Investigation into the delivery and evaluation of a unique Avena sativa (Oat) Lipid Extract on skin barrier using LC ‒ MS / MS , Raman spectroscopy, immunostaining analysis and skin efficacy

Objectives Oat lipids are rich in ceramides. In this investigation, we analysed the delivery of a specific Oat Lipid Extract derived from Avena sativa , comprising ‘skin identical’ ratios of fatty acids, ceramides and cholesterol/sterol. This investigation is the first reported investigation of oat lipids utilizing Raman spectroscopy for the identification of oat ceramides from A. sativa supported by Lipbarvis®, transmission electron microscopy and immunofluorescence analysis. Methods Oil lipid class compositions were determined by single‐dimension double‐development high‐performance thin‐layer chromatography. Ceramide class profiling was carried out using liquid chromatography with tandem mass spectrometry. Raman spectra of lipids were obtained by confocal Raman spectroscopy and immunostaining on human skin explants following treatment for 5 days. Length of lipid lamellae was determined using Lipbarvis® transmission electron microscopy followed by immuno‐histochemical analysis of hyaluronic acid and ceramides, on human skin following treatment for 56 days. Measurement of skin roughness (PRIMOS) and hydration (corneometer) were performed following treatment for 56 days. Results Gas–liquid chromatography and high‐performance thin‐layer chromatography profiling of Oat Lipid Extract, revealed that of the ceramide classes identified, skin identical sphingosine and phytosphingosine bases were present. Oat Lipid Extract has a typical total polar lipid content of 40 g kg −1 of which 4 g kg −1 ceramides, comprised ceramides/hydroxyceramides, gycosyl inositol phosphoryl ceramides and glucosylceramides. Raman profiling of Oat Lipid Extract was well correlated with stratum corneum and viable epidermis lipid profiles. Oat Lipid Extract induced a significant increase in neutral and polar lipid content. Lipbarvis® transmission electron microscopy and immunostaining showed significant increase in the length of the intercellular lipid lamellae and in the amount of hyaluronic acid and ceramides. Oat Lipid Extract significantly reduced skin roughness and increased skin hydration after 56 days of treatment. Conclusion Oat ceramides in the form of Oat Lipid Extract can be effectively delivered into the stratum corneum. The preliminary Raman and electron microscopy Lipbarvis® studies have given good insight into the possibility of Oat Lipid Extract mimicking the structure and function of the skin's barrier. The visible effect on the skin was observed with a decrease in skin roughness.