Topical N-Acetyl Glucosamine and Niacinamide Increase Hyaluronan
R. Osborne, Ph.D., L. A. Mullins, B.S. and L. R. Robinson, Ph.D. The Procter & Gamble Company, Cincinnati, Ohio USA
Hyaluronan is a mucopolysaccharide in the epidermis responsible for maintaining overall hydration and elasticity of the skin (1). A decline in epidermal hyaluronan content occurs during aging, contributing to decreased turgidity and increased wrinkle formation (2). N-Acetyl-glucosamine is a precursor of hyaluronan, and niacinamide is an essential co-factor of hyaluronan synthesis. In the current work, engineered human skin equivalent cultures were used to determine effects of topical N-acetyl glucosamine and niacinamide on hyaluronan and collagen expression, and for prediction of improved appearance of aging facial skin.
· To evaluate the effects of n-acetyl glucosamine and niacinamide on expression of hyaluronan and collagen in human skin cell cultures in vitro. · To confirm the in vitro responses via improved appearance of fine lines and wrinkles on facial skin in vivo.
In Vitro Human Skin Equivalents The MatTek Human Skin EpiDermFT Skin Model (MatTek Corp., Ashland, MA USA) was used for the in vitro experiments. This skin model (Fig. 1) contains a three-dimensional, highly differentiated human epidermis with 8-12 cell layers including basal, spinous, granular and stratum corneum layers; the epidermis is grown above a human dermal fibroblast-containing collagen matrix. The MatTek cultures are air-interfaced, and test substances (100 ul/culture) were applied topically to the stratum corneum surface for 20-24 hrs at 37°C.
Hyaluronan and Collagen Assays Hyaluronan and Procollagen 1 (the precursor to Collagen 1, the principal collagen of the skin) in cell extracts were measured by ELISA, using kits obtained from Corgenix (Westminster, CO USA) and Takara Bio Inc. (Shiga, Japan), respectively. Clinical Facial Study The clinical study was an 8-week double-blinded facial study of 35 to 60 year old women with moderate-severe fine lines and wrinkles. Facial moisturizer containing 2% N-acetyl glucosamine and 4% niacinamide was applied twice daily in a split face design, and compared to silicone-in-water vehicle control. At baseline, 4 and 8 weeks, digital facial images were obtained and analyzed for degree of facial fine lines and wrinkles, by expert grading.
Hyaluronan and Collagen In Vitro Following topical treatment of skin equivalents with N-acetyl glucosamine, hyaluronan increased significantly and dose-responsively by up to 30% relative to vehicle control (Fig. 2). In addition to its role in skin hydration, hyaluronan, as a structural component of skin, plays a role in skin remodeling and wound healing, including contributing to the formation of a scaffolding along which fibroblasts can migrate (3). In response to N-acetyl-glucosamine, procollagen 1 increased dramatically and significantly in the skin equivalent models (Fig. 3). Niacinamide at 4% increased hyaluronan and procollagen 1 by 12 and 40%, respectively. Fine Line and Wrinkle Improvements Women using a facial moisturizer containing a combination of 2% N-acetyl glucosamine and 4% niacinamide exhibited improvements in fine lines and wrinkles as compared to a vehicle product, with the greatest improvement at the earliest time point measured (4 weeks; Fig. 4), especially in the under-eye area of the face (Fig. 5).
•In in vitro human skin cultures, topical application of N-acetyl glucosamine and niacinamide stimulated hyaluronan synthesis. •These treatments also led to an increase in collagen (procollagen-1) expression. •Twice daily use of a facial moisturizer containing a combination of 2% N-acetyl glucosamine and 4% niacinamide for 4 to 8 weeks by women with moderate to severe fine and wrinkles reduced the appearance of facial fine lines and wrinkles, particularly in the eye area of the face. •The in vitro hyaluronan results suggest that this effacement of fine lines and wrinkles is due at least in part to improved hydration of the skin. References 1.Sayo T, Sakai S, Inoue S. Synergistic effect of N-acetylglucosamine and retinoids on hyaluronan production in human keratinocytes. Skin Pharmacol Physiol 2004; 17: 77-83. 2.Ghersetich I, Lotti T, Campanile G et al. Hyaluronic acid in cutaneous aging. Int J Dermatol 1994; 33: 119-22. 3.Weindl G, Schaller M, Schafer-Korting M, Korting HC. Hyaluronic acid in the treatment and prevention of skin diseases: molecular, biological, pharmaceutical and clinical aspects. Skin Pharmacol Physiol 2004; 17: 207-13.