cancer-prevention

Author: Yuri Clement

Objective Habitual green tea consumption has long been associated with health benefits including chemoprevention and cardiovascular protection. This non-systematic literature review presents the clinical evidence to date. Method A literature review of peer-reviewed articles on observational and interventional studies was conducted to include green tea, its extract or its purified polyphenol (−)-epigallocatechin-3-gallate (EGCG). Electronic databases searched included PubMed (1966–2009) and the Cochrane Library (Issue 4, 2008). Results Observational studies are inconclusive on the benefits of habitual consumption of green tea in the prevention of most cancers. However, there are trends towards prevention in breast and prostate cancers. Interventional studies have demonstrated reduction in relapses following surgical resection in colorectal adenomas and increased survival rates in epithelial ovarian cancer. Observational studies indicate that green tea may provide protection against hypertension and reduce the risk for stroke, and interventional studies are providing biochemical and physiological evidence. Conclusion Although the overall clinical evidence is inconclusive, habitual green tea consumption may be providing some level of chemoprevention in prostate and breast cancer. Green tea may also attenuate the risk factors association with the development of atherosclerosis thus reducing the incidence of cardiovascular events and stoke.

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Author: T. Malik and D.J. Haleem

Haloperidol (HAL) a conventional antipsychotic is known to induce oxidative stress-related anxiety. Parkinsonism and Tardive Dyskinesia (TD) in patients treated with drug. Antioxidative agents may suppress the neuroleptic induced anxiety and TD. The constituents of green tea have found antioxidative. In a view of antioxidative properties of green tea, the present study was designed to monitor a possible suppression of anxiety and Tardive Vacuous Chewing Movement (tVCM) by green tea in rat model of TD and anxiety. Associated changes of Dopamine (DA) and Serotonin (5-hydroxytryptamine; 5-HT) metabolism were also monitored in the dorsal (dStr) and ventral striatum (vStr). Rats on HAL for 8 weeks exhibited tVCMs and anxiety. Green tea Extract (GTE) alone as a sole source of water did not produce tVCMs and anxiety but HAL induced significant anxiety and tVCMs were 100% (two fold) greater than water treated group. The metabolism of DA as indicated by Homovanellic acid (HVA) concentration increased in the dStr of HAL plus GTE treated animals. HAL plus GTE treated group exhibited smaller increase of HVA. The mteabolism of 5-HT as indicated by 5-hydroxyindoleacetic acid (5-HIAA) concentration also increased in the dStr of HAL but not GTE treated animals. Groups of co-treated with HAL and GTE exhibited a large increase 5 HIAA in the dStr. The results suggested that interaction of HAL with some constituents of GTE may exacerbated HAL induced  anxiety and TD by producing an imbalance of DA/5-HT control over anxiety and motor impairment.

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“Do you want a vodka? No, a green tea please!” Epigallocatechin gallate and its possible role in oxidative stress and liver damage

Author: Lorenzo Leggio and Giovanni Addolorato

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Author: Rossana M. Costa and Ana S. Magalhães and José A. Pereira and Paula B. Andrade and Patrícia Valentão and Márcia Carvalho and Branca M. Silva

This study aimed to determine the phenolic profile and to investigate the antioxidant potential of quince (Cydonia oblonga) leaf, comparing it with green tea (Camellia sinensis). For these purposes, methanolic extracts were prepared and phenolics content of quince leaf was determined by HPLC/UV. The antioxidant properties were assessed by Folin–Ciocalteu reducing capacity assay and by the ability to quench the stable free radical 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and to inhibit the 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of human erythrocytes. 5-O-Caffeoylquinic acid was found to be the major phenolic compound in quince leaf extract. Quince leaf exhibited a significantly higher reducing power than green tea (mean value of 227.8 ± 34.9 and 112.5 ± 1.5 g/kg dry leaf, respectively). Quince leaf extracts showed similar DPPH radical-scavenging activities (EC50 mean value of 21.6 ± 3.5 μg/ml) but significantly lower than that presented by green tea extract (EC50 mean value of 12.7 ± 0.1 μg/ml). Under the oxidative action of AAPH, quince leaf methanolic extract significantly protected the erythrocyte membrane from hemolysis in a similar manner to that found for green tea (IC50 mean value of 30.7 ± 6.7 and 24.3 ± 9.6 μg/ml, respectively, P > 0.05). These results point that quince leaf may have application as preventive or therapeutic agent in diseases in which free radicals are involved.

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Author: Calin Stoicov and Reza Saffari and JeanMarie Houghton

Helicobacter infection, one of the most common bacterial infections in man worldwide, is a type 1 carcinogen and the most important risk factor for gastric cancer. Helicobacter pylori bacterial factors, components of the host genetics and immune response, dietary cofactors and decreased acid secretion resulting in bacterial overgrowth are all considered important factors for induction of gastric cancer. Components found in green tea have been shown to inhibit bacterial growth, including the growth of Helicobacter spp. In this study, we assessed the bactericidal and/or bacteriostatic effect of green tea against Helicobacter felis and H. pylori in vitro and evaluated the effects of green tea on the development of Helicobacter-induced gastritis in an animal model. Our data clearly demonstrate profound growth effects of green tea against Helicobacter and, importantly, demonstrate that green tea consumption can prevent gastric mucosal inflammation if ingested prior to exposure to Helicobacter infection. Research in the area of natural food compounds and their effects on various disease states has gained increased acceptance in the past several years. Components within natural remedies such as green tea could be further used for prevention and treatment of Helicobacter-induced gastritis in humans.

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Author: Qihua Gu and Chengping Hu and Qiong Chen and Ying Xia and Juntao Feng and Hongzhong Yang

Background A convenient animal model of primary lung cancer is compelling for investigation into the disease mechanisms and for development of therapeutic strategies. This study aims to develop a reproducible rat model for lung carcinoma by intra-pulmonary injection of 3,4-benzopyrene, and to evaluate the preventive effect of green tea on the formation of lung carcinoma. MethodsSprague–Dawley rats of the same ages were randomly assigned into three groups treated differently. Rats in group one were given green tea in drinking water (tea concentration: 1.2%; tea polyphenols in the tea solution: 0.3%); rats in the groups two and three were given blank drinking water. Rats in the groups one and two were injected intra-pulmonarily with 3,4-benzopyrene dissolved in corn oil (2 mg/0.2 mL/injection, fortnightly, 4 times in all); rats in the group three were injected with the vehicle corn oil as the control for injection. All the rats were sacrificed one year after the first intra-pulmonary injection. Tumors developed in rats and lung tissues were collected for carcinoma diagnosis and for p53 and bcl-2 expression. Results Intra-pulmonary injection of 3,4-benzopyrene steady induced lung carcinoma at a success rate of 75%. Administration with green tea drinking significantly reduced the incidence of lung carcinoma to 30%. Green tea up-regulated p53 expression in lung carcinoma, but significantly down-regulated bcl-2 expression. Conclusions Intra-pulmonary injection of 3,4-benzopyrene can steady induce lung carcinoma in rats, and green tea has preventive effect against lung cancer possibly by regulating expression of some critical genes such as p53 and bcl-2.

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Author: A.L. Molan and J. Flanagan and W. Wei and P.J. Moughan

The effects of selenium-containing green tea (SGT; 1.4 mg selenium/kg) and China green tea (CGT; 0.13 mg selenium/kg) on the in vitro growth of lactobacilli and bifidobacteria were investigated using pure and mixed cultures. SGT had significantly higher phenolic contents (TPC), higher reducing activity, higher DPPH free-radical scavenging activity, and higher ferrous-ion chelating activity (P < 0.05–0.0001) than CGT. The addition of aqueous extracts from CGT to Mann-Rogosa-Sharpe (MRS) broth at 10% and 25% (v/v) resulted in small but nonsignificant (P > 0.05) increases in the numbers of Lactobacillus rhamnosusand Bifidobacterium breve over the control incubations (without tea). Addition of 10% and 25% of SGT extract resulted in a significant increase (P < 0.05–0.0001) in the number of lactobacilli and bifidobacteria recovered from batch fermentation while CGT did not increase the number of bifidobacteria. The higher prebiotic activity of SGT over CGT may be related to the higher TPC or minerals, notably selenium or a combination of these factors. To test whether selenium itself has an effect on bacterial growth, Na-selenite and Na-selenate were added alone or in combination with CGT to the MRS broth containing pure culture of L. rhamnosus. Growth of this bacterium was enhanced relative to the control incubation of MRS only. When added in combination with CGT, Na-selenate was more effective at enhancing the growth of L. rhamnosus than Na-selenite. The prebiotic effect of SGT could be largely explained by its selenium content.

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Author: Ka H. Chan and Siu P. Ho and Sze C. Yeung and Wallace H.L. So and C.H. Cho and Marcel W.L. Koo and Wah K. Lam and Mary S.M. Ip and Ricky Y.K. Man and Judith C.W. Mak

Author: Feng Li and Juan Xu and Jing Zhou and Liyan Zhao and Jianchun Sheng and Guiju Sun and Qiuhui Hu

The anticlastogenic effect of micrometer powder of selenium-enriched green tea (MSTP) was evaluated by using a chromosomal aberration assay in mouse testicular cells. Animals fed with a Se-deficient diet were treated with MSTP, micrometer powder of regular green tea (MRTP), selenite, and MRTP + selenite for 30 days by an intragastric route, followed by treatment of mitomycin C (MMC) on day 19 through intraperitoneal injection (ip). Selenium status and antioxidant enzymes were measured. Results indicated that MSTP showed a significant capability to reduce the incidence of MMC-induced chromosomal aberrations in spermatocytes from 22.7% to 6.7%. This inhibitory was highest, for MSTP, at 73.1%, while it was only 38.4% for MRTP. After 30 days of a Se-deficient diet, mice, either with or without the MMC treatment, showed a lower selenium concentration in blood and liver as well as lower enzyme activity of the antioxidants, GPx and SOD. Supplementation with MSTP, selenite, or selenite + MRTP enhanced the activities of these antioxidant enzymes. This enhancement was accompanied with a concomitant elevation of selenium levels, which favored the synthesis of the seleno-enzyme GPx and protected the cells from the MMC-induced oxidative stress. Our results indicate that MSTP is both able to prevent the chromosomal aberrations induced by MMC in mouse spermatocytes and to enhance GPx and SOD activity in blood serum and liver.

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Author: Vadivel Senthil Kumaran and Karpagavinayagam Arulmathi and Periandavan Kalaiselvi

Objective The activities and capacities of antioxidant systems of tissue cells are declined during aging, leading to the gradual loss of pro-oxidant/antioxidant balance and accumulation of oxidative damage. Hence, the present study evaluated the role of green tea extract (GTE), rich in polyphenols, in combating age-associated macromolecular damage in rat cardiac tissue. Methods The antioxidant defense system, lipid peroxidation, protein oxidation, and redox status in heart tissue were studied using young and aged rats. Results Significant increases in lipid peroxidation, protein carbonyls, and marked decreases in glutathione redox status, protein thiols, and activities of enzymatic and non-enzymatic antioxidants were observed in aged rats compared with young rats. Supplementation of GTE (100 mg/kg of body weight per day) orally for 30 days ameliorated these changes significantly. Conclusion This study accredits GTE's antioxidant rejuvenating potency and its role in the amelioration of senescence-mediated redox imbalance in aged rat cardiac tissue.

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