240 � 220 = � 200 � � 180 -= u 160 � 140 ·-c -� 120 .... fl} � 100 80 KERATIN PEPTIDE HAND CREAM 105 � Base Cream - Keratin peptide cream * * * * * * 2 3 6 7 8 9 10 13 14 15 16 Time (days) Figure 4. Variation for the elasticity parameter R7 for dry skin volunteers during the treatment period. Changes were doubly evaluated versus basal and control values. (*p 0.05, significance is evaluated using ANOV A variance analysis between each percentage result and its corresponding control percentage result). decrease in TEWL. It can be seen that in the zones treated with the keratin peptide cream the variation of TEWL after SLS exposure is less, with a decrease in TEWL of about 15% compared to the control zone (Figure 5). 120 C:=J Base Cream - Keratin peptide cream = 11 0 ._, � -= 100 90 r.l E-- 80 Time Figure 5. Variation of TEWL for the volunteers with well-hydrated skin at two different intervals follow­ ing SLS exposure. Changes were doubly evaluated versus basal and control values.

106 JOURNAL OF COSMETIC SCIENCE * c=J Base Cream - - Keratin peptide ere am ';!. 180 � 160 C u � 140 CJ) C ·u 120 � �Q. 100 C � en 2h30s 24h Time Figure 6. Variation of skin capacitance for well-hydrated skin at two different intervals following SLS exposure. Changes were doubly evaluated versus basal and control values (*p 0.05, significance is evaluated using ANOVA variance analysis between each percentage result and its corresponding control percentage result). Exposure to SLS has the effect of dehydrating skin. However, results showed that there was a significantly smaller decrease in hydration for skin zones treated with the keratin peptide cream (Figure 6). CONCLUSIONS Treatment with keratin peptide hand cream on undisturbed skin showed different effects depending on the initial hydration status of the skin. The keratin peptide cream treat­ ment had beneficial effects on d ry skin as evidenced by a decreased TEWL and increased hydration and elasticity. Skin treated with keratin peptide cream is more resistant to the damaging effects of SLS. While the applied peptides may not prevent the interference of SLS with the lipid layer of the stratum corneum, they do appear to assist the skin in retaining moisture following SLS exposure, thereby preventing some of the damaging effects of the surfactant insult. REFERENCES (1) V. Rogiers and the EEMCO Group, EEMCO guidance for the assessment of transepidermal water loss in cosmetic sciences, Skin Pharmacol. Appl. Skin Physiol., 14, 117-128 (2001). (2) E. Berardesca and H. I. Maibach, Transepidermal water loss and skin surface hydration in the non­ invasive assessment of stratum corneum function, Derm. Beruf Umwelt., 38(2), 50-53 (1990).