heart-health

Author: Michael Xavier Doss and Shiva Prasad Potta and Jürgen Hescheler and Agapios Sachinidis

The prevention of cancer through dietary intervention is currently receiving considerable attention. Several epidemiological studies substantiate that green tea has a protective effect against a variety of malignant proliferative disorders such as lung cancer, breast cancer and prostate cancer. This preventive potential of green tea against cancer is attributed to the biologically active flavonoids called catechins. Epigallocatechin 3-o-gallate, the major catechin found in green tea, mediates diverse physiological and pharmacological actions in bringing about the regression of the tumors and also lowers the risk of nonmalignant cardiovascular proliferative diseases. Much of the current research is being focused on how these catechins specifically bring about the regression of the experimentally induced tumors both in vitro and in vivo. These catechins exert diverse physiological effects against proliferative diseases by several mechanisms, most of which are not completely characterized. This review summarizes the mechanisms by which these catechins play an essential role in regulating the process of carcinogenesis, with a special emphasis on how these catechins antagonize the growth factor-induced proliferative disorders.

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Author: Woochang Lee and Won-Ki Min and Sail Chun and Yong-Wha Lee and Hyosoon Park and Do Hoon Lee and You Kyoung Lee and Ji Eun Son

Objectives: Smoking is a risk factor for coronary artery disease and triggers vascular injury by platelet aggregation and induces atherosclerosis through induction of oxidative stress. Green tea is known to have antioxidant capacity and anti-platelet activity. Design and methods: Twenty adult male smokers ingested 600 mL of green tea for 4 weeks. Their lipid profile, C-reactive protein (CRP), total antioxidant capacity, oxidized LDL, soluble VCAM-1, soluble ICAM-1, and soluble P-selectin were measured at baseline and 2 and 4 weeks after green tea ingestion. Results: Plasma soluble P-selectin (sP-selectin) levels decreased significantly after 2 and 4 weeks of green tea ingestion compared with those before green tea ingestion (P < 0.001). Plasma concentrations of oxidized LDL decreased significantly after green tea ingestion (P < 0.05). Conclusions:The results of this study suggest the effect of green tea on sP-selectin and oxidized LDL.

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Author: Sibel Tas and Emre Sarandol and Sedef Ziyanok and Kemal Aslan and Melahat Dirican

In recent years, green tea has become a subject of interest because of its beneficial effects on human health. The purpose of this study was to determine the effects of green tea on serum paraoxonase/arylesterase activities and lipoprotein oxidizability in streptozotocin-induced diabetic rats (65 mg/kg [intraperitoneal]). Green tea was given in tap water (2%) for 3 and 6 weeks to control (CGT-3w and CGT-6w) and diabetic (DGT-3w and DGT-6w) rats, and they were compared with the control and diabetic groups (D-3w and D-6w), respectively. Serum insulin level was significantly increased in the DGT-6w group; serum lipid and plasma and tissue malondialdehyde levels were reduced in the DGT-3w and DGT-6w groups. Oxidizability of apolipoprotein B–containing lipoprotein fraction was found to be significantly reduced in the DGT-6w group. Serum total antioxidant capacity showed a significant increase in the CGT-6w and DGT-6w groups. Paraoxonase activity was significantly reduced in the D-3w and D-6w groups and increased in the DGT-6w group. We conclude that green tea might have antihyperlipidemic and antioxidative effects and may slow the progression of atherogenesis by reducing oxidation of lipoproteins and preserving paraoxonase activity.

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Author: Izabela Dobrzyńska and Barbara Szachowicz-Petelska and Justyna Ostrowska and Elżbieta Skrzydlewska and Zbigniew Figaszewski

It is known that aging is characterized by changes in cell metabolism resulting in modification of the structure and function of cell membrane components which is mainly the consequence of reactive oxygen species action. These disturbances are also enhanced by different xenobiotics, e.g. ethanol. Therefore, the aim of this paper is to examine green tea influence on total antioxidant status (TAS) and on composition and electric charge of erythrocyte membrane phospholipids in ethanol intoxicated rats of various ages. Antioxidant abilities of erythrocytes were estimated by measuring TAS. Qualitative and quantitative composition of phospholipids in the membrane was determined by HPLC, while the extent of erythrocytes lipid peroxidation was estimated by HPLC measurement of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels. Electrophoresis was used to determine the surface charge density of the rat erythrocyte membrane. It was shown that the process of aging was accompanied by a decrease in TAS and in the total amount of phospholipids as well as by enhancement of lipid peroxidation and increase in surface charge density of erythrocyte membrane. Ethanol administration caused, in term, decrease in TAS and increase in the level of all phospholipids and lipid peroxidation products. Ethanol as well significantly enhanced changes in surface charge density of erythrocyte membrane. The ingestion of green tea partially prevented decrease in erythrocyte antioxidant abilities observed during aging and ethanol intoxication. Moreover, long-term drinking of green tea protects the structure of the erythrocytes membrane disturbed during aging process and/or chronic ethanol intoxication.

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Author: Elżbieta Skrzydlewska and Agnieszka Augustyniak and Kamil Michalak and Ryszard Farbiszewski

Oxidative stress induced by chronic ethanol consumption, particularly in aging subjects, has been implicated in the pathophysiology of many neurodegenerative diseases. Antioxidants with polyphenol structures, such as those contained in green tea, given alone for 5 weeks in liquid Lieber de Carli diet followed by administration with ethanol for 4 weeks with ethanol have been investigated as potential therapeutic antioxidant agents in the brain in rats of three ages (2, 12, and 24 months). Ethanol consumption caused age-dependent decreases in brain superoxide dismutase, glutathione peroxidase, glutathione reductase, and catalase activities. In addition, ethanol consumption caused age-dependent decreases in the levels of GSH, selenium, vitamins, E, A and C, and β-carotene and increases in the levels of oxidized glutathione (GSSG). Changes in the brain's antioxidative ability were accompanied by enhanced oxidative modification of lipids (increases in lipid hydroperoxides, malondialdehyde, and 4-hydroxynonenal levels) and proteins (increases in carbonyl groups and bistyrosine). Reduced risk of oxidative stress and protection of the central nervous system, particularly in young and adult rats, after green tea supplementation were observed. Green tea partially prevented changes in antioxidant enzymatic as well as nonenzymatic parameters induced by ethanol and enhanced by aging. Administration of green tea significantly protects lipids and proteins against oxidative modifications in the brain tissue of young and adult rats. The beneficial effect of green tea can result from the inhibition of free radical chain reactions generated during ethanol-induced oxidative stress and/or from green tea-induced increases in antioxidative abilities made possible by increases in the activity/concentration of endogenous antioxidants.

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Author: Agnieszka Augustyniak and Ewa Waszkiewicz and Elżbieta Skrzydlewska

Objective The present study investigated the influence of green tea as a source of water-soluble antioxidants on the liver antioxidant potential of different aged rats chronically intoxicated with ethanol. Methods Rats (2, 12, and 24 mo old) were fed for 5 wk on a control or an ethanol Lieber-DeCarli diet with and without green tea (7 g/L). The activity and level of enzymatic and non-enzymatic antioxidants and the level of markers of protein and lipid oxidation in the liver of rats were examined. Results The activities of superoxide dismutase and catalase and levels of vitamins C, E, A, and β-carotene were significantly decreased, whereas activities of glutathione peroxidase and glutathione reductase and the level of reduced glutathione significantly increased during aging. The ethanol diet caused a significant decrease in activity of antioxidant enzymes and in the level of non-enzymatic antioxidants tested. Administration of green tea to ethanol-treated rats of different ages partly normalized the activity of enzymes and the level of non-enzymatic antioxidants. Changes in antioxidant ability observed during aging were accompanied by increased levels of markers of lipid and protein modifications that also were intensified by ethanol. Green tea caused a decrease in lipid and protein oxidation in aged and ethanol-treated rats. The protective effect of green tea was confirmed by the significantly lower activity of biomarkers of liver damage (alanine and aspartate aminotransferases) in the serum of rats that received green tea with ethanol compared with rats from the control ethanol group. Conclusions The use of green tea appears to be beneficial to rat liver by decreasing oxidative stress caused by ethanol and/or aging.

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Author: Daniela Erba and Patrizia Riso and Alessandra Bordoni and Paola Foti and Pier Luigi Biagi and Giulio Testolin

The antioxidant activity of green tea (GT) has been extensively studied; however, the results obtained from dietary intervention studies are controversial. In the present study we investigated the effect of the addition of two cups of GT (containing approximately 250 mg of total catechins) to a controlled diet in a group of healthy volunteers with respect to a group following the same controlled diet but not consuming GT. Antioxidant status and lipid profile in plasma, the resistance from oxidative damage to lipid and DNA, and the activity of glutathione peroxidase (GPX) in isolated lymphocytes were measured at the beginning and the end of the trial. After 42 days, consumption of GT caused a significant increase in plasma total antioxidant activity [from 1.79 to 1.98 μmol Trolox equivalent (TE)/ml, P<.001], significant decreases in plasma peroxides level (from 412 to 288 Carr U, P<.05) and induced DNA oxidative damage in lymphocytes (from 14.2% to 10.1% of DNA in tail, P<.05), a moderate although significant decrease in LDL cholesterol (from 119.9 to 106.6 mg/dL, P<.05) with respect to control. The present study suggests the ability of GT, consumed within a balanced controlled diet, to improve overall the antioxidative status and to protect against oxidative damage in humans.

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Author: Bauer E. Sumpio and Alfredo C. Cordova and David W. Berke-Schlessel and Feng Qin and Quan Hai Chen

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Author: Margriet Westerterp-Plantenga and Kristel Diepvens and Annemiek M.C.P. Joosen and Sonia Bérubé-Parent and Angelo Tremblay

Consumption of spiced foods or herbal drinks leads to greater thermogenesis and in some cases to greater satiety. In this regard, capsaicin, black pepper, ginger, mixed spices, green tea, black tea and caffeine are relevant examples. These functional ingredients have the potential to produce significant effects on metabolic targets such as satiety, thermogenesis, and fat oxidation. A significant clinical outcome sometimes may appear straightforwardly but also depends too strongly on full compliance of subjects. Nevertheless, thermogenic ingredients may be considered as functional agents that could help in preventing a positive energy balance and obesity.

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Author: Sreeparna Banerjee

The high polyunsaturated fatty acid content of oily fish such as mackerel (Scomber scombrus) makes it particularly susceptible to oxidative degradation. We have shown previously the presence of lipoxygenase (LOX), a lipid oxygenase, in mackerel muscle. In the current study, commercially available green tea polyphenols were shown to effectively inhibit the LOX activity of mackerel muscle. EGCG (epigallocatechin gallate) was the strongest inhibitor tested with an IC50 (concentration for half maximal inhibition) value of 0.13 nM. All the tea catechins showed a mixed non-competitive type inhibition. In addition, antioxidants such as BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene), esculetin, caffeic acid, ascorbic acid, and ethylene diamine tetraacetic acid (EDTA) were effective to varying degrees (IC50 values between 0.02 and >50 μM) in the inhibition of mackerel muscle LOX. Nordihydroguaiaretic acid (NDGA), a classical LOX inhibitor and potassium cyanide (KCN), a heme protein inhibitor were assayed for their inhibitory activities for comparison. Post harvest spoilage of fish account for loss of as much as 10% of the world’s catches of cultured fish. This data indicates that the green tea polyphenols, nature’s very potent antioxidants, may be used as an effective and natural means of reducing post harvest spoilage in fish.

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