title: Identification of novel homologous series of polyhydroxylated theasinensins and theanaphthoquinones in the SII fraction of black tea thearubigins using ESI/HPLC tandem mass spectrometry.
abstract: Thearubigins are the most abundant phenolic pigments found in black tea, produced by enzymatic oxidation of green tea flavan-3-ols in tea fermentation of until recently unknown composition. In this study electrospray ionization tandem LC-MS(n) experiments have been applied for the characterization of crude thearubigins isolated from black tea not exceeding 1000 Da. The aim of this study is to confirm the oxidative cascade hypothesis of tea fermentation. The data revealed the presence of two novel classes of compounds in thearubigin fractions. The first class of compounds revealed the presence of polyhydroxylated dimers of the theanaphthaquinone and theasinensin C structures, which were consistent with the polyhydroxylation hypothesis previously formulated. Furthermore, new classes of peroxo-/epoxy- compounds in the series of theasinensin A were identified, thus indicating the presence of H2O2 and its important contribution as a nucleophile in the tea fermentation process.
authors.affiliation: Chemistry, School of Engineering and Science, Jacobs University Bremen , 28759 Bremen, Germany.
authors.forename: Ghada H
authors.initials: GH
authors.lastname: Yassin
authors.forename: Jan H
authors.initials: JH
authors.lastname: Koek
authors.forename: Sujatha
authors.initials: S
authors.lastname: Jayaraman
authors.forename: Nikolai
authors.initials: N
authors.lastname: Kuhnert
mesh_terms: D001578:Benzopyrans / Q000032:analysis / Q000737:chemistry; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005285:Fermentation; D006861:Hydrogen Peroxide / Q000737:chemistry; D015394:Molecular Structure; D009285:Naphthoquinones / Q000032:analysis*; D010636:Phenols / Q000032:analysis / Q000737:chemistry; D059808:Polyphenols / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D001578:Benzopyrans; D009285:Naphthoquinones; D010636:Phenols; D059808:Polyphenols; C503232:theanaphthoquinone; C481298:theasinensin A; C000597883:theasinensin C; C086701:thearubigin; D002392:Catechin; D006861:Hydrogen Peroxide
keywords: black tea; oxidative cascade hypothesis; polyphenols,; tandem mass spectrometry; thearubigins