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

ABSTRACT: 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 ?g/ml) was about 10-fold stronger than arbutin (IC₅₀ = 51.54 ?g/ml). The p-CAEE inhibited tyrosinase in a noncompetitive model with the K _I and K _m of 1.83 ?g/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.

SUBMITTER: Li L

PROVIDER: S-EPMC7802545 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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

Li Lijun L Cai Yuchen Y Sun Xu X Du Xiping X Jiang Zedong Z Ni Hui H Yang Yuanfan Y Chen Feng F

Food science & nutrition 20201211 1

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 noncompeti ...[more]

PMID: 33473301

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Project description:Glutathione S-transferase (GST) and multidrug resistance-associated proteins (MRPs) play major roles in drug resistance in melanoma. In this study, we investigated caffeic acid phenethyl ester (CAPE) as a selective GST inhibitor in the presence of tyrosinase, which is abundant in melanoma cells. Tyrosinase bioactivates CAPE to an o-quinone, which reacts with glutathione to form CAPE-SG conjugate. Our findings indicate that 90% CAPE was metabolized by tyrosinase after a 60-min incubation. LC-MS/MS analyses identified a CAPE-SG conjugate as a major metabolite. In the presence of tyrosinase, CAPE (10-25?M) showed 70-84% GST inhibition; whereas in the absence of tyrosinase, CAPE did not inhibit GST. CAPE-SG conjugate and CAPE-quinone (25?M) demonstrated ?85% GST inhibition via reversible and irreversible mechanisms, respectively. Comparing with CDNB and GSH, the non-substrate CAPE acted as a weak, reversible GST inhibitor at concentrations >50?M. Furthermore, MK-571, a selective MRP inhibitor, and probenecid, a non-selective MRP inhibitor, decrease the IC(50) of CAPE (15?M) by 13% and 21%, apoptotic cell death by 3% and 13%, and mitochondrial membrane potential in human SK-MEL-28 melanoma cells by 10% and 56%, respectively. Moreover, computational docking analyses suggest that CAPE binds to the GST catalytic active site. Caffeic acid, a hydrolyzed product of CAPE, showed a similar GST inhibition in the presence of tyrosinase. Although, as controls, 4-hydroxyanisole and L-tyrosine were metabolized by tyrosinase to form quinones and glutathione conjugates, they exhibited no GST inhibition in the absence and presence of tyrosinase. In conclusion, both CAPE and caffeic acid selectively inhibited GST in the presence of tyrosinase. Our results suggest that intracellularly formed quinones and glutathione conjugates of caffeic acid and CAPE may play major roles in the selective inhibition of GST in SK-MEL-28 melanoma cells. Moreover, the inhibition of MRP enhances CAPE-induced toxicity in the SK-MEL-28 melanoma cells.

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

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Tyrosinase inhibition by <i>p</i>-coumaric acid ethyl ester identified from camellia pollen.

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