• Journal of Life Science
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• v.25 no.9
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• pp.961-969
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• 2015

Epigallocatechin gallate (EGCG), the main catechin in green tea, has been shown to have some beneficial effects against various human diseases, including diabetes, neurodegenerative disorders, cancer, cardiovascular disease and obesity. To investigate the mechanism of the suppressive effects of EGCG on inflammatory response in macrophages, alterations on the levels of nitric oxide (NO) regulatory factors and inflammatory cytokines were measured in lipopolysaccharide (LPS)-activated RAW264.7 cells. No significant toxicity was detected in RAW264.7 cells treated with 100–400 μM EGCG. Moreover, the optimal concentration of LPS was determined to be 1 μg/ml based on the results of cell viability assay, NO assay and IL-6 enzyme-linked immunsorbent assay (ELISA). Furthermore, NO levels decreased significantly by 68.2% in the 400 μM EGCG/LPS treated group, while the level of inducible nitric oxide synthase (iNOS) expression decreased by 12-17% in the 200 and 400 μM EGCG/LPS treated group. A significant decrease in transcription of pro-inflammatory cytokines (TNF- α and IL-1β) and anti-inflammatory cytokine (IL-10) was also detected in the EGCG/LPS treated group. However, IL-6 transcript and protein was maintained at a constant level when in the LPS treated group relative to the EGCG/LPS treated group. Overall, these results suggest that the differential regulation of inflammatory cytokines is an important factor influencing the suppressive effects of EGCG against LPS-activated inflammatory response in RAW264.7 cells.

• Molecular & Cellular Toxicology
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• v.5 no.4
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• pp.298-303
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• 2009

(-)-Epigallocatechin-3-gallate (EGCG), a major flavonoid in green tea has multiple health benefits including chemoprevention, anti-inflammatory, anti-diabetic, and anti-obesity effects. In connection with these effects, EGCG can be a candidate to help the treatment of metabolic diseases. Metformin is a widely used anti-diabetic drug regulating cellular energy homeostasis via AMP-activated protein kinase (AMPK) activation. Therefore, the combination of metformin with EGCG may have additive or synergistic effects on treatment of type 2 diabetes. Nevertheless, there is no report for the pharmacokinetic and/or pharmacodynamic interaction of EGCG with metformin. Here, we evaluated the pharmacokinetic and pharmacodynamic interaction between metformin and EGCG in rats. Pharmacokinetics parameters of metformin were measured after oral administration of metformin in rats pre-treated with EGCG (10 mg/kg) or saline for 7 days. The results showed that there is no significant difference in pharmacokinetic parameters between saline control and EGCG-treated group. In addition, the hepatic AMPK activation by metformin in EGCG-treated rats was also similar to the control. The lack of additive effects of EGCG on AMPK activation or intracellular uptake of metformin was also evaluated in cells in the presence or absence of EGCG. Treatment of HepG2 cells with EGCG inhibited the metformin-induced AMPK activation. Combined results suggested that EGCG has no effect on the pharmacokinetics of metformin but may contribute to metformin action.

• Journal of Life Science
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• v.32 no.11
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• pp.841-846
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• 2022

The purpose of this study was to evaluate the antioxidant properties of Rosa rugosa extract and to identify which of its components are responsible for these properties. Reactive oxygen species play an important role in diseases such as cancer, arteriosclerosis, and heart disease as a consequence of increased metabolic rates, gene mutations, and relative hypoxia. Therefore, the antioxidant effect of R. rugosa extract was confirmed by HPLC, HPLC-MS/MS, the total polyphenol content, the total flavonoid content, and the radical scavenging activity. HPLC and HPLC-MS/MS analyses were conducted to identify and quantify the main components of the R. rugosa extract. Gallic acid and epigallocatechin gallate were identified as the main components, with 17.4 and 4.35 mg/g dry matter (DM), respectively. The antioxidant activity of R. rugosa extract was evaluated based on its total polyphenol content, total flavonoid content, and radical scavenging activity, which were 72.3 mg gallic acid equivalent/g DM, 11.2 mg quercetin equivalent/g DM, and 87.9%, respectively. The radical scavenging activities of the main components, gallic acid and epigallocatechin gallate, were 80.5% and 89.7%, respectively. Therefore, R. rugosa has a high polyphenol content and antioxidant activity, and it can be used as a natural antioxidant in food, cosmetics, and pharmaceuticals.

• Journal of Veterinary Science
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• v.23 no.5
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• pp.74.1-74.16
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• 2022

Background: Previous studies have presented evidence to support the significant association between red meat intake and colon cancer, suggesting that heme iron plays a key role in colon carcinogenesis. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, exhibits anti-oxidative and anti-cancer effects. However, the effect of EGCG on red meat-associated colon carcinogenesis is not well understood. Objectives: We aimed to investigate the regulatory effects of hemin and EGCG on colon carcinogenesis and the underlying mechanism of action. Methods: Hemin and EGCG were treated in Caco2 cells to perform the water-soluble tetrazolium salt-1 assay, lactate dehydrogenase release assay, reactive oxygen species (ROS) detection assay, real-time quantitative polymerase chain reaction and western blot. We investigated the regulatory effects of hemin and EGCG on an azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colon carcinogenesis mouse model. Results: In Caco2 cells, hemin increased cell proliferation and the expression of cell cycle regulatory proteins, and ROS levels. EGCG suppressed hemin-induced cell proliferation and cell cycle regulatory protein expression as well as mitochondrial ROS accumulation. Hemin increased nuclear factor erythroid-2-related factor 2 (Nrf2) expression, but decreased Keap1 expression. EGCG enhanced hemin-induced Nrf2 and antioxidant gene expression. Nrf2 inhibitor reversed EGCG reduced cell proliferation and cell cycle regulatory protein expression. In AOM/DSS mice, hemin treatment induced hyperplastic changes in colon tissues, inhibited by EGCG supplementation. EGCG reduced the hemin-induced numbers of total aberrant crypts and malondialdehyde concentration in the AOM/DSS model. Conclusions: We demonstrated that EGCG reduced hemin-induced proliferation and colon carcinogenesis through Nrf2-inhibited mitochondrial ROS accumulation.

• Journal of Nutrition and Health
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• v.39 no.8
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• pp.748-755
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• 2006

The purpose of this study was to find out effects of treatment of ginsenoside Re, Rc and EGCG on mRNA expressions of leptin, hormone sensitive lipase (HSL) and resistin in 3T3-L1 adipocytes. The concentrations of EGCG were treated with $0.01{\times}10^{-7},\;0.1{\times}10^{-7},\;1{\times}10^{-7}\;and\;1{\times}10^{-6}\;or\;100{\mu}g/ml$ ginsenoside Re, Rc in culture cell for 13 days. mRNA expression of leptin wasn't expressed in preadipocyte but according to differentiation of adipocyte, the that of mRNA expression was decreased at gensenosids or EGCG treated cells compared with non treated adipocyte. Expression of HSL mRNA was increased in G-Re, G-Rc and EGCG treated cells compared with non treated cells. The resistin level was significantly decreased in adipocytes treated with G-Re, G-Rc and EGCG. These pattern was similar to leptin expression. These results support that treatment of gensenosides or EGCG in 3T3-L1 adipocyte resulted to affect of leptin and resistin as well as HSL mRNA levels, accordingly, levels of leptin and HSL will be acted by signalling body fat stores to the hypothalamus which in turn regulates food intake andenergy expenditure to maintain body weight homeostasis. And also regulation of resistin mRNA will prevent to diabetics attacked with obesity. In conclusion, we suggest that consumption of ginseng saponine or EGCG might prevent human diabetics or/and obesity.

• Journal of Food Hygiene and Safety
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• v.31 no.1
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• pp.1-7
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• 2016

In the present study, our aim was to determine whether green tea extract (GTE) and its major constituent, epigallocatechin-3-gallate (EGCG) have a protective effect on ethanol-induced cytotoxicity and DNA damage in NIH/3T3 and HepG2 cells. The cell viability and DNA single strand breaks were examined by MTT assay and alkaline single cell gel electrophoresis (Comet assay), respectively. Ethanol decreased the cell viability and also increased DNA single strand breaks in a concentration-dependent manner. On the other hand, GTE showed the protective effect of cytotoxicity and DNA damage induced by ethanol in both cell lines. GTE and EGCG, were found to possess the anti-oxidative and anti-genotoxic activities by evaluation with DPPH test, LDL oxidation assay, oxidative DNA damage assay and 8OH-2'dG generation test. These results were also verified by the experimental results demonstrating the lower cytotoxicity and genotoxicity of commercial green tea liqueur compared to pure ethanol in same concentration. Thus it is concluded that the supplementation of GTE or EGCG may mitigate the ethanol-induced cytotoxicity and DNA damage.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.1
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• pp.61-66
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• 2014

Lung cancer is still the number one cause of death from cancer worldwide. The clinical effect of platinum-based chemotherapy for non-small cell lung cancer is constrained by the resistance to drug. To overcome chemo-resistance, various modified treatment including combination therapy has been used, but overall survival has not been improved yet. In this study, chemo-resistant lung cancer cells, A549/Cis and H460/Cis, were developed by long-term exposure of cells to cisplatin and the proliferative capability of these resistant cells was verified to be reduced. We found cytotoxic effect of epigallocatechin gallate (EGCG), a major catechin derived from green tea, on both the parental lung cancer cells, A549 and H460, and their cisplatin resistant cells, A549/Cis and H460/Cis. ELISA and Western blot analysis revealed that EGCG was able to increase interlukine-6 (IL-6) production per cell, whereas its downstream effector Signal transducers and activators of transcription 3 (STAT3) phosphorylation was not changed by EGCG, indicating that IL-6/STAT3 axis is not the critical signaling to be inhibited by EGCG. We next found that EGCG suppresses the expression of both Axl and Tyro 3 receptor tyrosine kinases at mRNA and protein level, explaining the cytotoxic effect of EGCG on lung cancer cells, especially, regardless of cisplatin resistance. Taken together, these data suggest that EGCG impedes proliferation of lung cancer cells including their chemo-resistant variants through downregulation of Axl and Tyro 3 expression.

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.188-199
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• 2017

Objectives: This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. Materials and Methods: Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups (n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio-Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. Results: At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only (p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resindentin bond strength with no significant fall. Conclusions: Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

• Food Science and Biotechnology
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• v.15 no.2
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• pp.177-182
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• 2006

Polyphenol oxidase (PPO) was isolated from the flesh of Fuji apples by DEAE-Cellulose, ammonium sulfate precipitation, phenyl-Sepharose CL-4B, and Sephdex G-100 chromatography. The molecular mass of the purified PPO was estimated to be 40 kDa by SDS polyacrylamide gel electrophoresis. With regard to substrate specificity, maximum activity was achieved with chlorogenic acid as substrate, followed by catechin and catechol whereas, there was no detectable activity with hydroquinic acid, resorcinol, or tyrosine as substrate. The optimum pH and temperature with catechol as substrate were 6.5 and $35^{\circ}C$, respectively. The enzyme was most stable at pH 6.0 and unstable at acidic pH. The enzyme was stable when it was heated to $45^{\circ}C$ but heating at $50^{\circ}C$ for more than 30 min caused 50% loss of activity. Reduced $ZnSO_4$, L-cystein, epigallocatechin-3-o-gallate (EGCG), and gallocatechin gallate (GCG) also inhibited activity.

• Journal of Life Science
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• v.28 no.10
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• pp.1201-1211
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• 2018

The study compared the anti-aging, anti-adipogenesis, and anti-tumor effects of epigallocatechin-3- gallate (EGCG) in various cancer cell lines (SNU-601, MKN74, AGS, MCF-7, U87-MG, and A-549) and normal cell lines (MRC-5 fibroblasts, dental tissue-derived mesenchymal stem cells [DSC], and 3T3-L1 pro-adipocytes). Half inhibitory concentration ($IC_{50}$) values were significantly (p<0.05) higher in normal cell lines (~50 uM), when compared to that in cancer cell lines (~10 uM). For anti-aging effects, MRC-5 and DSC were exposed to 10 uM EGCG for up to five passages that did not display any growth arrest. Population doubling time and senescence-related ${\beta}-galactosidase$ ($SA-{\beta}-gal$) activity in treated cells were similar to untreated cells. For anti-adipogenic effects, mouse 3T3-L1 pre-adipocytes were induced to adipocytes in an adipogenic differentiation medium containing 10 uM EGCG, but adipogenesis in 3T3-L1 cells was not inhibited by EGCG treatment. For anti-tumor effects, the cancer cell lines were treated with 10 uM EGCG. PDT was significantly (p<0.05) increased in EGCG-treated SNU-601, AGS, MCF-7, and U87-MG cancer cell lines, except in MKN74 and A-549. The level of telomerase activity and cell migration capacity were significantly (p<0.05) reduced, while $SA-{\beta}-gal$ activity was highly up-regulated in EGCG treated-cancer cell lines, when compared to that in untreated cancer cell lines. Our results have demonstrated that EGCG treatment induces anti-tumor effects more efficiently as noted by decreased cell proliferation, cell migration, telomerase activity, and increased $SA-{\beta}-gal$ activity than inducing anti-aging and anti-adipogenesis. Therefore, EGCG at a specific concentration can be considered for a potential anti-tumor drug.