NAG AS EXFOLIATION ENHANCER 427 CLINICAL EFFECTS OF N-ACETYL-GLUCOSAMINE ON SKIN MOISTURATION AND DESQUAMATION Skin moisturization was evaluated using a Nova dermal phase meter (Table I). Moistur- ization was observed to increase by 12% and 18% over controls, at two and four weeks, respectively, in human skin. The two-week change was not statistically signifi cant, but this became signifi cant after four weeks. NAG was tested at 1% vs the placebo, on the back of the hands for their effect on skin desquamation and reduction of skin fl akiness via the D-squame disc method. After two and four weeks of treatment, the group using 1% NAG showed 39% and 38% decreases in fl akiness, whereas the placebo use resulted in a 30% increase (Table II). Table I Effect of 1% NAG on Skin Moisturization via the Dermal Phase Meter DPM values at p values at baseline vs Product Baseline 2 Weeks 4 Weeks 2 Weeks 4 Weeks 1% Glucosamine 145 131 131 0.16 0.11 Untreated control 159 125 116 0.06 0.01 p value (treated vs control) 0.11 0.16 0.009 % Increase (treated–control) 12 18 Four measurements were taken at each site at every time point. Measurements were performed on 45 panelists. Table II Desquamation Effi cacy of NAG in Vehicle via the D-Squame Disk Method % Decrease in fl akiness Product treatment group 2 Weeks 4 Weeks Placebo 6.0 -29.9 1% N-acetyl glucosamine 38.8 38.0 Four D-Squame discs were used on the face and hands of each of 45 panelists. Desquamation was evaluated from the D-Squame discs via image analysis as described in Methods. The average gray value corresponding to the sample density was measured. Figure 2. Protein levels of involucrin and keratin K1 and K10 in human keratinocytes treated with NAG. HaCaT cells were grown in six-well culture dishes to confl uence and treated with 50 mM, 125 mM, and 250 mM NAG for 24 hours. Each dose was run in triplicate. Cells were then scraped and processed as detailed in Methods. Experiments were repeated three times. Data is representative of one experiment.

JOURNAL OF COSMETIC SCIENCE 428 CONCLUSION There are many known benefi ts for the use of alpha-hydroxy acids on skin. There have also been recent reports that topical treatments with alpha-hydroxy acids increase skin dam- age resulting from UVB. Additionally, high concentrations of alpha-hydroxy acids have also been found to promote irritation. In order to fi nd alternatives to alpha-hydroxy acids, we investigated a variety of amino sugar compounds that were previously reported to inhibit the reaggregation of dissociated corneocytes by modulating cellular adhesion. Human keratinocytes in culture treated with 50 mM to 250 mM of NAG were released from the culture dish. This treatment appears to dissociate the keratinocytes from each other and from substrates. In addition, we observed an upregulation of differentiation markers, keratin 10 and involucrin, in keratinocytes treated with NAG. In vivo, we observed that topical treatments with a formulation containing NAG led to an increase in skin moisture levels and the normalization of stratum corneum exfoliation. In addition, high concentrations of NAG do not cause any noticeable irritation (data not shown). Topical doses as high as 5% and 10% did not produce any skin irritation. The benefi ts of topical N-acetyl-glucosamine are numerous and have been well documented by Bissett (11). These include accelerated wound healing, reduction of hyperpigmentation, and improved skin hydration. We have added to these benefi ts by showing an exfoliation enhancement. We propose the use of amino sugars, such as N-acetyl-glucosamine, as alter- native compounds to replace the use of alpha-hydroxy acids in skin care. REFERENCES (1) E. J. Van Scott and R. J. Yu, Control of keratinization with alpha-hydroxy acids and related compounds. I. Topical treatment of ichthyotic disorders, Arch. Dermatol., 110, 586–590 (1974). (2) M. J. Stiller, J. Bartolone, R. Stern, S. Smith, N. Kollias, R. Gillies, and L. A. Drake, Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin. A double-blind vehicle-con- trolled clinical trial, Arch. Dermatol., 132, 631–636 (1996). (3) N. V. Perricone, and J. C. DiNardo, Photoprotective and antiinfl ammatory effects of topical glycolic acid, Dermatol. Surg., 22, 435–437 (1996). (4) E. J. Van Scott and R. J. Yu, “Substances That Modify the Stratum Corneum by Modulating Its Formation,” in Principles of Cosmetics for the Dermatologist, P. Frost and S. N. Horwitz, Eds. (C. W. Mosby, St. Louis, 1982), pp. 70–74. (5) M. M. Brysk, S. Rajaraman, P. Penn, and E. Barlow, Glycoproteins modulate adhesion in terminally differentiated keratinocytes, Cell Tiss. Res., 225, 657–663 (1988). (6) D. L. Hudson, J. Sleeman, and F. M. Watt, CD44 is the major peanut lectin-binding glycoprotein of human epidermal keratinocytes and plays a role in intercellular adhesion, J. Cell Sci., 108, 1959–1970 (1995). (7) D. Cerimele, C. Del Forno, and F. Serri, Histochemistry of the intercellular substance of the normal and psoriatic human epidermis, Arch. Dermatol. Res., 262, 27–36 (1978). (8) S. Sakai, R. Yasuda, T. Sayo, O. Ishikawa, and S. Inoue, Hyaluronan exists in the normal stratum corneum, J. Invest. Dermatol., 114, 1184–1187 (2000). (9) P. Boukamp, R. T. Petrussevska, D. Breitkreutz, J. Hornung, A. Markham, and N. E. Fusenig, Normal keratinization in a spontaneously immortalized aneuploid human keratinocyte cell line, J. Cell. Biol., 106, 761–771 (1988). (10) J. C. Adams and F. M. Watt, Expression of beta 1, beta 3, beta 4, and beta 5 integrins by human epidermal keratinocytes and non-differentiating keratinocytes, J. Cell Biol., 115, 829–841 (1991). (11) D. Bissett, Glucosamine: An ingredient with skin and other benefi ts, J. Cosmet. Dermatol., 5, 309–315 (2006).