cancer-prevention

Author: Dominik Kmiecik and Józef Korczak and Magdalena Rudzińska and Joanna Kobus-Cisowska and Anna Gramza-Michałowska and Marzanna Hęś

Author: Mark E. Stearns and Min Wang

We have examined whether epigallocatechin-3-gallate (EGCG), and extract of green tea, in combination with taxane (i.e., paclitaxel and docetaxel), exerts a synergistic activity in blocking human prostate PC-3ML tumor cell growth in vitro and in vivo. Growth assays in vitro revealed that the IC50 values were ∼30 μM, ∼3 nM, and ∼6 nM, for EGCG, paclitaxel and docetaxel, respectively. Isobolograms generated from the data clearly indicated that EGCG in combination with paclitaxel or docetaxel had an additive effect in blocking tumor cell growth. EGCG combined with taxane also had an additive effect to increase the expression of apoptotic genes, (p53, p73, p21, and caspase 3) and the percent apoptosis observed in vitro and in tumor modeling studies in severe combined immunodeficient mice. The tumor modeling studies clearly showed that EGCG plus taxane injected intraperitoneally (i.p.) induced a significant increase in apoptosis rates (TUNEL assays) and eliminated preexisting tumors generated from PC-3ML cells implanted i.p., increasing disease-free survival rates to greater than 90%. More importantly, the combination therapy (i.p. biweekly) blocked metastases after intravenous injection of PC-3ML cells through the tail vein. In mice treated with EGCG plus taxane, the disease-free survival rates increased from 0% (in untreated mice) to more than 70% to 80% in treated mice. Taken together, these data demonstrate for the first time that EGCG in combination with taxane may provide a novel therapeutic treatment of advanced prostate cancer.

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Author: Radomir V. Malbaša and Eva S. Lončar and Jasmina S. Vitas and Jasna M. Čanadanović-Brunet

This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28 °C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.

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Author: Anna Hsu and Richard S. Bruno and Christiane V. Löhr and Alan W. Taylor and Rodrick H. Dashwood and Tammy M. Bray and Emily Ho

Chronic inflammation and nuclear factor-kappa B (NFκB) have been implicated in prostate cancer development; thus, dietary factors that inhibit NFκB may serve as effective chemo-preventative agents. Prostate cancer risk is significantly lower in Asian countries compared to the United States, which has prompted interest in the potential chemopreventative action of Asian dietary components such as soy and green tea. This study examined the effects of dietary soy and tea on NFκB activation and inflammation in vivo using a hormone-induced rat model for prostate cancer. Male Noble rats implanted with estradiol and testosterone were divided into 4 dietary groups: control, soy, tea, or soy+tea. NFκB activation and inflammatory cytokines were measured post implantation. The combination of soy and tea suppressed NFκB p50 binding activity and protein levels via induction of IκBα. Soy and tea also decreased prostate inflammatory infiltration, increased Bax/BcL2 ratio and decreased protein expression of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1β compared to control. Soy and tea attenuated prostate malignancy by decreasing prostate hyperplasia. These effects were not apparent in groups treated with soy or tea alone. The ongoing in vivo studies thus far suggest that combination of foods, such as soy and tea, may inhibit hormone-induced proinflammatory NFκB signals that contribute to prostate cancer development.

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Author: Renato G. Peres and Fernando G. Tonin and Marina F.M. Tavares and Delia B. Rodriguez-Amaya

A sulfated-β-cyclodextrin (s-β-CD) modified reduced flow micellar electrokinetic chromatography (RF-MEKC) method was developed and validated for the determination of catechins in green tea. The optimal electrolyte consisted of 0.2% triethylamine, 50 mmol/L SDS and 0.8% s-β-CD (pH = 2.9), allowing baseline separation of five catechins in 4 min. The samples and standards were injected at 0.6 psi for 5 s under constant voltage of −30 kV. Sample preparation simply involved extraction of 2 g of tea with 200 mL water at 95 °C under constant stirring for 5 min. The method demonstrated excellent performance, with limits of detection (LOD) and quantification (LOQ) of 0.02–0.1 and 0.1–0.5 μg/mL, respectively, and recovery percentages of 94–101%. The method was applied to six samples of Brazilian green tea infusions. Epigallocatechin gallate (23.4–112.4 μg/mL) was the major component, followed by epigallocatechin (18.4–78.9 μg/mL), epicatechin gallate (5.6–29.6 μg/mL), epicatechin (4.6–14.5 μg/mL) and catechin (3.2–8.2 μg/mL).

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Author: J.A. Macedo and V. Battestin and M.L. Ribeiro and G.A. Macedo

Green tea (Camellia sinensis) and yerba mate (Ilex paraguariensis) are rich in polyphenolic compounds, which are thought to contribute to the health benefits of tea. The aim of this study was to evaluate the potential antioxidant properties of green tea and yerba mate extracts before and after the enzymatic biotransformation reaction catalysed by the Paecilomyces variotii tannase. The antiradical properties of the tea extracts, as well as the standards of chlorogenic acid and EGCG, were assessed using the ORAC and DPPH assays before and after the tannase biotransformation. The antioxidant power of enzyme-treated green tea and yerba mate increased by 55% and 43%, respectively, compared with that of untreated teas. The antioxidant power of the standards was also highly increased by enzyme treatment. These results provide relevant data about the potential of the tannase application on various polyphenol sources and to increase the antioxidant power of two widely consumed beverages.

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Author: Alaa El-Din A. Bekhit and Vern Jou Cheng and Michelle McConnell and Jenny H. Zhao and Richard Sedcole and Roland Harrison

Grape skin extracts from pinot noir and pinot gris exhibited significant in vitroantiviral (influenza virus) activity. Five tea infusions from grape skins (Vitis vinifera var. pinot noir and pinot gris) without any additives (control pinot noir and control pinot gris) or by adding variable amounts of green tea and hibiscus were investigated as a means to utilise wine wastes. The antioxidant activities (DPPHscavenging capacity and superoxide anion radical scavenging capacity), total phenolics, the polyphenolics profile and objective colour measurements (CIELab) were determined on freeze-dried water extracts of all five tea infusions, hibiscus and green tea. The colour parameters, L∗ and a∗ values, varied widely (P < 0.05) for all the infusions as a result of having different levels and variety of pigments. The tea infusions exhibited weak antioxidant activity and the antiviral activity in grape skin appears not related to phenolics contents.

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Author: W.G. Pantsi and J.L. Marnewick and A.J. Esterhuyse and F. Rautenbach and J. van Rooyen

Rooibos, a unique South African herbal tea, is known to be an important source of unique polyphenolic compounds. In the present study we have quantified the main polyphenolic compounds in both fermented/traditional and unfermented/“green” rooibos (Aspalathus linearis) and evaluated its cardioprotective effects against ischaemia/reperfusion injury. Male Wistar rats consumed aqueous rooibos and green tea (Camellia sinensis) extracts (2%, w/v) for 7 weeks before their hearts were rapidly excised and perfused in a working heart perfusion apparatus. The results showed that the rooibos supplemented hearts significantly improved aortic output recovery after reperfusion when compared to the green tea supplemented hearts. Additionally, we showed that the rooibos extracts, containing the highest amount of flavonols, significantly decreased the level of cleaved caspase-3 and PARP, both pro-apoptotic proteins, during reperfusion when compared to green tea. Green tea supplementation increased phosphorylation of total PKB/Akt, Akt (threonine 308) and Akt (serine 473). The rooibos extracts did not cause significant change in the levels of the pro-survival PKB/Akt (threonine 308 and serinet 473). The GSH/GSSG ratio in the hearts of the green tea supplemented group was significantly (p < 0.05) lower when compared to RF (37.78 ± 28.63), RU (33.20 ± 4.13) and C (45.50 ± 14.96). The results clearly demonstrate the cardio-protective properties of aqueous rooibos extracts via the inhibition of apoptosis which can possibly be related to the flavonol content of this unique South African herbal tea.

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Author: Congde Huo and Q. Ping Dou and Tak Hang Chan

A series of phosphate or phosphate–acetate hybrid modified EGCG or EGCG G ring deoxy analogs were synthesized by a convenient semi-synthesis strategy from the abundant natural compound EGCG.

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Author: E.J. Okello and G.J. McDougall and S. Kumar and C.J. Seal

There is mounting evidence that the deposition and aggregation of β-amyloid peptides (Aβ) in the brain play a significant role in the development and pathogenesis of Alzheimer's disease. There is further evidence that free radical species such as hydrogen peroxide (H2O2) mediate Aβ induced toxicity. Previous studies have demonstrated that green tea polyphenols possess neuroprotective properties through their ability to ameliorate oxidative stress induced by free radical species. Green tea polyphenols have also been shown to enhance cognition in various animal models of induced cognitive impairment. Upon ingestion, green tea polyphenols are metabolised and undergo bio-transformation which affects their bioavailability and therefore efficacy. In this study, a green tea extract was subjected to a simulated gastrointestinal digestion and a ‘colon-available’ extract (CAGTE) prepared and assessed for its potential protective effects against H2O2 and Aβ(1–42) induced cytotoxicity using differentiated PC12 cells (dPC12) as a model for neuronal cells. CAGTE represents green tea phytochemicals potentially available after upper gastrointestinal digestion. CAGTE which was depleted in flavan-3-ols, as shown by LC–MS analysis, protected dPC12 cells at concentration ranges of 0.3–10 μg/ml and 0.03–0.125 μg/ml for H2O2 and Aβ(1–42), induced cytotoxicity, respectively. At high concentrations, CAGTE exhibited direct anti-proliferative effects, in line with the reputed anti-cancer properties of green tea polyphenols. These results demonstrate that potentially bioavailable green tea metabolites are able to ameliorate both H2O2 and Aβ(1–42) induced cytotoxicity.

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