• Journal of Nutrition and Health
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• v.34 no.7
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• pp.734-740
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• 2001

The purpose of this study was to investigate the effect of green tea catechins on the antioxidative defense enzyme activity of kidney in diabetic rats. Sprague-Dawley male rats weighting 100$\pm$10g were randomly assigned to one normal and three STZ-induced diabetic groups; catechin free diet(DM-0C group), 0.25% catechin diet(DM-0.25C group) and 0.5% catechin diet(DM-0.5C group). Diabetes was induced by intravenous of 55mg/Kg body weight of STZ in sodium citrate buffer(pH 4.3) after 4 weeks feeding of experimental diets. Rats were sacrified at the 6th day of diabetic states. Superoxide dismutase(SOD) activity in kidney was decreased by 25% and 20% in DM-0C and DM-0.25C groups compared with normal group, DM-0.5C group was not significantly different when compared with normal group. Glutathione peroxidase(GSHpx) activity in kidney was were no significant differences the diabetic groups compared to normal group. Xanthin oxidase(XOD) activity was increased by 110% and 63% in DM-0C and DM-0.25C groups compared with normal group, DM-0.5C group was not significantly different when compared with normal group. The contents of superoxide radical(O$_2$)in kindney were 116% and 33%, respectively, higher in DM-0C and DM-0.25C groups than normal group. DM-0.5C group and normal groups were similar levels in their superoxide radical contents of kidneys. Levels of TBARS(thiobarbituric acid reactive substance) in kidney were increased by 62% in DM-0C group, when compared with normal group, but those of DM-0.5C group were similar to that of normal groups. These results indicate that free radical generation system was weakened and free radical scavenger system was enhance in kidney of STZ-induced diabetics rats by dietary catechin. Thereby it may reduce renal disorders such as oxidative damage and aging of tissue.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05b
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• pp.59-72
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• 2002

The anticarcinogenic effects of epicatechin(EC) and ginsenoside Rb2(Rb2), which are major components of green tea and Korea ginsen, respectively, were investigated using a model system of gap junctional intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. 12-O-Tetradecanoylphorbol-13-accetate (TPA) and hydrogen preoxide, known as cancer promoters, inhibited GJIC in the epithelial cells as determined by the scrape loading/dye transfer assay, fluorescence redistribution assay after photobleaching, and immunofluorescent staining of connexin 43 using a laser confocal microscope. The inhibition of GJIC by TPA and H2O2 was prevented with treatment of Rb2 or Ec. The effect of EC on GJIC was stronger in TPA-treated cells than in H2O2-treated cells, while the effect of Rb2 was opoosite to that of EC. EC, at the concentration of 27.8$\mu$g/ml, prevented the TPA-induced GJIC inhibition by about 60%. Rb2, at the concentration of 277$\mu$g/ml, recovered the H2O2-induced GJIC inhibition by about 60%. These results suggest that Rb2 and EC may prevent human cancers by preventing the down-regulation of GJIC during the cancer promotion phase and that the anticancer effect of green tea and Korea ginseng may come from the major respective conponents, EC and Rb2.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.338-345
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• 2012

This study was developed to test the effectiveness catechin beverage drinking as exercise supplementary food for obese women. The effects of catekin were determined by weight, total cholesterol, triglycerides, High density lipoprotein cholesterol, high density lipoprotein cholesterol. Twenty-seven obese women were participated in this study. Eight women were tea catechin drinking group, Nine women were exercise group, and ten women were tea catekin drinking-combined with exercise group. After catechin drinking or exercise conducted, blood lipid factor were analyzed. body weight and triglycerides low density lipoprotein cholesterol levels were significantly decreased in tea catekin drinking combined with exercise group (p<0.001) and exercise group (p<0.001). total cholesterol were significantly decreased in three groups (p<0.05). It is thought that together catechin drinking and exercise can maximize weight loss of obese woman and reducing of blood lipid factor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.6
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• pp.818-823
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• 2011

Recently, we showed that green tea extract (GTE) markedly lowers the intestinal absorption of $^{14}C$-benzo[a]pyrene ($^{14}C$-BaP) and enhances its secretion into the biliary route, suggesting a protective role for GTE against body burden. These findings indicate that green tea could be used as an effective dietary means against the toxicity of BaP. The present study, therefore, was designed to investigate if green tea intake could affect the tissue distribution and deposition of $^{14}C$-BaP in rats. Male Sprague-Dawley rats had free access to a nutritionally adequate AIN-93G diet and deionized water. At ~340 g of weight, the rats were injected intraperitoneally with 27.4 kBq of [4-$^{14}C$]-BaP and 5.0 mg of BaP dissolved in $300\;{\mu}L$ of olive oil and then assigned randomly to the following two groups: one group (GTE) of rats was fed the AIN-93G diet with GTE via drinking water at approx. 4.7 mg of catechins/d, whereas the other was fed the same diet but without GTE (control). At 4 wk of dietary treatment with GTE, animals were euthanized and heart, liver, brain, spleen, kidney, retroperitoneal fat, testis, and epididymal fat were collected, weighed, and analyzed for tissue $^{14}C$-BaP. Both the control and GTE groups continuously gained weight throughout the study, but there was no significant difference between the groups. No significant differences were observed in the weights of heart, liver, brain, spleen, kidney, retroperitoneal fat, testis, and epididymal fat. However, the radioactivities of $^{14}C$-BaP, expressed in dpm/g, were significantly lower in the heart, liver, brain, spleen, and epididymal fat of rats receiving GTE as compared to their respective controls. These data indicate that green tea intake markedly lowers tissue accumulation of $^{14}C$-BaP. Taken together, these findings suggest that the decreased tissue levels of BaP by GTE intake may be associated with lowered intestinal absorption of BaP and its enhanced secretion into the bile.

• Korean Journal of Food Science and Technology
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• v.52 no.5
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• pp.427-434
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• 2020

This study was performed to compare nutritional compounds and physiological functions of five domestic and imported green tea cultivars at three time points. The five cultivars were compared for theanine, γ-aminobutyric acid, and catechin content by LC-MS/MS and HPLC. Furthermore, the five tea cultivars were functionally characterized with respect to antioxidant activity, brain cell protective effect, and inhibitions of α-glucosidase and HMG-CoA reductase activities. Among green tea cultivars, Chamnok had the highest content of catechins (198 mg/g DW), theanine (11.89 mg/g DW), and tannin (23.6 mg/g DW). Considering functional properties, Chamnok treatment resulted in the maximum viability of brain cells and reduced the cortisol content of SH-SY5Y cells. The inhibition of α-glucosidase and HMG-CoA reductase was the strongest following Chamnok treatment (72.9% and 69.8%, respectively). These results indicate that Chamnok could be optimal for consumption or favorable processing owing to its high nutritional compounds, such as theanine and catechin, and remarkable brain cell protective effects.

• Archives of Pharmacal Research
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• v.23 no.6
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• pp.605-612
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• 2000

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase IIgene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 $\mu\textrm{m}$with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 $\mu\textrm{m}$ to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP.

• Biomolecules & Therapeutics
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• v.21 no.1
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• pp.54-59
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• 2013

In this study, we investigated the effect of (-)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins from green tea leaves, on activities of cyclooxygenase (COX)-1 and thromboxane synthase (TXAS), thromboxane $A_2$ ($TXA_2$) production associated microsomal enzymes. EGCG inhibited COX-1 activity to 96.9%, and TXAS activity to 20% in platelet microsomal fraction having cytochrome c reductase (an endoplasmic reticulum marker enzyme) activity and expressing COX-1 (70 kDa) and TXAS (58 kDa) proteins. The inhibitory ratio of COX-1 to TXAS by EGCG was 4.8. These results mean that EGCG has a stronger selectivity in COX-1 inhibition than TXAS inhibition. In special, a nonsteroid anti-inflammatory drug aspirin, a COX-1 inhibitor, inhibited COX-1 activity by 11.3% at the same concentration ($50{\mu}M$) as EGCG that inhibited COX-1 activity to 96.9% as compared with that of control. This suggests that EGCG has a stronger effect than that of aspirin on inhibition of COX-1 activity. Accordingly, we demonstrate that EGCG might be used as a crucial tool for a strong negative regulator of COX-1/$TXA_2$ signaling pathway to inhibit thrombotic disease-associated platelet aggregation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.1
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• pp.1-10
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• 2008

Oral squamous cell carcinoma (OSCC) is the most frequent form of oral cancer and holds the eighth position in the cancer incidence ranking. OSCC patients are treated by classical therapeutic modalities consisting of surgery, radiotherapy, and/or chemotherapy. But OSCC still shows significant mortality rates. Thus, new therapeutic approaches have been investigated and the most promising one is naturally acquired agents with known anti-cancer effects. Genistein is a compound extracted from soy bean. Its anti-cancer effect on breast cancer is well established now and it is investigated whether it has similar effect on OSCC. It inhibited the growth and invasive-ness of OSCC cells in vitro, but these effects did not work in living animals in vivo. Catechin is a compound from green tea and its anti-cancer effect on OSCC is known better than other agents. Catechin showed its anti-cancer effect in vitro via induction of apoptosis, cell cycle arrest, inhibition of growth, and down-regulation of invasion/metastasis. These effects were confirmed in vivo with mouse model. Cordycepin is one of major pharmacologically important components in Cordyceps Militaris and may exert its anti-cancer effect as an adenosine receptor agonist. In recent study, it inhibited the proliferation of OSCC cells via A3 adenosine receptor. But because there is very scarce evidence on this effect, more researches are needed on this theme.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.6
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• pp.1187-1193
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• 1997

The purpose of this study was to investigate the effects of green tea catechin on lipid metabolism in streptozotocin(STZ)-induced diabetic rats. Male Sprague-Dawley rats weighing 150$\pm$10gm were randomly assigned to one normal and three STZ-induced diabetic groups. Diabetic animals were fed catechin free diet(DM-0C group), 0.5% catechin diet(DM-0.5C group) and 1% catechin diet(DM-1C group). Diabetes was experimentally induced by intravenous injection of 55mg/kg body wt of STZ in citrate buffer(pH 4.3) after feeding of three experimental diets for 4 weeks. Animals were sacrificed at the 6th day of diabetic states. Levels of blood glucose were three fold higher in all three STZ-induced diabetic groups than that of the normal group. The levels of plasma insulin were markedly lower in three STZ-induced diabetic groups than that of the normal group. The levels of plasma cortisol were increased in DM-0C group compared with that of the normal group. Triglyceride, total-cholesterol and LDL-cholesterol levels in serum were increased in DM-0C groups compared with the normal group but were not significantly different between catechin diet groups and normal group. Serum HDL-cholesterol levels were reduced in DM-0C and DM-0.5C groups by 38% and 25%, respectively and had similar tendency in the DM-1C group compared with that of control group. Atherogenic index have shown same pattern as the result of total cholesterol. Activities of 3-hydroxy-3-methylglutaryl Co enzyme A(HMG-CoA) reductase were higher in DM-0C groups than those of the normal group but were not significantly different between catechin diet groups and the normal group. It is concluded that dietary catechins can modulate lipid levels of serum and liver HMG-CoA reductase activity in diabetic rats.

• Journal of Dairy Science and Biotechnology
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• v.34 no.2
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• pp.69-74
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• 2016

The main constituent of tea catechins, EGCG [(-)-Epigallocatechin-3-gallate], could inhibit the growth of various microorganisms and differently affect gram-positive and gram-negative bacteria. Antimicrobial activity of EGCG, a compound from green tea (Camellia sinensis) extract, against Cronobacter spp. and Salmonella spp. was studied to evaluate the possibility of using EGCG as a natural food additive in various dairy products. In pure TSB culture, the growth of Cronobacter spp. was suppressed below the detection limit (1 log CFU/mL) depending on EGCG concentration ($600{\sim}800{\mu}g/mL$), after 5~16 days at $4^{\circ}C$. Similarly, the growth of Salmonella spp. was suppressed below the detection limit (1 log CFU/mL) depending on EGCG concentration ($400{\sim}800{\mu}g/mL$), after 5~16 days at $4^{\circ}C$. Therefore, these results suggest that EGCG could be used as an effective additive to inhibit the growth of Cronobacter spp. and Salmonella spp. in various dairy products, such as yoghurt, cheese, dried infant powder, and so on.