Diarylalkanoids as Potent Tyrosinase Inhibitors from the Stems of Semecarpus caudata.

Phu H Dang,Nhan T Nguyen,Hai X Nguyen,Truong N V Do,Mai T T Nguyen,Tho H Le,Siba Shanak

doi:10.1155/2021/8872920

Abstract

From a CHCl3-soluble extract of the stems of Semecarpus caudata (Anacardiaceae), two new diarylalkanoids, semedienone (1) and semetrienone (2), were isolated. Their structures were elucidated based on NMR spectroscopic data interpretation. These compounds possess strong tyrosinase inhibitory activity with the IC50 values of 0.033 and 0.11 μM, respectively. Docking studies of 1 and 2 with oxy-tyrosinase were carried out to analyze their interactions. Accordingly, semedienone (1) showed good interactions with the peroxide group and amino acid residues. The biosynthesis of the isolated diarylalkanoids was proposed.

Highlights

Melanin is a pigment that is essential for protecting human skin against UV radiation
Extraction and Isolation. e dried powdered stems of S. caudata were exhaustively extracted in a Soxhlet extractor
The HMBC correlations from H-6′, H-α, and H-β to C O, from H-α to C-c, from H-β to C-δ, from H-c to C-α, from H-c to C-β and C-1, and from H-δ to C-β and C-6 suggested the presence of the α,β,c,δ-unsaturated carbonyl moiety in 1. e NOESY correlations between H-5′ and H-6′, H-6′ and H-α, H-β and H-δ, H-c and H-6, and H-6 and H-5 indicated the relative configuration of 1 as shown in Figure 2. us, the structure of semedienone (1) was concluded as 2E,4E-1,5-bis(2,4-dihydroxyphenyl)penta-2,4dien-1-one

Summary

Introduction

Melanin is a pigment that is essential for protecting human skin against UV radiation. The abnormal accumulation of melanin induced skin pigmentation disorders. Hydroquinone, arbutin, kojic acid, azelaic acid, L-ascorbic acid, ellagic acid, and tranexamic acid are commercial tyrosinase inhibitors, which have been used as skin-whitening agents, but these compounds have certain drawbacks [3]. A previous study on the chemical constituents of Semecarpus caudata (Anacardiaceae), collected at Dong Nai Province in Vietnam, led to the isolation of six flavonoid derivatives and the evaluation of their tyrosinase inhibitory activity [4]. Our continued phytochemical study on the stems of S. caudata was carried out, leading to the isolation of seven compounds (1–7) including two new diarylalkanoids named semedienone (1) and semetrienone (2). Ese compounds were found to possess tyrosinase inhibitory activity. Molecular docking studies of 1 and 2 with the oxy-form of the copper-bound Streptomyces castaneoglobisporus tyrosinase were performed

Materials and Methods

Results and Discussion

OCH3 OH

Conclusions