CERAMIDE
Ceramides are among the most important dermal sphingolipids, which belong to the skin's own lipids. They make up about half of the stratum corneum lipids.
Ceramides have numerous structural and biological functions in the human epidermis, e.g. they are involved in the prevention of transepidermal water loss. In addition, ceramides regulate processes such as cell division and differentiation of keratinocytes. (1)
Ceramides are differentiated according to the length of their bound fatty acid or the sphingoid backbone, e.g. ceramides AP, NP or EOP. (1)
In a study it was found that the facial skin of patients with mild and moderate acne vulgaris contained a significantly lower percentage of ceramides and sphingosines and at the same time the transepidermal water loss was significantly increased compared to healthy controls. (2)
In vitro studies also showed that phytosphingosine inhibits the growth of bacteria, including Cutibacterium acnes, and subsequent in vivo studies confirmed the antimicrobial properties by significantly reducing the total bacterial count on unwashed hands. (1)
(1) Borodzicz, S., Rudnicka, L., Mirowska-Guzel, D. et al. The role of epidermal sphingolipids in dermatologic diseases. Lipids Health Dis 15, 13 (2016). https://doi.org/10.1186/s12944-016-0178-7
(2) Yamamoto, A., Takenouchi, K., & Ito, M. (1995). Impaired water barrier function in acne vulgaris. Archives of dermatological research, 287(2), 214-218. https://doi.org/10.1007/BF01262335