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The anti-oxidant capacity of green tea polyphenols in the oral cavity

Published online by Cambridge University Press:  30 August 2013

M. Asim ,
O. Han Liu ,
E. Okello ,
M. Birch-Machin ,
M. Foltz  and
G. Lietz
M. Asim
Affiliation:
Human Nutrition Research Centre, Agriculture Building, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
O. Han Liu
Affiliation:
Human Nutrition Research Centre, Agriculture Building, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
E. Okello
Affiliation:
Human Nutrition Research Centre, Agriculture Building, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
M. Birch-Machin
Affiliation:
Institute of Cellular Medicine, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
M. Foltz
Affiliation:
Molecular Aspects of Health, Unilever Research & Development, Vlaardingen, The Netherlands
G. Lietz
Affiliation:
Human Nutrition Research Centre, Agriculture Building, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK
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Abstract

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Information
Proceedings of the Nutrition Society , Volume 72 , Issue OCE4: Summer Meeting, 15–18 July 2013, Nutrition and healthy ageing , 2013 , E233
Copyright
Copyright © The Authors 2013 

Green tea polyphenols have attracted considerable attention in the past 20 years as potential therapeutics in the prevention of cancers, cardiovascular diseases, and neurodegenerative diseases( Reference Katiyar and Mukhtar 1 ). However, the bioavailability of tea polyphenols is limited by their extensive biotransformation through phase II enzymes (COMT, UGTs, and SULTs) after ingestion & absorption( Reference Hollman, Tijburg and Yang 2 ).

To test the antioxidant capacity of green tea in the oral cavity, we recruited nine volunteers and extracted their buccal mucosal cells before and after exposure to green tea at different timepoints. Reactive oxygen species (ROS) concentration was measured using the DCFH-DA assay, and absorption of catechins in the oral mucosa was determined by HPLC. The results showed significantly reduced ROS levels when comparing baseline to tea treated cells, with maximum reduction of ROS concentrations within 10 minutes of exposure. HPLC analysis indicated that only EGCG and ECG were absorbed by buccal mucosal cells (Figure 1).

Fig. 1. ROS concentrations in buccal mucosal cells depending on exposure to green tea polyphenols (left) and absorption of catechins in buccal cell extracts (right).

In summary, EGCG and ECG are absorbed in the oral cavity and reduce ROS concentrations after only 2.5 minutes of incubation. The study also observed large inter-individual variations in absorption of catechins and their associated antioxidant capacity which warrants further investigation.

References

1. Katiyar, S & Mukhtar, H (1996), Int J Oncol,. 8(2), 221–38.Google Scholar
2. Hollman, PC, Tijburg, LB & Yang, CS (1997) Crit Rev Food Sci Nutr. 37(8), 719–38.Google Scholar
Figure 0

Fig. 1. ROS concentrations in buccal mucosal cells depending on exposure to green tea polyphenols (left) and absorption of catechins in buccal cell extracts (right).