In the hot summer, the skin faces multiple challenges: high temperature, strong ultraviolet rays, increased sweat and oil secretion, etc. These factors can cause skin moisture loss and barrier damage, especially for sensitive skin, it is more likely to experience redness, itching, burning, stinging, dryness or tightness and other discomforts, which bring us a lot of trouble.
Solving skin problems ultimately comes down to ensuring the normal function of the skin barrier. Skin barrier damage is a crucial mechanism for the occurrence of skin sensitivity symptoms and is closely related to the occurrence and development of skin diseases. As the main component of stratum corneum lipids, ceramide plays a vital role. Therefore, in the era of functional skin care, ceramide has become the favorite of the "ingredient party". In the past few years, the global ceramide market has developed steadily.
Human skin itself contains a large amount of ceramide. Ceramide, together with cholesterol and free fatty acids, forms a multilayer lamellar membrane that fills the keratinocytes, accounting for about 40% to 55%. Ceramides in the basal cell layer and dermis are mainly distributed in the nuclear membrane, inner and outer membranes of mitochondria, etc.; ceramides in the upper epidermis are mainly distributed in the lamellar bodies, intercellular spaces of the stratum corneum, etc.
Ceramides are formed by amide bonds between sphingosines and long-chain fatty acids, synthesized and secreted by lamellar bodies, and can repair damaged skin barrier function by increasing the hydration of the skin and reducing the transepidermal water loss rate. Ceramides, like polypeptides, are a very large category. At present, studies have found that there are 16 subtypes. Different fatty acids and different long-chain bases constitute different subtypes of ceramides, and their proportions in the stratum corneum of the skin are different.
Ceramide NP is an important ceramide subtype in the stratum corneum of the skin, composed of phytosphingosine and hydroxy-free fatty acids. Compared with other ceramide subtypes, it accounts for the highest proportion in the human stratum corneum, reaching 22.1%. Ceramide NP is not a substance, but a general term for a large class of ceramides with similar structural principles. Both ceramide 3 and ceramide 3B belong to the category of ceramide NP. The fatty acid part of ceramide 3 is stearic acid, and ceramide 3B is oleic acid, which are respectively constructed with phytosphingosine through amide bonds.
(1) Moisturizing and locking water
Ceramide NP can quickly penetrate into the skin, associate with water molecules in the stratum corneum, and form a mesh structure to lock water, strengthen the adhesion between stratum corneum cells, improve skin dryness, and reduce skin desquamation. It can significantly promote the expression of filaggrin, and FLG is the main source of natural moisturizing factor NMF. As a highly effective moisturizer, the moisturizing effect of ceramide NP is 16 times that of hyaluronic acid, which is easily absorbed by the skin and can promote the penetration of other nutrients. The moisturizing effect on elderly dry skin is as high as 80%.
(2) Enhance skin barrier function
Ceramide NPs bind to cell surface proteins through ester bonds to form lipid-cell-protein wrapping, which not only maintains the integrity of the sebum membrane, but also strengthens the stratum corneum layer and enhances the cohesion of epidermal cells, thus achieving the effect of thickening the stratum corneum.
