Determination of fatty acid and sphingoid base composition of eleven ceramide subclasses in <Emphasis Type="Italic">stratum corneum</Emphasis> by UHPLC/scheduled-MRM

Introduction

Ceramides play a key role in skin barrier function in homeostatic and pathological conditions and can be sampled non-invasively through stratum corneum collection.

Objectives

To develop a novel UHPLC/Scheduled MRM method for the identification and relative distribution of eleven classes of ceramides, which are separated by UHPLC and determined by their specific retention times. The precise composition of the fatty acid and sphingoid base parts of each individual ceramide is determined via mass fragmentation.

Methods

More than 1000 human and pig ceramides were identified. Three human and minipig ceramide classes, CERAS], CERNS] and CEREOS] have been investigated in depth.

Results

Sphingoid bases were characterized by a prevalence of chain lengths with sizes from C16 to C22, whereas fatty acids were mainly observed in the range of C22–C26. Overall, the ceramide profiles between human and minipig stratum corneum were similar. Differences in the CERAS] and CERNS] classes included a more homogeneous distribution of fatty acids (16–30 carbon atoms) in minipig, whereas in human longer fatty acid chains (>?24 carbon atoms) predominated.

Conclusion

The method will be useful for the analysis of healthy and pathological skin in various specie, and the measurement of the relative distribution of ceramides as biomarkers for pharmacodynamic studies.