j. Cosmet. Sci., 53, 263-268 (September/October 2002) Application of a non-invasive method to study the moisturizinD effect of formulations containinD vitamins A or E or ceramide on human skin GISLAINE RICCI LEONARDI, LORENA RIGO GASPAR, and PATRICIA M. B. G. MAIA CAMPOS, Faculty of Health Sciences, Department of Pharmacy, Methodist University of Piracicaba, Piracicaba, S•7o Paulo (G. R.L.), and Faculty of Pharmaceutical Sciences of Ribeir•7o Preto, University of S•7o Paulo, Ribeir•7o Preto, S•7o Paulo (L.R.G., P.M.B.G.M.C.), Brazil. Accepted for publication April 30, 2002. Synopsis Moisturizers containing vitamins A and E as well as ceramides are believed to improve the skin condition by increasing the water content of the stratum corneum. The aim of this research was to evaluate, through the capacitance method (a non-invasive method), the moisturizing effect of an O/W emulsion (non-ionic self-emulsifying base) containing vitamin A palmirate, vitamin E acetate, and ceramide Ill on human skin. The studies were carried out on a group of 40 healthy Caucasian female test subjects between 30 and 45 years of age, using the Corneometer CM 825 PC. Skin measurements were taken from the volunteers at 7 and 30 days after daily use (twice a day) of the tested products. The presence of vitamins A and E or ceramide III did not cause an improvement in the hydration of the stratum corneum, which means that none of those compounds strengthens the hydration effectiveness of the base formulations used, at least at the doses tested. The interpretation of electrical measurement regarding skin moisture should be made with caution thus the results observed in this study show the importance of using different approaches (or methodologies) to verify the performance of the formulas tested. We conclude that, at the low doses typically used in cosmetic formulations, vitamins A and E and ceramide III are not likely to contribute to the hydrating effects of the base moisturizing formulation when assessed by capacitance. INTRODUCTION Vitamins A and E as well as ceramides have been widely used in cosmetic moisturizing products (1-4). The stimulatory effects of vitamin A tend to oppose changes that occur with aging (5). Several studies report the effects of vitamin A palmitate in the epithe- lization of dry and rough skin (5,6). Maia Campos and collaborators evaluated the effects Address all correspondence to Gislaine Ricci Leonardi. 263

264 JOURNAL OF COSMETIC SCIENCE of vitamin A and/or glycolic acid on guinea pig skin. They observed that vitamin A induced a thickening of the epithelium. This increased cellular volume was due to intra- and extracellular hydration (7). On the other hand, vitamin E acetate functions i, vivo as an antioxidant. It protects skin lipids and lipoproteins in cell membranes, and may exert a beneficial effect on the skin's water-binding ability. It has been suggested that vitamin E improves the moisturizing and elastic properties of the skin, thus inhibiting one of the processes that lead to skin aging (1). Ceramides have gained scientific importance among professionals in the field and consumers because they are natural constituents of skin lipids and the cutaneous permeability barrier. The cutaneous per- meability barrier protects the skin from drying out, and because of this, it is considered important for the protection and hydration of the skin (8-10). There are several methods for skin moisture assessments (11,12), based on different principles. The literature documents that the capacitance-measuring method (Corneom- eter © method) presents several advantages over other related methods (13). Serup eta/. (14) used different non-invasive methods (electrical conductance, electrical capacitance, and water evaporation) to evaluate the moisturizing effect of an O/W emulsion. Their study and others (15) showed that electrical capacitance is a reliable method to evaluate cutis moisture (14). The Corneometer © method gave a stable correlation with the real water content that exists in dry and dehydrated skin (15). Thus, the aim of this research was to evaluate the moisturizing effect of an O/W emulsion (non-ionic self-emulsifying base) with and without vitamin A palmitate, vi- tamin E acetate, or ceramide III on the human skin, by the capacitance method (a non-invasive method). EXPERIMENTAL PROCEDURE FORMULATIONS STUDIED We used an O/W emulsion consisting of 17% non-ionic self-emulsifying base, 3% squalane, 0.5 % imidazolidinyl urea, 0.2% methyl, 0.1% propylparaben, 10% glycerin, 0.3% glutathione, 0.04% DL alpha tocopherol, and distilled water, with or without the addition of vitamin A palmitate (5,000 UI/g), vitamin E acetate (20 mg/g) or ceramide III (1 mg/g). HYDRAT1ON TESTING ON THE SKIN This study was performed after it had been approved by the Committee of Research Ethics at the Clinical Hospital-Medical College of Ribeirio Preto, University of Sio Paulo. The investigations were carried out on a group of 40 healthy Caucasian female test subjects, ranging in age from 30 to 45 years. They showed no signs of skin disturbances and no hormonal alterations, and they were not using any medications. For a twenty- eight-day interval before the beginning of the test, the subjects refrained from using cosmetics. No other products were used on each forearm during the trial period. The test subjects were recruited and asked to sign an informed consent statement. A Corneometer CM 825 PC was used. The volunteers' skin was measured at 7 and 30 days after a twice-day use of the tested products. The region where the products were