Tyrosinase is a copper-containing enzyme, which is widely distributed in microorganisms, animals and plants and is a key enzyme in melanin biosynthesis, involved in determining the color of mammalian skin and hair [1]. Consequently, tyrosinase inhibitors are probably the most non-invasive strategy for the control of skin pigmentation. However, synthetic agents often result in inflammation of the skin, insufficient penetration or undefined clinical efficiency [2]. Currently, the development of more depigmenting agent from natural products continues to arouse great interest. In this investigation, t he phytochemical study , including fractionation and purification, of 95 % ethanol extract of Lotus receptacle led to the isolation of nine compounds and their structures were elucidated as (-)-epigallocatechin (1) , c atechin (2), p rocyanidin B2 (3) , q uercetin (4), h ibifolin (5) , dihydrokaempferol-7-O-β-D-glucoside (6), taxifolin (7), trans-dihydromorin (8), and oxyresveratrol (9) mainly based on their spectral and chemical clues . Among these nine compounds, eight compounds, compound 1 -3 and 5-8 , were isolated from Lotus receptacle for the first time. Compounds 1-4, 8 and 9 showed strong inhibitory activity against mushroom tyrosinase with IC50 values ranging from 5. 58 to 54.36 u M, comparing with kojic acid which was used as a positive control with IC50 value of 60 .14 u M. Therefore, the residues of Lotus receptacle may serve as potential candidates as remedy for hyperpigmentation and as skin-whitening agents in cosmetics industry.
References: 1. Parvez S, Kang M, Chung HS, et al. Phytother Res 2007; 21(9): 805-816. 2. Peng LH, Liu S, Xu SY, et al. Phytomedicine 2013; 20(12): 1082-1087.
Acknowledgements: This work was funded by the Science Foundation for Young Doctors of Jiangxi academy of science (2016-YYB-07), the Science and Technology Major Project Foundation of Jiangxi Academy of Sciences (2018-YZD2-18) .