Dark teas are prepared by a microbial fermentation process. Flavan-3-ol B-ring fission analogues (FBRFAs) are some of the key bioactive constituents that characterize dark teas. The precursors and the synthetic mechanism involved in the formation of FBRFAs are not known. Using a unique solid-state fermentation system with β-cyclodextrin inclusion complexation as well as targeted chromatographic isolation, spectroscopic identification, and Feature-based Molecular Networking on the Global Natural Products Social Molecular Networking web platform, we reveal that dihydromyricetin and the FBRFAs, including teadenol A and fuzhuanin A, are derived from epigallocatechin gallate upon exposure to fungal strains isolated from Fuzhuan brick tea. In particular, the strains from subphylum Pezizomycotina were key drivers for these B-/C-ring oxidation transformations. These are the same transformations seen during the fermentation process of dark teas. These discoveries set the stage to enrich dark teas and other food products for these health-promoting constituents.

中文翻译：

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体外固态发酵产生的代谢物的基于特征的分子网络分析揭示了表没食子儿茶素没食子酸酯的生物转化途径。

黑茶是通过微生物发酵工艺制备的。Flavan-3-ol B环裂变类似物（FBRFA）是黑茶的某些关键生物活性成分。参与FBRFA形成的前体和合成机理尚不清楚。在全球天然产物社交分子网络Web平台上，使用具有β-环糊精包合络合以及目标色谱分离，光谱鉴定和基于特征的分子网络的独特固态发酵系统，我们发现二氢杨梅素和FBRFA包括茶多酚A和扶桑宁A，是从表没食子儿茶素没食子酸酯暴露于从扶贫砖茶中分离出的真菌菌株后得到的。尤其是，来自Pezizomycotina亚种的菌株是这些B- / C-环氧化转化的关键驱动力。这些是在黑茶发酵过程中看到的相同转化。这些发现为富集这些促进健康的成分的黑茶和其他食品奠定了基础。