p-Coumaric acid, a constituent of Sasa quelpaertensis Nakai, inhibits cellular melanogenesis stimulated by alpha-melanocyte stimulating hormone.

Background: Recent study has demonstrated that Sasa quelpaertensis (Korean name, Jeju-Joritdae) extracts inhibit cellular melanogenesis implicating potential use in the control of skin pigmentation.
Objectives: The purpose of the present study was to elucidate the active constituents of this plant inhibiting melanogenesis and the associated mechanism.
Methods: The effect of the plant-derived materials on melanin production and/or tyrosinase expression was examined in murine melanoma B16/F10 cells and neonatal human melanocytes.
Results: When tested in melanoma B16/F10 cells treated with the alpha-melanocyte stimulating hormone (alpha-MSH), the aqueous ethanol extract of S. quelpaertensis culm inhibited the cellular melanogenesis more effectively than its leaf extract. A major active compound was isolated from the culm extract by solvent fractionation and column chromatography, and identified to be p-coumaric acid by spectroscopic and chromatographic analyses. The compound (p-coumaric acid) inhibited alpha-MSH-stimulated cellular melanogenesis more effectively than arbutin or other structurally similar compounds including 3-(4-hydroxyphenyl) propionic acid, cinnamic acid and caffeic acid. It also attenuated alpha-MSH-dependent increase of tyrosinase protein. The antimelanogenic effect of p-coumaric acid was also verified in neonatal human melanocytes.
Conclusions: The present study identified p-coumaric acid as a main constituent of S. quelpaertensis inhibiting cellular melanogenesis. Because of its structural similarity, p-coumaric acid may interfere with l-tyrosine action in the control of tyrosinase expression in response to alpha-MSH.