Suppressive Effects of Defatted Green Tea Seed Ethanol Extract on Cancer Cell Proliferation in HepG2 Cells
2011
Noh, K.H., Inje University, Gimhae, Republic of Korea | Min, K.H., Inje University, Gimhae, Republic of Korea | Seo, B.Y., Inje University, Gimhae, Republic of Korea | Kim, H.O., Inje University, Gimhae, Republic of Korea | Kim, S.H., Dong-Ju College, Busan, Republic of Korea | Song, Y.S., Inje University, Gimhae, Republic of Korea
Defatted green tea seed was extracted with 100% ethanol for 4 hr and then fractionated with petroleum ether, ethyl acetate and butanol. The ethanol and butanol extracts showed greater increases in antiproliferation potential against liver cancer cells than petroleum ether, ethyl acetate, H₂O, and hot water extracts did. Thus, this study was carried out to investigate the anti-proliferative actions of defatted green tea seed ethanol extract (DGTSE) in HepG2 cancer cells. The DGTSE contained catechins including EGC (1039.1±15.26 ㎍/g), tannic acid (683.5±17.61 ㎍/g), EC (62.4±5.00 ㎍/g), ECG (24.4±7.81 ㎍/g), EGCG (20.9±0.96 ㎍/g) and gallic acid (2.4±0.68 ㎍/g), but caffeic acid was not detected when analyzed by HPLC. The anti-proliferation effect of DGTSE toward HepG2 cells was 83.13% when treated at 10 ㎍/mL, of DGTSE, offering an IC∧50 of 6.58 ㎍/mL. DGTSE decreased CYP1A1 and CYP1A2 protein expressions in a dose-dependent manner. Quinone reductase and antioxidant response element (ARE)-luciferase activities were increased about 2.6 and 1.94-fold at a concentration of 20 ㎍/mL compared to a control group, respectively. Enhancement of phase Ⅱ enzyme activity by DGTSE was shown to be mediated via interaction with ARE sequences in genes encoding the phase enzymes. DGTSE significantly (p less than 0.05) suppressed prostaglandin E₂ level, tumor necrosis factor-α (TNF-α) protein expressions, and NFκB translocation, but did not affected nitric oxide production. From the above results, it is concluded that DGTSE may ameliorate tumor and inflammatory reactions through the elevation of phase Ⅱ enzyme activities and suppression of NFκB translocation and TNF-α protein expressions, which support the cancer cell anti-proliferative effects of DGTSE in HepG2 cells.
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