Tags

Type your tag names separated by a space and hit enter

Green tea extract and (-)-epigallocatechin-3-gallate, the major tea catechin, exert oxidant but lack antioxidant activities.
FASEB J. 2005 May; 19(7):807-9.FJ

Abstract

Green tea is the most widely consumed beverage. It has attained high reputation as a health-promoting dietary component ascribed to the antioxidant activity of (-)-epigallocatechin-3-gallate (EGCG), its main polyphenolic constituent. Evidence is increasing that tea constituents can be cell damaging and pro-oxidant themselves. These effects were suggested to be due to spontaneous H2O2 generation by polyphenols in solution. In the present study, we investigated the oxidant and antioxidant properties of green tea extracts (GTE) and of EGCG by means of the rodent macrophage-like RAW 264.7 and human promyelocytic leukemic HL60 cell lines. The results obtained show that both under cell-free conditions and in the presence of cells the oxidant activities of GTE and EGCG exceeded those of spontaneously generated H2O2 (FOX assay). Increase of intracellular oxidative stress was indicated by 2',7'-dichlorofluorescin probing, and the enhanced genotoxicity was demonstrated by the alkaline comet assay and by the micronucleus assay (cytokinesis block). Time- and dose-dependent induction of cell death was monitored by trypan blue exclusion, MTT assay, and Hoechst staining. Furthermore, in our systems in vitro, EGCG neither directly scavenges H2O2 nor mediates other antioxidant activities but rather increased H2O2-induced oxidative stress and DNA damage. In conclusion, our data suggest that detailed mechanistic studies on the effects of GTE and EGCG should be performed in vivo before excessive intake and/or topical application of green tea products can be recommended to healthy and/or diseased persons.

Authors+Show Affiliations

Institute of Cancer Research, Division of Applied and Experimental Oncology, Medical University of Vienna, Borschkegasse 8a, Vienna 1090, Austria. elbling.leonilla@meduniwien.ac.atNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

15738004

Citation

Elbling, Leonilla, et al. "Green Tea Extract and (-)-epigallocatechin-3-gallate, the Major Tea Catechin, Exert Oxidant but Lack Antioxidant Activities." FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology, vol. 19, no. 7, 2005, pp. 807-9.
Elbling L, Weiss RM, Teufelhofer O, et al. Green tea extract and (-)-epigallocatechin-3-gallate, the major tea catechin, exert oxidant but lack antioxidant activities. FASEB J. 2005;19(7):807-9.
Elbling, L., Weiss, R. M., Teufelhofer, O., Uhl, M., Knasmueller, S., Schulte-Hermann, R., Berger, W., & Micksche, M. (2005). Green tea extract and (-)-epigallocatechin-3-gallate, the major tea catechin, exert oxidant but lack antioxidant activities. FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology, 19(7), 807-9.
Elbling L, et al. Green Tea Extract and (-)-epigallocatechin-3-gallate, the Major Tea Catechin, Exert Oxidant but Lack Antioxidant Activities. FASEB J. 2005;19(7):807-9. PubMed PMID: 15738004.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Green tea extract and (-)-epigallocatechin-3-gallate, the major tea catechin, exert oxidant but lack antioxidant activities. AU - Elbling,Leonilla, AU - Weiss,Rosa-Maria, AU - Teufelhofer,Olga, AU - Uhl,Maria, AU - Knasmueller,Siegfried, AU - Schulte-Hermann,Rolf, AU - Berger,Walter, AU - Micksche,Michael, Y1 - 2005/02/28/ PY - 2005/3/2/pubmed PY - 2005/12/24/medline PY - 2005/3/2/entrez SP - 807 EP - 9 JF - FASEB journal : official publication of the Federation of American Societies for Experimental Biology JO - FASEB J VL - 19 IS - 7 N2 - Green tea is the most widely consumed beverage. It has attained high reputation as a health-promoting dietary component ascribed to the antioxidant activity of (-)-epigallocatechin-3-gallate (EGCG), its main polyphenolic constituent. Evidence is increasing that tea constituents can be cell damaging and pro-oxidant themselves. These effects were suggested to be due to spontaneous H2O2 generation by polyphenols in solution. In the present study, we investigated the oxidant and antioxidant properties of green tea extracts (GTE) and of EGCG by means of the rodent macrophage-like RAW 264.7 and human promyelocytic leukemic HL60 cell lines. The results obtained show that both under cell-free conditions and in the presence of cells the oxidant activities of GTE and EGCG exceeded those of spontaneously generated H2O2 (FOX assay). Increase of intracellular oxidative stress was indicated by 2',7'-dichlorofluorescin probing, and the enhanced genotoxicity was demonstrated by the alkaline comet assay and by the micronucleus assay (cytokinesis block). Time- and dose-dependent induction of cell death was monitored by trypan blue exclusion, MTT assay, and Hoechst staining. Furthermore, in our systems in vitro, EGCG neither directly scavenges H2O2 nor mediates other antioxidant activities but rather increased H2O2-induced oxidative stress and DNA damage. In conclusion, our data suggest that detailed mechanistic studies on the effects of GTE and EGCG should be performed in vivo before excessive intake and/or topical application of green tea products can be recommended to healthy and/or diseased persons. SN - 1530-6860 UR - https://www.unboundmedicine.com/medline/citation/15738004/Green_tea_extract_and_____epigallocatechin_3_gallate_the_major_tea_catechin_exert_oxidant_but_lack_antioxidant_activities_ L2 - https://doi.org/10.1096/fj.04-2915fje DB - PRIME DP - Unbound Medicine ER -