Tyrosinase inhibition by -coumaric acid ethyl ester identified from camellia pollen.

A tyrosinase inhibitor was separated from camellia pollen with the aid of solvent fraction, macroporous adsorptive resin chromatography, and high-speed countercurrent chromatography. The inhibitor was identified to be -coumaric acid ethyl ester (-CAEE) by nuclear magnetic resonance and mass spectrum. Its inhibitory activity (IC = 4.89 μg/ml) was about 10-fold stronger than arbutin (IC = 51.54 μg/ml). The -CAEE inhibited tyrosinase in a noncompetitive model with the and of 1.83 μg/ml and 0.52 mM, respectively. Fluorescence spectroscopy analysis showed the -CAEE quenched an intrinsic fluorescence tyrosinase. UV-Vis spectroscopy analysis showed the -CAEE did not interact with copper ions of the enzyme. Docking simulation implied the CAEE induced a conformational change in the catalytic region and thus changed binding forces of L-tyrosine. Our findings suggest that -CAEE plays an important role in inhibiting tyrosinase and provides a reference for developing pharmaceutical, cosmetic, and fruit preservation products using pollen.