Effects of (-)-epigallocatechin-3-O-gallate (green tea tannin) on the life span of stroke-prone spontaneously hypertensive rats

From Diospyros kaki L. (Persimmon) Phytochemical Profile and Health Impact to New Product Perspectives and Waste Valorization

Persimmon (Diospyros kaki L.) fruit's phytochemical profile includes carotenoids, proanthocyanidins, and gallic acid among other phenolic compounds and vitamins. A huge antioxidant potential is present given this richness in antioxidant compounds. These bioactive compounds impact on health benefits. The intersection of nutrition and sustainability, the key idea behind the EAT-Lancet Commission, which could improve human health and decrease the global impact of food-related health conditions such as cancer, heart disease, diabetes, and obesity, bring the discussion regarding persimmon beyond the health effects from its consumption, but also on the valorization of a very perishable food that spoils quickly. A broad option of edible products with better storage stability or solutions that apply persimmon and its byproducts in the reinvention of old products or even creating new products, or with new and better packaging for the preservation of food products with postharvest technologies to preserve and extend the shelf-life of persimmon food products. Facing a global food crisis and the climate emergency, new and better day-to-day solutions are needed right now. Therefore, the use of persimmon waste has also been discussed as a good solution to produce biofuel, eco-friendly alternative reductants for fabric dyes, green plant growth regulator, biodegradable and edible films for vegetable packaging, antimicrobial activity against foodborne methicillin-resistant Staphylococcus aureus found in retail pork, anti-Helicobacter pylori agents from pedicel extracts, and persimmon pectin-based emulsifiers to prevent lipid peroxidation, among other solutions presented in the revised literature. It has become clear that the uses for persimmon go far beyond the kitchen table and the health impact consumption demonstrated over the years. The desired sustainable transition is already in progress, however, mechanistic studies and clinical trials are essential and scaling-up is fundamental to the future.

Altered Properties of Neurons and Astrocytes and the Effects of Food Components in Stroke-Prone Spontaneously Hypertensive Rats

ABSTRACT

In stroke-prone spontaneously hypertensive rats (SHRSP), stroke induces neuronal vulnerability and neuronal death, while astrocytes show a weakened support function toward neurons. Moreover, certain food components have been demonstrated to prevent the occurrence of stroke. This review aims to explain the stroke-related properties of SHRSP-derived neurons and astrocytes. In addition, it describes the effects of particular dietary phytochemicals on SHRSP. In this study, we obtained information using PubMed, ScienceDirect, and Web of Science. We searched for the functions of neurons and astrocytes and the molecular mechanism of ischemic stroke induction. We summarized the recent literature on the underlying mechanisms of stroke onset in SHRSP and the alleviating effects of typical food-derived phytochemical components. Neuronal death in SHRSP is induced by hypoxia-reoxygenation, suggesting the involvement of oxidative stress. Furthermore, the production of lactate, l-serine, and glial cell line-derived neurotrophic factor in SHRSP-derived astrocytes was reduced compared with that in control Wistar-Kyoto rats. Vitamin E exerts an inhibitory effect on hypoxia-reoxygenation-induced neuronal death in SHRSP. Curcumin, epigallocatechin gallate, resveratrol, and carotenoids can prevent the development of stroke in SHRSP. In particular, the properties of SHRSP-derived neurons and astrocytes affect stroke-induced neuronal death. This review suggests the potential and therapeutic applications of dietary phytochemicals in reducing stroke risk and lowering blood pressure in SHRSP, respectively, by targeting various processes, including oxidative stress, apoptosis, and inflammation. Thus, future research on SHRSP brain cells with a genetic predisposition to stroke can consider using these food ingredients to develop approaches for stroke prevention.

Catechinic acid, a natural polyphenol compound, extends the lifespan of Caenorhabditis elegans via mitophagy pathways

Catechinic acid (CA), widely present in tea and fruits, has vital biological and pharmacological properties. CA plays an important role in the regulation of lifespan. However, the mechanism behind its anti-aging properties remains poorly characterized. In the present study, Caenorhabditis elegans (C. elegans) was used as a model organism. It was found that CA induced mitophagy which prevented the accumulation of dysfunctional mitochondria with age and profoundly extended lifespan. Notably, CA significantly improved the fitness of aging worms, particularly the treatment slowed age-related decline in observed spontaneous movements. Furthermore, CA was found to eliminate dysfunctional mitochondria in the gut and muscle cells, and demonstrated that the lifespan-prolonging effects of CA can be attributed to mitophagy along with the likely regulation of the genes bec-1 and pink-1. The results of this study indicated that pharmacologically induced mitophagy has a profound impact on aging, providing a novel therapeutic intervention against aging and age-related diseases.

Oxidative Stress Mediates the Fetal Programming of Hypertension by Glucocorticoids

The field of cardiovascular fetal programming has emphasized the importance of the uterine environment on postnatal cardiovascular health. Studies have linked increased fetal glucocorticoid exposure, either from exogenous sources (such as dexamethasone (Dex) injections), or from maternal stress, to the development of adult cardiovascular pathologies. Although the mechanisms are not fully understood, alterations in gene expression driven by altered oxidative stress and epigenetic pathways are implicated in glucocorticoid-mediated cardiovascular programming. Antioxidants, such as the naturally occurring polyphenol epigallocatechin gallate (EGCG), or the superoxide dismutase (SOD) 4-hydroxy-TEMPO (TEMPOL), have shown promise in the prevention of cardiovascular dysfunction and programming. This study investigated maternal antioxidant administration with EGCG or TEMPOL and their ability to attenuate the fetal programming of hypertension via Dex injections in WKY rats. Results from this study indicate that, while Dex-programming increased blood pressure in male and female adult offspring, administration of EGCG or TEMPOL via maternal drinking water attenuated Dex-programmed increases in blood pressure, as well as changes in adrenal mRNA and protein levels of catecholamine biosynthetic enzymes phenylalanine hydroxylase (PAH), tyrosine hydroxylase (TH), dopamine beta hydroxylase (DBH), and phenylethanolamine N-methyltransferase (PNMT), in a sex-specific manner. Furthermore, programmed male offspring displayed reduced antioxidant glutathione peroxidase 1 (Gpx1) expression, increased superoxide dismutase 1 (SOD1) and catalase (CAT) expression, and increased pro-oxidant NADPH oxidase activator 1 (Noxa1) expression in the adrenal glands. In addition, prenatal Dex exposure alters expression of epigenetic regulators histone deacetylase (HDAC) 1, 5, 6, 7, 11, in male and HDAC7 in female offspring. These results suggest that glucocorticoids may mediate the fetal programming of hypertension via alteration of epigenetic machinery and oxidative stress pathways.

Epigallocatechin gallate enhances treatment efficacy of oral nifedipine against pregnancy-induced severe pre-eclampsia: A double-blind, randomized and placebo-controlled clinical study

WHAT IS KNOWN AND OBJECTIVE

Oral nifedipine is commonly used to treat pre-eclampsia, one of the most severe complications during pregnancy, but its clinical efficacy is less than ideal. Epigallocatechin gallate (EGCG), a natural compound from green tea, could benefit cardiovascular health especially hypertension. We investigated the clinical efficacy of EGCG, when complemented with oral nifedipine, in treating pre-eclampsia.

METHODS

A total of 350 pregnant women with severe pre-eclampsia were recruited and randomized to receive oral nifedipine, together with placebo (NIF+placebo) or EGCG (NIF+EGCG). The primary treatment outcome was the time needed to control blood pressure and interval time before a new hypertensive crisis, whereas the secondary treatment outcome was the number of treatment doses to effectively control blood pressure, maternal adverse effects and neonatal complications.

RESULTS AND DISCUSSION

Comparing NIF+EGCG group to NIF+placebo group, the time needed to control blood pressure was significantly shorter (NIF+EGCG 31.2±16.7 minutes, NIF+placebo 45.3±21.9 minutes; 95% CI 9.7-18.5 minutes), whereas interval time before a new hypertensive crisis was significantly prolonged (NIF+EGCG 7.2±2.9 hours, NIF+placebo 4.1±3.7 hours; 95% CI 2.3-3.9 hours), and the number of treatment dosages needed to effectively control blood pressure was also lower. Between the two treatment groups, no differences in incidence rates of maternal adverse effects or neonatal complications were observed.

WHAT IS NEW AND CONCLUSIONS

EGCG is both safe and effective in enhancing treatment efficacy of oral nifedipine against pregnancy-induced severe pre-eclampsia, but formal validation is required prior to its recommendation for use outside of clinical trials.

Differing chemical compositions of three teas may explain their different effects on acute blood pressure in spontaneously hypertensive rats

BACKGROUND

Heavy tea consumption is suggested to be unsuitable for hypertensive people. However, the bioactive substances in different varieties of tea leaves are very different. This study compares the effects of three Chinese teas - C. sinensis, C. ptilophylla and C. assamica var. kucha - on blood pressure (BP) and heart rate in spontaneously hypertensive rats (SHRs).

RESULTS

Intragastric administration of C. sinensis extract led to an acute increase in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate in SHRs. However, C. ptilophylla and C. assamica var. kucha exerted no obvious influences on SBP, DBP or heart rate. Similar to the extract of C. sinensis, intragastric administration of caffeine also led to an acute increase in BP and heart rate in SHRs. In contrast, theobromine and theacrine - purine alkaloids predominantly contained in C. ptilophylla and C. assamica var. kucha, respectively - had no pressor effects. The effect of caffeine on BP was related to the regulation of plasma epinephrine and norepinephrine levels in SHRs.

CONCLUSION

The different effects of C. sinensis, C. ptilophylla and C. assamica var. kucha on BP might be explained, at least partially, by the differences in the varieties and contents of purine alkaloids.

The effects of a multiflavonoid supplement on vascular and hemodynamic parameters following acute exercise

Antioxidants can decrease oxidative stress and combined with acute exercise they may lead to further decreases in blood pressure. The purpose of this study was to investigate the effects of 2 weeks of antioxidant supplementation on vascular distensibility and cardiovascular hemodynamics during postexercise hypotension. Methods. Twenty young subjects were randomized to placebo (n = 10) or antioxidant supplementation (n = 10) for two weeks. Antioxidant status, vascular distensibility, and hemodynamics were obtained before, immediately, and 30 minutes after an acute bout of aerobic exercise both before and after supplementation. Results. Two weeks of antioxidant supplementation resulted in a greater systolic blood pressure (SBP) decrease during postexercise hypotension (PEH) and significant decreases in augmentation index versus placebo (12.5% versus 3.5%, resp.). Also ferric-reducing ability of plasma (FRAP) increased significantly (interaction P = 0.024) after supplementation. Conclusion. Supplementation showed an additive effect on PEH associated with increased FRAP values and decreases in systolic blood pressure and augmentation index.

Polyphenols and human health: prevention of disease and mechanisms of action

Polyphenols are found ubiquitously in plants and their regular consumption has been associated with a reduced risk of a number of chronic diseases, including cancer, cardiovascular disease (CVD) and neurodegenerative disorders. Rather than exerting direct antioxidant effects, the mechanisms by which polyphenols express these beneficial properties appear to involve their interaction with cellular signaling pathways and related machinery that mediate cell function under both normal and pathological conditions. We illustrate that their interactions with two such pathways, the MAP kinase (ERK, JNK, p38) and PI3 kinase/Akt signaling cascades, allow them to impact upon normal and abnormal cell function, thus influencing the cellular processes involved in the initiation and progression of cancer, CVD and neurodegeneration. For example, their ability to activate ERK in neurons leads to a promotion of neuronal survival and cognitive enhancements, both of which influence the progression of Alzheimer’s disease, whilst ERK activation by polyphenols in vascular endothelial cells influences nitric oxide production, blood pressure and ultimately CVD risk. The main focus of this review is to provide an overview of the role that polyphenols play in the prevention of cancer, cardiovascular disease and neurodegeneration. We present epidemiological data, human intervention study findings, as well as animal and in vitro studies in support of these actions and in each case we consider how their actions at the cellular level may underpin their physiological effects.

Strategies for antiplatelet targets and agents

Platelets play a key role in thrombosis and haemostasis, which can be either beneficial or deleterious depending on the circumstance. Antiplatelet therapy is the 'cornerstone' in the prevention and treatment of thrombotic diseases. Platelet activation is a complex process known as transmembrane signaling which then serves to activate the platelet via a cascade of biochemical interactions. Currently available strategies of antiplatelet therapy are generally based on the signaling pathway of platelet activation, which possess the characters that mono-agent, mono-target, and mainly irreversible inhibition. Therefore, both established and novel antiplatelet agents have their own pros and cons and such problems as resistance, drug-drug interaction, discontinuation and monitoring, etc. have been appeared. Due to the problems existing in current antiplatelet agents, future new strategies for antiplatelet targets, agent-developing and treatment might probably include three aspects: targeting the factors associated with platelet hyperactivity, developing novel antiplatelet agents with multiple targets, mild and reversible properties from natural products, and keeping healthy lifestyle and emphasizing prevention.

A comparative study of grape seed extract and vitamin E effects on silica-induced pulmonary fibrosis in rats

Due to the production of reactive oxygen species (ROS), oxidative stress has been implicated in the pathogenesis of silica-induced lung fibrosis. So it is hypothesized that grape seed extract (GSE) or vitamin E (Vit E) as antioxidants may ameliorate some symptoms of the disease. Male Wistar albino rats were divided into 7 groups: rats in group I instilled intratracheally (IT) with a single dose of silica suspension (50mg/rat) as positive control (PC). Treatment groups (II-IV) received Vit E (20 IU/kg/day), GSE (150 mg/kg/day), or Vit E+GSE simultaneously orally 1 day after instillation of silica. Groups V and VI were given oral GSE or Vit E after instillation of the equivalent volume of saline (IT) as controls for GSE or Vit E. Rats of group VII only instilled saline (IT) as negative control. After 90 days animals were sacrificed and plasma-malondialdehyde (p-MDA) and lung tissue hydroxyproline (HP) were quantified. The lungs were also investigated for histopathological changes. The mean concentrations of p-MDA and HP in studied groups (I-VII) were 1.95, 2.77, 0.72, 0.81, 0.64, 0.94, 1.02 micromolMDA/L(plasma) and 28.476, 27.85, 22.83, 22.64, 15.40, 18.31, 18.51 mgHP/g(tissue), respectively. Silica caused a significant increase in HP content of lungs and MDA levels in the plasma except in GSE-treated groups (III and IV). According to the results of this study GSE could reduce the fibrogenic effect of silica. However; no synergistic effect was observed after co-administration of GSE and Vit E.

The effect of consuming instant black tea on postprandial plasma glucose and insulin concentrations in healthy humans

OBJECTIVE

To determine the effects of black tea on postprandial plasma glucose and insulin concentrations in healthy humans in response to an oral glucose load.

METHODS

A four-way randomised, crossover trial was designed in which 16 healthy fasted subjects would consume 75g of glucose in either 250ml of water (control), 250ml of water plus 0.052g of caffeine (positive control) or 250 ml of water plus 1.0g or 3.0g of instant black tea. Blood samples were collected at fasting and at 30min intervals for 150min from commencement of drink ingestion. Glucose and insulin concentrations were measured using standard methodology. The tea was chemically characterised using colorimetric and HPLC methods.

RESULTS

Chemical analysis showed that the tea was rich in polyphenolic compounds (total, 350mg/g). Results from only 3 treatment arms are reported because the 3.0g tea drink caused gastrointestinal symptoms. Plasma glucose concentrations <60min in response to the drinks were similar, but were significantly reduced at 120min (P<0.01), following ingestion of the 1.0g tea drink, relative to the control and caffeine drinks. Tea consumption resulted in elevated insulin concentrations compared with the control and caffeine drinks at 90min (P<0.01) and compared with caffeine drink alone at 150min (P<0.01).

CONCLUSIONS

The 1.0g tea drink reduced the late phase plasma glucose response in healthy humans with a corresponding increase in insulin. This may indicate that the attenuation in postprandial glycemia was achieved as a result of an elevated insulin response following stimulation of pancreatic beta-cells. This effect may be attributable to the presence of phenolic compounds in the tea.

Effects of green tea and EGCG on cardiovascular and metabolic health

Since ancient times green tea has been considered a health-promoting beverage. In recent years, scientists throughout the world have investigated the potential benefits of green tea and its most abundant catechin, epigallocatechin gallate (EGCG). The anti-cancer effects of green tea and EGCG were the focus of early research, and encouraging data from in vitro, animal model, and human studies have emerged. Due to the dominant role of cardiovascular disease and the dramatic rise of obesity and type 2 diabetes mellitus as major and interlinked healthcare problems, green tea and EGCG are increasingly being investigated in these areas. Dose-response relationships observed in several epidemiological studies have indicated that pronounced cardiovascular and metabolic health benefits can be obtained by regular consumption of 5-6 or more cups of green tea per day. Furthermore, intervention studies using similar amounts of green tea, containing 200-300 mg of EGCG, have demonstrated its usefulness for maintaining cardiovascular and metabolic health. Additionally, there are numerous in vivo studies demonstrating that green tea and EGCG exert cardiovascular and metabolic benefits in these model systems. Therefore, green tea and EGCG can be regarded as food components useful for the maintenance of cardiovascular and metabolic health. To prove the effectiveness for disease prevention or treatment, several multi-center, long-term clinical studies investigating the effects of one precisely-defined green tea product on cardiovascular and metabolic endpoints would be necessary. The aim of this manuscript is to provide an overview of the research investigating the effects of green tea and green tea catechins on cardiovascular and metabolic health.

Effect of grape seed extract on lipid peroxidation, antioxidant activity and peripheral blood lymphocytes in rats exposed to x-radiation

The present studies were designed to evaluate supplemental grape seed extract (GSE) and vitamin E supplements on lipid peroxidation, on antioxidant systems and peripheral blood lymphocytes in rats exposed to x-rays. Three groups of rats were investigated: a control group (CG) received intraperitoneal (i.p.) physiological serum 1 mL/day (n=10), i.p.; a vitamin E group (VG) received 50 mg/kg/day (n=10); an i.p. grape seed extract group received 50 mg/kg/day (n=10). Four weeks later, a 6 Gy radiation dose was given to the rats. Blood samples were taken 24 h later after irradiation and lymphocyte, malondialdehyde (MDA), reduced glutathione (GSH), nitrate, nitrite, reduced ascorbic acid, retinol, beta-carotene and ceruloplasmin concentrations were analysed. The levels of GSH (p<0.05), retinol (p<0.001), beta-carotene (p<0.05) and ceruloplasmin concentration (p<0.001) in the GSE group were found to be higher than in the control group but the level of MDA (p<0.001) and nitrite concentration (p<0.05) in rats supplemented with GSE were found to be lower than in the control group. The results indicate that GSE enhanced the antioxidant status and decreased the incidence of free radical-induced lipid peroxidation in blood samples of rats exposed to x-radiation. The antioxidant effect of GSE given to animals was more effective than vitamin E administered before whole-body irradiation in rats.

Green tea and stroke prevention: Emerging evidence

BACKGROUND

Stroke is a leading cause of morbidity and mortality in many countries. Green tea is a simple and inexpensive beverage that is showing promise in the prevention of several diseases, including stroke. However, epidemiological studies examining the preventive effects of tea on stroke have generated inconsistent results.

OBJECTIVE

To review the emerging evidence for green tea in stroke prevention.

METHODS

Published articles were located by searching the PubMed, ProQuest, CINAHL and other databases, using the keywords 'tea' and 'stroke' with no restriction on publication date. Reference lists of identified articles were also searched for relevant publications.

RESULTS

Two published epidemiological studies on green tea reported positive findings. A large number of studies have also proposed biological mechanisms by which tea or tea components may reduce the stroke risk. Additional studies are required from a variety of populations, assessing duration and different types of tea consumption on subtypes of stroke to provide further evidence.

CONCLUSION

Green tea is a safe and cheap beverage. Its consumption should be encouraged because it could potentially serve as a practical method for stroke prevention.

Effects of tea and tea flavonoids on endothelial function and blood pressure: a brief review

1. The consumption of tea worldwide is second only to water. Thus, any physiological effects of tea could have a significant impact on population health. 2. Tea is the major contributor to total flavonoid intake in many populations. Flavonoids in tea have been shown to have a range of activities and effects that could contribute to improved health. Tea intake and the intake of flavonoids found in tea have been associated with reduced risk of cardiovascular disease in several cross-sectional and prospective population studies. A variety of possible mechanisms have been investigated. The focus of the present review is on the mounting evidence that tea flavonoids can improve endothelial function and lower blood pressure. 3. In vitro studies using isolated vessels have shown that tea flavonoids possess vasodilator activity. Results of human intervention trials have shown that increased flavonoid intake from tea, as well as other dietary sources, can improve endothelial function. Emerging data also suggest that the degree of benefit may be related to flavonoid metabolism. 4. The effects of tea flavonoids on blood pressure are less consistent. Results of animal studies and population studies are consistent with a blood pressure-lowering effect of tea. However, short-term intervention trials, mainly in normotensive individuals, have not demonstrated any blood pressure reduction with tea. 5. Overall, the available data suggest that the effects of tea flavonoids on endothelial function and, perhaps, blood pressure may be responsible, at least in part, for any benefits of drinking tea on the risk of cardiovascular disease.

Mechanisms of action of green tea catechins, with a focus on ischemia-induced neurodegeneration

Catechins are dietary polyphenolic compounds associated with a wide variety of beneficial health effects in vitro, in vivo and clinically. These therapeutic properties have long been attributed to the catechins' antioxidant and free radical scavenging effects. Emerging evidence has shown that catechins and their metabolites have many additional mechanisms of action by affecting numerous sites, potentiating endogenous antioxidants and eliciting dual actions during oxidative stress, ischemia and inflammation. Catechins have proven to modulate apoptosis at various points in the sequence, including altering expression of anti- and proapoptotic genes. Their anti-inflammatory effects are activated through a variety of different mechanisms, including modulation of nitric oxide synthase isoforms. Catechins' actions of attenuating oxidative stress and the inflammatory response may, in part, account for their confirmed neuroprotective capabilities following cerebral ischemia. The versatility of the mechanisms of action of catechins increases their therapeutic potential as interventions for numerous clinical disorders. However, more epidemiological and clinical studies need to be undertaken for their efficacy to be fully elucidated.

Hemodynamic impact of an ephedra-free multicomponent weight-loss supplement

PURPOSE

The effect of Metabolife Ephedra-Free on blood pressure (BP) and hemodynamics was studied.

METHODS

Healthy volunteers were randomly assigned to take a single dose of Metabolife Ephedra-Free or matching placebo and then crossed over to the opposite treatment after a seven-day washout period. BP was measured at baseline and one, three, and five hours after administration. Cardiac index, systemic vascular resistance index (SVRI), and total thoracic fluid content were determined in a subgroup of subjects.

RESULTS

Twenty patients (mean +/- S.D. age, 24.8 +/- 1.9 years) completed the study. No significant differences in systolic or diastolic BP were found between the Metabolife Ephedra-Free and placebo groups. In the subgroup (n = 8), SVRI was higher (but not significantly so) in the Metabolife Ephedra-Free group than in the placebo group at one hour (2162.5 +/- 421.1 versus 1934.6 +/- 344.2 dyn x sec x cm(-5) x m(2)); the difference was significant at five hours (1981.6 +/- 293.3 versus 1765.1 +/- 340.3 dyn x sec x cm(-5) x m(2)).

CONCLUSION

Single doses of Metabolife Ephedra-Free did not affect BP in healthy young volunteers. SVRI did not exceed the normal range but was elevated at five hours compared with SVRI in placebo recipients.

Green tea polyphenol extract attenuates ischemia/reperfusion injury of the gut

Various studies have clearly demonstrated that green tea catechins possess potent antioxidative properties, and the preventive effects against various oxidative diseases have been reported. The aim of this study was to investigate the effect of green tea extract on the tissue injury caused by ischemia/reperfusion (I/R) of the gut. I/R injury of the intestine was caused by clamping both the superior mesenteric artery and the celiac trunk for 45 min followed by release of the clamp allowing reperfusion for 1 h or 4 h. This procedure results in splanchnic artery occlusion (SAO) shock. Rats subjected to SAO developed a significant fall in mean arterial blood pressure, and only 10% of the animals survived for the entire 4-h reperfusion period. Surviving animals were sacrificed for histological examination and biochemical studies. Rats subjected to SAO displayed a significant increase in tissue myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels, significant increases in plasma tumor necrosis factor (TNF)-alpha levels and marked injury to the distal ileum. Increased immunoreactivity to nitrotyrosine was observed in the ileum of rats subjected to SAO. Staining of sections of the ileum obtained from SAO rats with anti-intercellular adhesion molecule (ICAM-1) antibody and with anti-P-selectin antibody resulted in diffuse staining. Administration of green tea extract (20 and 10 mg kg(-1) i.v.) 15 min prior to the onset of gut reperfusion significantly reduced in a dose-dependent manner the fall in mean arterial blood pressure, the mortality rate, infiltration of the reperfused intestine with polymorphonuclear neutrophils (MPO activity), lipid peroxidation (MDA levels), production of TNF-alpha, and histological evidence of gut injury. Administration of green tea extract also markedly reduced nitrotyrosine formation and the up-regulation of ICAM-1 and P-selectin during reperfusion. In order to clarify that green tea extract might be useful in the therapy of I/R injury, we also investigated the effect of green tea extract (20 mg kg(-1) i.v.) when administered 5 min after the onset of gut reperfusion. Similar to the pretreatment approach, the post-treatment also significantly reduced the gut injury induced by I/R. These results demonstrate that green tea extract significantly reduces I/R injury of the intestine.

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.

Epigallocatechin-3-gallate causes the p21/WAF1-mediated G1-phase arrest of cell cycle and inhibits matrix metalloproteinase-9 expression in TNF-α-induced vascular smooth muscle cells

It has been suggested that epigallocatechin-3-gallate (EGCG), a major catechin found in green tea, plays a role in preventing the progression of atherosclerosis. Although EGCG has anti-atherogenic effects on vascular smooth muscle cells (VSMC), the molecular mechanisms associated with TNF-alpha-induced VSMC are not known with certainty. To determine whether EGCG has the capacity to modulate VSMC responses, cell cycle regulation and MMP-9 expression were examined in TNF-alpha-induced VSMC. Treatment with EGCG, which blocks the cell cycle in the G(1) phase, induced a down-regulation of cyclins and CDKs and an up-regulation in the expression of p21/WAF1, a CDK inhibitor, whereas the up-regulation of p27 by EGCG was not observed. Moreover, treatment with EGCG markedly increased the promoter activity of the p21/WAF1 gene. Immunoblot and deletion analysis results for the p21/WAF1 promoter showed that EGCG induced the expression of p21/WAF1 independent of the p53 pathway. Zymographic and immunoblot analyses showed that EGCG suppressed TNF-alpha-induced MMP-9 expression in a dose-dependent manner. Further experiments demonstrated that EGCG reduced the transcriptional activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), two important nuclear transcription factors that are involved in MMP-9 expression. Collectively, these results suggest that EGCG inhibits G(1) to S-phase cell cycle progress and MMP-9 expression through the transcription factors NF-kappaB and AP-1 in TNF-alpha-induced VSMC.

Epigallocatechin-3-gallate inhibits STAT-1 activation and protects cardiac myocytes from ischemia/reperfusion-induced apoptosis

We have previously demonstrated that STAT-1 plays a critical role in promoting apoptotic cell death in cardiac myocytes following ischemia/reperfusion (I/R) injury. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, has recently been reported to inhibit STAT-1 activity in noncardiac cells. In the present study, we have assessed the protective effects of EGCG and green tea extract (GTE) infusion on both cultures of cardiac myocytes and the isolated rat heart. EGCG reduced STAT-1 phosphorylation and protected cardiac myocytes against I/R-induced apoptotic cell death. Moreover, EGCG reduced the expression of a known STAT-1 pro-apoptotic target gene, Fas receptor. More interestingly, oral administration of GTE as well as EGCG infusion limited the extent of infarct size and attenuated the magnitude of myocyte apoptosis in the isolated rat heart exposed to I/R injury. This reduction cell death was associated with improved hemodynamic recovery and ventricular function in the ischemic/reperfused rat heart. This is the first report to show that consumption of green tea is able to mediate cardioprotection and enhance cardiac function during I/R injury. Because GTE-mediated cardioprotection is achieved, at least in part, through inhibition of STAT-1 activity, we may postulate that a similar action can be implemented in the clinical setting to minimize STAT-1 activation levels in patients with acute coronary artery disease (CAD).

Antiplatelet effect of green tea catechins: a possible mechanism through arachidonic acid pathway

We have previously reported that green tea catechins (GTC) showed an antithrombotic activity, which might be due to antiplatelet effect rather than anticoagulation. The present study was performed to investigate the effect of GTC on the arachidonic acid (AA) metabolism in order to elucidate a possible antiplatelet mechanism. GTC inhibited the collagen-, AA- and U46619-induced rabbit platelet aggregation in vitro in a concentration-dependent manner, with IC50 values of 61.0+/-2.5, 105.0+/-4.9 and 67.0+/-3.2 microg/ml, respectively. Moreover, GTC administered orally into rats inhibited the AA-induced platelet aggregation ex vivo by 46.9+/-6.1% and 95.4+/-2.2% at the doses of 25 and 50 mg/kg, respectively. [3H]AA liberation induced by collagen in [3H]AA incorporated rabbit platelets was significantly suppressed by GTC compared to the control. GTC also significantly inhibited the thromboxane A2 (TXA2) and prostaglandin D2 (PGD2) generations induced by addition of AA in intact rabbit platelets. GTC significantly inhibited TXA2 synthase activity in a concentration-dependent manner. Moreover, adenosine triphosphate (ATP) release from dense granule was inhibited by GTC in washed platelets. These results suggest that the antiplatelet activity of GTC may be due to the inhibition of TXA2 formation through the inhibition of AA liberation and TXA2 synthase.

STAT-1: a novel regulator of apoptosis

Extracellular signalling molecules binding to their specific receptors are able to modulate gene expression, leading to changes in development, cell growth and homeostasis. The signal transducers and activators of transcription (STAT) protein family members are among the best studied of the latent cytoplasmic signal-dependent transcription factors. The STAT factors are activated via phosphorylation on the C-terminal domain following cytokine signalling or by various stress-induced stimuli. Recently, STAT-1 has been implicated in modulating pro- and anti-apoptotic genes following several stress-induced responses. These effects are dependent on STAT-1 phosphorylation on serine-727 and require the C-terminal transactivation domain of STAT-1 to enhance its pro-apoptotic effect or inhibit its anti-apoptotic effects. The STAT-1 C-terminal domain has been demonstrated to be important for protein-protein interaction with other transcriptional activators. The reports that STAT-1-deficient mice develop spontaneous and chemically induced tumours more rapidly compared to wild-type mice and that STAT-1-deficient cells are more resistant to agents that induce apoptosis strongly support the argument that STAT-1 acts as a tumour suppressor.

IGF-I activity may be a key determinant of stroke risk--a cautionary lesson for vegans

IGF-I acts on vascular endothelium to activate nitric oxide synthase, thereby promoting vascular health; there is reason to believe that this protection is especially crucial to the cerebral vasculature, helping to ward off thrombotic strokes. IGF-I may also promote the structural integrity of cerebral arteries, thereby offering protection from hemorrhagic stroke. These considerations may help to explain why tallness is associated with low stroke risk, whereas growth hormone deficiency increases stroke risk--and why age-adjusted stroke mortality has been exceptionally high in rural Asians eating quasi-vegan diets, but has been declining steadily in Asia as diets have become progressively higher in animal products. There is good reason to suspect that low-fat vegan diets tend to down-regulate systemic IGF-I activity; this effect would be expected to increase stroke risk in vegans. Furthermore, epidemiology suggests that low serum cholesterol, and possibly also a low dietary intake of saturated fat--both characteristic of those adopting low-fat vegan diets--may also increase stroke risk. Vegans are thus well advised to adopt practical countermeasures to minimize stroke risk--the most definitive of which may be salt restriction. A high potassium intake, aerobic exercise training, whole grains, moderate alcohol consumption, low-dose aspirin, statin or policosanol therapy, green tea, and supplementation with fish oil, taurine, arginine, and B vitamins--as well as pharmacotherapy of hypertension if warranted--are other practical measures for lowering stroke risk. Although low-fat vegan diets may markedly reduce risk for coronary disease, diabetes, and many common types of cancer, an increased risk for stroke may represent an 'Achilles heel'. Nonetheless, vegans have the potential to achieve a truly exceptional 'healthspan' if they face this problem forthrightly by restricting salt intake and taking other practical measures that promote cerebrovascular health.

Powdered green tea has antilipogenic effect on Zucker rats fed a high-fat diet

The effect of powdered green tea on the lipid metabolism was studied in male Zucker rats fed a 50% sucrose diet containing 15% butter. The oral treatment of 130 mg powdered green tea per day depressed body weight increase and various adipose tissue weights but food intake was unaffected. The treatment also slightly increased the plasma triglycerides. These effects were likely mediated by the inhibition of lipogenesis in the adipose tissues. The experimental group had a higher concentration of liver total lipid, triglycerides and plasma protein, and lower liver weights than the controls. This may be due to lipid deposition in the liver because of the reduction in adipose tissue weights. It was found that powdered green tea lowered the plasma total cholesterol but liver total cholesterol was unaffected. The results indicate that the hypocholesterolemic activity of powdered green tea might be due to the inhibition of the synthesis of cholesterol in the liver.

Effect of Undaria pinnatifida (Wakame) on the development of cerebrovascular diseases in stroke-prone spontaneously hypertensive rats

1. We showed that a nutritional factor was able to attenuate the development of hypertension and its related diseases in stroke-prone spontaneously hypertensive rats (SHRSP). In the present study, the effect of Wakame, an edible brown seaweed, on the development of stroke was examined in SHRSP. 2. We studied the treatment with 5% (w/w in a diet) Wakame powder in salt-loaded (0.5% NaCl in drinking water) SHRSP. Salt-loaded animals treated with 5% cellulose or kaolin were used as controls. Wakame significantly delayed the development of stroke signs (P < 0.05) and significantly improved the survival rate of salt-loaded SHRSP (P < 0.05). There was no significant difference in the elevation of blood pressure among the three groups during the observation period. 3. We isolated fucoxanthin, a carotinoid, from Wakame powder and studied its preventive effect on ischaemic cultured neuronal cell death. Fucoxanthin significantly attenuated neuronal cell injury in hypoxia and re-oxygenation (P < 0.05). 4. Based on these results, we conclude that Wakame has a beneficial effect on cerebrovascular diseases in SHRSP, independent of hypertension. It is possible that fucoxanthin in Wakame may have a preventive effect against ischaemic neuronal cell death seen in SHRSP with stroke.

Neuroprotective effects of the green tea components theanine and catechins

The neuroprotective effects of theanine and catechins contained in green tea are discussed. Although the death of cultured rat cortical neurons was induced by the application of glutamic acid, this neuronal death was suppressed with exposure to theanine. The death of hippocampal CA1 pyramidal neurons caused by transient forebrain ischemia in the gerbil was inhibited with the ventricular preadministration of theanine. The neuronal death of the hippocampal CA3 region by kainate was also prevented by the administration of theanine. Theanine has a higher binding capacity for the AMPA/kainate receptors than for NMDA receptors, although the binding capacity in all cases is markedly less than that of glutamic acid. The results of the present study suggest that the mechanism of the neuroprotective effect of theanine is related not only to the glutamate receptor but also to other mechanisms such as the glutamate transporter, although further studies are needed. One of the onset mechanisms for arteriosclerosis, a major factor in ischemic cerebrovascular disease, is probably the oxidative alteration of low-density lipoprotein (LDL) by active oxygen species. The oxidative alterations of LDL were shown to be prevented by tea catechins. Scavenging of *O(2)(-) was also exhibited by tea catechins. The neuroprotective effects of theanine and catechins contained in green tea are a focus of considerable attention, and further studies are warranted.

Effects of catechins on vascular tone in rat thoracic aorta with endothelium

The effects of eight catechin derivatives on vascular tone in rat thoracic aorta were examined. Catechin derivatives (10 microM) potentiated the contractile response to phenylephrine in endothelium-intact arteries. The potentiations produced by EGCg and EGC were almost absent in endothelium-denuded arteries and abolished by N(G)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis. The catechin derivatives also inhibited endothelium-dependent relaxation in response to acetylcholine. The order of catechin derivatives ranked in terms of both increasing vascular reactivity and impairing endothelium-dependent relaxation was similar; (-)-gallocatechin (GC) >or= (-)-epigallocatechin (EGC) >or= (-)-gallocatechin gallate (GCg) >or= (-)-epigallocatechin gallate (EGCg) >or= (-)-catechin (C) >or= (-)-epicatechin (EC) >or= (-)-catechin gallate (Cg) >or= (-)-epicatechin gallate (ECg). In addition, EGC inhibited the endothelium-independent relaxation evoked by both sodium nitroprusside and NOC-7, a spontanous NO releaser, but EGCg inhibited only that by NOC-7. These findings indicate that catechin derivatives produce a potentiation of the contractile response and an inhibition of the vasorelaxant response, probably through inactivation of endothelium-derived nitric oxide (NO), and that the hydroxyl on C-5 of the B ring together with the stereoscopic structure between the C-3 group and the B ring of flavanols was of importance in mediating the above effects and that the substitution of a gallate group of C-3 attenuated the effects, probably due to a decreased response to solube guanylate cyclase in vascular smooth muscle cells.

Vitamin C is one of the lipolytic substances in green tea

We have studied the influence of vitamin C contained in green tea on the lipolysis of well-differentiated 3T3-L1 cells. When mature adipocytes were exposed to vitamin C the triglyceride concentration was decreased (p < 0.05) and the activity of glycerophosphate dehydrogenase, a marker of adipose conversion, was significantly inhibited (p < 0.01). These data suggest that green tea may have a lipolytic activity due to the mechanism by which the vitamin C contained in it inhibits triglyceride accumulation.

Epigallocatechin-3-gallate inhibits basic fibroblast growth factor-induced intracellular signaling transduction pathway in rat aortic smooth muscle cells

Daily green tea drinking showed preventive effects on the progression of atherosclerosis. Although epigallocatechin-3-gallate [EGCG] has anti-proliferative effects on various cells, relatively little is known about the molecular mechanisms of the anti-proliferative effects of EGCG. To determine whether the transduction signals and protooncogene expression were affected by EGCG, this study investigated the molecular mechanism of the anti-proliferative effects in basic fibroblast growth factor (bFGF)-stimulated rat aortic smooth muscle cells (RAoSMCs). EGCG inhibited the proliferative response stimulated by 10% fetal bovine serum dose dependently in RAoSMCs (median inhibitory concentration [IC50]: 28.4 x 10(-6) M ). EGCG also inhibited the migration of bFGF-stimulated RAoSMCs in a dose-dependent manner, showing that 21.8 x 10(-6) M of EGCG significantly inhibited the migration by 75 +/- 5% in comparison with bFGF-stimulated migration. In RAoSMCs, EGCG dramatically inhibited Ras activation and c-jun N-terminal kinase (JNK) activity without affecting protein kinase C expression. Induction of c-jun mRNA stimulated by bFGF was significantly reduced dose dependently up to 87.3 x 10(-6) M of EGCG. These results indicate that the anti-proliferative effect of EGCG on RAoSMCs is partly Ras/JNK mediated, independent of protein kinase C, and is attributable to the downregulation of c-jun expression.

Antiplatelet activity of green tea catechins is mediated by inhibition of cytoplasmic calcium increase

We have previously reported that green tea catechins (GTC) display a potent antithrombotic activity, which might be due to antiplatelet rather than anticoagulation effects. In the current study, we investigated the antiplatelet mechanism of GTC. We tested the effects of GTC on the aggregation of human platelets and on the binding of fluorescein isothiocyanate-conjugated fibrinogen to human platelet glycoprotein (GP) IIb/IIIa. GTC inhibited the collagen-, thrombin-, adenosine diphosphate (ADP)-, and calcium ionophore A23187-induced aggregation of washed human platelets, with 50% inhibitory concentration values of 0.64, 0.52, 0.63, and 0.45 mg/ml, respectively. GTC significantly inhibited fibrinogen binding to human platelet surface GPIIb/IIIa complex but failed to inhibit binding to purified GPIIb/IIIa complex. These results indicate that the antiplatelet activity of GTC may be due to inhibition of an intracellular pathway preceding GPIIb/IIIa complex exposure. We also investigated the effects of GTC on intracellular calcium levels, which are critical in determining the activation status of platelets and on induction of platelet aggregation by thapsigargin, which is a selective inhibitor of the Ca(2+)-ATPase pump. Pretreatment of human platelets with GTC significantly inhibited the rise in intracellular Ca(2+) concentration induced by thrombin treatment, and GTC significantly inhibited the thapsigargin-induced platelet aggregation. We also examined the effect of GTC on the second messenger, inositol 1,4,5-triphosphate (IP(3)). GTC significantly inhibited the phosphoinositide breakdown induced by thrombin. Taken together, these observations suggest that the antiplatelet activity of GTC is be mediated by inhibition of cytoplasmic calcium increase, which leads to the inhibition of fibrinogen-GPIIb/IIIa binding via the activation of Ca(2+)-ATPase and inhibition of IP(3) formation.

Therapeutic potential of dietary phase 2 enzyme inducers in ameliorating diseases that have an underlying inflammatory component

Many diseases associated with ageing have an underlying oxidative stress and accompanying inflammatory component, for example, Alzheimer's disease or atherosclerosis. Reviewed in this manuscript are: the role of oxidative stress in activating the transcription factor nuclear factor kappa B (NFκB), the role of NFκB in activating pro-inflammatory gene transcription, strong oxidants produced by cells, anti-oxidant defense systems, the central role of phase 2 enzymes in the anti-oxidant defense, dietary phase 2 enzyme inducers and evidence that dietary phase 2 enzymes decrease oxidative stress. It is likely that a diet containing phase 2 enzyme inducers may ameliorate or even prevent diseases that have a prominent inflammatory component to them. Research should be directed into the potential therapeutic effects of dietary phase 2 enzyme inducers in ameliorating diseases with an underlying oxidative stress and inflammatory component to them.Key words: Alzheimer's disease, atherosclerosis, diet, glutathione, inflammation, stroke.

Neuroprotective effect of green tea extract in experimental ischemia-reperfusion brain injury

Eicosanoids accumulation and formation of oxygen free radicals have been implicated in the pathogenesis of ischemia/reperfusion brain injury. In the present study, we examined whether green tea extract protects against ischemia/reperfusion-induced brain injury by minimizing eicosanoid accumulation and oxygen radical-induced oxidative damage in the brain. Green tea extract (0.5%) was orally administered to Wistar rats for 3 weeks before induction of ischemia. Ischemia was induced by the occlusion of middle cerebral arteries for 60 min and reperfusion was achieved for 24 h. Infarction volume in the ipsilateral hemisphere of ischemia/reperfusion animals was 114 +/- 16 mm(3) in the 0.5% green tea pretreated animals compared to 180 +/- 54 mm(3) in left hemisphere of nontreated animals. Green tea extract (0.5%) also reduced ischemia/reperfusion-induced eicosanoid concentration: Leukotriene C(4) (from 245 +/- 51 to186 +/- 22), prostoglandin E(2) (from 306 +/- 71 to 212 +/- 43) and thromboxane A(2) (327 +/- 69 to 251 +/- 87 ng/mg protein). Ischemia/reperfusion-induced increases of hydrogen peroxide level (from 688 +/- 76 to 501 +/- 99 nmole/mg protein), lipid peroxidation products (from 1010 +/- 110 to 820 +/- 70 nmole/mg protein) and 8-oxodG formation (from 1.3 +/- 0.3 to 0.8 +/- 0.2 ng/microg DNA, x10(-2)) were also reduced. Moreover, 0.5% green tea extract also reduced the apoptotic cell number (from 44 +/- 11 to 29 +/- 1 in the striatum, and from 72 +/- 11 to 42 +/- 5 apoptotic cells/high power field in the cortex region). Green tea extract pretreatment also promoted recovery from the ischemia/reperfusion-induced inhibition of active avoidance. The present study shows that the minimizing effect of green tea extract on the eicosanoid accumulation and oxidative damage in addition to the reduction of neuronal cell death could eventually result in protective effect on the ischemia/reperfusion-induced brain injury and behavior deficit.

Up-regulation of endothelial nitric oxide activity as a central strategy for prevention of ischemic stroke - just say NO to stroke!

Nitric oxide (NO) produced by the endothelium of cerebral arterioles is an important mediator of endothelium-dependent vasodilation (EDV), and also helps to prevent thrombosis and vascular remodeling. A number of risk factors for ischemic stroke are associated with impaired EDV, and this defect is usually at least partially attributable to a decrease in the production and/or stability of NO. These risk factors include hypertension, high-sodium diets, homocysteine, diabetes, visceral obesity, and aging. Conversely, many measures which may provide protection from ischemic stroke - such as ample dietary intakes of potassium, arginine, fish oil, and selenium - can have a favorable impact on EDV. Protection afforded by exercise training, estrogen replacement, statin drugs, green tea polyphenols, and cruciferous vegetables may reflect increased expression of the endothelial NO synthase. IGF-I activity stimulates endothelial NO production, and conceivably is a mediator of the protection associated with higher-protein diets in Japanese epidemiology and in hypertensive rats. These considerations prompt the conclusion that modulation of NO availability is a crucial determinant of risk for ischemic stroke. Multifactorial strategies for promoting effective cerebrovascular NO activity, complemented by measures that stabilize platelets and moderate blood viscosity, should minimize risk for ischemic stroke and help maintain vigorous cerebral perfusion into ripe old age. The possibility that such measures will also diminish risk for Alzheimer's disease, and slow the normal age-related decline in mental acuity, merits consideration. A limited amount of ecologic epidemiology suggests that both stroke and senile dementia may be extremely rare in cultures still consuming traditional unsalted whole-food diets. Other lines of evidence suggest that promotion of endothelial NO activity may decrease risk for age-related macular degeneration.

Induction of apoptosis by hydrolyzable tannins from Eugenia jambos L. on human leukemia cells

Eugenia jambos L. (Myrtaceae) is an antipyretic and anti-inflammatory herb of Asian folk medicine. A 70% acetone extract exerted the strongest cytotoxic effects on human leukemia cells (HL-60) from a preliminary screening of 15 plants. The cytotoxic principles were separated by bio-assay-guided fractionation to HL-60 cells; two hydrolyzable tannins (1-O-galloyl castalagin and casuarinin) were isolated from the 70% acetone extract. All significantly inhibited human promyelocytic leukemia cell line HL-60 and showed less cytotoxicity to human adenocarcinoma cell line SK-HEP-1 and normal cell lines of human lymphocytes and Chang liver cells. Thus, these compounds were exhibited the dose-dependent manner in HL-60 cells and the IC(50) were 10.8 and 12.5 microM, respectively. Flow cytometric analysis demonstrated the presence of apoptotic cells with low DNA content, a decrease of cell population at G(2)/M phase, and a concomitant increase of cell population at G(1) phase. The apoptosis induced by these two compounds was also demonstrated by DNA fragmentation assay and microscopic observation. These results suggest that the cytotoxic mechanism of both antitumor principle constituents might be the induction of apoptosis in HL-60 cells.

Vegan proteins may reduce risk of cancer, obesity, and cardiovascular disease by promoting increased glucagon activity

Amino acids modulate the secretion of both insulin and glucagon; the composition of dietary protein therefore has the potential to influence the balance of glucagon and insulin activity. Soy protein, as well as many other vegan proteins, are higher in non-essential amino acids than most animal-derived food proteins, and as a result should preferentially favor glucagon production. Acting on hepatocytes, glucagon promotes (and insulin inhibits) cAMP-dependent mechanisms that down-regulate lipogenic enzymes and cholesterol synthesis, while up-regulating hepatic LDL receptors and production of the IGF-I antagonist IGFBP-1. The insulin-sensitizing properties of many vegan diets--high in fiber, low in saturated fat--should amplify these effects by down-regulating insulin secretion. Additionally, the relatively low essential amino acid content of some vegan diets may decrease hepatic IGF-I synthesis. Thus, diets featuring vegan proteins can be expected to lower elevated serum lipid levels, promote weight loss, and decrease circulating IGF-I activity. The latter effect should impede cancer induction (as is seen in animal studies with soy protein), lessen neutrophil-mediated inflammatory damage, and slow growth and maturation in children. In fact, vegans tend to have low serum lipids, lean physiques, shorter stature, later puberty, and decreased risk for certain prominent 'Western' cancers; a vegan diet has documented clinical efficacy in rheumatoid arthritis. Low-fat vegan diets may be especially protective in regard to cancers linked to insulin resistance--namely, breast and colon cancer--as well as prostate cancer; conversely, the high IGF-I activity associated with heavy ingestion of animal products may be largely responsible for the epidemic of 'Western' cancers in wealthy societies. Increased phytochemical intake is also likely to contribute to the reduction of cancer risk in vegans. Regression of coronary stenoses has been documented during low-fat vegan diets coupled with exercise training; such regimens also tend to markedly improve diabetic control and lower elevated blood pressure. Risk of many other degenerative disorders may be decreased in vegans, although reduced growth factor activity may be responsible for an increased risk of hemorrhagic stroke. By altering the glucagon/insulin balance, it is conceivable that supplemental intakes of key non-essential amino acids could enable omnivores to enjoy some of the health advantages of a vegan diet. An unnecessarily high intake of essential amino acids--either in the absolute sense or relative to total dietary protein--may prove to be as grave a risk factor for 'Western' degenerative diseases as is excessive fat intake.

Antithrombotic activities of green tea catechins and (-)-epigallocatechin gallate

The antithrombotic activities and mode of action of green tea catechins (GTC) and (-)-epigallocatechin gallate (EGCG), a major compound of GTC, were investigated. Effects of GTC and EGCG on the murine pulmonary thrombosis in vivo, human platelet aggregation in vitro, and ex vivo, and coagulation parameters were examined. GTC and EGCG prevented death caused by pulmonary thrombosis in mice in vivo in a dose-dependent manner. They significantly prolonged the mouse tail bleeding time of conscious mice. They inhibited adenosine diphosphate- and collagen-induced rat platelet aggregation ex vivo in a dose-dependent manner. GTC and EGCG inhibited ADP-, collagen-, epinephrine-, and calcium ionophore A23187-induced human platelet aggregation in vitro dose dependently. However, they did not change the coagulation parameters such as activated partial thromboplastin time, prothrombin time, and thrombin time using human citrated plasma. These results suggest that GTC and EGCG have the antithrombotic activities and the modes of antithrombotic action may be due to the antiplatelet activities, but not to anticoagulation activities.