Screening and Characterizing Tyrosinase Inhibitors from Salvia miltiorrhiza and Carthamus tinctorius by Spectrum-Effect Relationship Analysis and Molecular Docking.

Ya-Li Wang,Qiao-Qiao Li,Feng-Qing Yang,Guang Hu,Qian Zhang,Yuan-Jia Hu,Yu-Xiu Yang,Hua Chen

doi:10.1155/2018/2141389

Abstract

Tyrosinase (TYR) is a rate-limiting enzyme in the synthesis of melanin, while direct TYR inhibitors are a class of important clinical antimelanoma drugs. This study established a spectrum-effect relationship analysis method and high-performance liquid chromatography-mass spectrometry (LC-MS) analysis method to screen and identify the active ingredients that inhibited TYR in Salvia miltiorrhiza–Carthamus tinctorius (Danshen–Honghua, DH) herbal pair. Seventeen potential active compounds (peaks) in the extract of DH herbal pair were predicted, and thirteen of them were tentatively identified by LC-MS analysis. Furthermore, TYR inhibitory activities of five pure compounds obtained from the DH herbal pair were validated in the test in which kojic acid served as a positive control drug. Among them, three compounds including protocatechuic aldehyde, hydroxysafflor yellow A, and tanshinone IIA were verified to have high TYR inhibitory activity (IC50 value of 455, 498, and 1214 μM, resp.) and bind to the same amino acid residues in TYR catalytic pocket according to the results of the molecular docking test. However, the other two compounds lithospermic acid and salvianolic acid A had a weak effect on TYR, as they do not combine with the active amino acid residues or act on the active center of TYR. Therefore, the developed methods (spectrum-effect relationship analysis and molecular docking) could be used to effectively screen TYR inhibitors in complex mixtures such as natural products.

Highlights

Tyrosinase (TYR) belongs to the type 3 copper protein family containing dinuclear copper ions and widely exists in nature from microorganisms to humans [1]
Tyrosinase, kojic acid, and L-tyrosine were dissolved in 50 mM sodium phosphate buffer before use. e reference compounds protocatechuic aldehyde, hydroxysafflor yellow A, tanshinone IIA, lithospermic acid, and salvianolic acid A (≥98%, determined by HPLC) were obtained from PUSH Bio-Technology Co., Ltd. (Chengdu, China)
Other DH herbal pair extracts (1 : 1, 3 : 1, 5 : 1, and 1 : 2) displayed a stronger inhibitory effect than single herbal extracts, which indicated that a synergistic effect of the herbal pair may occur on the inhibition of tyrosinase activity. erefore, DH herbal pair was used as the research object for screening their tyrosinase inhibitors

Summary

Introduction

Tyrosinase (TYR) belongs to the type 3 copper protein family containing dinuclear copper ions and widely exists in nature from microorganisms to humans [1]. It is a critical enzyme in the synthesis process of melanin pigments, catalyzing orthohydroxylation of monophenols to o-diphenols and to the corresponding o-quinones [2]. It is reported that the polyphenols and flavonoids isolated from natural plants have significant tyrosinase inhibition effect and less potential side effects [9, 10] From this point of view, it is of great importance to screen TYR inhibitors from natural products

Methods

Results

Conclusion