• Archives of Pharmacal Research
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• v.27 no.3
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• pp.334-339
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• 2004

In this study, the effects of (-)-epigallocatechin-3-gallate (EGCG) and/or hinokitiol (${\beta}-thujaplicin$) on melanogenesis were investigated. Our results showed that both EGCG and hinokitiol significantly inhibited melanin synthesis in a concentration-dependent manner, and that their hypopigmenting effects were stronger than that of kojic acid, which is known to inhibit melanin formation in melanocytes and melanoma cells. Interestingly, EGCG did not show any additive hypopigmenting effect in combination with kojic acid, though EGCG did show a synergistic effect in combination with hinokitiol. Several reports indicate that the activation of extracellular signal-regulated kinase (ERK) induces microphthalmia-associated transcription factor (MITF) degradation. Accordingly, the effects of EGCG and hinokitiol on the ERK signaling pathway were examined. EGCG and hinokitiol induced neither ERK activation nor MITF degradation. On the other hand, both EGCG and hinokitiol reduced the protein levels of MITF and of tyrosinase, the rate limiting melanogenic enzyme, whereas kojic acid had no effect. In addition, hinokitiol strongly downregulated the activity of tyrosinase, whereas EGCG or kojic acid had only a little effect. These results show that both EGCG and hinokitiol reduce MITF production, and suggest that reduced tyrosinase activity by hinokitiol explains their synergistic effect on melanogenesis.

• Korean Journal of Pharmacognosy
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• v.45 no.2
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• pp.127-134
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• 2014

A great interest is emerging about green tea as a tool against human cancer proliferation or inflammation, as pointed out by recent reports describing the inhibitory action of epigallocatechin gallate (EGCG) on angiogenesis, urokinase, metalloproteinases, and induction of inducible nitric oxide synthase. We proposed that EGCG may regulate a multi target signaling having wider spectra of action than those actions of single enzymes. CSK (c-terminal Src kinase) protein is a non-receptor tyrosine kinase involved in the cross-talk and mediation of many signaling pathways that promote cell proliferation, adhesion, invasion, migration, and tumorigenesis. Based on the knowledge that CSK activation is important for cancer proliferation we hypothesized that CSK could be a target of EGCG. Here we showed that EGCG effectively suppressed the growth of CSK MEF cell when compare with CSK knockout MEF cell growth. These results indicate that EGCG could be used as a chemoprevention to modulate CSK signal pathway in inflammatory processes and tumor formation.

• Journal of the Korean Wood Science and Technology
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• v.33 no.5 s.133
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• pp.86-91
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• 2005

Six compounds were isolated from the EtOAc and $Et_2O$ fractions of the bark of Rhus chinensis by repeated column chromatography with $SiO_2$ and Sephadex LH-20. The structures were determined by instrumental analysis using MS and NMR spectrophotometer as: gallic acid (1), methyl gallate (2), 6, 7-dimethoxycoumarin (3), orcinol-${\beta}$-D-glucoside (4), scopoletin (5), semialactone (6). Among these compounds, 6,7-dimethoxycoumarin (3) was isolated from this plant for the first time. To measure the antioxidant activity, the DPPH radical scavenging activity test was performed. Gallic acid (1) showed the strongest activity, while orcinol-${\beta}$-D-glucoside (4), semialactone (5) and scopoletin (6) had the low activities.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10557-10563
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• 2015

It is well known that conventional chemotherapy and radiation therapy can result in toxicity to both normal cells and tumor cells, which causes limitations in the application of these therapeutic strategies for cancer control. Novel and effective therapeutic strategies for cancers with no or low toxicity for normal cells are a high priority. Therefore, natural products with anticancer activity have gained more and more attention due to their favorable safety and efficacy profiles. Pre-clinical and clinical studies have demonstrated that several representative natural compounds such as resveratrol, epigallocatechin-3-gallate, curcumin, allicin and ginsenosides have obvious anticancer potential. In this article, we summarize autophagy-associated targeting pathways of such natural products for inducing the death of cancer cells, and discuss the core autophagic pathways involved in cancer treatments. Recent advances in the discovery, evaluation and exploitation of natural compounds as therapeutic agents for cancers will provide references and support in pre-clinical and clinical application of novel natural drugs for the treatment of primary and metastatic tumors in the future.

• Advances in Traditional Medicine
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• v.7 no.3
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• pp.311-320
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• 2007

The present study was designed to estimate the protective effect of (-) epigallocatechin gallate (EGCG) on ethanol-induced liver injury in rats. Chronic ethanol administration (6 g/kg/day ${\times}$ 60 days) caused liver damage that was manifested by the elevation of markers of liver dysfunction - aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, bilirubin and ${\gamma}$-glutamyl transferase in plasma and reduction in liver glycogen. The activities of alcohol metabolizing enzymes such as alcohol dehydrogenase and aldehyde dehydrogenase were found to be altered in alcohol-treated group. Ethanol administration resulted in the induction of cytochrome p450 and cytochrome-$b_{5}$ activities and reduction of cytochrome-c reductase and glutathione-S-transferase, a phase II drug metabolizing enzyme. Further, ethanol reduced the viability of isolated hepatocytes (ex vivo) as assessed by trypan blue exclusion test and induced hepatocyte apoptosis as assessed by propidium iodide staining. Treatment of alcoholic rats with EGCG restored the levels of markers of liver injury and mitigated the alterations in alcohol metabolizing and drug metabolizing enzymes and cyt-c-reductase. Increased hepatocyte viability and reduced apoptotic nuclei were observed in alcohol + EGCG-treated rats. These findings suggest that EGCG acts as a hepatoprotective agent against alcoholic liver injury.

• Analytical Science and Technology
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• v.5 no.3
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• pp.333-338
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• 1992

The tea tannins, epigallocatechin, epigallocatechin gallate, were successfully separated by a Sephadex LH-20 column by the acetone based gradient elution. Each fractions was collected by monitoring at 280nm. Purified fractions were directly characterized by fast atom bombardment mass spectrometry. Epigallocatechin and epigallocatechin gallate were identified and shown as low as 70% purity in the reversed phase column. This revised method is more advantageous than known methods in purity and rapidity.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.5
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• pp.325-329
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• 2010

Vascular NADPH oxidase plays a pivotal role in producing superoxide in endothelial cells and thus acts in the initiation and development of inflammatory cardiovascular diseases such as atherosclerosis. Epigallocatechin-3-gallate (EGCG), the major catechin derived from green tea, has multiple beneficial effects for treating cardiovascular disease but the effect of EGCG on the expression of vascular NADPH oxidase remains unknown. In this study, we investigated the mechanism(s) by which EGCG might inhibit the expression of subunits of NADPH oxidase, namely $p47^{phox}$, $p67^{phox}$ and $p22^{phox}$, induced by angiotensin II (Ang II) in human umbilical vein endothelial cells. Ang II increased the expression levels of $p47^{phox}$, $p67^{phox}$, and $p22^{phox}$, but EGCG counteracted this effect on $p47^{phox}$. Moreover, EGCG did not affect the production of reactive oxygen species induced by Ang II. These data suggest a novel mechanism whereby EGCG might provide direct vascular benefits for treating inflammatory cardiovascular diseases.

• Korean Journal of Pharmacognosy
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• v.30 no.3
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• pp.295-300
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• 1999

Seven compounds were isolated from the n-BuOH extract of the dried stem barks of Rhus javanica L. On the basis of physico-chemical, spectroscopic evidences and comparison with authentic samples, the compounds $1{\sim}7$ were identified as gallic acid (1), methyl gallate (2), scopoletin (3), scopolin (4), $1,\;2,\;3,\;4,\;6-penta-O-galloyl-{\beta}-D-glucose$ (5), orcinol (6) and $orcinol-{\beta}-D-glucoside$ (7). Among these compounds, scopolin, $orcinol-{\beta}-D-glucoside$ were isolated from this plant for the first time.

• Natural Product Sciences
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• v.23 no.4
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• pp.274-280
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• 2017

In a search for novel treatments for diabetic complications from natural resources, we found that the ethyl acetate-soluble fraction from the 80% ethanol extract of the leaves of Homonoia riparia has a considerable inhibitory effect on advanced glycation end product (AGE) formation. Bioassay-guided isolation of this fraction resulted in identification of 15 phenolic compounds (1 - 15). These compounds were evaluated in vitro for inhibitory activity against the formation of AGE. The majority of tested compounds, excluding ethyl gallate (15), markedly inhibited AGE formation, with $IC_{50}$ values of $2.2-89.9{\mu}M$, compared with that of the positive control, aminoguanidine ($IC_{50}=962.3{\mu}M$). In addition, the effects of active isolates on the dilation of hyaloid-retinal vessels induced by high glucose (HG) in larval zebrafish was investigated; (-)-epigallocatechin-3-O-gallate (6), corilagin (7), and desmanthine-2 (11) significantly decreased HG-induced dilation of hyaloid-retinal vessels compared with the HG-treated control group.

• Korean Journal of Food Science and Technology
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• v.31 no.1
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• pp.20-23
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• 1999

This study was conducted to investigate the content and composition of tea catechins at different plucking time and different position of tea leaves. The bud and first leaf, second leaf, third leaf, and fourth leaf were collected on May, July, and August. The catechin content was highest in leaves picked on August among those collected from different months. When compared with the different part of tea leaves, the bud and the first tea leaf contained the highest catechin, and the fourth left contained the lowest catechin. Analysis of catechin composition in the tea leaves, showed that epigallocatechin gallate was the highest, and the other contents were following order: epicatechin gallate, epicatechin, epigallocatechin.