Bioavailabilities of tea polyphenols in humans and rodents.

Lambert, Joshua D.; Hong, Jungil; Lu, Hongcheng; Meng, Xiaofeng; Lee, M. J.; Yang, C. S.; Jain, Nidhi; Siddiqi, M. A.; Weisburger, John H.

doi:10.1079/9781845931124.0025

Cited by 3 publications

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“…Unlike other polyphenols, EGCg can be absorbed without metabolic modification. Consumption of green tea by humans produces peak plasma EGCg concentrations ranging from 0.04 to 1.0 μM, 7 a level effective for the suppression of tumor growth in cell culture studies. 8 However, EGCg is chemically highly reactive and requires stabilization during transport to prevent potentially damaging side reactions and to maintain its activity.…”

Section: Introductionmentioning

confidence: 99%

Role of the Flavan-3-ol and Galloyl Moieties in the Interaction of (−)-Epigallocatechin Gallate with Serum Albumin

Hagerman

2014

J. Agric. Food Chem.

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The principal green tea polyphenol, (−)-epigallocatechin-3-O-gallate (EGCg), may provide chemoprotection against conditions ranging from cardiovascular disease to cancer. Binding to plasma proteins stabilizes EGCg during its transport to targeted tissues. This study explored the details EGCg binding to bovine serum albumin. Both fluorescence lifetime and intensity data showed that the hydrophobic pocket between subdomains IIA and IIIA is the binding site for EGCg. Fluorescence and circular dichroism were used to establish the roles of the flavan-3-ol and galloyl moieties of the EGCg in binding and to demonstrate a binding-dependent conformational change in the protein. Competitive binding experiments confirmed the location of binding, and molecular modeling identified protein residues that play key roles in the interaction. This model of EGCg–BSA interactions improves the understanding of the likely physiological fate of this green tea-derived bioactive polyphenol.

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Section: Introductionmentioning

confidence: 99%

Role of the Flavan-3-ol and Galloyl Moieties in the Interaction of (−)-Epigallocatechin Gallate with Serum Albumin

Hagerman

2014

J. Agric. Food Chem.

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“…(−)−Epigallocatechin gallate (EGCG) is a non-hydrolysable tannin or polyphenol, found in particularly high concentrations in green tea (270 mg l −1 ). Approximately 2 h after drinking a cup of green tea, the EGCG serum concentration reaches a peak level of approximately 0.2 μM [ 1 , 2 ]. In mice, a second dose of EGCG 6 h later increased tissue concentrations by a factor of 4–6 above that found for a single dose, suggesting that drinking green tea throughout the day could result in significantly higher concentrations than this [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Multi-site binding of epigallocatechin gallate to human serum albumin measured by NMR and isothermal titration calorimetry

Eaton

Williamson

2017

Bioscience Reports

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The affinity of epigallocatechin gallate (EGCG) for human serum albumin (HSA) was measured in physiological conditions using NMR and isothermal titration calorimetry (ITC). NMR estimated the Ka (self-dissociation constant) of EGCG as 50 mM. NMR showed two binding events: strong (n1=1.8 ± 0.2; Kd1 =19 ± 12 μM) and weak (n2∼20; Kd2 =40 ± 20 mM). ITC also showed two binding events: strong (n1=2.5 ± 0.03; Kd1 =21.6 ± 4.0 μM) and weak (n2=9 ± 1; Kd2 =22 ± 4 mM). The two techniques are consistent, with an unexpectedly high number of bound EGCG. The strong binding is consistent with binding in the two Sudlow pockets. These results imply that almost all EGCG is transported in the blood bound to albumin and explains the wide tissue distribution and chemical stability of EGCG in vivo.

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“…Tea is one of the main sources of flavonoids in the diet. After consumption of green tea, peak plasma concentrations of epigallocatechin gallate, epigallocatechin and epicatechin were reported as 0.04–1 μM, 0.3–5 μM and 0.1–2.5 μM, respectively, in humans [ 27 ], but the theaflavins and thearubigins in black tea were less well absorbed with peak plasma concentrations of 2 nM reported for the theaflavins.…”

Section: Plasma Antioxidant Capacitymentioning

confidence: 99%

Significance of Dietary Antioxidants for Health

Gordon

2011

IJMS

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Since evidence became available that free radicals were involved in mechanisms for the development of major diseases, including cardiovascular disease and cancer, there has been considerable research into the properties of natural dietary antioxidants. However, it has become clear that dietary antioxidants can only have beneficial effects in vivo by radical scavenging or effects on redox potential if they are present in tissues or bodily fluids at sufficient concentrations. For many dietary components, absorption is limited or metabolism into derivatives reduces the antioxidant capacity. For many dietary phytochemicals, direct antioxidant effects may be less important for health than other effects including effects on cell signalling or gene expression in vivo.

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Bioavailabilities of tea polyphenols in humans and rodents.

Abstract: This chapter reviews the literature (human and animal research) concerning the biotransformation and bioavailability of tea polyphenols.

Cited by 3 publications

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Role of the Flavan-3-ol and Galloyl Moieties in the Interaction of (−)-Epigallocatechin Gallate with Serum Albumin

Role of the Flavan-3-ol and Galloyl Moieties in the Interaction of (−)-Epigallocatechin Gallate with Serum Albumin

Multi-site binding of epigallocatechin gallate to human serum albumin measured by NMR and isothermal titration calorimetry

Significance of Dietary Antioxidants for Health

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