• Restorative Dentistry and Endodontics
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• 제38권4호
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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 the Korean Society of Food Science and Nutrition
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• 제36권8호
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• pp.983-988
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• 2007

Epigallocatechin gallate (EGCG), a principal antioxidant derived from green tea, is one of the most extensively investigated chemopreventive phytochemicals. However, the effect of EGCG on proliferation in MDA-MB-231 breast cancer cell is not well known. We investigated the effect of EGCG on protein and mRNA expression related to cell proliferation in MDA-MB-231 human breast cancer cell lines. We cultured MDA-MB-231 cells in the presence of 0, 5, 10 and 20 ${\mu}m$ of EGCG. EGCG significantly inhibited the cancer cell proliferation (p<0.05). In MDA-MB-231 huamn breast cancer cell, EGCG lowered $ErbB_2$ and $ErbB_3$ protein as well as mRNA expression. In addition, protein and mRNA expression of phosphorylated Akt and total Akt were significantly decreased (p<0.05). We suggest that EGCG inhibits cell proliferation through $ErbB_2$, $ErbB_3$ and Akt cell signaling.

• Archives of Pharmacal Research
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• 제29권10호
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• pp.874-878
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• 2006

Methyl gallate (MG) is a medicinal herbal product that is isolated from Paeonia lactiflora that inhibits cyclooxygenase-2 (COX-2) dependent phases of prostaglandin $D_2\;(PGD_2)$ generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an $IC_{50}$ values of $17.0\;{\mu}M$. This compound also found inhibited the COX-2-dependent conversion of the exogenous arachidonic acid to $PGD_2$ in a dose-dependent manner with an $IC_{50}$ values of $190\;{\mu}M$, using a COX enzyme assay kit. However, at concentrations up to $80\;{\mu}M$, MG did not inhibit COX-2 protein expression in BMMC, indicating that MG inhibits COX-2 activity directly. Furthermore, MG consistently inhibited the production of leukotriene $C_4\;(LTC_4)$ in a dose dependent manner, with an $IC_{50}$ value of $5.3\;{\mu}M$. These results demonstrate that MG has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity, which might provide the basis for novel anti-inflammatory drugs.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1717-1722
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• 2008

The 70 kDa heat-shock protein (Hsp70) involved in various cellular functions, such as protein folding, translocation and degradation, regulates apoptosis in cancer cells. Recently, it has been reported that the green tea flavonoid (−)-epigallocatechin 3-gallate (EGCG) induces apoptosis in numerous cancer cell lines and could inhibit the anti-apoptotic effect of human Hsp70 ATPase domain (hATPase). In the present study, docking model between EGCG and hATPase was determined using automated docking study. Epi-gallo moiety in EGCG participated in hydrogen bonds with side chain of K71 and T204, and has metal chelating interaction with hATPase. Hydroxyl group of catechin moiety also participated in metal chelating hydrogen bond. Gallate moiety had two hydrogen bondings with side chains of E268 and K271, and hydrophobic interaction with Y15. Based on this docking model, we determined two pharmacophore maps consisted of six or seven features, including three or four hydrogen bonding acceptors, two hydrogen bonding donors, and one lipophilic. We searched a flavonoid database including 23 naturally occurring flavonoids and 10 polyphenolic flavonoids with two maps, and myricetin and GC were hit by map I. Three hydroxyl groups of B-ring in myricetin and gallo moiety of GC formed important hydrogen bonds with hATPase. 7-OH of A-ring in myricetin and OH group of catechin moiety in GC are hydrogen bond donors similar to gallate moiety in EGCG. From these results, it can be proposed that myricetin and GC can be potent inhibitors of hATPase. This study will be helpful to understand the mechanism of inhibition of hATPase by EGCG and give insights to develop potent inhibitors of hATPase.

• Journal of Life Science
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• 제13권6호
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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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• 제15권5호
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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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• 제49권4호
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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.

• Journal of the Korean Society of Food Science and Nutrition
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• 제45권7호
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• pp.1065-1070
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• 2016

This study assessed the antioxidant activity and residue level of phenolic antioxidants in autoxidation of linoleic acid. The antioxidant activity of phenolic antioxidants was measured based on peroxide value of linoleic acid at $50^{\circ}C$ for 8 days. We further evaluated the residue level of phenolic antioxidants in the autoxidation period by HPLC-UV. The residue level of antioxidants changed with time starting on day 0 (100%) and was determined by 100-remaining of antioxidants (%). Our results showed that peroxide values ranged from 0.33 to 10.18 meq/kg in propyl gallate, from 0.67 to 11.01 meq/kg in dodecyl gallate, from 0.01 to 10.34 meq/kg in octyl gallate, from 0.01 to 4.17 meq/kg in butylated hydroxytoluene (BHT), from 1.00 to 5.85 meq/kg in butylated hydroxyanisole (BHA), from 0.33 to 4.18 meq/kg in 2,4,5-trihydroxybutyrophenone, and from 1.00 to 11.01 meq/kg in tert-butylhydroquinone (TBHQ). Among the residue levels of antioxidants, on day 8, BHT showed the highest level while TBHQ showed the lowest. BHT showed the highest correlation coefficient, whereas BHA showed the lowest. This study proves that the residual level of phenolic antioxidants has a good correlation with the degree of autoxidation in linoleic acid.

• Journal of the Korean Society of Food Science and Nutrition
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• 제32권4호
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• pp.501-505
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• 2003

In order to use as a new functional food material, chemical components of propolis and its extracts were surveyed. The contents of crude fat, nitrogen free extract, crude protein, ash and crude fiber in propolis were 86.41%, 7.32%, 2.71%, 1.05% and 0.20%, respectively. The mineral contents were in the order of Na (120.40 mg%), Ca (115.40 mg%), K (105.87 mg%) and Ca were higher in water extract than alcohol extract. Free sugars were composed of sucrose 152 mg%, glucose 114 mg% and fructose 6 mg%. The major amino acids of propolis were lysine 395.29 mg%, cystine 267.66 mg% and glutamic acid 248.14 mg%, respectively. Eight fatty acids in propolis were identified and the major fatty acids were oleic acid (51.89%), myristic acid (20.86%) and palmitic acid (20.28%). Myricetin, quercetin, apigenin and kaempferol were shown as major flavonols and total flavonol contents were higher in 50% ethanol extract than any other extracts. Major Polyphenol compounds in four kinds of extracts were gallic acid, chlorogenic acid, catechin, epigallocatechin gallate, epicatechin and epicatechin gallate.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제38권2호
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• pp.171-179
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• 2012

This study is focused on finding new natural materials that have antimicrobial activity. We found that 3 plants extracts, Magnolia sieboldii K. Koch (M. sieboldii K. Koch), Rhus chinensis (R. chinensis) and Metasequioa glyptostroboides (M. glyptostroboides), have antimicrobial activities by disk diffusion method. We determined the Minimum Inhibitory Concentation (MIC) of each and found that 0.3 ~ 0.35 % of M. glyptostroboides essential oil and 0.35 ~ 0.4 % of M. sieboldii K. Koch extracts inhibited fungal growth and 0.45 ~ 0.5 % of R. chinensis extracts inhibited bacterial growth. We isolated compounds from extracts and verified what have antimicrobial activity. As a result we found that caryophyllene oxide and caryophyllene isolated from M. glyptostroboides, costunolide and dehydrocostus lactone from M. sieboldii K. Koch and ethyl gallate, ethyl-3-gallate from R. chinensis have antimicrobial activities. In accordance with antimicrobial activity, O/W cosmetic emulsion containing mixture of 3 plants extracts showed preservative efficacy against both bacteria and fungi. Based on the above data we suggest that extracts from M. siebodii K. Koch, R. chinensis, and M. glyptostroboides, replace chemical synthetic preservatives and be applied as a natural preservative.