Hostname: page-component-cd9895bd7-7cvxr Total loading time: 0 Render date: 2024-12-27T09:23:24.964Z Has data issue: false hasContentIssue false
  • English
  • Français

Comparison of antioxidant activity and bioavailability of tea epicatechins with their epimers

Published online by Cambridge University Press:  09 March 2007

Jin Ze Xu ,
Sai Ying Venus Yeung ,
Qi Chang ,
Yu Huang  and
Zhen-Yu Chen
Jin Ze Xu
Affiliation:
Food and Nutritional Sciences Programme, Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Sai Ying Venus Yeung
Affiliation:
Food and Nutritional Sciences Programme, Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Qi Chang
Affiliation:
Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Yu Huang
Affiliation:
Department of Physiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
Zhen-Yu Chen*
Affiliation:
Food and Nutritional Sciences Programme, Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
*
*Corresponding author: Dr Zhen-Yu Chen, fax +852 26037246, email zhenyuchen@cuhk.edu.hk
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Canned and bottled tea drinks contain not only green tea epicatechins (GTE), namely (−)-epigallocatechin gallate (EGCG), (−)-epicatechin gallate (ECG), (−)-epigallocatechin (EGC) and (−)-epicatechin (EC), but also four GTE epimers, namely (−)-gallocatechin gallate (GCG), (−)-catechin gallate (CG), (−)-gallocatechin (GC) and (−)-catechin (C). In the present study we examined the antioxidant activity and bioavailability of these epimers compared with their corresponding precursors. The epimerisation reaction was induced by autoclaving GTE extract derived from longjing green tea at 120°C for 20 min. Isolation and purification of each GTE and epimer were accomplished by various column chromatographic and semi-preparative HPLC techniques. The antioxidant activity of each epimer with its corresponding GTE precursor was conducted in the three in vitro systems, namely human LDL oxidation, ferric reducing–antioxidant power (FRAP), and anti-2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assays. The results of all three assays demonstrated that CG had similar antioxidant activity with its precursor ECG, while GC was less potent as an antioxidant than its precursor EGC. Regarding EGCG and GCG, the antioxidant potency was similar for both LDL oxidation and DPPH free radical assays, but GCG was statistically less effective than EGCG in the FRAP assay. For EC and C, the latter had less anti-free radical activity in the DPPH assay, but in LDL oxidation and FRAP assays the antioxidant activity was similar. Oral and intravenous dosing of GTE–epimer mixture led to increase in total plasma antioxidant capacity in rats. In general, both epicatechins and epimers had low bioavailability (0·08–0·31) and most of the observed differences between epicatechins and their corresponding epimers were small, even if they were statistically significant in some cases. It was concluded that the epimerisation reaction occurring in manufacturing canned and bottled tea drinks would not significantly affect antioxidant activity and bioavailability of total tea polyphenols.

Keywords

CatechinEpicatechinEpigallocatechinEpimerisationGallocatechinTea drinks
Type
Research Article
Information
British Journal of Nutrition , Volume 91 , Issue 6 , June 2004 , pp. 873 - 881
Copyright
Copyright © The Nutrition Society 2004

References

Ahmad, N & Mukhtar, H (1999) Green tea polyphenols and cancer: Biological mechanisms and practical implications. Nutr Rev 57, 78–83.CrossRefGoogle ScholarPubMed
Benzie, IFF & Strain, JJ (1999) Ferric reducing antioxidant power assay: direct measurement of total antioxidant activity of biological fluids and modified version for simultaneous measurement of total antioxidant power and ascorbic acid concentration. Methods Enzymol 299, 15–27.CrossRefGoogle ScholarPubMed
Blois, MS (1958) Antioxidant determination by the use of a stable free radical. Nature 181, 1199–1200.CrossRefGoogle Scholar
Chen, LS, Lee, MJ, Li, H & Yang, CS (1997) Absorption, distribution and elimination of tea polyphenols in rats. Drug Metab Dispos 25, 1045–1050.Google ScholarPubMed
Chen, ZY, Zhu, QY, Tsang, D & Huang, Y (2001) Degradation of green tea catechins in tea drinks. J Agric Food Chem 49, 477–482.CrossRefGoogle ScholarPubMed
Duffy, SJ, Keaney, JF Jr, Holbrook, M. Gokce, N, Swerdloff, PL, Frei, B & Vita, JA (2001) Short- and long-term black tea consumption reverses endothelial dysfunction in patients with coronary heart disease. Circulation 104, 151–156.CrossRefGoogle Scholar
Hertog, MGL, Feskens, EJM, Hollman, PCH, Katan, MB & Kromhout, D (1993) Dietary antioxidant flavonoids and risk of coronary heart disease: The Zutphen Elderly Study. Lancet 342, 1007–1011.CrossRefGoogle ScholarPubMed
Hodgson, JM, Puddey, IB, Burke, V, Watts, GE & Beilin, LJ (2002) Regular ingestion of black tea improves brachial artery vasodilator function. Clin Sci 102, 195–201.CrossRefGoogle ScholarPubMed
Huang, Y, Chan, NWK, Lau, CW, Yao, XQ, Chan, FL & Chen, ZY (1999) Involvement of endothelium/nitric oxide in vasorelaxation induced by purifed green tea (–)-epicatechin. Biochim Biophys Acta 1427, 322–328.CrossRefGoogle Scholar
Imai, K & Nakachi, K (1995) Cross sectional study of effects of drinking green tea on cardiovascular and liver disease. Br Med J 310, 693–696.CrossRefGoogle Scholar
Kono, S, Shinchi, K, Ikeda, N, Yanai, F & Imanishi, K (1992) Green tea consumption and serum lipid profile: a cross-sectional study in Northern Kyush. Jpn Prev Med 21, 526–531.CrossRefGoogle Scholar
Leenen, R, Roodenburg, AJ, Tijburg, L & Wiseman, SA (2000) A single dose of tea with or without milk increases plasma antioxidant activity in humans. Eur J Clin Nutr 54, 87–92.CrossRefGoogle ScholarPubMed
Lowry, OH, Rosebrough, NJ, Farr, AL & Randall, R (1951) Protein measurement with the Folin–phenol reagent. J Biol Chem 193, 265–275.CrossRefGoogle ScholarPubMed
Pahl, H, Wang, G & Esterbauer, H (1994) Methods to determine oxidation of low-density lipoproteins. Methods Enzymol 233, 425–434.CrossRefGoogle Scholar
Spencer, JPE (2003) Metabolism of tea flavonoids in the gastrointestinal tracts. J Nutr 133, 3255S–3261S.CrossRefGoogle Scholar
Stensvold, I, Tverdal, A, Solvoll, K & Foss, DP (1992) Tea consumption. Relationship to cholesterol, blood pressure, and coronary and total mortality. Prev Med 21, 546–553.CrossRefGoogle ScholarPubMed
Wiseman, S, Weisgerber, U, Tijburg, L & Korver, O (1999) The food industry and functional foods: Tea antioxidant and cardiovascular disease. In Antioxidant Food Supplements in Human Health, pp.445–460 [Packer, L, Hiramatsu, M & Yoshikawa, T, editor]. San Diego, CA: Academic Press.CrossRefGoogle Scholar
Young, W, Hotovec, RL & Romero, AG (1967) Tea and atherosclerosis Nature 216, 1015–1016.CrossRefGoogle ScholarPubMed
Xu, JZ, Leung, LK, Huang, Y & Chen, ZY (2003) Epimerisation of tea polyphenols in tea drinks. J Sci Food Agric 83, 1617–1621.CrossRefGoogle Scholar
Zhang, A, Chan, PT, Luk, YS, Ho, WKK & Chen, ZY (1997) Inhibitory effect of jasmine green tea epicatechin isomers on LDL-oxidation. J Nutr Biochem 8, 334–340.CrossRefGoogle Scholar
Zhu, M, Chen, Y & Li, RC (2000) Oral absorption and bioavailability of tea catechins. Planta Med 66, 444–447.CrossRefGoogle ScholarPubMed
Zhu, QY, Zhang, A, Tsang, D, Huang, Y & Chen, ZY (1997) Stability of green tea catechin. J Agric Food Chem 45, 4624–4628.CrossRefGoogle Scholar