Abstract
Ascorbic acid (AsA) is well-known as a multifunctional water soluble vitamin that shows antipigmentation effects in epidermal melanocytes and stimulates collagen synthesis in dermal fibroblasts. 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 results, 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 spinous and/or granular cell layers of reconstructed human epidermal equivalents. In a human volunteer 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.
