High Performance Liquid Chromatography and Metabolomics Analysis of Tannase Metabolism of Gallic Acid and Gallates in Tea Leaves

• Published in: Journal of agricultural and food chemistry Vol. 68; no. 17; pp. 4946 - 4954
• Main Authors: Liu, Mingli, Xie, Haofen, Ma, Yan, Li, Hongye, Li, Chongping, Chen, Lijiao, Jiang, Bin, Nian, Bo, Guo, Tianjie, Zhang, Zhengyan, Jiao, Wenwen, Liu, Qianting, Ling, Tiejun, Zhao, Ming
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 29.04.2020
• Subjects: Aspergillus niger - chemistry; Aspergillus niger - enzymology; Aspergillus niger - metabolism; Camellia sinensis - chemistry; Camellia sinensis - metabolism; Camellia sinensis - microbiology; Carboxylic Ester Hydrolases - chemistry; Carboxylic Ester Hydrolases - metabolism; Chromatography, High Pressure Liquid - methods; Fermentation; Fungal Proteins - chemistry; Fungal Proteins - metabolism; Gallic Acid - chemistry; Gallic Acid - metabolism; Metabolomics - methods; Plant Leaves - chemistry; Plant Leaves - metabolism; Plant Leaves - microbiology; metabolomics analysis; gallate; tannase; antioxidant activity; gallic acid; pu-erh tea
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.0c00513

Tannase (E.C. 3.1.1.20) is hypothesized to be involved in the metabolism of gallates and gallic acid (GA) in pu-erh tea fermentation. In this work, we measured tannase in Aspergillus niger fermented tea leaves and confirmed the production of fungal tannase during pu-erh tea fermentation. A decrease in catechin and theaflavin gallates and a significant increase in GA content and the relative peak areas of ethyl gallate, procyanidin A2, procyanidin B2, procyanidin B3, catechin-catechin-catechin, epiafzelechin, and epicatechin-epiafzelechin [variable importance in the projection (VIP) > 1.0, p < 0.05, and fold change (FC) > 1.5] were observed using high performance liquid chromatography (HPLC) and metabolomics analysis of tea leaves fermented or hydrolyzed by tannase. In vitro assays showed that hydrolysis by tannase or polymerization of catechins increased the antioxidant activity of tea leaves. In summary, we identified a metabolic pathway for gallates and their derivatives in tea leaves hydrolyzed by tannase as well as associated changes in gallate and GA concentrations caused by fungal tannase during pu-erh tea fermentation.