KERA TIN PEPTIDE HAND CREAM 103 140 c=l Base C ream Keratin peptide cream - � 1 2 0 - � 1 0 0 80 Fin a I Figure 1. Final percentage of TEWL for the dry skin volunteers. Changes were doubly evaluated versus basal and control values. Results of skin hydration tests by capacitance measurement indicated that there was a trend of increased hydration for the keratin peptide cream treatment. This increase was consistent for the dry skin volunteers (Figure 2), reaching an increase of 20% during the treatment period, even though it is not statistically significant. For the elasticity parameters RS and R 7, the results showed a consistent trend of increasing elasticity in the zones treated with the keratin peptide cream, reaching a 1 5 0 - 145 � - 140 � 135 130 "fi 125 t 120 = ,a 1 1 5 ·o 1 1 o � 1 05 U 100 ] 9 5 rn 9 0 c=J Base Cream Kera tin peptide cream Time (days) Figure 2. Variation of skin capacitance after topical applications for dry skin volunteers during the treatment period. Changes were doubly evaluated versus basal and control values.

104 JOURNAL OF COSMETIC SCIENCE significant increase in elasticity for almost all measurements during the treatment period (Figures 3 and 4). It was predictable that only small differences in TEWL, hydration, and elasticity were obtained in the volunteers with already hydrated skin. However, treatment with keratin peptide cream on undisturbed hand skin showed beneficial effects on the volunteers with dry skin, significantly increasing the elasticity and showing trends of decreasing TEWL and increasing hydration. EFFECT OF KERATIN PEPTIDE HAND CREAM ON SODIUM LAUR YL SULPHATE (SLS) DISTURBED SKIN It is well known that commonly used surfactants can irritate and damage the skin, decreasing its natural barrier function and thus its ability to retain moisture. To inves­ tigate the protective effect of the keratin peptide cream on hand skin, all skin zones (previously treated over a period of two weeks with keratin peptide cream, base cream, or control) received the same SLS application, and biophysical parameters were measured at 2 h 30 min and 24 h following SLS exposure. The effect on SLS both on hydration and TEWL is always more marked for well-hydrated skin, and thus the differences obtained when the creams are applied are also more significant. The results obtained in this study showed that treatment of the skin with 1 keratin peptide cream provided protection from SLS exposure evidenced by a smaller decrease in hydration and a smaller increase in TEWL values, particularly for volunteers with well-hydrated skin. TEWL values show an initial increase in TEWL at 2 h 30 min, as a result of SLS exposure, followed by a recovery of the barrier function of the skin, demonstrated by a 240 :g 120 .... fl.I Cl 100 � 80 1 2 C:J Base Cream - Keratin peptide cream * * 3 6 7 8 9 10 13 14 15 16 Time (days) Fi gu re 3. Variation for rhe elasticity parameter R5 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).