sciences. Psychology; Hydrazones; Hydrazones - analysis; Hydrazones - chemistry; Hydroxyl groups; Ionization; Ions; Mass spectrometry; Medicin och hälsovetenskap; Other biological molecules; Oxidation; Oxidation-Reduction; Scientific imaging; Sensitivity analysis; Spectrometry, Mass, Electrospray Ionization - methods; Spectroscopy; Steroids; Sterols - analysis; Sterols - chemistry; Terpenes, steroids. Hormones; Steroid; Analysis; Mass spectrometry MS/MS; Fragmentation pattern; Oxidation; Derivatization; Degradation product; Mass spectrometry; Cholesterol; Electrospray
• ISSN: 1044-0305; 1879-1123
• DOI: 10.1016/j.jasms.2005.10.012

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 3β-hydroxy-Δ
5 structure were converted by cholesterol oxidase to 3-oxo-Δ
4 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.