Sunscreens and Other Products

By: Charles Fox

Posted: December 23, 2005, from the December 2004 issue of Cosmetics & Toiletries.

Quasi-ceramides in barrier reinforcement: Takagi et al report on the barrier reinforcing function of synthetic compounds called quasi-ceramides.

The stratum corneum consists of corneocyte and intercellular lipids. Although the lipids are only 10% of the total weight of the stratum corneum, they enable an effective permeability barrier function by forming the lamellae structure. Ceramides comprise almost half of these lipids.

Among the ceramides, the acylceramides are particularly important for permeability barrier function. The acylceramide is considered to maintain barrier function by stabilizing the lamellae structure. For example, lower amounts of acylceramides (caused by diets deficient in essential fatty acids) correspond to an understabilized lamellae structure accompanied with low barrier function. Acylceramides are useful for barrier reinforcement, however they are not readily available for use in skin care products because of their high cost and low stability.

Takagi et al have confirmed the barrier reinforcing function of acylceramides and have developed quasi-ceramides by synthesizing compounds that may stabilize the lamellae structure. These researchers found that diamide derivatives, which have the long hydrophobic region with hydrophilic residue on both sides, can stabilize the lamellae structure and reinforce the barrier function in rats whose diets are deficient in essential fatty acids. For the complete article, click on "Purchase this article."

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