Isolation and analysis of a polymeric thearubigin fraction from tea

Bailey, Richard G.; Nürsten, Harry E.; McDowell, Ian

doi:10.1002/jsfa.2740590314

Cited by 69 publications

(21 citation statements)

References 30 publications

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“…The theafulvin fraction produced only traces of material detectable at 380 nm, confirming the observation of Bailey et al(1992) that it is essentially free from flavonol glycosides. Slightly larger amounts of quercetin and kaempferol were found in the CTR (see Fig 3), but myricetin could not be detected.…”

Section: Products Detected At 380 Nmsupporting

confidence: 79%

“…The ( -)-epigallocatechingallate (EGCG) was isolated from green tea using Sephadex column chromatography as described by Robertson and Bendall (1983). A Lattakari Assam black tea (Importers Ltd, Guildford, UK) was used as the source of the caffeine-precipitatable thearubigin (CTR) fraction (Powell et al 1993) and the theafulvin fraction (Bailey et al 1992). The theaflavin-3monogallate was isolated using the HPLC method developed by Opie et al (1990) but on a semi-preparative column (150 x 10 mm) with a 3 ml min-' flow rate.…”

Section: Methodsmentioning

confidence: 99%

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Use of Porter's reagents for the characterisation of thearubigins and other non‐proanthocyanidins

et al. 1995

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A previously published method for the HPLC analysis of the anthocyanidin pigments produced by the autoxidative depolymerization of proanthocyanidins by heating in a solution of n-butanol/HCl (95/5 v/v) and iron(II1) salts (Porter's reagents) has been refined. The pigments are detected by monitoring at 530 nm, but by monitoring the eluate also at 280 nm and 380 nm a wider variety of products resulting from the same autoxidation and/or hydrolysis/ transesterification reactions can be detected. Such products have been shown to include aglycones (particularly flavonols from flavonol glycosides) and n-butyl gallate (from galloyl esters). The advantages of monitoring the wider range of transformation products are illustrated by applying the method to the characterisation of two heterogeneous thearubigin fractions isolated from black tea liquor. The caffeine-precipitatable thearubigin fraction contained 181 g proanthocyanidins kg-' (as procyanidin dimer equivalents), a trace ( 2 2 g kg-') of flavonols (as aglycones), 74 g kg-' galloyl ester and 5.6 g kg-' elemental N (determined by microanalysis): caffeine was not detectable and some 74% of the fraction remains uncharacterised. The theafulvin fraction contained 105 g proanthocyanidins kg-' (as procyanidin dimer equivalents), c 1 g kg-' quercetin and 71 g kg-' galloyl ester, but neither caffeine nor elemental N was detectable; some 82% of the fraction remains uncharacterised. The proanthocyanidins of both hump fractions contained not only prodelphinidins and procyanidins but also propelargonidins which have not previously been reported in tea.

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Section: Products Detected At 380 Nmsupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Use of Porter's reagents for the characterisation of thearubigins and other non‐proanthocyanidins

et al. 1995

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“…Known as fermentation, this processing significantly alters the flavonoid profile (Astill et al 2001). Specifically, oxidation of catechin monomers results in generation of complex products, including theaflavin (TF), TF-monogallate (TFMG), TF-digallate (TFDG), theasinensins, and thearubigins, which provide characteristic color and flavor to black tea (Bailey et al 1992, Menet et al 2004, Tanaka et al 2002. Although the extent of fermentation varies significantly (between products and regions), generally, monomer oxidation (particularly EGCG and EGC) reduces the levels of catechins relative to green tea.…”

Section: Monomeric Flavan-3-ol (Catechins)mentioning

confidence: 99%

Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Neilson

Ferruzzi

2011

Annu. Rev. Food Sci. Technol.

103

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Flavan-3-ols are a major subclass of the class of plant phytochemicals known as flavonoids. Flavan-3-ols are commonly found in fruit, vegetable, and botanical products, including tea, cocoa, grapes, and apples. Both monomeric catechins and polymeric procyanidins are common in the diet, along with several derivatives produced by degradation of these species during processing. Both epidemiological and biological evidence suggests a health-protective role for dietary flavan-3-ols, leading to increased interest in the bioavailability of these compounds from foods. Flavan-3-ol bioavailability depends on numerous factors, including digestive release, absorption, metabolism, and elimination. In addition to these in vivo factors, the complexity of whole-food systems (physical form, flavan-3-ol form and dose, macronutrient and micronutrient profile, processing, etc.) influences the absorption efficiency and circulating profile of flavan-3-ols. An understanding of how food matrices may influence flavan-3-ol absorption will provide a framework to design and develop functional products that positively affect flavan-3-ol absorption and, by extension, potential bioactivity.

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“…More recently, Nonaka and Nishioka applied newly developed chromatographic techniques to the separation of the polyphenols of fermented teas and successfully demonstrated the structures of a number of catechin oxidation products (Hashimoto et al, 1987;Hashimoto et al, 1988;Hashimoto et al, 1989;Hashimoto et al, 1992). At the same time, chemical studies on other constituents, which comprise a major part of black tea polyphenols as a whole, continued (Brown et al, 1969;Cattel & Nursten, 1977;Robertson & Bendall, 1983;Bailey et al, 1992;Ozawa et al, 1996). However, they were hampered by the complexity and difficulty of purification, and the major part of black tea polyphenols, especially those with larger molecular size, still remain to be clarified.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Tea Catechins: Chemical Structures and Reaction Mechanism

Tanaka

Kouno

2003

FSTR

107

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Black tea accounts for almost 80% of the world's tea production and is the most important source of polyphenol in the world. However, little has been known about the chemistry of black tea polyphenols due to their complexity. Since most of the black tea polyphenols are produced by enzymatic oxidation of green tea catechins, in vitro model fermentation experiments using purified catechins are very useful, and recently structures of some novel oxidation products of theaflavins, black tea pigments, have been elucidated. In addition, accumulation of unstable dimer quinones of epigallocatechin and its gallate during tea fermentation has been demonstrated, and the dimer quinones are converted to theasinensins, another major polyphenol characteristic of black tea, on heating. Formation and degradation of theaflavins and epigallocatechin dimer quinones are major pathways in catechin oxidation during tea fermentation and understanding the chemical mechanism is important in clarifying black tea polyphenols.

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Isolation and analysis of a polymeric thearubigin fraction from tea

Cited by 69 publications

References 30 publications

Use of Porter's reagents for the characterisation of thearubigins and other non‐proanthocyanidins

Use of Porter's reagents for the characterisation of thearubigins and other non‐proanthocyanidins

Influence of Formulation and Processing on Absorption and Metabolism of Flavan-3-Ols from Tea and Cocoa

Oxidation of Tea Catechins: Chemical Structures and Reaction Mechanism

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