Antioxidant effects of green tea and its polyphenols on bladder cells

Abstract

Genitourinary tract inflammation/ailments affect the quality of life and health of a large segment of society. In recent years, studies have demonstrated strong anti-oxidant effects of green tea and its associated polyphenols in inflammatory states. This in vitro study examined the antioxidant capabilities (and putative mechanisms of action) of green tea extract (GTE), polyphenon-60 (PP-60, 60 % pure polyphenols), (−)-epicatechin-3-gallate (ECG) and (−)-epigallocatechin-3-gallate (EGCG) in normal/malignant human bladder cells following catechin treatment ± 1 mM H 2 O 2 (oxidative agent). Cell viability, apoptosis and reactive oxygen species (ROS) formation were evaluated. Our results showed that H 2 O 2 exposure significantly reduced normal (UROtsa) and highgrade (TCCSUP, T24) bladder cancer (BlCa) cell viability compared with control-treated cells (p < 0.001). No affect on low-grade RT4 and SW780 BlCa cell viability was observed with exposure to H 2 O 2 . Compared to H 2 O 2 -treated UROtsa, treatment with PP-60, ECG and EGCG in the presence of H 2 O 2 significantly improved UROtsa viability (p < 0.01), with strongest effects evoked by ECG. Additionally, though not as effective as in UROtsa cells, viability of both high-grade TCCSUP and T24 BlCa cells, in comparison to H 2 O 2 -treated cells, were significantly improved (p < 0.01) by treatment with PP-60, ECG, and EGCG in the presence of H 2 O 2 . Overall, our findings demonstrate that urothelium cell death via H 2 O 2 -induced oxidative stress is mediated, in part, through superoxide (O 2 −· ), and potentially, direct H 2 O 2 mechanisms, suggesting that green tea polyphenols can protect against oxidative stress/damage and bladder cell death.

Dietary flavanols exert different effects on antioxidant defenses and apoptosis/proliferation in Caco-2 and SW480 colon cancer cells

“…dramatic depletion of GSH intracellular levels and a diminished cell viability and proliferation. In this regard, other studies have reported a decreased steady-state generation of ROS induced by EGCG and ECG, which has been related to a suppression of ONOO− formation and/or modulation of nitrite levels by both catechins due to their high antioxidant capacity (Coyle et al, 2008). …”

“…Flavanols EC, ECG and PB2 possess a well characterized in vitro antioxidant activity, and recent studies have shown that these catechins are effective free radical scavengers and interfere with the oxidative/antioxidative potential of hepatic (Coyle et al, 2008;Chen et al, 2002;Granado-Serrano et al, 2007, 2009bMartin et al, 2008) and colonic cells (Rodríguez-Ramiro et al, 2011).…”

White Tea (Camellia sinensis Kuntze) Exerts Neuroprotection against Hydrogen Peroxide-Induced Toxicity in PC12 Cells

“…In addition, non-fermented teas, such as green and white, are considered good sources of natural antioxidants. Whereas green tea composition and bioactivity has been in-depth investigated [8][9][10][11][12][13], there are few studies about white tea extracts. Antioxidant and lipolytic activities of white tea have been reported [14,15]; however, the neuroprotective effect of this variety has never been established in neuronal-like cells.…”

Cancer Chemoprevention by Dietary Polyphenols

“…Other study has demonstrated the anti-oxidant properties of green tea extract (GTE) against human bladder uroepithelial cells. The data demonstrate that under in vitro conditions, green tea extract can afford both normal and tumorigenic human bladder urothelial cells protection (i.e., prevent apoptosis) to various degrees after chemical insult with H2O2 [60].…”