Publications by authors named "Mamoru Isemura"

Epidemiological studies have shown that the consumption of green tea has beneficial effects against cancer. Basic studies have provided evidence that epigallocatechin gallate (EGCG) is a major contributor to these effects. Matrix metalloproteinases (MMPs) are zinc-dependent metalloproteinases with the ability to degrade the extracellular matrix proteins and are involved in various diseases including cancer in which MMPs have a critical role in invasion and metastasis.

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Growing evidence has been accumulated to show the anticancer effects of daily consumption of polyphenols. These dietary polyphenols include chlorogenic acid, curcumin, epigallocatechin-3--gallate, genistein, quercetin, and resveratrol. These polyphenols have similar chemical and biological properties in that they can act as antioxidants and exert the anticancer effects via cell signaling pathways involving their reactive oxygen species (ROS)-scavenging activity.

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Several epidemiological studies and clinical trials have reported the beneficial effects of green tea, coffee, wine, and curry on human health, with its anti-obesity, anti-cancer, anti-diabetic, and neuroprotective properties. These effects, which have been supported using cell-based and animal studies, are mainly attributed to epigallocatechin gallate found in green tea, chlorogenic acid in coffee, resveratrol in wine, and curcumin in curry. Polyphenols are proposed to function via various mechanisms, the most important of which is related to reactive oxygen species (ROS).

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Many observational and clinical studies have shown that consumption of diets rich in plant polyphenols have beneficial effects on various diseases such as cancer, obesity, diabetes, cardiovascular diseases, and neurodegenerative diseases (NDDs). Animal and cellular studies have indicated that these polyphenolic compounds contribute to such effects. The representative polyphenols are epigallocatechin-3--gallate in tea, chlorogenic acids in coffee, resveratrol in wine, and curcumin in curry.

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Tea and coffee are consumed worldwide and epidemiological and clinical studies have shown their health beneficial effects, including anti-cancer effects. Epigallocatechin gallate (EGCG) and chlorogenic acid (CGA) are the major components of green tea polyphenols and coffee polyphenols, respectively, and believed to be responsible for most of these effects. Although a large number of cell-based and animal experiments have provided convincing evidence to support the anti-cancer effects of green tea, coffee, EGCG, and CGA, human studies are still controversial and some studies have suggested even an increased risk for certain types of cancers such as esophageal and gynecological cancers with green tea consumption and bladder and lung cancers with coffee consumption.

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Article Synopsis
  • Green tea has been extensively researched for its numerous health benefits, particularly its potential effects on cancer, obesity, diabetes, inflammation, and neuroprotection against neurological disorders.
  • Studies show that while (-)-epigallocatechin gallate (EGCG) from green tea has low and short-lived concentrations in the bloodstream, it is metabolized in the intestines, forming compounds that may still impact brain health.
  • Recent experiments suggest these EGCG metabolites can cross the blood-brain barrier and promote neuronal growth, indicating they might be key in combating neurodegenerative diseases along with EGCG itself.
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Catechin, the name of which is derived from catechu of the extract of L [...

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Epidemiological and laboratory studies have shown that green tea and green tea catechins exert beneficial effects on a variety of diseases, including cancer, metabolic syndrome, infectious diseases, and neurodegenerative diseases. In most cases, (-)-epigallocatechin gallate (EGCG) has been shown to play a central role in these effects by green tea. Catechins from other plant sources have also shown health benefits.

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Green tea has been shown to have beneficial effects on many diseases such as cancer, obesity, inflammatory diseases, and neurodegenerative disorders. The major green tea component, epigallocatechin-3--gallate (EGCG), has been demonstrated to contribute to these effects through its anti-oxidative and pro-oxidative properties. Furthermore, several lines of evidence have indicated that the binding affinity of EGCG to specific proteins may explain its mechanism of action.

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Green tea has been shown to have beneficial effects against cancer, obesity, atherosclerosis, diabetes, bacterial and viral infections, and dental caries. The catechin (-)-epigallocatechin-3-gallate (EGCG) has shown the highest biological activity among green tea catechins (GTCs) in most of the studies. While several epidemiological studies have shown the beneficial effects of tea and GTCs on obesity, some studies have failed to do this.

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Background: Green tea has been shown to have beneficial effects against a variety of diseases such as cancer, obesity, diabetes, cardiovascular disease, and neurodegenerative diseases. Through cellular, animal, and human experiments, green tea and its major component, epigallocatechin-3-gallate (EGCG) have been demonstrated to have anti-inflammatory effects. Our previous findings have indicated that green tea and EGCG suppress the gene and/or protein expression of inflammatory cytokines and inflammation-related enzymes.

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We conducted a preliminary investigation of the effects of visible light irradiation on plant extracts, and we observed a strong suppressive effect on interleukin (IL) 2 expression with the inhibition of c-Jun amino-terminal kinase (JNK) phosphorylation in Jurkat cells by visible light irradiation to ethanol extract from green soybeans (LIEGS). This effect was produced only by extracts from green soybeans (Glycine max) and not other-color soybeans. LIEGS suppressed the lipopolysaccharide-induced IL-6, IL-12 and TNF-α expression levels in human monocyte THP-1 cells in a concentration-dependent manner.

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Green tea and tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been shown to have various health benefits including anti-cancer, anti-metastasis, and anti-cardiovascular disease effects. Our previous studies demonstrated that three plasma proteins, fibronectin, histidine-rich glycoprotein, and fibrinogen were bound by EGCG, and that one specific domain in fibronectin was responsible for its binding interaction with EGCG. Fibrinogen consists of 6 chains linked by the disulfide bonds of two each of the α-, β-, and γ-chains.

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The present study was performed to investigate the immune-modulating activities of extracts from green soybean (Glycine max) in a 2,4-toluene diisocyanate (TDI)-inducing guinea pig rhinitis model and a human trial study for allergic rhinitis. Hot water extracts of green soybean were chosen for animal experimentation on the basis of their ability to regulate the production of B cell-activating factor of the TNF family and a proliferation-inducing ligand in mouse spleen cells. Green soybean extracts significantly decreased the levels of ovalubumin (OVA)-specific IgE in mice and significantly suppressed the TDI-induced nasal mucosa secretion.

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Green tea is manufactured from the leaves of the plant Camellia sinensis Theaceae and has been regarded to possess anti-cancer, anti-obesity, anti-atherosclerotic, anti-diabetic, anti-bacterial, and anti-viral effects. Many of the beneficial effects of green tea are related to the activities of (-)-epigallocatechin gallate (EGCG), a major component of green tea catechins. For about 20 years, we have engaged in studies to reveal the biological activities and action mechanisms of green tea and EGCG.

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Many biological activities of green tea have been attributed to a major constituent, (minus;)-epigallocatechin gallate (EGCG). We previously reported that EGCG and an EGCG-free fraction derived from green tea modulated the gene expression of gluconeogenic enzymes, glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, in the mouse liver. EGCG is also known to affect the gene expression of enzymes related to lipid metabolism.

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Green tea has been shown to have many beneficial health effects. We have previously reported that dietary (-)-epigallocatechin-3-O-gallate (EGCG), the major polyphenol in green tea, reduced gene expressions of gluconeogenic enzymes, glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), in the normal mouse liver. In the present study, we examined the effects of intragastrical administration of EGCG on the expression of gluconeogenesis-related genes in the mouse intestine.

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Background: Lectins are proteins that bind specifically to the carbohydrate moiety of glyco-conjugates. Japanese mistletoe lectin given intragastrically affected cytokine gene expression in the mouse intestine. This study examines the actions of Lens culinaris agglutinin (LCA) on the gene expression of gluconeogenic enzymes in the intestine.

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Tea has many beneficial effects. We have previously reported that green tea and a catechin-rich green tea beverage modulated the gene expression of the gluconeogenic enzymes glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) in the normal murine liver. In the present study, we examined the effects of oral administration of oolong tea on the hepatic expression of gluconeogenesis-related genes in the mouse.

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Many biological activities of green tea have been attributed to a major constituent, (-)-epigallocatechin gallate (EGCG). We previously reported that EGCG and a catechin-rich green tea beverage modulated the gene expression of gluconeogenic enzymes, glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), in the mouse liver. However, it remains to be examined whether or not a constituent other than EGCG contributes to the change in gene expression of these enzymes.

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Rat hepatoma H4IIE cells were stimulated with dexamethasone and dibutyryl cAMP to increase gene expressions of gluconeogenic enzymes, glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK). Inclusion of catechin-rich green tea beverage (GTB) in the culture medium reduced the up-regulation of these genes as well as that of hepatocyte nuclear factor 4 alpha (HNF4alpha) gene. GTB was fractionated into chloroform-soluble (Fraction I), ethyl acetatesoluble (Fraction II), methanol-soluble (Fraction III) and residual (Fraction IV) fractions.

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Mistletoe lectins have various biological activities including anti-cancer and immunomodulatory effects. We previously isolated a lectin (ML-J) from Japanese mistletoe. In the present study, we examined the effects of ML-J on cytokine gene expression in human colon adenocarcinoma Caco-2 cells and in the mouse intestine.

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Green tea and its constituent (-)-epigallocatechin-3-O-gallate (EGCG) are known to have apoptosis-inducing activity on tumor cells including human leukemia HL-60 cells, providing an explanation for their anti-cancer effects. In the present study, we compared the sensitivity of undifferentiated cells and differentiated HL-60 cells with normal-like phenotypic characters. HL-60 cells treated with three differentiating agents were found to be resistant to EGCG-mediated apoptosis as compared with undifferentiated cells.

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Normal rats were given catechin-rich green tea as drinking fluid and the effects on hepatic gene expression were examined. The results of DNA microarray analysis and quantitative real-time reverse transcription-polymerase chain reaction indicated the down-regulated expression of genes for glucose-6-phosphatase (G6Pase) and fatty acid synthase, and the up-regulated expression of peroxisome proliferator activated receptor alpha in the rats given green tea for 4 weeks as compared with the water-given animals. One may expect anti-diabetic activity by catechin-rich green tea through its chronic down-regulatory effect on G6Pase expression.

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