The aim of this study was to characterize the evolution of the Skin Surface Lipids composition in the case of the very skin aging, 

Data were collected from the forehead of 22 young volunteers (18-24 years old) and 18 elderly volunteers (70-75 years old). The amount of sebum and porphyrin area were obtained respectively by sebumetry and image analysis. To obtain relevant information about molecular composition of high complex lipid mixtures, Skin Surface Lipids (SSLs) were analyzed in one run keeping the lipid structures intact, using High Temperature Gas Chromatography coupled with Mass Spectrometry (HTGC/MS). 

Major adaptations in the skin of people over 70 years were highlighted at the surface. As expected, a decrease of the sebum content at the skin surface is observed for elderly. A modification of the relative SSLs composition was also observed, with a significant decrease of the intensity of many lipid components of the hydrolipidic film. However, we have shown an increase in the intensity and the proportion of 2,3-oxidosqualene, which can be formed enzymatically by squalene monooxygenase. We also observed an inverse relationship between triglycerides and their hydrolysis products: a decrease of the proportion of the triglycerides and an increase of free fatty acids, monoglycerides and diglycerides. These observations may show an increase of the triglyceride’s hydrolysis for elderly.

These results confirm a decrease of the sebaceous activity for elderly with an important evolution of its composition. Interestingly, despite the global decrease of lipids amount the 2,3-oxidosqualene content increased with age. These adaptations could be related to modifications of the enzymatic activity. These latter may be linked to changes in the activity of the microbiota.

Very skin aging and Skin Surface Lipids composition: increase of the 2,3-oxidosqualene