Tyrosinase Inhibitors from the Stems of Streblus Ilicifolius.

Nhan T Nguyen,Truong N V Do,Phu H Dang,Tuyen Q H Le,Hai X Nguyen,Tho H Le,Mai T T Nguyen,Hilal Zaid

doi:10.1155/2021/5561176

Abstract

Two new stilbene derivatives, named strebluses C and D, were isolated from the EtOAc-soluble fraction of the stems of Streblus ilicifolius (Moraceae). Its absolute configuration was elucidated based on NMR spectroscopic data interpretation and optical rotation calculation. Streblus C possesses strong tyrosinase inhibitory activity with an IC50 value of 0.01 μM. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. The analysis of the docked poses confirmed that 1 showed better binding affinity for oxy-tyrosinase than that of 2.

Highlights

Tyrosinase (EC 1.14.18.1), which is a binuclear coppercontaining monooxygenase, is a key enzyme in the oxidation of phenol to the corresponding o-quinone [1, 2]
In our continued studies on the screening of medicinal plants for tyrosinase inhibitory activity [8,9,10,11,12], it was found that a MeOH-soluble extract of the stems of Streblus ilicifolius showed a strong inhibitory effect, with an IC50 value of 0.63 μg·mL−1. us, our study on chemical constituents of the stems of S. ilicifolius was carried out, leading to the isolation of two undescribed stilbene derivatives, strebluses C (1) and D (2)
Extraction and Isolation. e dried powdered stems of S. ilicifolius were exhaustively extracted in a Soxhlet extractor with n-hexane, EtOAc, and MeOH to yield the corresponding fractions. e EtOAc-soluble fraction was repeatedly chromatographed using silica gel CC and preparative TLC to obtain two undescribed stilbene derivatives, strebluses C (1) and D (2) (Figure 1)

Summary

Introduction

Tyrosinase (EC 1.14.18.1), which is a binuclear coppercontaining monooxygenase, is a key enzyme in the oxidation of phenol to the corresponding o-quinone [1, 2] It plays a main factor causing freckles, brown age spots, and melasma. Some commercial compounds, such as hydroquinone, arbutin, kojic acid, azelaic acid, L-ascorbic acid, ellagic acid, and tranexamic acid, were reported as the well-known tyrosinase inhibitors. In our continued studies on the screening of medicinal plants for tyrosinase inhibitory activity [8,9,10,11,12], it was found that a MeOH-soluble extract of the stems of Streblus ilicifolius showed a strong inhibitory effect, with an IC50 value of 0.63 μg·mL−1. Molecular docking studies of 1 and 2 with the oxyform of the copper-bound Streptomyces castaneoglobisporus tyrosinase were performed

Materials and Methods

Results and Discussion

Conclusions