High performance liquid chromatography and metabolomics analysis of tannase metabolism of gallic acid and gallates in tea leaves.

High performance liquid chromatography and metabolomics analysis of tannase metabolism of gallic acid and gallates in tea leaves.

J Agric Food Chem. 2020 Apr 10;:

Authors: Mingli L, Xie HF, Ma Y, Li HY, Li CP, Chen LJ, Jiang B, Nian B, Guo TJ, Zhang ZY, Jiao WW, Liu QT, Ling TJ, Zhao M

Abstract
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.

PMID: 32275834 [PubMed – as supplied by publisher]

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