SEOUL, Korea—In a Korean study that evaluated the effects of major lipid ingredients in moisturizers— cholesterol; linoleic acid; and N-oleoyl-phytosphingosine, a synthetic ceramide—on skin responses to UV in tape-stripped human skin in vivo, topical cholesterol protected the barrier-disrupted skin against UV-induced damage, while linoleic acid or N-oleoyl-phytosphingosine alone have the potential to aggravate the damage (J Dermatolo Sci. Dec. 30, 2011).
Because little is known about the ability of lipid ingredients in moisturizers with molecular weights of less than 500 to penetrate human skin and affect skin responses to UV, researchers evaluated the effects of three major lipid ingredients in moisturizers on skin responses to UV in the tape-stripped skin of healthy volunteers. After two days of lipid-application, the areas were irradiated with UV, and skin samples were obtained 24 hours after irradiation.
Compared to vehicle, topical cholesterol significantly decreased the degree of dermal inflammatory infiltrates and exocytosis, and also decreased the expression of MMP-1, IL-6 and IL-1beta mRNA. In contrast, topical linoleic acid increased the induction of apoptotic cells, and the expression of MMP-1 and IL-6 mRNA. N-oleoyl-phytosphingosine increased the expression of MMP-1 and IL-6 mRNA, while decreasing the expression of COX-2 mRNA.
