potential of non-aqueous capillary electrophoresis- MASS SPECTROMETRY in analysis of oxysterols


Michal Greguš^1,2, Hanne Røberg-Larsen^3, Elsa Lundanes^3, Steven Ray Wilson^3, František Foret^1,
                                          Petr Kubáň^1,2


       ^1Bioanalytical Instrumentation, CEITEC MU, Brno, Czech Republic, gregus@mail.muni.cz

                ^2Department of Chemistry, Masaryk University, Brno, Czech Republic

                       ^3Department of Chemistry, University of Oslo, Norway


Oxidized metabolites of cholesterols, oxysterols (OHC), are important in numerous biological
processes and pose multiple roles in the body. A variety of isomers exists, with different
biological roles, e.g. 27-hydroxycholesterol (27-OHC) is a selective estrogen receptor modulator.
Other isomers are for instance: 24S-OHC, 25-OHC, 7β-OHC, 22R-OHC, etc.). 27-OHC can promote
proliferation of estrogen receptor (ER) positive breast cancer by binding to ER and metastasis by
binding to liver X receptor. Traditionally, separations of oxysterols are performed by gas
chromatography (GC) or liquid chromatography (LC) after derivatization with MS detection.
Separation of oxysterols by aqueous CE is difficult mainly because of their low solubility in water
and levelling effect of water.

In this study we explore the potential of non-aqueous capillary electrophoresis coupled to mass
spectrometry (NACE-MS) for better separation of the oxysterol isomers. The developed method was
successfully applied for separation of derivatized oxysterols from excess derivatization reagent,
resulted to simplified sample preparation (i.e. no need for SPE extraction before LC-MS analysis)
and hence to reduction of total analysis time and sample handling. Separation of
25-hydroxychlesterol/27-hydroxycholesterol in model sample solution is shown.


Acknowledgement

The authors acknowledge the financial support within the Programme EEA and Norway Grants – EEA
Scholarship Programme; Bilateral Scholarship Programme (Agreement No.: NF-CZ07-INS-6-321-2016). The
authors acknowledge the financial support from the Grant Agency of the Czech Republic (Grant No.
P206/13/21919S).