Isolation of tyrosinase and melanogenesis inhibitory flavonoids from Juniperus chinensis fruits.

Sang-A Park,Jongmin Ahn,Jinwoong Kim,Hae Young Chung,Sang Gyun Noh,Jonghwan Jegal,Hee Jin Jung,Min Hye Yang,Ki Wung Chung

doi:10.1080/09168451.2018.1511367

Abstract

A new biflavonoid, amentoflavone-7-O-β-D-glucoside, and thirteen known flavonoids were isolated from the fruits of Juniperus chinensis using a bioactivity-guided method and their tyrosinase inhibitory effects were tested using a mushroom tyrosinase bioassay. Two isolates, hypolaetin-7-O-β-D-glucoside and quercetin-7-O-α-L-rhamnoside, were found to reduce tyrosinase activity at a concentration of 50 μM. Quercetin-7-O-α-L-rhamnoside attenuated cellular tyrosinase activity and melanogenesis in α-MSH plus IBMX-stimulated B16F10 melanoma cells. Molecular docking simulation revealed that quercetin-7-O-α-L-rhamnoside inhibits tyrosinase activity by hydrogen bonding with residues His85, His244, Thr261, and Gly281 of tyrosinase. Abbreviations: EtOH, ethanol; CH2Cl2, dichloromethane; EtOAc, ethylacetate; n-BuOH, n-butanol; MeOH, metanol; CHCl3,chloroform; DMSO, dimethylsulfoxide; DMEM, Dulbecco's modified Eagle's medium; FBS, fetal bovine serum; α-MSH, α-melanocyte stimulating hormone; L-DOPA, L-3, 4-dihydroxyphenylalanine.

Highlights

Visible skin pigmentation primarily depends on the functions of melanocytes, the pigment melanin-producing cells that specialize in the synthesis and distribution of melanin [1,2]
The 95% EtOH extract of J. chinensis fruit was suspended in distilled water and partitioned sequentially against CH2Cl2, EtOAc, and n-BuOH
Compound 3 was isolated from J. chinensis for the first time and most potently inhibited mushroom tyrosinase, which concurs with our previous report on the activity of hypolaetin-7-O-β-D-glucoside isolated from J. communis [30]

Summary

Introduction

Visible skin pigmentation primarily depends on the functions of melanocytes, the pigment melanin-producing cells that specialize in the synthesis and distribution of melanin [1,2]. KEYWORDS Juniperus chinensis fruit; amentoflavone-7-O-β-Dglucoside; quercetin-7-O-αL-rhamnoside; tyrosinase; melanogenesis We undertook to isolate and identify flavonoids from the fruits of J. chinensis with tyrosinase inhibitory activities using cellular and non-cellular systems and to investigate the mechanisms involved by molecular docking.

Results

Conclusion