SOYBEAN PHYTOSTEROLS AND SKIN BARRIER RECOVERY 223 80 "' 70 60 50 Et:. 40 ai a.: 30 20 10 0 DCONTROL DWHITE SPS After 1 day After3 days Aftar7 days Figure 2. Percentage of barrier recovery (P.B.R.), obtained one day, three days, and seven days after tape stripping, for stripped skin sites treated with white and SPS formulations or not treated (control). their role in the stabilization of the phospholipid bilayers in the cell membrane. Both phytosterols and cholesterol present in the skin surface lipids were transferred from the plasma to the skin after their absorption from the diet in small quantities from the intestine (19). It is well known, furthermore, that cholesterol plays an important role in skin homeostasis, accelerating barrier recovery by regulating endogenous factors in the epidermis (20). From the results obtained it could be hypothesized that the increased recovery rate of skin barrier function, observed after SPS application in stripped cuta­ neous sites, could be due to a "cholesterol-like" mechanism involving phytosterol species contained in SPS form. CONCLUSION This study shows clearly that, related to the methodological strategies applied, soybean phytosterols exert positive results on skin repair after damage. Furthermore, the spec­ trophotometric evaluation used in the present study to determine the percutaneous absorption of an erythematogenous substance, such as MN, seems to be a valid alter­ native to traditional TEWL measurement to obtain, indirectly, evidence on the recovery rate of disrupted skin. REFERENCES (1) K. R. Feingold and P. M. Elias, "The Environmental Interface: Regulation of Permeability Barrier Homeostasis," in Dry Skin and Moisturizers, Chemistry and Function, M. Loden and H. I. Maibach. Eds. (CRC Press, Boca Raton, FL, 2000), pp. 45-58.

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