LIPO-AMINO ACID CHOLESTERYL DERIVATIVES 357 Model A Model B Figure 4. Optical texture of Models A and B under cross polarization. e 115 i I 0 20 25 0 5 10 20 25 20 (degree) 20 (degree) Model A Model B Figure 5. Small-angle X-ray diffraction patterns of Model A and Model B. untreated sites, the sites treated with sample exhibited recovery in TEWL. Recovery of TEWL in skin treated with AGCE-301 was significantly greater than with petrolatum (day 1 p 0.05). No significant difference was observed in TEWL recovery between AGCEs and cholesteryl hydroxy stearate. CHARACTERIZATION OF STRATUM CORNEUM LIPID MODEL When water was added and the heating and cooling process was repeated several times,

358 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 4 1 • mean_+S.E. o -2 -1 o 1 2 3 4 days after application = blank -- Model A o Model B [] Petrolatum Figure 6. Dermal scores following application of stratum corneum lipid model. model A (the model containing ceramide) exhibited the formation of a lameliar struc- ture, demonstrated by the optical texture under cross-polarization shown in Figure 4. Under the same conditions, model B with AGCE also showed the same optical texture, indicating that AGCEs have the potential to form a lameliar structure. The small-angle X-ray diffraction spectra for model A showed a pronounced peak at 59 fl., corresponding to the double-layer spacing, and a hollow peak around 5 fi- for lateral spacing (Figure 5). This is a typical pattern for lipid layers with bimolecular lameliar structures. Model B showed a similar spectrum, expect that the double-layer spacing occurred at 63 fi-. Thus, it was confirmed that the formation of lipid bilayers in models A and B mimicked the natural intercellular lipid layers in the stratum corneum. RECOVERY EFFECT OF STRATUM CORNEUM LIPID MODEL FOR DAMAGED SKIN Damaged skin treated with model B recovered significantly better in visual appearance compared with skin treated with petrolatum (day 3 p 0.05). No significant differences were observed between model A and model B with respect to the recovery of visual appearance (Figures 6, 7). The visual appearance of damaged skin treated with models