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Abstract
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 characterise 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 (FBMN) on
the Global Natural Products Social Molecular Networking (GNPS) web-platform, we
reveal that dihydromyricetin
and the FBRFAs, including teadenol A and fuzhuanin A, are derived from
epigallocatechin gallate (EGCG) 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.
Content
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ChemRxiv-SI-2
ChemRxiv-SI-1
