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Ammonium chloride andl-tyrosine enhance melanogenesis in vitro but not in vivo even in combination with ultraviolet radiation

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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.

Keywords: ammonium chloride; kodak gray scale; l-tyrosine; melanogenesis; pigmentation; simulated solar radiation

Document Type: Research Article


Affiliations: Bispebjerg Hospital, Department of Dermatology, Copenhagen, Denmark

Publication date: 2007-10-01

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