Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro

  • Authors:
    • Chun Hay Ko
    • Karen Li
    • Pak Cheung Ng
    • Kwok Pui Fung
    • Chung Leung Li
    • Raymond Pui-On Wong
    • Kit Man Chui
    • Goldie Jia-Shi Gu
    • Edmund Yung
    • Chi Chiu Wang
    • Tai Fai Fok
  • View Affiliations

  • Published online on: November 1, 2006     https://doi.org/10.3892/ijmm.18.5.987
  • Pages: 987-994
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Abstract

Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are vulnerable to chemical-induced hemolysis if exposed to oxidative agents. Recent studies reported that green tea and its constituents might act as pro-oxidants. Our objective was to investigate effects of tea and its polyphenolic components on the oxidative status of human G6PD-deficient erythrocytes. Erythrocytes of G6PD-deficient (n=8) and normal (n=8) subjects were incubated with water extracts of 3 types of tea samples (black tea, green tea and decaffeinated green tea extract) and 6 polyphenols. The resulting levels of reduced glutathione (GSH) and glutathione disulphide (GSSG), methemoglobin and plasma hemoglobin were quantified by HPLC and biochemical assays. The tea extracts significantly reduced GSH and increased GSSG levels in G6PD-deficient erythrocytes in a dose-dependent manner (0.5-10 mg/ml), but not in normal erythrocytes. Similar dose-dependent responses to (−)-epigallocatechin (EGC) and (−)-epigallocatechin-3-gallate (EGCG), but not to the other polyphenols, were observed. In G6PD-deficient cells, GSH was reduced by 43.3% (EGC at 0.05 mg/ml) and 33.3% (EGCG at 0.5 mg/ml), compared with pre-challenged levels. The concentration of methemoglobin was increased significantly when challenged with tea extracts, and EGC. Plasma hemoglobin levels were higher in G6PD-deficient samples after exposure to tea extracts, EGCG, EGC and gallic acid, compared with those in normal blood. Tea extracts and polyphenols significantly altered the oxidative status of G6PD-deficient erythrocytes in vitro as demonstrated by the decrease of GSH, and increased GSSG, methemoglobin and plasma hemoglobin. Our data caution against the excessive consumption of concentrated tea polyphenolic products by G6PD-deficient subjects.

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November 2006
Volume 18 Issue 5

Print ISSN: 1107-3756
Online ISSN:1791-244X

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Spandidos Publications style
Ko CH, Li K, Ng PC, Fung KP, Li CL, Wong RP, Chui KM, Gu GJ, Yung E, Wang CC, Wang CC, et al: Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro. Int J Mol Med 18: 987-994, 2006
APA
Ko, C.H., Li, K., Ng, P.C., Fung, K.P., Li, C.L., Wong, R.P. ... Fok, T.F. (2006). Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro. International Journal of Molecular Medicine, 18, 987-994. https://doi.org/10.3892/ijmm.18.5.987
MLA
Ko, C. H., Li, K., Ng, P. C., Fung, K. P., Li, C. L., Wong, R. P., Chui, K. M., Gu, G. J., Yung, E., Wang, C. C., Fok, T. F."Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro". International Journal of Molecular Medicine 18.5 (2006): 987-994.
Chicago
Ko, C. H., Li, K., Ng, P. C., Fung, K. P., Li, C. L., Wong, R. P., Chui, K. M., Gu, G. J., Yung, E., Wang, C. C., Fok, T. F."Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro". International Journal of Molecular Medicine 18, no. 5 (2006): 987-994. https://doi.org/10.3892/ijmm.18.5.987