Ceramides (Cer) that contain the trihydroxylated sphingoid base phytosphingosine (4-hydroxysphinganine, t18:1 or P) were first discovered in the plant kingdom. Later, these members of the sphingolipid family, also called phytoceramides (phytoCer), were detected in human tissues that express desaturase 2. Large quantities of phytoCer have been found in the extracellular spaces of the stratum corneum (SC), the uppermost epidermal layer. The SC is the primary skin barrier; it protects the body from desiccation and entry of harmful substances from the environment[1].
[1] Barbora ?kolová. “Phytosphingosine, sphingosine and dihydrosphingosine ceramides in model skin lipid membranes: permeability and biophysics.” Biochimica et biophysica acta. Biomembranes 1859 5 (2017): Pages 824-834.
