Skin Moisturizing Effect through the Stimulation of the Cornified Cell Envelope Formation by Bis-Glyceryl Ascorbate

Ascorbic acid （ AsA ） is well-known as a multifunctional water soluble vitamin that shows anti-pigmentation effects in epidermal melanocytes and stimulates collagen synthesis in dermal fibro-blasts. However, AsA has some disadvantages in cosmetic formulations since it is quite unstable in aqueous solutions and emulsions. To improve the stability of AsA in cosmetic formulations, we developed a novel AsA derivative, bis-glyceryl ascorbate （ VC-DG ） , which introduces 2 glycerol groups into AsA, and confirmed that VC-DG has a higher stability than AsA and maintains its bioactivities as well as AsA. In this study, we evaluated the skin moisturizing effects of VC-DG focusing on the cornified cell envelope （ CE ） to develop its unique biological activities. As the re-sults, VC-DG up-regulated the mRNA and protein expression levels of CE-related substances, such as involucrin, loricrin and transglutaminase-1, which in turn significantly increased CE formation in normal human epidermal keratinocytes. Additionally, topical application of VC-DG increased the protein expression levels of involucrin, loricrin and transglutaminase-1 in the spi-nous and ／ or granular cell layers of reconstructed human epidermal equivalents. In a human vol-unteer test, the application of VC-DG increased the skin surface water content. Therefore, we consider VC-DG to be an effective ingredient that improves skin hydration through enhancing CE formation.