Fractionation and chemistry of ethyl acetate-soluble thearubigins from black tea |
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Authors: | DJ Cattell HE Nursten |
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Institution: | Procter Department of Food and Leather Science, University of Leeds, Leeds LS2 9JT, England |
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Abstract: | Sephadex LH-20 chromatography was used to fractionate purified ethyl acetate-soluble thearubigins, prepared from an aqueous ethanolic extract of black tea. Three subfractions were so produced, each having a MW of about 1500 and each being degradable into cyanidin, delphinidin, gallic acid, the same two flavan-3-ols, and the same two flavan-3-ol gallates, though in different yield. Some evidence for the presence of benzotropolone moieties in at least one of the subfractions was obtained. Overall the ethyl acetate-soluble thearubigins are viewed as pentameric flavan-3-ols/flavan-3-ol gallates, containing both hydrolysable and non-hydrolysable interflavanoid links, as well as benzotropolone units, rather than as polymeric proanthocyanidins, a term previously used for all thearubigin subgroups. |
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Keywords: | Theaceae black tea thearubigins polymeric flavans benzotropolones |
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