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Detection of oxysterols in oxidatively modified low density lipoprotein by MALDI‐TOF MS
Author(s) -
Hasegawa Masahiro,
Hakamata Hideki,
Matsunaga Io,
Kusu Fumiyo
Publication year - 2011
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.201000366
Subject(s) - saponification , chemistry , oxysterol , chromatography , derivatization , hexane , extraction (chemistry) , cholesterol , mass spectrometry , biochemistry
A simple method for the detection of oxysterols in oxidatively modified LDL (Ox‐LDL) has been developed using MALDI‐TOF MS. To identify the ion peaks of oxysterols, seven major oxysterols in Ox‐LDL (7α‐hydroxycholesterol, 7β‐hydroxycholesterol, 7‐ketocholesterol, 5α,6α‐epoxycholesterol, 5β,6β‐epoxycholesterol, 25‐hydroxychokesterol, (25 R )‐26‐hydroxycholesterol), and cholesta‐3,5‐dien‐7‐one were analyzed by MALDI‐TOF MS. Among these oxysterols, 7‐ketocholesterol, a very abundant oxysterol in Ox‐LDL, was found to show a characteristic peak of [M + H] + at m/z 401. Cholesta‐3,5‐dien‐7‐one, which is known as a degradation product of 7‐ketocholesterol upon saponification of Ox‐LDL, gave a major peak of [M + H] + at m/z 383. In contrast, other oxysterols showed similar peak patterns at m/z 367 and 385. These results were applied to the analysis of Ox‐LDL by MALDI‐TOF MS after saponification and hexane‐extraction, detecting ion peaks at m/z 367, 383, 385, and 401. This MALDI‐TOF MS method has a potential as a simple tool to show the presence of oxysterols in Ox‐LDL without derivatization and chromatographic separation.