Composition of the neutral lipids of bovine meibomian secretions

Lipids secreted form the bovine meibomian glands were assigned to following classes: cholesteryl esters (A) (fatty acyl chain lengths from 15 to 27 carbon atoms), 41%; wax esters, 29%; triacylglycerols, 10%; and cholesteryl ester (B) (fatty acyl chain lengths from 14 to 18 carbons), 15%. The remaining 5% consisted of cholesterol, fatty acids, and highly polar material. Analysis of the lipids showed that only the cholesteryl esters (A) contained fatty acyl chains greater than or equal to C20:0. One third of the fatty acyl chains of the wax esters and the cholesteryl esters (B) was iC15:0. The fatty alcohol moieties of the wax esters were found to be branched chain, C23:0-C27:0. A computer-based programmable gas-liquid chromatographic procedure using 10% apolar 10C on Gas Chrom Q could be used to distinguish both iso and anteiso fatty alcohols and esters of fatty acids.