Comparison of three strategies for the isolation of black tea thearubigins with a focus on countercurrent chromatography

Stodt, Ulf W.; Stark, Janina; Engelhardt, Ulrich H.

doi:10.1016/j.jfca.2015.07.002

Cited by 13 publications

(13 citation statements)

References 25 publications

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“…In the reported caffeine precipitation method [20], 20 mM of caffeine was used. We proposed that higher concentrations of caffeine could precipitate more polyphenols.…”

Section: Resultsmentioning

confidence: 99%

“…These results indicated that some TRs could be extracted away by ethyl acetate, which explained why the pre-extraction of ethyl acetate before caffeine precipitation (methods 3 and 3′) generated the lowest amount of crude TRs amongst all the methods. TRs-e1 and TRs-e2 could be the TRs fraction that was included in Roberts’ SI fraction, which contains large proportions of catechin monomers and TFs [20]. …”

Section: Resultsmentioning

confidence: 99%

“…To investigate the impacts of 1) concentrations of caffeine to precipitate tea polyphenols, 2) the order of decaffeination by chloroform and the partition against ethyl acetate, and 3) the pre-extraction of ethyl acetate before caffeine precipitation on the purity and amount of the TRs, we tried six different methods to prepare the crude TRs (Figure 1). In the reported caffeine precipitation method [20], 20 mM of caffeine was used. We proposed that higher concentrations of caffeine could precipitate more polyphenols.…”

Section: Resultsmentioning

confidence: 99%

“…At that time, Powell began to investigate the TRs via the caffeine precipitation method [19]. During the past sixty years, many scientists have been working on the isolation, purification, and characterization of TRs [1, 18, 20–23]. Most of the reports on the separation of TRs were based on and modified from the Roberts’ method and the caffeine precipitation method.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the reports on the separation of TRs were based on and modified from the Roberts’ method and the caffeine precipitation method. However, Roberts’ method involves many steps and cannot produce pure TRs, and the TRs from the caffeine precipitation method still showed a hump with many floating peaks [20]. Ulf W Stodt prepared the more clean TRs via Amberlite XAD-7 resin and high-speed counter-current chromatography but with low yields [20].…”

Section: Introductionmentioning

confidence: 99%

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A new method to prepare and redefine black tea thearubigins

Wang

Zhang

et al. 2018

Journal of Chromatography A

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Thearubigins (TRs) are the major components of black tea, which are formed during the fermentation reactions. Although anti-inflammatory and anti-cancer activities of TRs have been reported, the prepared TRs according to the literature methods still contain many floating peaks. It is puzzling whether the observed activities are from TRs or these floating peaks. Thus, it is urgent to develop a method to prepare pure TRs and redefine them. In the present study, we developed a new method, the combination of caffeine precipitation and Sephadex LH-20 column chromatography, to prepare pure TRs. The floating peaks on the hump of the crude TRs were removed, and pure TRs were prepared. The chemical profile of the floating peaks was established using LC/MS, and the major compounds in this fraction were identified as apigenin glycosides, quercetin glycosides, kaempferol glycosides, theaflavins, theasinensin, and galloylglucoses based on the analysis of their tandem mass spectra and in comparison with literature data. This study will pave the way to further study the chemistry and biological activities of TRs and the health effects of black tea consumption.

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“…In the reported caffeine precipitation method [20], 20 mM of caffeine was used. We proposed that higher concentrations of caffeine could precipitate more polyphenols.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%