The peroxyl radicals react further more rapidly with plasmalogens instead of unsaturated phospholipids and thus prevent the formation of substances that would lead into destruction of the lipid layer. Therefore plasmalogens impede the damage of UV-induced oxidative stress caused to unsaturated phospholipids. This view of the ether lipid function suits well also with the tear fluid lipid layer,NVP-BEZ235 as half of the lipids are unsaturated and the lipids are repeatedly exposured to UV light from the sun. The high abundance of ether lipids in tear fluid would also be relevant in the light of this theory, because the molar proportion of plasmalogens relative to the unsaturated lipids in the monolayer has to be greater than 25% in order to have an efficient antioxidative effect. As nearly half of the lipids identified in tear fluid are unsaturated phospholipids,Afatinib the molar proportion of plasmalogens to unsaturated phospholipids is 2363%. In addition to the phospholipase A2 activity mentioned above, plasmalogen oxidation may also be another source of lysophospholipids as oxidized plasmalogens degrade into lysophospholipids and aldehydes. Kulovesi and co-workers studied the three dimensional organization and behavior of an artificial tear fluid lipid layer comprising of 60 mol% of phospholipids, 20% free fatty acids, 10% cholesteryl esters and 10% triglycerides. The lipidome obtained here coincides well with this model composition. Even though not observed in this study, the lipid layer most probably contains also free fatty acids because of the abundance of lysophospholipids. These results support the view demonstrated with the artificial model that the lipid layer is a highly organized layered structure i.e. phospholipid monolayer at the air-water interface provides a hydrophobic interface to where non-polar lipids are able to spread on. Here we emphasized the significance of polar/non-polar lipid interface in macroscopic scale with the non-polar olive oil spreading experiments. The contact angles on eggPC-monolayer-coated mica surface showed much lower values compared to the hydrophilic blank mica surface representing air-water interface. Both curves show similar shapes having a steep slope in early phase of the spreading, which then rapidly proceeds towards plateau.