Recovery of Low-molecular Weight Galloyltannins from Agricultural Residue of Juglans sigillata Dode Seed Husks and their Tyrosinase Inhibitory Effect
Chuan-Ling Si,
Lei Wu,
Ting Shen,
Xiao-Feng Huang,
Zhen-Guo Du,
Xiao-Dan Ren,
Xue-Gang Luo,
Wei-Cheng Hu
Affiliations
Chuan-Ling Si
Tianjin Key Lab of Pulp & Paper, College of Materials Science & Chemical Engineering, Tianjin University of Science & Technology. No.29 at 13th Avenue of TEDA, Tianjin 300457, P.R. China
Lei Wu
Tianjin Key Laboratory of Pulp & Paper, Tianjin University of Science & Technology, Tianjin 300457, China
Ting Shen
Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake, Huaiyin Normal University, Huaian 223300, China
Xiao-Feng Huang
Tianjin Key Laboratory of Pulp & Paper, Tianjin University of Science & Technology, Tianjin 300457, China
Zhen-Guo Du
Tianjin Key Laboratory of Pulp & Paper, Tianjin University of Science & Technology, Tianjin 300457, China
Xiao-Dan Ren
Tianjin Key Laboratory of Pulp & Paper, Tianjin University of Science & Technology, Tianjin 300457, China
Xue-Gang Luo
Key Laboratory of Industrial Fermentation Microbiology of Ministry of Education, and Tianjin Key Laboratory of Industrial Microbiology, Tianjin University of Science & Technology, Tianjin 300457, China
Wei-Cheng Hu
Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake, Huaiyin Normal University, Huaian 223300, China
The phytochemical investigation, including fractionation and purification of 70% acetone extracts of Juglans sigillata seed husks, an agricultural residue, led to the isolation of five low-molecular weight galloyltannins. The structures of the extractives were elucidated as 1,2,6-tri-O-galloyl-β-D-glucose (1), 3,4,6-tri-O-galloyl-β-D-glucose (2), 2,3,4,6-tetra-O-galloyl-β-D-glucose (3), 1,2,3,4,6-penta-O-galloyl-β-D-glucose (4), and tannic acid (5), primarily based on their spectral (NMR and MS) and chemical evidence. Galloyltannins 1-5 showed strong inhibitory activity against mushroom tyrosinase, with IC50 values ranging from 35.27 to 76.37 μM; kojic acid, which was used as a positive control, had an IC50 value of 342.14 μM. It was further found that 1-5 inhibited melanin production and exhibited intracellular tyrosinase activity, as well as down-regulated mRNA and protein expression levels of tyrosinase, in B16F10 mouse melanoma cells. Therefore, the isolated extractives from seed husks of J. sigillata may serve as potential candidates for hyperpigmentation remediation and as skin-whitening agents in the cosmetics industry.
