• The Korean Journal of Physiology and Pharmacology
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• v.11 no.5
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• pp.163-169
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• 2007

The neurotoxicity of amyloid $\beta(A\beta)$ is associated with an increased production of reactive oxygen species and apoptosis, and it has been implicated in the development of Alzheimer's disease. While(-)-epigallocatechin-3-gallate(EGCG) suppresses $A\beta$-induced apoptosis, the mechanisms underlying this process have yet to be completely clarified. This study was designed to investigate whether EGCG plays a neuroprotective role by activating cell survival system such as protein kinase C(PKC), extracellular-signal-related kinase(ERK), c-Jun N-terminal kinase(JNK), and anti-apoptotic and pro-apoptotic genes in SH-SY5Y human neuroblastoma cells. One ${\mu}M\;A{\beta}_{1-42}$ decreased cell viability, which was correlated with increased DNA fragmentation evidenced by DAPI staining. Pre-treatment of SH-SY5Y neuroblastoma cells with EGCG($1{\mu}M$) significantly attenuated $A{\beta}_{1-42}$-induced cytotoxicity. Potential cell signaling candidates involved in this neuroprotective effects were further examined. EGCG restored the reduced PKC, ERK, and JNK activities caused by $A{\beta}_{1-42}$ toxicity. In addition, gene expression analysis revealed that EGCG prevented both the $A{\beta}_{1-42}$-induced expression of a pro-apoptotic gene mRNA, Bad and Bax, and the decrease of an anti-apoptotic gene mRNA, Bcl-2 and Bcl-xl. These results suggest that the neuroprotective mechanism of EGCG against $A{\beta}_{1-42}$-induced apoptotic cell death includes stimulation of PKC, ERK, and JNK, and modulation of cell survival and death genes.

• Restorative Dentistry and Endodontics
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• v.38 no.4
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• pp.241-247
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• 2013

Objectives: The aim of this study was to determine the effect of epigallocatechin gallate (EGCG) on the shear bond strength of composite resin to bleached enamel. Materials and Methods: Ninety enamel surfaces of maxillary incisors were randomly divided into 9 groups as follows: G1: control (no bleaching); G2: bleaching; G3: bleaching and storage for seven days; G4 - 6: bleaching and application of 600, 800 and 1,000 ${\mu}mol$ of EGCG-containing solution for 10 minutes, respectively; G7 - 9: bleaching and application of 600, 800 and 1,000 ${\mu}mol$ of EGCG-containing solution for 20 minutes, respectively. The specimens were bleached with 30% hydrogen peroxide gel and a composite resin cylinder was bonded on each specimen using a bonding agent. Shear bond strength of the samples were measured in MPa. Data was analyzed using the two-way ANOVA and Tukey HSD tests (${\alpha}$ = 0.05). Results: The maximum and minimum mean shear bond strength values were observed in G1 and G2, respectively. Time and concentration of EGCG showed no significant effects on bond strength of the groups (p > 0.05). Multiple comparison of groups did not reveal any significant differences between the groups except for G2 and all the other groups (p < 0.05). Conclusions: There is a significant decrease in bond strength of composite resin to enamel immediately after bleaching. A delay of one week before bonding and the use of EGCG increased bond strength of composite resin to bleached enamel.

• Journal of Life Science
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• v.13 no.6
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• pp.924-932
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• 2003

Epigallocatechin-3 Gallate (EGCG), a major constituent of green tea, has attracted increasing interest because of its many reported health benefits. Here we demonstrate for the first time that EGCG stimulates phospholipase D (PLD) activity in U87 human astroglioma cells. EGCG-induced PLD activation was abolished by the phospholipase C (PLC) inhibitor and a lipase inactive PLC-\gama1$ mutant, and was dependent on intracellular $Ca^{ 2+}$, and possibly involved $Ca^{ 2+}$ calmodulin-dependent protein kinase II (CaM kinase II). Interestingly, EGCG induced translocation of PLC-\gama1$ from the cytosol to the membrane and PLC-\gama1$interaction with PLD1. Taken together, these results demonstrate for the first time that in human astroglioma cells, EGCG regulates PLD activity via a signaling pathway involving a PLC-\gama1$ (inositol 1,4,5-trisphosphate-$Ca^{ 2+}$)-CaM kinase II-PLD pathway.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.5
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• pp.259-266
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• 2011

The aim of this study was to evaluate the preventive role of epigallocatechin-3 gallate (EGCG, a derivative of green tea) in ischemia/reperfusion (I/R) injury of isolated rat hearts. It has been suggested that EGCG has beneficial health effects, including prevention of cancer and heart disease, and it is also a potent antioxidant. Rat hearts were subjected to 20 min of normoxia, 20 min of zero-flow ischemia and then 50 min of reperfusion. EGCG was perfused 10 min before ischemia and during the whole reperfusion period. EGCG significantly increased left ventricular developed pressure (LVDP) and increased maximum positive and negative dP/dt (+/-dP/dtmax). EGCG also significantly increased the coronary flow (CF) at baseline before ischemia and at the onset of the reperfusion period. Moreover, EGCG decreased left ventricular end diastolic pressure (LVEDP). This study showed that lipid peroxydation was inhibited and Mn-SOD and catalase expressions were increased in the presence of EGCG. In addition, EGCG increased levels of Bcl-2, Mn-superoxide dismutase (SOD), and catalase expression and decreased levels of Bax and increased the ratio of Bcl-2/Bax in isolated rat hearts. Cleaved caspase-3 was decreased after EGCG treatment. EGCG markedly decreased the infarct size while attenuating the increase in lactate dehydrogenase (LDH) levels in the effluent. In summary, we suggest that EGCG has a protective effect on I/R-associated hemodynamic alteration and injury by acting as an antioxidant and anti-apoptotic agent in one.

• Korean Journal of Pharmacognosy
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• v.49 no.4
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• pp.328-335
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• 2018

'EGCG(epigallocatechin gallate) rich Green Tea extract(EGTE)' was prepared by a convenient chromatographical manner using water and alcohol which was regarded as the most suitable and appropriate process for food manufacturing. The EGCG content in EGTE was estimated above 97%. Analysis of polyphenol components in green tea, i.e., catechin(C), epigallocatechin(EGC), epicatechin(EC), epigallocatechin gallate(EGCG), epicatechin gallate(ECG) and caffeine was performed by HPLC. The optimized HPLC method exhibited a good linearity of calibration curve, accuracy and precision. The long-term stability evaluation of EGTE was carried out with a powdered formulation and solution formulation by estimating the color change and measuring the EGCG content by HPLC analysis for one year. The EGCG content of the powdered EGTE stored in a transparent bottle at room temperature was retained over 97% at the end of the experimental period. The EGCG content of 0.1% water solution of EGTE stored in a transparent bottle at RT were observed to decrease below 30%, whereas that stored at $2^{\circ}C$ retained over 70%, respectively. These results suggested that a powdered formulation could be recommended for the commercialized nutraceutical product of EGTE rather than a solution formulation.

• Food Science and Preservation
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• v.16 no.6
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• pp.946-952
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• 2009

We investigated the physicochemical properties and antioxidant activities of green tea with respect to extraction conditions. The values of pH, and the L, a, and b Hunter parameters of green tea beverage 1 (GTB 1), green tea beverage 2 (GTB 2), and commercial green tea beverage (CGTB) were 6.22, 96.91, -1.06, and 7.77 5.40, 96.39, -1.73, and 13.68 and 6.20, 95.40, -4.75, and 25.51, respectively. The total free amino acid content of GTB 1 and 2, and CGTB, were 253.21, 262.65, and 58.36 mg/100 mL, and the major free amino acids were aminoadipic acid (102.56, 136.29, and 27.02 mg/100 mL), arginine (23.32, 30.75, and 7.31 mg/100 mL), and serine (18.22, 17.96, and 5.94 mg/100 mL). The levels of total phenolics and caffeine were higher in GTB 2 (852.58 and $225.51\;{\mu}g/mL$) than in GTB 1 (500.65 and $317.34\;{\mu}g/mL$) or CGTB (387.14 and $164.53\;{\mu}g/mL$). The catechin content of GTBs 1 and 2, and CGTB, were 294.8, 415.7, and $130.99\;{\mu}g/mL$, respectively. The major catechins of GTB 1 and 2, and CGTB were epigallocatechin, catechin, and epigallocatechin gallate, in that order, and the epigallocatechin contents were 186.50 in GTB 1, 268.10 in GTB 2, and $82.26\;{\mu}g/mL$ in CGTB. GTB 1 and 2 and CGTB showed substantial dose-dependent antioxidative activities. The DPPH radical-scavenging activities of GTB 1 and 2, and CGTB, were 85.48, 87.09, and 87.03%, respectively at a concentration of $125\;{\mu}g/mL$. The ferric reducing/antioxidant activities (FRAPs) of GTB 1 and 2 and CGTB were 2.66, 2.70 and 2.67 absorbance at a concentration of $1,000\;{\mu}g/mL$. Sensory evaluation tests revealed no significant differences among the three green tea beverages.

• Journal of the Korean Society of Food Culture
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• v.18 no.5
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• pp.443-456
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• 2003

The lyophilization of the solution extracted from 60 percent of acetone applied to persimmon leaves, the compounding process in accordance with the solution's concentration, and the gel filteration through Sephadex G-50 of biologically activated substances obstructing enzyme activity, such as tyrosinase, xanthine oxidase, and angiotesin converting enzyme (ACE) led to the assumption that polyphenol was the compound serving as biologically activated substances obstructing enzyme activity. Xanthine oxidase involved in pruine metabolism oxidizes hypoxanthine to xanthine and xanthine to uric acid. In the continuous study for natural compound, nine flavan-3-ols have been isolated from the persimmon leaves. The structures of (+)-catechin, (+)-gallocatechin, procyanidin B-1, pyrocyanidin C-1, prodelphinidin B-3, gallocatechin-$(4{\alpha}{\rightarrow}8)$-catechin, procyanidin B-7-3-O-gallate, procyanidin C-1-3'-3'-3'-O-trigallate and (-)-epigallocatechin-$(4{\alpha}{\rightarrow}8)$-epigallocatechin-$(4{\alpha}{\rightarrow}8)$-catechin were established by NMR and their inhibitory effect on xanthine oxidase activity was investigated. Procyanidin B-7-3-O-gallate, (-)-epigallocatechin-$(4{\alpha}{\rightarrow}8)$-epigallocatechin-$(4{\alpha}{\rightarrow}8)$-catechin and procyanidin C-1-3'-3'-3'-O-trigallate showed 94%, 90.69%, 80.90% inhibition at $100\;({\mu})M$ and inhibited on the angiotensin converting enzyme respectively. Procyanidin B-7-3-O-gallate and procyanidin C-1-3'-3'-3'-O-trigallate showed 66%, 63% inhibition at $100\;({\mu})M$ and inhibited on the xanthine oxidase competitively. Procyanidin C-1-3'-3'-3'-O-trigallate showed 70% inhibition at $100\;({\mu})M$ and inhibited on the tyrosinase competitively.

• 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.

• Journal of Chest Surgery
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• v.40 no.4 s.273
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• pp.256-263
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• 2007

Background: Intimal hyperpiasia is characterized by a proliferation of vascular smooth muscle cells in the intimal layer Epigallocatechin-3-gallate (EGCG) is known to suppress smooth muscle cell proliferation. We propose that EGCG may have a protective effect against the development of intimal hyperplasia through the suppression of smooth muscle cell proliferation. Material and Method: Human umbilical vein endothelial cells (HUVEC) and rat aortic smooth muscle cells (RASMC) were cultured with different concentrations of EGCG, and proliferation and migration speed were measured. In 20 dogs, the autologous jugular veins were interposed into the carotid arteries. For the study group (n=10), the graft was stored for 30 minutes in EGCG solution and 300mM EGCG was applied to the perivascular space after grafting. After 6 weeks, the intimal and medial thickness was measured. Result: The proliferation of RASMC and HUVEC was suppressed with EGCG. The migration of RASMC was suppressed with EGCG, but that of HUVEC was not affected. In the in vivo study, the intimal thickness was thinner in EGCG group than in the control group (p<0.05), but the medial thickness did not show any difference. The intimal/medial thickness ratio was lower in the EGCG group (p<0.05). Conclusion: EGCG suppresses intimal hyperplasia after vascular grafting, and this may be mediated by prevention of migration and proliferation of vascular smooth muscle cells. The use of EGCG may offer new therapeutic modality to prevent intimal hyperplasia.

• Korean Journal of Food Science and Technology
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• v.43 no.4
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• pp.483-489
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• 2011

Epigallocatechin-3-gallate (EGCG) is a polyphenolic compound frequently found in green tea, and its physiological actions have been extensively investigated. In the present study, changes in chemical stability and cytotoxic properties of EGCG in the presence of different types of antioxidants were investigated. The antioxidants used modulated the chemical stability of EGCG. Superoxide dismutase (SOD) significantly increased EGCG stability; EGCG was less stable in the presence of catalase. Ascorbic acid, N-acetylcysteine (NAC), and glutathione (GSH) stabilized EGCG concentration dependently. The $H_2O_2$ level generated from EGCG was decreased by catalase, SOD, and NAC but not by GSH. The cytotoxic effects of EGCG also decreased in the presence of NAC, catalase, and SOD. GSH, however, showed a complicated modulatory pattern according to the EGCG and GSH concentrations, and ascorbic acid rather enhanced EGCG toxicity. The results suggest that certain antioxidants could modulate the cytotoxic properties of EGCG in a cell culture system not only by removing reactive oxygen species but by modulating chemical stability and other factors, which should be considered carefully when studying reactive oxygen species-dependent mechanisms of EGCG.