Mechanism of Creaming Down Based on Chemical Characterization of a Complex of Caffeine and Tea Catechins

Ishizu, Tomoko; Tsutsumi, Hiroyuki; Satō, Takashi

doi:10.1248/cpb.c16-00131

Cited by 33 publications

(16 citation statements)

References 21 publications

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“…Polyphenols are one of the main components of plants that are found in all the vegetables, flowers, and fruits. [ 5 ] The biologic properties of polyphenols include their antioxidative[ 6 ] and anti-inflammatory[ 7 ] effects. Advances in science and research have emphasized their potential activity in preventing orodental diseases including prevention of dental caries.…”

Section: Introductionmentioning

confidence: 99%

Antibacterial effects of different concentrations of Althaea officinalis root extract versus 0.2% chlorhexidine and penicillin on Streptococcus mutans and Lactobacillus (in vitro)

Haghgoo

Mehran

Afshari

et al. 2017

J Int Soc Prevent Communit Dent

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Section: Introductionmentioning

confidence: 99%

Antibacterial effects of different concentrations of Althaea officinalis root extract versus 0.2% chlorhexidine and penicillin on Streptococcus mutans and Lactobacillus (in vitro)

Haghgoo

Mehran

Afshari

et al. 2017

J Int Soc Prevent Communit Dent

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“…Ishizu et al. () dissolved equimolar amounts of caffeine and catechins in water at 90°C and left them at room temperature for a day. The content of the various catechins and caffeine was determined in the sticky precipitate and the supernatant.…”

Section: Assessmentmentioning

confidence: 99%

“…A brown-white turbidity and precipitation occur when hot tea beverages cool down (Ishizu et al, 2014(Ishizu et al, , 2016. This phenomenon is called 'creaming' or 'creaming down' and the sticky precipitate consists of a caffeine-catechin complex.…”

Section: Chemical Compositionmentioning

confidence: 99%

“…This phenomenon is called 'creaming' or 'creaming down' and the sticky precipitate consists of a caffeine-catechin complex. Ishizu et al (2016) dissolved equimolar amounts of caffeine and catechins in water at 90°C and left them at room temperature for a day. The content of the various catechins and caffeine was determined in the sticky precipitate and the supernatant.…”

Section: Chemical Compositionmentioning

confidence: 99%

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Scientific opinion on the safety of green tea catechins

Younes¹,

Aggett²,

Aguilar³

et al. 2018

EFS2

153

107

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The EFSA ANS Panel was asked to provide a scientific opinion on the safety of green tea catechins from dietary sources including preparations such as food supplements and infusions. Green tea is produced from the leaves of Camellia sinensis (L.) Kuntze, without fermentation, which prevents the oxidation of polyphenolic components. Most of the polyphenols in green tea are catechins. The Panel considered the possible association between the consumption of (-)-epigallocatechin-3-gallate (EGCG), the most relevant catechin in green tea, and hepatotoxicity. This scientific opinion is based on published scientific literature, including interventional studies, monographs and reports by national and international authorities and data received following a public 'Call for data'. The mean daily intake of EGCG resulting from the consumption of green tea infusions ranges from 90 to 300 mg/day while exposure by high-level consumers is estimated to be up to 866 mg EGCG/day, in the adult population in the EU. Food supplements containing green tea catechins provide a daily dose of EGCG in the range of 5-1,000 mg/day, for adult population. The Panel concluded that catechins from green tea infusion, prepared in a traditional way, and reconstituted drinks with an equivalent composition to traditional green tea infusions, are in general considered to be safe according to the presumption of safety approach provided the intake corresponds to reported intakes in European Member States. However, rare cases of liver injury have been reported after consumption of green tea infusions, most probably due to an idiosyncratic reaction. Based on the available data on the potential adverse effects of green tea catechins on the liver, the Panel concluded that there is evidence from interventional clinical trials that intake of doses equal or above 800 mg EGCG/day taken as a food supplement has been shown to induce a statistically significant increase of serum transaminases in treated subjects compared to control.

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“…Therefore, we attempted crystallization of the precipitate of the creaming-down reaction made from an aqueous solution of caffeine and EGCg, and as a result obtained a crystal that was determined to be a 2 : 2 EGCg complex of caffeine by X-ray crystallographic analysis [3][4][5] (Fig. 2a).…”

Section: Introductionmentioning

confidence: 99%

Development of High-Order Functions Using (−)-Epigallocatechin-3-<i>O</i>-gallate in Water

Ishizu

2020

CHEMICAL & PHARMACEUTICAL BULLETIN

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The high-order functions of molecular capture and chiral recognition of tea gallated catechins ()-epigallocatechin-3-O-gallate (EGCg) in water were investigated. A solution of equimolar amounts of a variety of heterocyclic compounds and EGCg in water afforded adhesive precipitates containing the heterocyclic compounds and EGCg at a molar ratio of 1 : 1, based on the integrated value of NMR proton signals. The molecular capture abilities of a variety of heterocyclic compounds using EGCg from the aqueous solutions were evaluated with the ratios of the heterocyclic compounds included in the precipitates of EGCg complex to the total heterocyclic compounds used. In the 1 H-NMR spectrum of a solution containing cyclo(L-Pro-Gly), cyclo(D-Pro-Gly), and EGCg in a D 2 O solution, a difference in the chemical shift of the 1 H-NMR signal for some protons of the Pro residue was observed. Judging from the crystal structures of the 2 : 2 EGCg complexes of cyclo(L-Pro-Gly), cyclo(D-Pro-Gly), the difference in the chemical shift derived mainly from a magnetic anisotropic shielding effect by the ring current from the B ring of EGCg.In the 1 H-NMR spectrum of a solution containing the pharmaceuticals racemic (R,S)-propranolol, (R,S)-diprophylline, (R,S)-proxyphylline and EGCg in D 2 O, splitting of the 1 H-NMR signals of the pharmaceuticals was observed. It was suggested that the pharmaceuticals formed diastereomers of EGCg complexes, as a result chirality of the pharmaceuticals was recognized by EGCg in the D 2 O solution.

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Mechanism of Creaming Down Based on Chemical Characterization of a Complex of Caffeine and Tea Catechins

Cited by 33 publications

References 21 publications

Antibacterial effects of different concentrations of Althaea officinalis root extract versus 0.2% chlorhexidine and penicillin on Streptococcus mutans and Lactobacillus (in vitro)

Antibacterial effects of different concentrations of Althaea officinalis root extract versus 0.2% chlorhexidine and penicillin on Streptococcus mutans and Lactobacillus (in vitro)

Scientific opinion on the safety of green tea catechins

Development of High-Order Functions Using (−)-Epigallocatechin-3-<i>O</i>-gallate in Water

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