cancer-prevention

Author: Arpita Basu and Nancy M. Betts and Afework Mulugeta and Capella Tong and Emily Newman and Timothy J. Lyons

Green tea, a popular polyphenol-containing beverage, has been shown to alleviate clinical features of the metabolic syndrome. However, its effects in endogenous antioxidant biomarkers are not clearly understood. Thus, we tested the hypothesis that green tea supplementation will upregulate antioxidant parameters (enzymatic and nonenzymatic) in adults with the metabolic syndrome. Thirty-five obese participants with the metabolic syndrome were randomly assigned to receive one of the following for 8 weeks: green tea (4 cups per day), control (4 cups water per day), or green tea extract (2 capsules and 4 cups water per day). Blood samples and dietary information were collected at baseline (0 week) and 8 weeks of the study. Circulating carotenoids (α-carotene, β-carotene, lycopene) and tocopherols (α-tocopherol, γ-tocopherol) and trace elements were measured using high-performance liquid chromatography and inductively coupled plasma mass spectroscopy, respectively. Serum antioxidant enzymes (glutathione peroxidase, glutathione, catalase) and plasma antioxidant capacity were measured spectrophotometrically. Green tea beverage and green tea extract significantly increased plasma antioxidant capacity (1.5 to 2.3 μmol/L and 1.2 to 2.5 μmol/L, respectively; P < .05) and whole blood glutathione (1783 to 2395 μg/g hemoglobin and 1905 to 2751 μg/g hemoglobin, respectively; P < .05) vs controls at 8 weeks. No effects were noted in serum levels of carotenoids and tocopherols and glutathione peroxidase and catalase activities. Green tea extract significantly reduced plasma iron vs baseline (128 to 92μg/dL, P < .02), whereas copper, zinc, and selenium were not affected. These results support the hypothesis that green tea may provide antioxidant protection in the metabolic syndrome.

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Author: Pooja Bhardwaj and Deepa Khanna

Green tea, Camellia sinensis (Theaceae), a major source of flavonoids such as catechins, has recently shown multiple cardiovascular health benefits through various experimental and clinical studies. These studies suggest that green tea catechins prevent the incidence of detrimental cardiovascular events, and also lower the cardiovascular mortality rate. Catechins present in green tea have the ability to prevent atherosclerosis, hypertension, endothelial dysfunction, ischemic heart diseases, cardiomyopathy, cardiac hypertrophy and congestive heart failure by decreasing oxidative stress, preventing inflammatory events, reducing platelet aggregation and halting the proliferation of vascular smooth muscle cells. Catechins afford an anti-oxidant effect by inducing anti-oxidant enzymes, inhibiting pro-oxidant enzymes and scavenging free radicals. Catechins present anti-inflammatory activity through the inhibition of transcriptional factor NF-κB-mediated production of cytokines and adhesion molecules. Green tea catechins interfere with vascular growth factors and thus inhibit vascular smooth muscle cell proliferation, and also inhibit thrombogenesis by suppressing platelet adhesion. Additionally, catechins could protect vascular endothelial cells and enhance vascular integrity and regulate blood pressure. In this review various experimental and clinical studies suggesting the role of green tea catechins against the markers of cardiovascular disorders and the underlying mechanisms for these actions are discussed.

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Author: Abdul-Lateef Molan

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Author: Ramalingam Sundaram and Rajendran Naresh and Palanivelu Shanthi and Panchanatham Sachdanandam

The study was undertaken to evaluate the antidiabetic effect of green tea extract on carbohydrate metabolic key enzymes in control and streptozotocin high fat diet -induced diabetic rats. The daily oral treatment of green tea extract (300 mg/kg body weight) to diabetic rats for 30 days resulted in a significant reduction in the levels of plasma glucose, glycosylated hemoglobin (HbA1c) and increase in the levels of insulin and hemoglobin. The altered activities of the key enzymes of carbohydrate metabolism such as hexokinase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen phosphorylase in liver of diabetic rats were significantly reverted to near normal levels by the administration of green tea extract. Further, green tea extract administration to diabetic rats improved muscle and hepatic glycogen content suggesting the antihyperglycemic potential of green tea extract in diabetic rats. The obtained results were compared with metformin, a standard oral hypoglycemic drug. Thus, this study indicates that the administration of green tea extract to diabetic rats resulted in alterations in the metabolism of glucose with subsequent reduction in plasma glucose levels.

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Author: Martina Bancirova

The antioxidant properties of the black and green tea are well known. The latent bloodstains are detectable by luminol. The bloodstains also can be cover up by drinks and foods containing the antioxidants; thus their presence can cause a decrease of the luminol light emission (false-negative results). The aim of this study was to quantify the light emission decrease of the chemiluminescent mixture prepared according to Weber (containing NaOH) and the chemiluminescent mixture of pH 7.4 (for the determination of the total antioxidant capacity) for the open air-dried sample. The black and green teas and white wine were used as the antioxidant's samples (high and low total antioxidant capacity). The significant decrease of the luminol chemiluminescent emission caused by the presence of the black and green teas (and comparable for both of them) was observed in comparison with the presence of white wine.

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Author: Eugenia Gallo and Valentina Maggini and Margherita Berardi and Alessandra Pugi and Rosario Notaro and Giulia Talini and Giancarlo Vannozzi and Siro Bagnoli and Paolo Forte and Alessandro Mugelli and Vito Annese and Fabio Firenzuoli and Alfredo Vannacci

A case of autoimmune liver hepatitis is reported: the onset was triggered by consumption of green tea infusion in a patient taking oral contraceptives and irbesartan. We hypothesize that our patient, carrying genetic variant of hepatic metabolism making her particularly susceptible to oxidative stress, developed an abnormal response to a mild toxic insult, afforded by a combination of agents (oral contraceptives + irbesartan + green tea) that normally would not be able to cause damage. Her particular hepatic metabolism further increased the drugs’ concentration, favoring the haptenization of liver proteins, eventually leading to the development of an autoimmune hepatitis.

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Author: Dominique Trudel and David P. Labbé and Monica Araya-Farias and Alain Doyen and Laurent Bazinet and Thierry Duchesne and Marie Plante and Jean Grégoire and Marie-Claude Renaud and Dimcho Bachvarov and Bernard Têtu and Isabelle Bairati

Objectives A two-stage, single-arm, phase II study was conducted to assess the effectiveness and safety of an epigallocatechin gallate (EGCG)-enriched tea drink, the double-brewed green tea (DBGT), as a maintenance treatment in women with advanced stage serous or endometrioid ovarian cancer (clinicaltrials.gov, NCT00721890). Methods Eligible women had FIGO stage III-IV serous or endometrioid ovarian cancer. They had to undergo complete response after debulking surgery followed by 6 to 8 cycles of platinum/taxane chemotherapy at the Centre Hospitalier Universitaire de Québec. They all had to drink the DBGT, 500 mL daily until recurrence or during a follow-up of 18 months. The primary endpoint was the absence of recurrence at 18 months. Statistical analyses were done according to the principle of intention to treat. Using a two-stage design, the first stage consisted of 16 enrolled patients. At the end of the follow-up, if 7 or fewer patients were free of recurrence, the trial stopped. Otherwise, accrual would continue to a total of 46 patients. Results During the first stage of the study, only 5 of the 16 women remained free of recurrence 18 months after complete response. Accordingly, the clinical trial was terminated. Women's adherence to DBGT was high (median daily intake during intervention, 98.1%, interquartile range: 89.7–100%), but 6 women discontinued the intervention before the end of their follow-up. No severe toxicity was reported. Conclusions DBGT supplementation does not appear to be a promising maintenance intervention in women with advanced stage ovarian cancer after standard treatment.

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Author: Voravuth Somsak and Ubonwan Jaihan and Somdet Srichairatanakool and Chairat Uthaipibull

Impairment of renal function from oxidative stress during malaria infection is one of the leading causes of death in endemic areas. Since blood urea nitrogen and creatinine levels in plasma can be used as markers for monitoring renal damage, this study investigated the effect of green tea extract on reduction of blood urea nitrogen and creatinine levels during malaria infection using Plasmodium berghei ANKA infected mice as in vivo model. For in vivo testing, ICR mice were infected with 1 × 10 7 parasitized erythrocytes and green tea extract was subsequently administered orally twice a day for 10 consecutive days. Parasitemia was estimated by standard microscopy, and blood urea nitrogen and creatinine levels in plasma were also measured. It was found that parasitemia kept increasing until animal death, and is strongly correlated with high blood urea nitrogen and creatinine. The highest levels of blood urea nitrogen and creatinine in plasma were found on day 10 after infection. However, blood urea nitrogen and creatinine levels in plasma were reduced and decreased significantly (p < 0.01) in green tea extract treated mice, compared with untreated group. It can be concluded that green tea extract can protect and maintain renal function during malaria infection, and this extract can be developed for use as a supplement and combination therapy.

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Author: Naghma Khan and Hasan Mukhtar

Prostate cancer (PCa) is the most common malignancy found in American men and the risk factors for PCa include age, family history, ethnicity, hormonal status, diet and lifestyle. For the successful development of cancer-preventive/therapeutic approaches, consumption of dietary agents capable of inhibiting or delaying the growth and proliferation of cancer cells without significantly affecting normal cells could be an effective strategy. Polyphenols derived from green tea, termed as green tea polyphenols (GTP) have received great attention in recent years for their beneficial effects, in particular, their significant involvement in cancer chemoprevention and chemotherapy. Several studies have reported beneficial effects of GTP using in vitro and in vivo approaches and in human clinical trials. Among green tea catechins, epigallocatechin-3-gallate (EGCG) is best studied for its cancer preventive properties. In this review article, we present available scientific literature about the effects of GTP and EGCG on signaling pathways in PCa.

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Author: Anna Lante and Dario Friso

Epigallocatechin-3-gallate (EGCG) is considered the most significant tea catechin because it has the highest free radical scavenging activity and because of its role in preventing carcinogenesis. Thus, adding green tea infusion to food products imparts a safe, natural antioxidant that prevents rancidity and promotes good health. Even if mild technologies could be developed to optimize the extraction of EGCG from green tea, questions remain regarding the best means of delivering EGCG through food and its disposition in the body after ingestion. Recent reports indicate that the bioavailability of EGCG is very poor due to its large molecular size and number of hydrogen bonds. The present study demonstrates the use of ultrasound to extract catechins from green tea leaves with improved EGCG yield, and subsequent preparation of water-in-oil (W/O) green tea nanoemulsions with soy, peanut, sunflower, and corn oils. The green tea/peanut oil emulsion displayed the highest oxidative stability. All W/O emulsions examined demonstrated a shear thinning behavior in good agreement with the Carreau model (R2 = 0.980 ± 0.033). Values for shear viscosity at a shear rate of 10 s−1 were found to be compatible with the semi-empirical equation of Larson and McClements, with an effective volume fraction slightly higher than the actual volume fraction and still increasing with homogenization time. Moreover, the specific surface area of the nanoemulsions was very high and with an average value of about 40 m2/mL.

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