470 JOURNAL OF COSMETIC SCIENCE and 2 containing CAAS (p 0.05) and AA (p 0.01) during six hours, respectively. In the cases of combination formulations 5 and 6, both of their effects were higher than those of formulations 2, 3, or 4. A CAAS:T combination was more effective than an AA:T combination up to the sixth hour (p 0.05 ). Results obtained from the w/o emulsion creams were very similar to those from the o/w emulsion creams. T (Formulation 10) displayed the highest hydration profile among the formulations containing a single vitamin. CAAS (Formulation 9) and AA (Formulation 8) followed T (p 0.01). Formulations 11 and 12 containing AA:T and CAAS:T combinations in w/o emulsion creams gave higher moisrurization values, as can be seen in Figure 2. Combination of the two vitamins in creams resulted in synergism in skin hydration. The highest hydration was observed with Formulation 12 containing the CAAS:T combination, followed by Formulation 11 containing the AA:T combination (p 0.01). LONG-TERM TRIAL Mean changes in the relative corneometer unit versus time for the long-term trial are shown in Figures 3 and 4. The skin-hydrating effect of CAAS was more obviously found close to that of T, especially in the w/o emulsion creams. Formulations 9 and 10 containing CAAS and T showed a significant difference in skin conductance (p 0.05 ). However, the hydrating profiles of both these formulations were significantly higher ·c ::::J QJ 0 QJ 0 u QJ m � C QJ C m u C m QJ ::i! - :l � - 1 2 3 lime (week) 4 D1 ■ 2 ■ 3 ■ 4 □ 5 □ 6 Figure 3. Mean values of the changes in skin conductance on the inner forearms of ten volunteers following twice-daily applications of the o/w emulsion creams during four weeks in a long-term trial (Formulations 1-6).

·c :::I .... Cl) Cl) E 0 Cl) E 0 Cl) - :::I � � m � - .E Cl) C m .c u C m Cl) MOISTURIZING EFFECTS OF AA, CAAS, AND TOCOPHEROL 471 30 25 20 15 10 5 0 1 2 3 lime (week) 4 □ 7 ■ B ■ 9 ■ 10 o 11 a 12 Figure 4. Mean values of the changes in skin conductance on the inner forearms of ten volunteers following twice-daily applications of the w/o emulsion creams during four weeks in a long-term trial (Formulations 7-12). compared to that of Formulation 8 containing AA (p 0.001). Formulation 12 dis­ played the highest hydrating profile, followed by Formulation 11 in the long-term trial (p 0.05). INFLUENCE OF OCCLUSION ON SKIN HYDRATION Occlusion is an important factor for skin hydration. Occlusion leads to enhanced pen­ etration into the skin. In both of the trials, the placebo w/o emulsion cream (Formulation 7) generally displayed a higher moisturizing effect than the placebo o/w emulsion cream (Formulation 1) (p 0.001 in the short-term trial and p 0.05 in the long-term trial) (Figures 1-4, Table I). We believe that this general effect is attributed to the difference in lipid content of the emulsions (Table I). It was reported that the extent of the occlusive effect depends on various factors, including the lipid concentration of the base formulation (25 ). CONCLUSIONS As a result, statistical analysis gave information that T was more effective in increasing skin conductance compared with AA and CAAS. However, the moisturizing potential of CAAS was sufficiently high for it to be a good candidate for effective skin hydration.