Ammonium chloride andl-tyrosine enhance melanogenesis in vitro but not in vivo even in combination with ultraviolet radiation
Melanogenesis can be induced in vitro in melanoma cells and melanocytes by adding substances able to neutralize intracellular acidic organelles like melanosomes. Further addition ofl-tyrosine enhances the melanogenesis by increasing the tyrosinase activity. As such, the property of tyrosine as a pigmentation enhancer is used in promoting creams containing tyrosine. The objective of this study was to investigate whether such an effect could actually be seen in a short term in vivo mouse study. Methods:
Lightly pigmented C3.Cg/TifBomTac hairless mice capable of pigmenting had ammonium chloride (NH4Cl) and/orl-tyrosine applied topically (1/day for 3 weeks). Pigmentation of the mice was determined using the Kodak Gray Scale at days 0, 7, 14, and 21. Results:
Both NH4Cl andl-tyrosine yielded no significant effect, either alone or in combination, when applied using either hydrogel or moisturizing cream. Exposing mice to simulated solar radiation (4 standard erythema doses, 3/week) yielded increased pigmentation. However, no statistically significant difference was found between treatment with simulated solar radiation alone or in combination with NH4Cl andl-tyrosine. Conclusion:
In spite of the commercial value of addingl-tyrosine to ‘pigmentation-enhancing’ creams, topically appliedl-tyrosine showed no pigmentation-enhancing effect, neither alone nor in combination with ultraviolet (UV) radiation, providing a basis to contest such promotional measures.
Document Type: Research Article
Affiliations: Bispebjerg Hospital, Department of Dermatology, Copenhagen, Denmark
Publication date: 2007-10-01