On the importance of chain branching in tear film lipid layer wax and cholesteryl esters

The tear film lipid layer (TFLL) is important to the maintenance of ocular surface health. Surprisingly, information on the individual roles of the myriad of unique lipids found therein is limited. The most abundant lipid species are the wax esters (WE) and cholesteryl esters (CE), and, especially t...

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Bibliographic Details
Published in:Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2022-06, Vol.214, p.112429-112429, Article 112429
Main Authors: Viitaja, Tuomo, Raitanen, Jan-Erik, Hynynen, Antti, Moilanen, Jukka, Svedström, Kirsi, Paananen, Riku O., Ekholm, Filip S.
Format: Article
Language:English
Subjects:
Biophysics
Chemical synthesis
Cholesterol Esters - chemistry
Esters
Lipids - chemistry
Structural elucidation
Tear film lipid layer
Tears - chemistry
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Summary:The tear film lipid layer (TFLL) is important to the maintenance of ocular surface health. Surprisingly, information on the individual roles of the myriad of unique lipids found therein is limited. The most abundant lipid species are the wax esters (WE) and cholesteryl esters (CE), and, especially their branched analogs. The isolation of these lipid species from the TFLL has proved to be tedious, and as a result, insights on their biophysical profiles and role in the TFLL is currently lacking. Herein, we circumvent these issues by a total synthesis of the most abundant iso-methyl branched WEs and CEs found in the TFLL. Through a detailed characterization of the biophysical properties, by the use of Langmuir monolayer and wide-angle X-ray scattering techniques, we demonstrate that chain branching alters the behavior of these lipid species on multiple levels. Taken together, our results fill an important knowledge gap concerning the structure and function of the TFLL on the whole. [Display omitted] •The total synthesis of TFLL iso-branched wax and cholesteryl esters is reported.•The complete NMR-spectroscopic characterization of such species is reported.•Iso-branching lowers the melting points and alters the packing of TFLL wax and cholesteryl esters.•Films of iso-branched wax esters display evaporation resistant properties.•Subtle structural differences in TFLL wax esters may alter their role in the TFLL.
ISSN:0927-7765
1873-4367
DOI:10.1016/j.colsurfb.2022.112429