A comprehensive profiling of sulfatides in myelin from mouse brain using liquid chromatography coupled to high-resolution accurate tandem mass spectrometry

- Thirty seven sulfatides have been simultaneously determined in myelin by LC-ESI-MS/MS.
- Wrong-way-round ionization effect allowed to obtain very good sensitivity in ESI(+).
- MS/MS fragmentation pattern allowed differentiating structural isomers.
- High mass accuracy was necessary to get a reliable identification of sulfatides.
- Sulfatides with hydroxylated and/or odd numbered fatty acid chains increase with age.

Sulfatides are sulfoglycolipids found in the myelin sheath. The composition ratio of sulfatide molecular species changes with age, and it has also been associated with the pathogenesis of various human central nervous system diseases. However, profiling sulfatides in biological samples is difficult, due to the great variety of molecular species. In this work, a new, easy and reliable liquid chromatography-electrospray tandem mass spectrometry (LC-ESI(+)-MS/MS) method has been developed to profile sulfatide content in biological samples of myelin. The 'wrong-way-round' ionization effect has been described for this type of molecules for the first time, making it possible to correctly identify as many as 37 different sulfatides in mouse brain myelin samples, including molecules with different fatty acid chain lengths and varying degrees of unsaturation and hydroxylation. A chemometric analysis of their relative abundances showed that the main difference among individuals of different ages was the content of sulfatides with odd-numbered fatty acid chains, in addition to hydroxylated species.

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