Fatty acid composition of cholesteryl esters of human meibomian gland secretions

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Very long chain cholesteryl esters (CE) are a major group of lipids found in meibomian gland secretions (MGS, also called meibum). MGS are produced by the meibomian glands of human and animal eyelids. They are a critical part of the tear film which covers the exposed ocular surface and serves various physiological roles. The composition of CE of MGS is complex, and still remains poorly understood. Here, a liquid chromatographyion trap mass spectrometry (LCMS) procedure developed to analyze CE is described, and a detailed composition of human meibomian CE is reported. MGS were collected from donors, analyzed without any modifications by LCMS in positive and negative ion modes (PIM and NIM), and quantified using lipid standards where available. CE comprised about 30% of human meibum by mass. More than 40 individual CE species were found and characterized. In PIM, CE were observed as spontaneously in-source generated product ionsm/z 369. The signals of the proton adducts of intact CE (M+H)+ were of very low intensity. In NIM, all tested CE spontaneously fragmented in-source producing signals of their respective FA. By combining the LC and MS information, the most abundant CE were found to be based on FA ranging from C16to at least C32 in the following order C26:0 > C25:0 > C24:0 > C 27:0 > C24:1 =C18:1 =C20:0 > other CE. We conclude that the FA composition of CE can be successfully established in LCMS experiments conducted in NIM. Meibomian CE have a large presence of both saturated and unsaturated FA with an average molar ratio of 4 to 1, respectively.

Original languageEnglish (US)
Pages (from-to)726-733
Number of pages8
Issue number10
StatePublished - Oct 2010


  • Fatty acids
  • High performance liquid chromatography
  • Human meibum
  • Mass spectrometry
  • Meibomian secretions
  • Very long chain cholesteryl esters

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry


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