Tyrosinase inhibition by p ‐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 p‐coumaric acid ethyl ester (p‐CAEE) by nuclear magnetic resonance and mass spectrum. Its inhibitory activity (IC50 = 4.89 μg/ml) was about 10‐fold stronger than arbutin (IC50 = 51.54 μg/ml). The p‐CAEE inhibited tyrosinase in a noncompetitive model with the K I and K m of 1.83 μg/ml and 0.52 mM, respectively. Fluorescence spectroscopy analysis showed the p‐CAEE quenched an intrinsic fluorescence tyrosinase. UV‐Vis spectroscopy analysis showed the p‐CAEE did not interact with copper ions of the enzyme. Docking simulation implied the p‐CAEE induced a conformational change in the catalytic region and thus changed binding forces of L‐tyrosine. Our findings suggest that p‐CAEE plays an important role in inhibiting tyrosinase and provides a reference for developing pharmaceutical, cosmetic, and fruit preservation products using pollen.
p‐Coumaric acid ethyl ester was first found in camellia pollen. The inhibition is reversible and dose‐dependent. p‐Coumaric acid ethyl ester altered the structure of tyrosinase. p‐Coumaric acid ethyl ester and pollen had potential applications for pharmaceutical, cosmetic, and fruit preservation. p‐Coumaric acid ethyl ester (p‐CAEE) can inhibit the activity of tyrosinase in a noncompetitive manner and can cause the transformation of tyrosinase.