Chinese green tea lowers cholesterol level through an increase in fecal lipid excretion

Effects of thermally processed oil on weight loss in rats

We have previously proposed that thermally processed oil holds promise as a dietary supplement intended for weight loss. We employed a thermal process whereby oil was heated to 180 degrees C for 10 h in the absence and presence of gluten. We compared the effects of three diets, untreated oil, heated oil, heated oil and gluten on body weight, retroperitoneal weight and lipid composition and fecal lipid contents. Ten week-old male Wistar rats were fed ad libitum a diet containing 7 wt% of the oil for 12 weeks. The oil heated with gluten showed low levels of food efficiency and oil absorption ratios, and high levels of fecal oil excretion, oil content and bile acid content. Diets containing thermally treated oils resulted in significantly lower retroperitoneal tissue weights and lipid contents as compared to the control group; the groups fed the heated oil and gluten diets showed a general decrease in the fatty acid (especially linoleic acid) amount. In conclusion, oil heated with gluten was not fully digested and thus excreted without showing any detrimental effects on either the organs or feces. This resulted in safe and effective weight loss in growing adult rats.

Hypocholesterolemic effect of stilbenes containing extract-fraction from Cajanus cajan L. on diet-induced hypercholesterolemia in mice

Cajanus cajan (L) is a natural plant which contains a lot of potential active components. In the present study, we identified the effects of the stilbenes containing extract-fraction from Cajanus cajan L (sECC) on diet-induced (for 4 weeks) hypercholesterolemia in Kunming mice. All experimental mice were divided into 5 groups: control group, model group, sECC-treated with 200 or 100 mg/kg/day, and simvastatin group. The effects of sECC were investigated by monitoring serum and liver lipid profile (cholesterol homeostasis and triglyceride) as well as serum superoxide dismutase activity in those mice. To further explore the mechanism of sECC, hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), cholesterol 7α-hydroxylase (CYP7A1), and low density lipoprotein receptor (LDL receptor) expressions in cholesterol homeostasis were analyzed by reverse transcription PCR. After 4 weeks pretreatment, compared with model group, the increased serum and hepatic total cholesterol were markedly attenuated by sECC (200 mg/kg) by 31.4% and 22.7% (p<0.01), respectively, the triglyceride levels of serum and liver were also lowered by 22.98% and 14.39%, respectively. At the same time, serum LDL cholesterol decreased by 52.8% (p<0.01) accompanied with the activities of serum superoxide dismutase increased by 20.98%. Atherogenic index and body weight were also reduced markedly. The mRNA expressions of HMG-CoA reductase, CYP7A1, and LDL-receptor were significantly enhanced in the mice administered with sECC (200 mg/kg/day), whereas those expressions were suppressed by the hypercholesterolemic diet. These data indicate that sECC reduces the atherogenic properties of dietary cholesterol in mice. Its hypocholesterolemic effect may involve enhancement of the hepatic LDL-receptor and cholesterol 7alpha-hydroxylase expression levels and bile acid synthesis.

Cholesterol-lowering nutraceuticals and functional foods

Epidemiological studies have demonstrated that elevated levels of plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) are the major risk factors for coronary heart disease (CHD), whereas high concentrations of plasma high-density lipoprotein cholesterol (HDL-C) and a low ratio of TC to HDL-C are protective against CHD. A relationship between plasma TC and the risk of CHD is well established at concentrations above 240 mg/dL. In addition to the use of three main classes of cholesterol-lowering medications, including HMG-CoA reductase inhibitors, anion-exchange resins, and fibrates, a nutritionally balanced diet that reduces saturated fat and cholesterol intake has traditionally been the first goal of dietary therapy in lowering plasma TC. In recent years, nutraceuticals and functional foods have attracted much interest as possible alternative therapies for lowering plasma TC, especially for hypercholesterolemia patients, whose blood cholesterol level is marginally high (200-240 mg/dL) but not high enough to warrant the prescription of cholesterol-lowering medications. This review summarizes the findings of recent studies on the production, application, efficacy, and mechanisms of popular cholesterol-lowering nutraceuticals and functional foods.

Total polyphenol content and antioxidant capacity of commercially available tea (Camellia sinensis) in Argentina

Tea, Camellia sinensis (L.) O. Kuntze (Theaceae) is cultivated in Argentina in the northeastern region (provinces of Misiones and Corrientes), between 26 degrees and 28 degrees south latitude, the southernmost area of the world where tea is cultivated. The objective of this work was to determine the total polyphenol content and the in vitro antioxidant capacity of green and black tea cultivated and industrialized in Argentina. Twelve samples of eight brands were analyzed. The total polyphenol content was determined according to the International Organization for Standardization method (ISO) 14502-1 for the determination of substances characteristic of green and black tea. The antioxidant capacity was determined by the ferric thiocyanate method (FTC) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical scavenging assay. Green tea showed a higher polyphenol content than black tea. The total polyphenol concentration in green tea was found to vary from 21.02 +/- 1.54 to 14.32 +/- 0.45% of gallic acid equivalents (GAE), whereas in black tea, the polyphenol content ranged from 17.62 +/- 0.42 to 8.42 +/- 0.55% of GAE (P < 0.05). A similar profile was observed for the antioxidant capacity determined by both methods. The antioxidant activities were well correlated with the total polyphenol content (r (2) = 0.9935 for the ferric thiocyanate method and r (2) = 0.9141 for the 1,1-diphenyl-2-picrylhydrazyl free-radical scavenging assay). This is the first systematic screening for the quantification of polyphenols and antioxidant activity in tea commercialized in Argentine markets. The results obtained herein allow one to conclude that Argentine tea is of very good quality when compared to teas from other sources.

Green tea catechin enhances cholesterol 7α-hydroxylase gene expression in HepG2 cells

Green tea catechins are known to have hypocholesterolaemic effects in animals and human subjects. In the present study, we investigated the effects of green tea catechins on the mRNA level and promoter activity of hepatic cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids, in human hepatoma cells. Real-time PCR assays showed that different catechins, ( − )-epicatechin gallate (ECG), ( − )-epigallocatechin-3-gallate (EGCG), ( − )-epigallocatechin (EGC) and ( − )-epicatechin (EC), up regulated the CYP7A1 mRNA level by 5·5-, 4·2-, 2·9- and 1·9-fold, respectively, compared with the control. The − 1312/+358 bp of the CYP7A1 promoter was subcloned into the pGL3 basic vector that includes luciferase as a reporter gene. ECG or EGCG significantly increased CYP7A1 promoter activity by 6·0- or 4·0-fold, respectively, compared with the control. Also, EGCG stimulated CYP7A1 at both mRNA level and promoter activity in a dose-dependent manner. These results suggest that the expression of the CYP7A1 gene may be directly regulated by green tea catechins at the transcriptional level.

Evaluation of toxicity of green tea catechins with 90-day dietary administration to F344 rats

Green tea catechins (GTC), polyphenols extracted from the stalks and leaves of Camellia sinensis, are found in the different types of tea beverages and as antioxidant additives to many foods, snacks, fats and fatty oils. As a part of their safety assessment, subchronic toxicity was investigated in male and female F344 rats with dietary administration at concentrations of 0 (control), 0.3%, 1.25% and 5.0% for 90 days. The average daily intakes of GTC in each group were 180, 764 and 3525mg/kg body weight/day, respectively for males, and 189, 820 and 3542mg/kg body weight/day, respectively for females. No mortality or obvious clinical signs were observed throughout the experimental period but body weights were reduced from week 1 to the end of the experiment in 5.0% males. In serum biochemistry, alanine transaminase and alkaline phosphatase in 5.0% males and females and aspartate transaminase in 5.0% females were increased, together with the relative liver weights in both sexes receiving 5.0%. Although decreases were evident for total cholesterol in 0.3-5.0% males and triglycerides in 1.25% and 5.0% males and 5.0% females, these changes were not considered to be adverse. Hematology and histopathological observation revealed no GTC-related toxicological changes. Based on above findings, the no observed adverse effect level (NOAEL) of GTC was estimated to be 1.25% (764mg/kg body weight/day for males and 820mg/kg body weight/day for females).

Dose-dependent hypocholesterolemic actions of dietary apple polyphenol in rats fed cholesterol

The dose-dependent hypocholesterolemic and antiatherogenic effects of dietary apple polyphenol (AP) from unripe apple, which contains approximately 85% catechin oligomers (procyanidins), were examined in male Sprague-Dawley rats (4 wk of age) given a purified diet containing 0.5% cholesterol. Dietary AP at 0.5 and 1.0% levels significantly decreased the liver cholesterol level compared with that in the control (AP-free diet-fed) group. Dietary AP also significantly lowered the serum cholesterol level compared with that in the control group. However, the HDL cholesterol level was significantly higher in the 1.0% AP-fed group than in the control group. Accordingly, the ratio of HDL-cholesterol/total cholesterol was significantly higher in the 0.5% AP-fed group and 1.0% AP-fed group than in the control group. Moreover, the atherogenic indices in the 0.5 and 1.0% AP-fed groups were significantly lower than those in the control group. The activity of hepatic cholesterol 7alpha-hydroxylase tended to be increased by dietary AP in a dose-dependent manner. In accord with this observation, dietary AP increased the excretion of acidic steroids in feces. Dietary AP also significantly promoted the fecal excretion of neutral steroids in a dose-dependent manner. These observations suggest that dietary AP at a 0.5 or 1.0% level exerts hypocholesterolemic and antiatherogenic effects through the promotion of cholesterol catabolism and inhibition of intestinal absorption of cholesterol.

A green tea extract lowers plasma cholesterol by inhibiting cholesterol synthesis and upregulating the LDL receptor in the cholesterol-fed rabbit

Green tea extracts enriched in catechins decrease plasma cholesterol in hamsters, mice and rats. The aims of this study were to determine whether a catechin-enriched extract of green tea could lower plasma cholesterol in the cholesterol-fed rabbit and to determine the mechanism of action. Four groups of six New Zealand White rabbits were initially made hypercholesterolaemic by feeding a 0.25% (w/w) cholesterol diet for 2 weeks before the diet was supplemented with a catechin extract from green tea at 0, 0.5, 1 or 2% (w/w) for 4 weeks. Administration of the crude catechin extract from green tea significantly (p<0.05) lowered cholesterol in plasma (-60%), VLDL+IDL (-70%), LDL (-80%), liver (total by -25% and unesterified by -15%) and aorta (-25%) compared to control. There was a significant reduction in the cholesterol synthesis index (-60%) and a significant increase in hepatic LDL receptor activity (+80%) and protein (+70%) but there was no change in the intrinsic capacity to absorb cholesterol from the intestines. These results suggest that green tea catechins lowered plasma, liver and aortic cholesterol in the cholesterol-fed rabbit by lowering cholesterol synthesis and upregulating the hepatic LDL receptor.

A green tea catechin extract upregulates the hepatic low-density lipoprotein receptor in rats

Green tea extracts have hypocholesterolaemic properties in epidemiological and animal intervention studies. Upregulation of the low-density lipoprotein (LDL) receptor may be one mechanism to explain this as it is the main way cholesterol is removed from the circulation. This study aimed to determine if a green tea extract could upregulate the hepatic LDL receptor in vivo in the rat. A green tea extract (GTE) enriched in its anti-oxidant constituents, the catechins, was fed to rats (n = 6) at concentrations of either 0, 0.5, 1.0 or 2.0% (w/w) mixed in with their normal chow along with 0.25% (w/w) cholesterol for 12 days. Administration of the GTE had no effect on plasma total or LDL cholesterol concentrations but high-density lipoprotein significantly increased (41%; p < 0.05). Interestingly, there was a significant increase in LDL receptor binding activity (2.7-fold) and LDL receptor protein (3.4-fold) in the 2% (w/w) treatment group compared to controls. There were also significant reductions in liver total and unesterified cholesterol (40%). Administration of the GTE significantly reduced cholesterol absorption (24%) but did not affect cholesterol synthesis. These results show that, despite no effect on plasma cholesterol, the GTE upregulated the LDL receptor in vivo. This appears to be via a reduction in liver cholesterol concentration and suggests that the green tea extract was able to increase the efflux of cholesterol from liver cells.

Using nutrition for intervention and prevention against environmental chemical toxicity and associated diseases

BACKGROUND

Nutrition and lifestyle are well-defined modulators of chronic diseases. Poor dietary habits (such as high intake of processed foods rich in fat and low intake of fruits and vegetables), as well as a sedentary lifestyle clearly contribute to today's compromised quality of life in the United States. It is becoming increasingly clear that nutrition can modulate the toxicity of environmental pollutants.

OBJECTIVES

Our goal in this commentary is to discuss the recommendation that nutrition should be considered a necessary variable in the study of human disease associated with exposure to environmental pollutants.

DISCUSSION

Certain diets can contribute to compromised health by being a source of exposure to environmental toxic pollutants. Many of these pollutants are fat soluble, and thus fatty foods often contain higher levels of persistent organics than does vegetable matter. Nutrition can dictate the lipid milieu, oxidative stress, and antioxidant status within cells. The modulation of these parameters by an individual's nutritional status may have profound affects on biological processes, and in turn influence the effects of environmental pollutants to cause disease or dysfunction. For example, potential adverse health effects associated with exposure to polychlorinated biphenyls may increase as a result of ingestion of certain dietary fats, whereas ingestion of fruits and vegetables, rich in antioxidant and anti-inflammatory nutrients or bioactive compounds, may provide protection.

CONCLUSIONS

We recommend that future directions in environmental health research explore this nutritional paradigm that incorporates a consideration of the relationships between nutrition and lifestyle, exposure to environmental toxicants, and disease. Nutritional interventions may provide the most sensible means to develop primary prevention strategies of diseases associated with many environmental toxic insults.

Absorption of dietary cholesterol oxidation products and their downstream metabolic effects are reduced by dietary apple polyphenols

Exogenous and endogenous cholesterol oxidation products (COPs) perturb various metabolic processes, and thereby they may induce various homeostasis-related disorders. Here, we observed that procyanidin-rich dietary apple polyphenol (APP) from unripe apples alleviates the perturbation of lipid metabolism by decreasing the exogenous COP levels in rats. Dietary COPs may be the greatest source of COPs found in the human body. Rats (4 weeks of age) were fed AIN-purified diets containing 0.3% COPs supplemented with 0.5 or 2.5% APP for 3 weeks. Dietary APP alleviated the growth inhibition action of the exogenous COPs. The modulations of the liver lipid profile by COPs remained unchanged. However, serum total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels increased following the intake of dietary APP. Further, dietary APP inhibited the increase in lipid peroxide levels in the liver and serum by COPs. The activity of hepatic Delta6 desaturase was lowered by dietary APP in a dose-dependent manner, although exogenous COPs generally increased the activity of this enzyme. In keeping with this observation, Delta6 desaturation indices in the phospholipids and cholesteryl esters of the liver and serum lipids were lower in the APP-fed groups than those in the control group. Dietary APP also promoted the excretion of exogenous COPs, cholesterol, and acidic steroids in feces. Therefore, the inhibition of intestinal absorption of COPs may partly contribute to the alleviation of the perturbation of lipid metabolism and lipid peroxidation levels. Thus, APP may be an important removal agent of exogenous toxic material such as COPs contained in processed or fast foods.

Red grape juice polyphenols alter cholesterol homeostasis and increase LDL-receptor activity in human cells in vitro

Red grape juice (RGJ) polyphenols have been shown to reduce circulating levels of LDL cholesterol and to increase LDL receptor activity. To explore the effect of RGJ-derived polyphenols on intracellular cholesterol homeostasis, human hepatocarcinoma HepG2 and promyelocytic HL-60 cell lines were incubated in serum-free medium, with or without LDL, in the presence or absence of RGJ. In the presence of LDL, RGJ increased both the activity and cell surface expression of the LDL receptor, and increased the cell total cholesterol content. In cells exposed to LDL, RGJ also increased levels of the active form of sterol regulatory element-binding protein-1 and mRNA expression of the LDL receptor and hydroxymethylglutaryl-CoA reductase. In contrast, RGJ caused a marked reduction in the expression of CYP7A1, apolipoprotein B, ABCA1, and ABCG5. Experiments using the acyl-CoA cholesterol acyltransferase inhibitor S-58035 indicated that no measurable free cholesterol from endocytosed LDL reaches the endoplasmic reticulum in cells treated with RGJ. Finally, fluorescence microscopy revealed that in RGJ-treated cells, DiI-labeled LDL did not colocalize with CD63, a protein localized at steady state in the internal vesicles of late endosomes. These results indicate that RGJ polyphenols disrupt or delay LDL trafficking through the endocytic pathway, thus preventing LDL cholesterol from exerting regulatory effects on intracellular lipid homeostasis.

Polyphenol-enriched oolong tea increases fecal lipid excretion

OBJECTIVE

To assess possibility of polyphenol-enriched oolong tea to reduce dietary lipid absorption in humans.

DESIGN

Twelve healthy adult subjects, three males and nine females, aged (mean+/-s.d.) 22.0+/-1.8 years, respectively, were randomly divided into two groups. The participants were followed a double-blind placebo-controlled crossover design, including 7-day washout periods and 10-day treatment periods. During the treatment periods, subjects were given about 38 g of lipids from potato chips (19 g each within 30 min after lunch and dinner) and total 750 ml beverages (placebo- or polyphenol-enriched oolong tea) at three meals. Blood samples were collected for biochemical examination at days 8, 18, 25 and 35 of the study period. On the last 3 days of each treatment period, feces were collected to measure the excretion of lipids.

RESULTS

Lipid excretion into feces was significantly higher in the polyphenol-enriched oolong tea period (19.3+/-12.9 g/3 day) than in the placebo period (9.4+/-7.3 g/3 day) (P < 0.01). Cholesterol excretion tended to increase in polyphenol-enriched oolong tea period (1.8+/-1.2 g/3 day) compared with that of placebo (1.2+/-0.6 g/3 day) (P = 0.056).

CONCLUSIONS

The results of this study indicated that polyphenol-enriched oolong tea could increase lipid excretion into feces when subjects took high-lipid diet.

Puerarin decreases serum total cholesterol and enhances thoracic aorta endothelial nitric oxide synthase expression in diet-induced hypercholesterolemic rats

Hypercholesterolemia is a dominant risk factor for the development and progression of atherosclerosis and cardiovascular diseases. Natural compounds have been proved to be useful in lowering serum cholesterol to slow down the progression of cardiovascular diseases. Pueraria lobata is employed clinically to treat cardiovascular diseases in China. In the present study, the atheroscleroprotective potential of the herb's major active compound, puerarin, was investigated by monitoring serum lipid profile and major enzyme expressions on cholesterol homeostasis in Sprague-Dawley rats fed with control diet, hypercholesterolmic diet or hypercholesterolmic diet plus administration of puerarin (300 mg/kg/day, p.o.) for 4 weeks. Puerarin markedly attenuated the increased total cholesterol induced by hypercholesterolmic diet in both serum and liver. It caused a significant reduction in the atherogenic index. Expression of mRNA for hepatic 7alpha-hydroxylase (CYP7A1) was significantly enhanced but not for those of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and lanosterol 14alpha-demethylase (CYP51). To further explore the atheroscleroprotective potential of puerarin, acetylcholine induced endothelium-dependent vasorelaxation and endothelial nitric oxide synthase (eNOS) expression on isolated thoracic aortas were analyzed. Animals administered with puerarin suppressed the hypercholesterolemic diet induced impairment of eNOS expression, whereas there was no significant difference in the endothelium-dependent vasorelaxation among various groups of animals. These data indicated that puerarin reduced the atherogenic properties of dietary cholesterol in rats. Its hypocholesterolemic function may be due to the promotion of cholesterol and bile acids excretion in liver. Whether puerarin targets directly on cholesterol homeostasis or both cholesterol homeostasis and endothelial function remains to be determined.

Tea, obesity, and diabetes

Tea has been found to possess widespread biological functions based on a variety of laboratory data. The effects of tea on obesity and diabetes have received increasing attention. This paper reviews the evidence for the connections among tea catechins, and obesity and diabetes. Tea catechins, especially (-)-epigallocatechin gallate (EGCG), appear to have antiobesity and antidiabetic effects. While few epidemiological and clinical studies show the health benefits of EGCG on obesity and diabetes, the mechanisms of its actions are emerging based on the various laboratory data. These mechanisms may be related to certain pathways, such as through the modulations of energy balance, endocrine systems, food intake, lipid and carbohydrate metabolism, the redox status, and activities of different types of cells (i. e., fat, liver, muscle, and beta-pancreatic cells). Because the EGCG receptor, the so-called 67-kDa laminin receptor (LR), has been discovered with colocalization of other types of LR and cytoskeleton in both cancer cells and normal cells, this may explain that EGCG possesses numerous actions. The mechanistic results of this review may possibly be utilized in the treatment of obesity, diabetes, and other related diseases using tea- and EGCG-based folk medicines.

Green tea and its polyphenolic catechins: medicinal uses in cancer and noncancer applications

Can drinking several cups of green tea a day keep the doctor away? This certainly seems so, given the popularity of this practice in East Asian culture and the increased interest in green tea in the Western world. Several epidemiological studies have shown beneficial effects of green tea in cancer, cardiovascular, and neurological diseases. The health benefits associated with green tea consumption have also been corroborated in animal studies of cancer chemoprevention, hypercholesterolemia, artherosclerosis, Parkinson's disease, Alzheimer's disease, and other aging-related disorders. However, the use of green tea as a cancer chemopreventive or for other health benefits has been confounded by the low oral bioavailability of its active polyphenolic catechins, particularly epigallocatechin-3-gallate (EGCG), the most active catechin. This review summarizes the purported beneficial effects of green tea and EGCG in various animal models of human diseases. Dose-related differences in the effects of EGCG in cancer versus neurodegenerative and cardiovascular diseases, as well as discrepancies between doses used in in vitro studies and achievable plasma understanding of the in vivo effects of green tea catechins in humans, before the use of green tea is widely adopted as health-promoting measure.

Camellia sinensis: historical perspectives and future prospects

As the source of brewed tea preparations, Camellia sinensis has operated for centuries at the interface of agriculture, politics, and biology. The purpose of this review is to present an inter-disciplinary survey of issues surrounding cultivation, processing, and consumption of the tea plant. Particular attention is given to the biologic effects of tea: first, assessing at the level of human physiology its value as a chemopreventive and chemotherapeutic agent; second, examining effects of production upon local ecosystems, due to resource demands and industrial farming practices. In sum, C. sinensis emerges as a potentially powerful contributor to both public health and economic growth if its role is managed from a prospective, sustainable, and evidence-based vantage.

Medicinal benefits of green tea: Part I. Review of noncancer health benefits

Tea, in the form of green or black tea, is one of the most widely consumed beverages in the world. Extracts of tea leaves also are sold as dietary supplements. However, with the increasing interest in the health properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and noncancer health benefits of both green and black tea. In Part II, a review of anticancer properties of green tea extracts is presented. Green tea contains a unique set of catechins that possess biological activity in antioxidant, anti-angiogenesis, and antiproliferative assays potentially relevant to the prevention and treatment of various forms of cancer. Although there has been much focus on the biological properties of the major tea catechin epigallocatechin gallate (EGCg) and its antitumor properties, tea offers other health benefits; some due to the presence of other important constituents. Characteristics unrelated to the antioxidant properties of green and black teas may be responsible for tea's anticancer activity and improvement in cardiac health and atherosclerosis. Theanine in green tea may play a role in reducing stress. Oxidized catechins (theaflavins in black tea) may reduce cholesterol levels in blood. Synergistic properties of green tea extracts with other sources of polyphenolic constituents are increasingly recognized as being potentially important to the medicinal benefits of black and green teas. Furthermore, due to presumed antioxidant and antiaging properties, tea is now finding its way into topical preparations. Each of these aspects is surveyed.

Effect of red wine on oxidative stress and hypercholesterolemia induced by feeding a high-cholesterol diet in rat

The effect of red wine on oxidative stress and hypercholesterolemia induced by feeding a high-cholesterol diet (supplemented with 1.65% of cholesterol (w/w) for 4 weeks) to female Wistar rats was examined. When red wine was simultaneously supplemented to high-cholesterol diet, total cholesterol, triglycerides, atherogenic index and lipid peroxidation products significantly decreased compared with the high-cholesterol diet alone, while GSH content and antioxidative enzymes activities were enhanced. In the hypercholesterolemic rat the excretion of fecal bile acids, as well as their plasma and hepatic concentrations were increased significantly. Administration of red wine enhanced these values, indicating an increase in the cholesterol degradation. These results suggest that red wine may have a protective effect against oxidative stress, hypercholesterolemia and atherogenic index induced by high-cholesterol diet.

All teas are not created equal: the Chinese green tea and cardiovascular health

Tea is one of the most widely consumed beverages in the world, next only to water. It can be categorized into three types, depending on the level of fermentation, i.e., green (unfermented), oolong (partially fermented) and black (fermented) tea. In general, green tea has been found to be superior to black tea in terms of antioxidant activity owing to the higher content of (-)-epigallocatechin gallate. The processes used in the manufacture of black tea are known to decrease levels of the monometric catechins to a much greater extent than the less severe conditions applied to other teas. The cardioprotective effect of flavonoids from green tea can be attributed to not only antioxidant, antithrombogenic and anti-inflammatory properties but also improvement of coronary flow velocity reserve. In this article, I will discuss the effects of green tea on atherosclerosis, coronary heart disease, hypertension, diabetes, metabolic syndrome and obesity, and, finally, its comparison with black tea.

Tea catechins with a galloyl moiety suppress postprandial hypertriacylglycerolemia by delaying lymphatic transport of dietary fat in rats

Tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), have been shown to be epimerized to (-)-catechin (C), (-)-gallocatechin (GC), (-)-catechin gallate (CG), and (-)-gallocatechin gallate (GCG), respectively, during heat treatment. In this study, we examined the effect of tea catechins rich in ECG and EGCG and heat-treated tea catechins rich in CG and GCG on postprandial hypertriacylglycerolemia in rats. Both tea catechins and heat-treated tea catechins suppressed postprandial hypertriacylglycerolemia. Lymphatic recovery of (14)C-trioleoylglycerol in rats cannulated in the thoracic duct was delayed by the administration of tea catechins and heat-treated tea catechins. Tea catechins and heat-treated tea catechins had the same effect on all variables tested. These catechin preparations dose-dependently inhibited the activity of pancreatic lipase in vitro. When purified catechins were used, only those with a galloyl moiety inhibited the activity of pancreatic lipase. These results suggest that catechins with a galloyl moiety suppress postprandial hypertriacylglycerolemia by slowing down triacylglycerol absorption through the inhibition of pancreatic lipase. Because postprandial hypertriacylglycerolemia is a risk factor for coronary heart disease, our results suggest that catechins with a galloyl moiety may prevent this disease.

Suppressive effects of cacao liquor polyphenols (CLP) on LDL oxidation and the development of atherosclerosis in Kurosawa and Kusanagi-hypercholesterolemic rabbits

We investigated the properties of cacao liquor polyphenols (CLP), which have an antioxidative effect on low-density lipoprotein (LDL) and an anti-atherosclerotic effect in the spontaneous familial hypercholesterolemic model, the Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbit. After 6 months of dietary administration of CLP at 1% (w/w) to the KHC rabbits, a higher total cholesterol concentration was observed in the treatment group compared to the control group. However, no other effects were noted in lipid profiles in plasma or lipoproteins. The plasma concentration of thiobarbituric acid reactive substances (TBARS), which is a lipid-peroxidation index, was significantly decreased 1 month after the start of CLP administration compared to that of the control group. The antioxidative effect of CLP on LDL was observed from 2 to 4 months of administration. The area of atherosclerotic lesions in the aorta in the CLP group (32.01+/-1.58%) was significantly smaller than that in the control group (47.05+/-3.29%), and the tissue cholesterol and TBARS concentrations were lower in the CLP group than in the control group. The anti-atherosclerotic effect of CLP was confirmed both rheologically and histopathologically. An in vitro study using KHC rabbit-derived LDL revealed that CLP significantly prolonged the lag time of LDL oxidation that was induced by a lipophilic azo-radical initiator, 2,2'-azobis(4-methoxy)-2,4-dimethylvaleronitrile (V-70), or Cu(2+) from a low concentration of 0.1 microg/mL. The antioxidative effect of CLP was superior to those of the well-known antioxidative substances, vitamin C, vitamin E and probucol. Therefore, CLP suppressed the generation of atherosclerosis, and its antioxidative effect appeared to have an important role in its anti-atherosclerotic activity.

In Vitro and in Vivo Antimicrobial Action of Tea: The Commonest Beverage of Asia

The methanolic extract of leaves of Camellia sinensis (L) O. KUNTZE was screened for antimicrobial property against 111 bacteria comprising 2 genera of Gram positive and 7 genera of Gram negative bacteria. Most of these strains were inhibited by the compound at 10-50 microg/ml level and few strains were sensitive even at lower concentrations (5 microg/ml). The bacteria could be arranged in the decreasing order of sensitivity towards the compound in the following manner: Staphylococcus aureus, Vibrio cholerae, Escherichia coli, Shigella spp., Salmonella spp., Bacillus spp., Klebsiella spp. and Pseudomonas aeruginosa. The antibacterial activity of compound could also be confirmed in vivo. When it was given to Swiss strain of white mice at different dosages (30, 60 microg/mouse), it could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to Chi square test the in vivo data were highly significant (p<0.001).

Flavonoids for reduction of atherosclerotic risk

Flavonoids are polyphenolic compounds found in fruits, vegetables, and beverages derived from plants. Foods thought historically by many societies to have healing properties--cocoa, red wine, and tea--are particularly rich in flavonoids. A majority of prospective cohort studies demonstrate a significant inverse association between flavonoid consumption and cardiovascular risk. Short-term studies demonstrate numerous plausible mechanisms by which flavonoids may confer cardiovascular protection: they inhibit low-density lipoprotein oxidation, reduce thrombosis, improve endothelial function, and reduce inflammation. No long-term, randomized, controlled trials of flavonoids with hard clinical endpoints have been conducted. Although there are no recommended daily intake goals for flavonoids, the data presented provide additional rationale to eat a diet containing a variety of flavonoid-rich foods and beverages.

Direct inhibition of the ubiquitin–proteasome pathway by ester bond-containing green tea polyphenols is associated with increased expression of sterol regulatory element-binding protein 2 and LDL receptor

Green tea has been shown to lower plasma cholesterol, associated with up-regulation of the low-density lipoprotein receptor (LDLR) although the responsible molecular mechanism is unknown. Previously, we reported that ester bond-containing green tea polyphenols (GTPs), such as (-)-epigallocatechin-3-gallate [(-)-EGCG], potently inhibit the tumor cellular proteasome activity, which may contribute to the cancer-preventative effect of green tea. In the current study, we hypothesize that the proteasome is a heart disease-associated molecular target of GTPs. We have shown that ester bond-containing GTPs, including (-)-EGCG, potently inhibit the proteasomal activity in intact hepatocellular carcinoma HepG2 and cervical carcinoma HeLa cells, as evident by accumulation of ubiquitinated proteins and three natural proteasome targets (p27, IkappaB-alpha and Bax). (-)-EGCG selectively inhibits the chymotrypsin-like, but not trypsin-like, activity of the proteasome. Associated with proteasome inhibition by ester bond-containing GTPs, there was a significant, time- and concentration-dependent increase in levels of the cleaved, activated, but not the precursor, form of sterol regulatory element-binding protein 2 (SREBP-2), an essential factor for LDLR transcription. Subsequently, LDL receptor expression was increased dramatically in HepG2 and HeLa cells treated with (-)-EGCG. Our results suggest that ester bond-containing GTPs inhibit ubiquitin/proteasome-mediated degradation of the active SREBP-2, resulting in up-regulation of LDLR. This identified molecular mechanism may be related to the previously reported cholesterol-lowering and heart disease-preventative effects of green tea.

Anti-Trypanosoma cruzi activity of green tea (Camellia sinensis) catechins

The trypanocidal action of green tea catechins against two different developmental stages of Trypanosoma cruzi is reported for the first time. This activity was assayed with the nonproliferative bloodstream trypomastigote and with the intracellular replicative amastigote parasite forms. An ethyl acetate fraction from Camellia sinensis green tea leaves, which contains most of the polyphenolic compounds and the maximal trypanocidal activity, was obtained by fractionation of the aqueous extract with organic solvents. The active compounds present in this extract were further purified by LH-20 column chromatography and were identified by high-performance liquid chromatography analysis with a photo diode array detector and gas chromatography coupled to mass spectroscopy. The following flavan-3-ols derivatives, known as catechins, were identified: catechin, epicatechin, gallocatechin, epigallocatechin, catechin gallate, epicatechin gallate, gallocatechin gallate, and epigallocatechin gallate. The purified compounds lysed more than 50% of the parasites present in the blood of infected BALB/c mice at concentrations as low as 0.12 to 85 pM. The most active compounds were gallocatechin gallate and epigallocatechin gallate, with minimal bactericidal concentrations that inhibited 50% of isolates tested of 0.12 and 0.53 pM, respectively. The number of amastigotes in infected Vero cells decreased by 50% in the presence of each of these compounds at 100 nM. The effects of the catechins on the recombinant T. cruzi arginine kinase, a key enzyme in the energy metabolism of the parasite, were assayed. The activity of this enzyme was inhibited by about 50% by nanomolar concentrations of catechin gallate or gallocatechin gallate, whereas the other members of the group were less effective. On the basis of these results, we suggest that these compounds could be used to sterilize blood and, eventually, as therapeutic agents for Chagas' disease.

Effect of EGCG on lipid absorption and plasma lipid levels in rats

Catechins, compounds derived from green tea, have been shown to reduce plasma cholesterol levels and the rate of cholesterol absorption. We investigated the dose response and the mechanism of action of epigallocatechin gallate (EGCG) on these parameters in rats. Wistar rats were fed a diet high in cholesterol and fat containing either none, 0.25% (0.2 g/day/kg BW), 0.5% (0.4 g/day/kg/BW) or 1.0% (0.7 g/day/kg BW) of EGCG. After 4 weeks of treatment, total cholesterol and low density lipoprotein plasma levels were significantly reduced in the group fed 1% EGCG when compared to the no treatment group. Plasma triglycerides and high-density lipoprotein levels did not change significantly. Following a single oral application of a liquid test-meal, intestinal cholesterol absorption in Wistar rats was 79.3% in the control group. In the group treated with 0.1 g/kg BW EGCG intestinal cholesterol absorption decreased to 73.7% and in the group treated with 0.5 g/kg BW of EGCG intestinal cholesterol absorption fell significantly to 62.7% (P = 0.005). Total fat absorption was very efficient in the control group (99.5% of the applied dose) and decreased significantly but moderately in the group treated with the highest doses of EGCG (0.75, 1 g/kg BW). In an in-vitro biliary micelle model, the addition of 55 microM to 1300 microM EGCG not only decreased cholesterol solubility dose-dependently in these micelles but also altered the size of the mixed lecithin/taurocholate/cholesterol micelles as demonstrated by light scattering. This study provides evidence suggesting that the cholesterol-lowering effect of green tea is mainly elicited by EGCG, one of the most abundant catechins contained in green tea. It is suggested that one of the underlying mechanisms by which EGCG affects lipid metabolism is by interfering with the micellar solubilization of cholesterol in the digestive tract, which then in turn decreased cholesterol absorption.

Lack of inhibitory effects of green tea catechins in 1,2-dimetylhydrazine-induced rat intestinal carcinogenesis model: comparison of the different formulations, administration routes and doses

Differences in the modifying effects of green tea catechins (GTC) on intestinal carcinogenesis by different formulations, doses and administration routes were investigated in male rats pretreated with 1,2-dimethylhydrazine (DMH). One hundred and eighty nine F344 male rats received subcutaneous injections of DMH at 40 mg/kg body weight twice a week for 3 weeks. Three days after completion of the carcinogen treatment, they were divided into nine groups. Each was administered a different source of 0.1% or 0.01% of GTC (Mitsui Norin Co. (M) or Taiyo Kagaku Co. (T)) either in the diet (D) or the drinking water (W), or basal diet and tap water alone without GTC for 33 weeks and then killed for autopsy. The survival rate tended to be lower with 0.01% MGTC (W) group than in the other groups. In the large intestine, although the multiplicity and/or incidences of adenomas showed tendencies for dose-dependent decrease in all GTC groups, and the average volumes of tumors tended to be decrease dose-dependently in the MGTC (W) and TGTC (W) groups, the multiplicity of carcinomas did not show such a trend, rather being significantly increased in the 0.01% MGTC (D) and 0.1% TGTC (W) groups. In the small intestine, the incidence and the multiplicity of tumors in all GTC treated groups had a tendency to decrease. On the other hand, the volume of tumors was increased with statistical significance in the 0.01% MGTC (W) and 0.1% TGTC (W) groups. Thus it can be concluded that GTC does not exert chemopreventive effects on intestinal carcinogenesis irrespective of its formulation, dose or route of administration.

Salacia reticulata and its polyphenolic constituents with lipase inhibitory and lipolytic activities have mild antiobesity effects in rats

Salacia (S.) reticulata, a Hippocrateaceae plant distributed in Sri Lankan and Indian forests, has been used as a supplementary food in Japan to prevent obesity and diabetes. We examined the antiobesity effects of the hot water-soluble extract (SRHW) from the roots of S. reticulata using obese rat models and an in vitro study. Body weight (P = 0.07) and periuterine fat storage (P = 0.10) in female Zucker fatty rats (8-9 wk old) tended to be suppressed by oral administration of SRHW (125 mg/kg) for 27 d. Male rats fed a high fat diet were not affected by SRHW. Furthermore, SRHW inhibited porcine pancreatic lipase (PL), rat adipose tissue-derived lipoprotein lipase (LPL) and glycerophosphate dehydrogenase (GPDH) activities with 50% inhibitory concentrations (IC(50)) of 264 (95% confidence limits: 203-393) mg/L, 15 (12-18) mg/L and 54 (35-85) mg/L, respectively, but did not inhibit hormone-sensitive lipase activity in rat adipose tissue. Next, we examined the effects of polyphenols, di- and triterpenes and salacinol isolated from the roots of S. reticulata on lipid metabolizing enzymes and lipolysis. (-)-Epigallocatechin and (-)-epicatechin-(4beta-->8)-(-)-4'-O-methylepigallocatechin inhibited PL activity with IC(50) of 88 (not calculated) and 68 (26-122) mg/L, respectively. (-)-Epicatechin, 3beta, 22beta-dihydroxyolean-12-en-29-oic acid and the tannin fraction inhibited LPL activity with IC(50) of 81 (54-214), 89 (62-214) and 35 (24-62) mg/L. Only the tannin fraction inhibited GPDH activity with an IC(50) of 6.8 (3.4-10.9) mg/L. These constituents may be involved in the lipase and GPDH inhibitory activities of SRHW. On the other hand, SRHW at 100 mg/L tended to enhance lipolysis in rat adipocytes (P = 0.06). Significant lipolytic effects were exerted by mangiferin, (-)-4'-O-methylepigallocatechin and maytenfolic acid at 100 mg/L (P < 0.01). In conclusion, polyphenolic compounds may be involved in the antiobesity effects of SRHW in rats through inhibition of fat metabolizing enzymes (PL, LPL and GPDH) and enhanced lipolysis.

Green tea catechins enhance tumor development in the colon without effects in the lung or thyroid after pretreatment with 1,2-Dimethylhydrazine or 2,2′-dihydroxy-di-n-propylnitrosamine in male F344 rats

Modifying effects of green tea catechins (GTCs) on the post-initiation stage of colon, lung and thyroid carcinogenesis were examined in F344 male rats. Groups of 20 animals were given subcutaneous injections of 40 mg/kg body wt of 1,2-dimethylhydrazine twice a week for 2 weeks or oral administration of 0.1% 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN) in the drinking water for 2 weeks for initiation. They then received diet containing 1 or 0.1% green tea catechin or basal diet alone for 33 weeks. Histopathological examination after final sacrifice showed that although total incidence and multiplicity of colon tumors were not significantly different from controls, values for colon adenomas were decreased while those for carcinomas and the average size of tumors were significantly increased in the 0.1% GTC group. A similar tendency was observed for the 1% GTC group. Incidences and/or multiplicity of lung hyperplasia and tumors, and thyroid lesions did not significantly vary among the DHPN-treated groups. These results indicate that GTCs do not inhibit, but rather may enhance colon carcinogenesis, while not influencing lung and thyroid carcinogenesis under the present experimental conditions.