cancer-prevention

Matcha/green tea has for many centuries been regarded as an essential part of good health in Japan and China. Many believe it can help reduce the risk of cancer, and a growing body of evidence backs this up.

Recent Research Papers on
cancer-prevention

Subacute oral toxicity of chlorpyriphos and protective effect of green tea extract

Author: S. Mahaboob Khan and Gurjot Kour

This paper reports the effect of green tea administration following subacute toxicity caused by exposure to organophosphorus pesticide chlorpyriphos in liver of rats. Four groups containing five male Sprague–Dawley rats each were selected. Group I served as control. Group II rats were permitted free access to solubilised crude extract of green tea (1.5%w/v in water) as the sole drinking fluid. Group III rats were given a single daily oral dose of chlorpyriphos (30 mg/kg bodyweight in corn oil). Group IV rats received oral dose of pesticide and green tea extract simultaneously. All rats were sacrificed after 15 days. Significant damage to liver was observed via increased serum levels of transaminases and alkaline phosphatase. Lipid peroxidation showed a 5-fold increase in pesticide exposed rats compared to control. In contrast, levels of antioxidant GSH, glutathione-dependent enzymes like glutathione peroxidase (GPx), glutathione S-transferase (GST) and free radical scavengers like catalase (CAT) and superoxide dismutase (SOD) were significantly lower than those of the control group reinforcing oxidative damage. The use of green tea extract appeared to be beneficial to rats, although not to a great extent in significantly reducing and reversing the damage sustained by pesticide exposure and favors recovery.

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Tea polyphenols for health promotion

Author: Naghma Khan and Hasan Mukhtar

People have been consuming brewed tea from the leaves of the Camellia sinensis plant for almost 50 centuries. Although health benefits have been attributed to tea, especially green tea consumption since the beginning of its history, scientific investigations of this beverage and its constituents have been underway for less than three decades. Currently, tea, in the form of green or black tea, next to water, is the most widely consumed beverage in the world. In vitro and animal studies provide strong evidence that polyphenols derived from tea may possess the bioactivity to affect the pathogenesis of several chronic diseases. Among all tea polyphenols, epigallocatechin-3-gallate has been shown to be responsible for much of the health promoting ability of green tea. Tea and tea preparations have been shown to inhibit tumorigenesis in a variety of animal models of carcinogenesis. However, with increasing interest in the health promoting properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and health benefits of tea with special reference to cancer and cardiovascular diseases.

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Prevention of Hypertension, Cardiovascular Damage and Endothelial Dysfunction with Green Tea Extracts

Author: Michele Antonello and Domenico Montemurro and Massimo Bolognesi and Marco Di Pascoli and Anna Piva and Franco Grego and Daniele Sticchi and Luisa Giuliani and Spiridione Garbisa and Gian Paolo Rossi

Background: We investigated the effect of green tea extract (GTE) in arterial hypertension with high oxidative stress. Angiotensin (Ang) II induces endothelial dysfunction (ED) that is crucial for the development of atherosclerosis and hypertension. Methods: Male Sprague-Dawley rats, 13 weeks old, randomly assigned to drinking water with or without GTE (6 mg/mL) received a vehicle, a high (700 μg/kg/d) or a low (350 μg/kg/d) Ang II dose for 13 days, by osmotic mini-pumps. Blood pressure (BP) was measured with telemetry. After sacrifice, left ventricular (LV) mass index, small mesenteric artery media-to-lumen ratio, and concentration–response curves of phenylephrine-precontracted arteries to acetylcholine were evaluated. The effect of the superoxide dismutase (SOD-1) analog tempol on artery responses to acetylcholine was assessed. Oxidative stress was measured by plasma hydroperoxides and nitrotyrosine levels. The mRNA of heme oxygenase 1 (HO-1), NADPH oxidase endothelial p22phox subunit, and SOD-1 was also measured in the aorta. Results: Compared with vehicle high Ang II increased BP, LV mass index, media-to-lumen ratio, and hydroperoxide radicals. The GTE blunted these increases, prevented the increase in HO-1, p22phox, and SOD-1 mRNA in aorta caused by Ang II, and reduced them below baseline levels. Low Ang II dose increased BP values and plasma hydroperoxides only during the first week. Both Ang II doses shifted rightward the curves to acetylcholine; this was prevented in vivo by GTE and abolished in vitro by tempol. Conclusions: The GTE prevented hypertension and target organ damage induced by a high Ang II dose, likely by prevention or scavenging of superoxide anion generation.

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Albumin causes a synergistic increase in the antioxidant activity of green tea catechins in oil-in-water emulsions

Author: M. Pilar Almajano and M. Eugenia Delgado and Michael H. Gordon

Model oil-in-water emulsions containing epicatechin (EC) and epigallocatechin gallate (EGCG) showed a synergistic increase in stability in emulsions containing added albumin. EGCG showed a stronger synergy (35%) with ovalbumin than did EC. Oxidation of the oil was monitored by determining peroxide values and hexanal contents. The effect of bovine serum albumin (BSA) on model oil-in-water emulsions containing each of the green tea catechins [epicatechin gallate (ECG), EGCG, EC and epigallocatechin (EGC)] was studied during storage at 30 °C. The green tea catechins showed moderate antioxidant activity in the emulsions with the order of activity being ECG ≈ EGCG > EC > EGC. Although BSA had very little antioxidant activity in the absence of phenolic antioxidants, the combination of BSA with each of the catechins showed strong antioxidant activity. BSA, in combination with EC, EGCG or EGC, showing the strongest antioxidant activity with good stability after 45 days storage. Model experiments with the catechins stored with BSA in aqueous solutions confirmed that protein–catechin adducts with antioxidant activity were formed between the catechins and protein. The antioxidant activity of the separated protein–catechin adducts increased strongly with storage time and was stronger for EGCG and ECG than for EC or EGC.

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Ascorbate, green tea and grape seed extracts increase the shelf life of low sulphite beef patties

Author: Sancho Bañón and Pedro Díaz and Mariano Rodríguez and María Dolores Garrido and Alejandra Price

Green tea (GTE) and grape seed (GSE) extracts are proposed as preservatives for increasing the shelf life of low sulphite raw beef patties. The antioxidant and antimicrobial activities of both extracts were compared with ascorbate. Five groups were established for the patties: Control (with no additives), S (100 SO2), SA (100 SO2 + 400 sodium ascorbate), ST (100 SO2 + 300 GTE) and SG (100 SO2 + 300 GSE) (mg per kg of meat). Patties were stored at 4 °C in aerobic packaging for 0, 3, 6 or 9 days under retail display conditions. Meat spoilage (total viable and coliform counts, pH, lightness, chroma, hue angle, metmyoglobin and TBARS) was determined. The sensory contribution of the extracts to cooked patties was evaluated (colour, odour, flavour and texture). The results pointed to the possibility of using low SO2-vegetable extract combinations to preserve raw meat products. ST, SG and SA delayed microbial spoilage, redness loss and lipid oxidation, thus increasing the shelf life of the raw sulphite beef patties by 3 days. ST, SG and SA also delayed the onset of rancid flavours in cooked patties. No anomalous sensory traits were caused by either extract. Ascorbate, GTE and GSE improved the preservative effects of SO2 on beef patties, especially against meat oxidation. This suggested that the quantity of SO2 added can be reduced to obtain healthier raw meat products.

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A Prospective Study of Green Tea Consumption and Oral Cancer Incidence in Japan

Author: Reiko Ide and Yoshihisa Fujino and Yoshiharu Hoshiyama and Tetsuya Mizoue and Tatsuhiko Kubo and Truong-Minh Pham and Kiyoyumi Shirane and Noritaka Tokui and Kiyomi Sakata and Akiko Tamakoshi and Takesumi Yoshimura

Purpose To examine the relation of green tea consumption with oral carcinogenesis, we prospectively analyzed data from a nationwide large-scale cohort study in Japan. Methods A total of 20,550 men and 29,671 women aged 40–79 years, without any history of oral and pharyngeal cancer at baseline survey, were included in the present study. During a mean follow-up period of 10.3 years, 37 oral cancer cases were identified. The Cox proportional hazard model was used to estimate the hazard ratio (HR) and 95% confidence interval (95% CI) for oral cancer according to green tea consumption by sex, while adjusting for age, smoking, alcohol drinking, and other dietary factors. Results For women, the HRs of oral cancer for green tea consumption of 1–2, 3–4, and 5 or more cups per day were 0.51 (95% CI: 0.10–2.68), 0.60 (95% CI: 0.17–2.10), and 0.31 (95% CI: 0.09–1.07), respectively, compared with those who drank less than one cup per day (p for trend, 0.08). For men, no such trends were observed. Conclusions Our findings did not suggest a prominent inverse association of green tea consumption with oral cancer, although there was a tendency for a reduced risk in women.

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Green tea and skin cancer: photoimmunology, angiogenesis and DNA repair

Author: Suchitra Katiyar and Craig A. Elmets and Santosh K. Katiyar

Human skin is constantly exposed to numerous noxious physical, chemical and environmental agents. Some of these agents directly or indirectly adversely affect the skin. Cutaneous overexposure to environmental solar ultraviolet (UV) radiation (290–400 nm) has a variety of adverse effects on human health, including the development of melanoma and nonmelanoma skin cancers. Therefore, there is a need to develop measures or strategies, and nutritional components are increasingly being explored for this purpose. The polyphenols present in green tea (Camellia sinensis) have been shown to have numerous health benefits, including protection from UV carcinogenesis. (−)-Epigallocatechin-3-gallate (EGCG) is the major and most photoprotective polyphenolic component of green tea. In this review article, we have discussed the most recent investigations and mechanistic studies that define and support the photoprotective efficacy of green tea polyphenols (GTPs) against UV carcinogenesis. The oral administration of GTPs in drinking water or the topical application of EGCG prevents UVB-induced skin tumor development in mice, and this prevention is mediated through: (a) the induction of immunoregulatory cytokine interleukin (IL) 12; (b) IL-12-dependent DNA repair following nucleotide excision repair mechanism; (c) the inhibition of UV-induced immunosuppression through IL-12-dependent DNA repair; (d) the inhibition of angiogenic factors; and (e) the stimulation of cytotoxic T cells in a tumor microenvironment. New mechanistic information strongly supports and explains the chemopreventive activity of GTPs against photocarcinogenesis.

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Influence of green tea on enzymes of carbohydrate metabolism, antioxidant defense, and plasma membrane in rat tissues

Author: Sara Anees Khan and Shubha Priyamvada and Natarajan A. Arivarasu and Sheeba Khan and Ahad Noor Khan Yusufi

Objective Green tea, consumed worldwide since ancient times, is considered beneficial to human health. We hypothesized that green tea would enhance antioxidant defenses and specific metabolic activities of rat intestine, liver, and kidney to improve their functions. Methods The effect of green tea given to rats in the diet or drinking water for 25 d was determined on blood chemistry and on activities of enzymes of carbohydrate metabolism, brush border membrane, and antioxidant defense. Results Serum glucose, cholesterol, phosphate, and body weight decreased, whereas the activities of lactate and malate dehydrogenases and glucose-6- and fructose 1,6-bis-phosphatases increased in the intestine and kidney but slightly changed in the liver. Activity of glucose-6-phosphate dehydrogenase profoundly increased in the renal cortex but decreased in other tissues. Lipid peroxidation increased in the intestine and renal medulla and decreased in the renal cortex and liver; catalase increased in all tissues but the medulla. Superoxide dismutase activity decreased in the intestine but increased in renal tissues. Activities of brush border membrane enzymes in general increased in the intestine and kidney. Conclusion Green tea consumption resulted in enhanced enzyme activities of carbohydrate metabolism and antioxidant defenses, which may lead to improved health.

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Drying of aqueous green tea extracts using a supercritical fluid spray process

Author: D. Meterc and M. Petermann and E. Weidner

Natural extracts are widely used in groceries, in pharmaceutics and nutraceuticals. For foods these extracts are mainly used for flavoring or coloring the products. For pharmaceuticals and nutraceuticals active ingredients like antioxidants are of special interest. Traditionally these extracts are obtained by water or organic solvent extraction. Afterwards the liquid extracts are dried with classical spray drying techniques or freeze drying. In this work a new process for the gentle drying of natural extracts is presented. The process is based on a high-pressure spray technique called particles from gas saturated solutions (PGSS). The solution to be dried is dosed with a high-pressure pump to a static mixer, where compressed and preheated carbon dioxide is added. Afterwards this mixture is rapidly depressurized from high pressure via a nozzle into a spray tower, operated at ambient pressure—fine droplets are formed. By adjusting the pre-expansion conditions it is possible to evaporate the solvent in spray tower. The solvent can be withdrawn with the expanded carbon dioxide and finally a dry powder of the extract is obtained. Like the most supercritical fluid processes the drying is carried out at low temperature (30–60 °C) and in an inert, oxygen-free atmosphere. This makes the process very promising for sensitive substances. First investigations with this technique were made with green tea extracts, which contain antioxidants polyphenols. Dry and free flowing powders were obtained by the spray process without degradation of the active ingredients.

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Green tea extract as a natural antioxidant to extend the shelf-life of fresh-cut lettuce

Author: Ana B. Martín-Diana and Daniel Rico and Catherine Barry-Ryan

Green tea extract (GT) was evaluated as a preservative treatment for fresh-cut lettuce. Different quality markers, e.g. respiration, browning, ascorbic acid and carotenoid content were evaluated. GT concentration (0.25, 0.5 and 1 g 100 mL− 1) and temperature (20 °C and 50 °C) were tested. Optimal GT treatment (0.25 g 100 mL− 1 at 20 °C) was compared with chlorine (120 ppm at 20 °C). High GT concentrations (0.5 g 100 mL− 1 and 1.0 g 100 mL− 1) maintained better prevent ascorbic acid and carotenoid loss than 0.25 g 100 mL− 1 GT and chlorine. GT increased browning of samples, probably due to the content of polyphenols of the treatment; the use of heat-shock reduced this negative effect. GT and heat-shock combined also showed negative effects, reducing the antioxidant content (ascorbic acid and carotenoids). No significant differences were observed between chlorine and optimal GT (0.25 g 100 mL− 1 at 20 °C) in browning appearance and sensory properties. GT better kept the antioxidant activity of the samples than chlorine. Industrial relevance An alternative treatment for minimally processed Iceberg lettuce is tested, based on its antioxidant capacity. Minimally processed industry is constantly looking for new treatments to avoid the use of chlorine which is a standard at the moment.

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