JOURNAL OF COSMETIC SCIENCE 8 and to protect skin from microbiological infections. However, too much sebum secretion could make the skin surface very oily and might promote acne for some people (2,3). Thus, sebum control is an important factor for facial skin care, especially for young adults with excess sebum secretion. It is generally accepted that the water content of the SC and skin sebum secretion are coordinative and important factors in the appearance and function of skin. A high water content, low transepidermal water loss (TEWL), and low sebum secretion are considered to be main features of fair skin. Thus, optimized facial care cosmetics should be developed that can supply a proper moisturizing effect and at the same time remove excessive amounts of sebum in facial skin (4). To substantiate the effi cacy claimed for cosmetic products, non-invasive bioengineering instruments have been introduced into cosmetology (5). The Corneometer has gained worldwide acceptance as an effi cient instrument to detect water content variation in the SC, based on electrical capacitance measurement (6,7). The Tewameter is the device com- monly used to determine TEWL, which measures the water vapor pressure gradient ac- cording to Fick’s law, to evaluate skin barrier function integrity (8,9). The Sebumeter has become an acceptable method for detecting sebum secretion levels, which is determined by the photometric transparency of absorbed sebum onto a plastic fi lm (10,11). To explore the proper personal care regimen for facial skin, we have investigated the pro- tection effect of some cosmetics on human skin under a simulated rigorous environment (12). Here, we investigated moisturizing and anti-sebum secretion effects by measuring skin water content, TEWL, and skin sebum secretion before and after cosmetic applica- tion on human facial skin. MATERIALS AND METHODS TEST PRODUCTS The test products, including product 1, product 2, and product 3, were mainly composed of glycosyl trehalose, Laminaria ochroleuca extract, sodium hyaluronate, niacinamide, glyc- erin, panthenol, and tocopherol, and were provided by Procter & Gamble (China) Ltd. Some of the ingredients were newly researched actives claimed by P&G. For example, Laminaria ochroleuca extract was extracted from a plant that grew in a desert environ- ment and could survive the rigorous droughty climate. Product 1 was colorless, non- aromatic, and water-like product 2 was a white and faintly scented cream and product 3 was a white sun protection cream with 2-ethylhexyl salicylate and titanium dioxide as the sunscreen actives, and labeled as SPF18, PA++. Product 1 was applied fi rst and then fol- lowed by product 2. While product 3 was required to be used according to a test protocol, it was applied following the application of product 2. SUBJECTS Thirty healthy female subjects, with normal or slight oily types of facial skin, partici- pated in this study. Their ages ranged between 25 and 34 years, and the average age was 29 ± 3 years. The criteria for non-inclusion were the presence of any dermatitis and/or

MOISTURIZING/ANTI-SEBUM EFFECTS ON SKIN 9 other skin diseases and allergy, or participation in any other study. An informed consent form was obtained and signed by each subject. FACIAL SKIN WATER CONTENT, TEWL, AND SEBUM SECRETION MEASUREMENTS Skin water content was estimated with a CM 825 Corneometer (Courage + Khazaka Company, Cologne, Germany), and the results were expressed in arbitrary units (a.u). TEWL was measured using a TM 300 Tewameter (Courage + Khazaka) and expressed in g/h.m2. Facial sebum secretion was measured using an SM 815 Sebumeter (Courage + Khazaka) and expressed in μg/cm2. TEST PROCEDURE Before each test, the subjects cleaned their faces with a standard lotion according to a standard procedure and rested for 30 min in the air-conditioned laboratory with a con- stant 22° ± 1°C room temperature and 50 ± 5% relative humidity. The subject’s cheeks were used as test areas. For the kinetics test, one 3-cm × 3-cm area on one cheek was treated with product 1, product 2, and then with product 3, and the corresponding area on the other cheek was left untreated as a control according to permuting order. Measurements were taken 0, 2, 4, and 8 h after product application, with an amount equaling 2 μl/cm2 or 2 mg/cm2 on the fi rst day. For the three-week test, the cheeks were treated with product 1, product 2, and then with product 3, with no control area. Measurements were taken once a week over a period of three weeks, and the subjects were instructed to use the products twice a day at home. At the end of the last test, the 8-h kinetics test was performed again, as on the fi rst day, and the subjects fi lled out a questionnaire to present their feelings about the products after using them for three weeks. STATISTICAL ANALYSIS The difference between the measurements was statistically evaluated with analysis of variance (ANOVA) and the Student’s t-test. The p value of 0.05 was considered signifi - cant. STATISTICA 7.1 (Statsoft Company, Tulsa, OK) software was used. RESULTS KINETICS TESTS ON THE FIRST DAY For the areas treated with products on the fi rst day, the Corneometer measurements gave an increased level, with the highest value measured 4 h after application (Figure 1). All the differences from baseline were signifi cant in the statistical analysis ( p 0.05), whereas for the untreated area almost constant levels were found during the 8-h test period.