Tags

Type your tag names separated by a space and hit enter

Scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative DNA damage by aqueous extracts from green and black teas.
Free Radic Biol Med. 1999 Jun; 26(11-12):1427-35.FR

Abstract

Aqueous extracts of green and black teas have been shown to inhibit a variety of experimentally induced animal tumors, particularly ultraviolet (UV) B light-induced skin carcinogenesis. In the present study, we compared the effects of different extractable fractions of green and black teas on scavenging hydrogen peroxide (H2O2), and UV irradiation-induced formation of 8-hydroxy 2'-deoxyguanosine (8-OHdG) in vitro. Green and black teas have been extracted by serial chloroform, ethyl acetate and n-butanol, and divided into four subfractions designated as GT1-4 for green tea and BT1-4 for black tea, respectively. The total extracts from green and black teas exhibited a potent scavenging capacity of exogenous H2O2 in a dose-dependent manner. It appeared that the total extracts from black tea scavenged H2O2 more potently than those from green tea. When tested individually, the potency of scavenging H2O2 by green tea subfractions was: GT2 > GT3 > GT1 > GT4, whereas the order of efficacy for black tea was: BT2 > BT3 > BT4 > BT1. In addition, we demonstrated that total fractions of green and black teas substantially inhibited the induction of 8-OHdG in calf thymus by all three portions of UV spectrum (UVA, B and C). Consistent with the capacity of scavenging H2O2, the subfractions from black tea showed a greater inhibition of UV-induced 8-OHdG than those from green tea. At low concentrations, the order of potency of quenching of 8-OHdG by green tea subfractions was: GT2 > GT3 > GT4 > GT1 and the efficacy of all subfractions became similar at high concentrations. All subfractions of the black tea except BT1 strongly inhibited UV-induced 8-OHdG and the order of potency was: BT2 > BT3 > BT4 > BT1. Addition of (-)-epigallocatechin gallate (EGCG), an ingredient of green tea extract, to low concentration of green and black tea extracts substantially enhanced the scavenging of H2O2 and quenching of 8-OHdG, suggesting the important role of EGCG in the antioxidant activities of tea extracts. The potent scavenging of oxygen species and blocking of UV-induced oxidative DNA damage may, at least in part, explain the mechanism(s) by which green/black teas inhibit photocarcinogenesis.

Authors+Show Affiliations

Department of Dermatology, Mount Sinai-NYU Medical Center, New York, NY 10029, USA. hw@doc.mssm.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

10401606

Citation

Wei, H, et al. "Scavenging of Hydrogen Peroxide and Inhibition of Ultraviolet Light-induced Oxidative DNA Damage By Aqueous Extracts From Green and Black Teas." Free Radical Biology & Medicine, vol. 26, no. 11-12, 1999, pp. 1427-35.
Wei H, Zhang X, Zhao JF, et al. Scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative DNA damage by aqueous extracts from green and black teas. Free Radic Biol Med. 1999;26(11-12):1427-35.
Wei, H., Zhang, X., Zhao, J. F., Wang, Z. Y., Bickers, D., & Lebwohl, M. (1999). Scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative DNA damage by aqueous extracts from green and black teas. Free Radical Biology & Medicine, 26(11-12), 1427-35.
Wei H, et al. Scavenging of Hydrogen Peroxide and Inhibition of Ultraviolet Light-induced Oxidative DNA Damage By Aqueous Extracts From Green and Black Teas. Free Radic Biol Med. 1999;26(11-12):1427-35. PubMed PMID: 10401606.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Scavenging of hydrogen peroxide and inhibition of ultraviolet light-induced oxidative DNA damage by aqueous extracts from green and black teas. AU - Wei,H, AU - Zhang,X, AU - Zhao,J F, AU - Wang,Z Y, AU - Bickers,D, AU - Lebwohl,M, PY - 1999/7/13/pubmed PY - 1999/7/13/medline PY - 1999/7/13/entrez SP - 1427 EP - 35 JF - Free radical biology & medicine JO - Free Radic Biol Med VL - 26 IS - 11-12 N2 - Aqueous extracts of green and black teas have been shown to inhibit a variety of experimentally induced animal tumors, particularly ultraviolet (UV) B light-induced skin carcinogenesis. In the present study, we compared the effects of different extractable fractions of green and black teas on scavenging hydrogen peroxide (H2O2), and UV irradiation-induced formation of 8-hydroxy 2'-deoxyguanosine (8-OHdG) in vitro. Green and black teas have been extracted by serial chloroform, ethyl acetate and n-butanol, and divided into four subfractions designated as GT1-4 for green tea and BT1-4 for black tea, respectively. The total extracts from green and black teas exhibited a potent scavenging capacity of exogenous H2O2 in a dose-dependent manner. It appeared that the total extracts from black tea scavenged H2O2 more potently than those from green tea. When tested individually, the potency of scavenging H2O2 by green tea subfractions was: GT2 > GT3 > GT1 > GT4, whereas the order of efficacy for black tea was: BT2 > BT3 > BT4 > BT1. In addition, we demonstrated that total fractions of green and black teas substantially inhibited the induction of 8-OHdG in calf thymus by all three portions of UV spectrum (UVA, B and C). Consistent with the capacity of scavenging H2O2, the subfractions from black tea showed a greater inhibition of UV-induced 8-OHdG than those from green tea. At low concentrations, the order of potency of quenching of 8-OHdG by green tea subfractions was: GT2 > GT3 > GT4 > GT1 and the efficacy of all subfractions became similar at high concentrations. All subfractions of the black tea except BT1 strongly inhibited UV-induced 8-OHdG and the order of potency was: BT2 > BT3 > BT4 > BT1. Addition of (-)-epigallocatechin gallate (EGCG), an ingredient of green tea extract, to low concentration of green and black tea extracts substantially enhanced the scavenging of H2O2 and quenching of 8-OHdG, suggesting the important role of EGCG in the antioxidant activities of tea extracts. The potent scavenging of oxygen species and blocking of UV-induced oxidative DNA damage may, at least in part, explain the mechanism(s) by which green/black teas inhibit photocarcinogenesis. SN - 0891-5849 UR - https://www.unboundmedicine.com/medline/citation/10401606/Scavenging_of_hydrogen_peroxide_and_inhibition_of_ultraviolet_light_induced_oxidative_DNA_damage_by_aqueous_extracts_from_green_and_black_teas_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0891-5849(99)00005-2 DB - PRIME DP - Unbound Medicine ER -