Comprehensive analysis of the major lipid classes in sebum by rapid resolution high-performance liquid chromatography and electrospray mass spectrometry

Mauro Picardo,Jo-Linda Sinagra,Marisa Galante,Matteo Ludovici,Emanuela Camera

doi:10.1194/jlr.d008391

Abstract

Sebum is a complex lipid mixture that is synthesized in sebaceous glands and excreted on the skin surface. The purpose of this study was the comprehensive detection of the intact lipids that compose sebum. These lipids exist as a broad range of chemical structures and concentrations. Sebum was collected with SebuTape(TM) from the foreheads of healthy donors, and then separated by HPLC on a C8 stationary phase with sub 2 µm particle size. This HPLC method provided high resolution and excellent reproducibility of retention times (RT). Compound mining was performed with time of flight (TOF) and triple quadrupole (QqQ) mass spectrometers (MS), which allowed for the classification of lipids according to their elemental composition, degree of unsaturation, and MS/MS fragmentation. The combination of the two MS systems detected 95 and 29 families of triacylglycerols (TAG) and diacylglycerols (DAG), respectively. Assignment was carried out regardless of positional isomerism. Among the wax esters (WE), 28 species were found to contain the 16:1 fatty acyl moiety. This method was suitable for the simultaneous detection of squalene and its oxygenated derivative. A total of 9 cholesterol esters (CE) were identified and more than 48 free fatty acids (FFA) were detected in normal sebum. The relative abundance of each individual lipid within its own chemical class was determined for 12 healthy donors. In summary, this method provided the first characterization of the features and distribution of intact components of the sebum lipidome.

Highlights

Sebum is a complex lipid mixture that is synthesized in sebaceous glands and excreted on the skin surface
Selected reference compounds were investigated for application of the chosen RR-reversed phase (RP)-high performance liquid chromatography (HPLC)/time of flight (TOF)-mass spectrometers (MS) and MS/MS conditions to the analysis of general lipid classes in sebum
The method adopted in this study provided information on the range of carbon atoms and the number of double bonds in sebaceous lipid components, which were detected in their intact form

Summary

Introduction

Sebum is a complex lipid mixture that is synthesized in sebaceous glands and excreted on the skin surface. The relative abundance of each individual lipid within its own chemical class was determined for 12 healthy donors This method provided the first characterization of the features and distribution of intact components of the sebum lipidome.—Camera, E., M. GC/MS and HPLC/MS analyses of methyl and trimethyaminoethyl esters of hydrolyzed FA have been used extensively [8,9,10,11] These approaches have reduced the complexity of the data, allowing for easy detection of the FA component. To understand the distribution of individual sebum constituents, the ideal analytical approach would allow for the simultaneous detection and identification of intact species belonging to different lipid classes. Sebum was separated using a C8 stationary phase with sub 2 μm p.s., which offered improved selectivity as well as a shorter time for the simultaneous analysis of lipids belonging to different sebaceous classes. A thorough understanding of sebum composition gives new opportunities to further investigate the regulation of the sebaceous lipidome

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