Further Development and Application of an LC/MS Analysis of Plasma Oxysterol

Importance: Oxysterols are biologically active derivatives of cholesterol of recent interest that encompass roles in signaling, regulation, immunity and disease biomarker amongst others. We examined the liquid chromatography-mass spectrometry (LC-MS) analysis of 6 clinically relevant oxysterols in order to improve the quantitation, chromatographic resolution and assay throughput. We also explore the use oxysterols as biomarkers in diagnosing and delineating clinical phenotypes of multiple sclerosis. Method: We evaluated the effect of column temperature, mobile phase solvent [acetonitrile (ACN) or methanol] and stationary phase chemistries [alkyl-silica (C18 and C8), biphenyl and aqueous (polar) C18] on chromatographic resolution and run-time of underivatized oxysterols. We applied the optimized method to a prospective, longitudinal study including 139 subjects [39 healthy controls, 61 relapsing-remitting MS (RR-MS), 39 progressive MS (P-MS)] to measure oxysterol levels at baseline and 5-year follow-up. Results: Traditional C18 (ODS) exhibited the greatest selectivity among the stationary phases tested. Colder column temperatures improve resolution for all stationary phases. Increased ACN enhanced resolution and shortened analytical runtime but decreased MS detector signal. Levels of 24-HC (p = 0.004), 25-HC (p = 0.029) and 27-HC (p = 0.026) were increased in P-MS patients while levels of 7-KC (p = 0.047) and 7-HC (p = 0.001) were decreased in RR-MS patients with no changes in healthy controls, all over the period of 5-years. Conclusion: Direct analysis of underivatized oxysterols is favored by colder column temperature using a C18 stationary phases and methanol based solvent gradient. The oxysterol network seems to be disrupted in MS patients compared to healthy control.

Grantor dc:publisher

State University of New York at Buffalo

Year dc:date.issued

2018

Author dc:creator

• Bhattacharya, Sonia Bholanath

Contributors dc:contributor

• Browne, Richard
• Biotechnical and Clinical Laboratory Sciences

• analytical chemistry
• biochemistry

Statement dc:rights

• Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions.
• Copyright retained by author.

Language dc:language

eng

Handle dc:identifier

http://hdl.handle.net/10477/77979

OAI record oai:identifier

https://ubir.buffalo.edu/oai/request?verb=GetRecord&metadataPrefix=qdc&identifier=oai%3Aubir.buffalo.edu%3A10477%2F77979