Theaflavin-3,3'-digallate, a component of black tea: an inducer of oxidative stress and apoptosis.
Treatment of human oral squamous carcinoma HSC-2 cells and normal GN46 fibroblasts with theaflavin-3,3'-digallate (TF-3), a polyphenol in black tea, showed a concentration and time dependent inhibition of growth, with the tumor cells more sensitive than the fibroblasts. In buffer and in cell culture medium, TF-3 generated reactive oxygen species, with lower levels detected in buffer amended with catalase and superoxide dismutase, indicating the generation of hydrogen peroxide and superoxide, respectively, and suggesting that TF-3 may be an inducer of oxidative stress. The toxicity of TF-3 was decreased in the presence of catalase, pyruvate, and divalent cobalt, all scavengers of reactive oxygen species, but was potentiated in the presence of diethyldithiocarbamate, an inhibitor of superoxide dismutase. The intracellular level of glutathione in HSC-2 cells was lessened after a 4-h exposure to 250 and 500 microM TF-3. However, for GN46 fibroblasts, a 4-h exposure to 250 microM TF-3 stimulated, but to 500 microM TF-3 lessened, intracellular glutathione. Treatment of the cells with the glutathione depleters, 1,3-bis(2-chloroethyl)-N-nitrosourea, 1-chloro-2,4-dinitrobenzene, and d,l-buthionine-[S,R]-sulfoximine potentiated the toxicity of TF-3. Induction of apoptotic cell death in HSC-2 cells treated with TF-3 was noted by apoptotic cell morphologies, by TUNEL staining, by PARP cleavage, and by elevated activity of caspase-3. Apoptosis was not noted in GN46 fibroblasts treated with TF-3.
Schuck
Alyssa G
AG
Department of Biology, Stern College for Women, Yeshiva University, 245 Lexington Avenue, New York, NY 10016, USA.
Ausubel
Miriam B
MB
Zuckerbraun
Harriet L
HL
Babich
Harvey
H
D017209:Apoptosis / Q000187:drug effects*; D044946:Biflavonoids / Q000302:isolation & purification / Q000494:pharmacology*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002392:Catechin / Q000302:isolation & purification / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents; D005347:Fibroblasts; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D008856:Microscopy, Fluorescence; D009499:Neutral Red; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species; D013662:Tea / Q000737:chemistry*
D044946:Biflavonoids; D004396:Coloring Agents; D017382:Reactive Oxygen Species; D013662:Tea; D009499:Neutral Red; C077197:theaflavin digallate; D005707:Gallic Acid; D002392:Catechin; D006861:Hydrogen Peroxide; D053148:Caspase 3; D005978:Glutathione