Hypopigmentary Effects of Ethyl P ‐Methoxycinnamate Isolated from Kaempferia galanga

We isolated crystals from the chloroform fraction of an ethanol extract of Kaempferia galanga and identified it as ethyl p ‐methoxycinnamate through nuclear magnetic resonance analysis. In the present study, we found that ethyl p ‐methoxycinnamate significantly decreased melanin synthesis in B16F10 murine melanoma cells stimulated with α‐melanocyte stimulating hormone (α‐MSH). In a cell‐free system, however, ethyl p ‐methoxycinnamate did not directly inhibit tyrosinase, the rate‐limiting enzyme of melanogenesis. Instead, it inhibited tyrosinase activity in B16F10 cells in a dose‐dependent manner. Furthermore, Western blot analysis showed that ethyl p ‐methoxycinnamate decreased microphthalmia‐associated transcription factor and tyrosinase levels in α‐MSH‐stimulated B16F10 cells. These results indicate that the pigment‐inhibitory effect of ethyl p ‐methoxycinnamate results from downregulation of tyrosinase. Ethyl p ‐methoxycinnamate isolated from K. galanga could be developed as a skin whitening agent to treat hyperpigmentary disorders. Copyright © 2013 John Wiley & Sons, Ltd.