• Natural Product Sciences
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• v.22 no.2
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• pp.87-92
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• 2016

Endothelial dysfunction in atherosclerosis is associated with increasing oxidative stress that could be reversed by antioxidant. Therefore epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and catechin (C) of tea flavonoids were investigated for their roles in regenerating endothelial cell. Peripheral blood mononuclear cells (PB-MNCs) were isolated, plated and cultured in medium with/without treatment of EGCG, ECG, EGC and C. Results showed that among all EGCG, ECG, EGC and C concentrations tested, $12.5{\mu}mol/L$ was not cytotoxic for peripheral blood-derived endothelial progenitor cells (PB-EPCs). Treatment of EGCG, ECG, EGC or C increased the percentages of CD34, CD133, VEGFR-2 expressions and suppressed hydrogen peroxide-induced percentages of reactive oxygen species (ROS) level in PB-EPCs. Taken together, our current results showed that EGCG, ECG, EGC or C of tea flavonoids could induce differentiation of PB-MNCs into PB-EPCs as well as protect PB-EPCs from oxidative damage by suppresing the intracellular ROS levels.

• Biomolecules & Therapeutics
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• v.11 no.4
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• pp.238-244
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• 2003

Nicotine is one of the major hazardous components in cigarettc smoke. Nicotine deals a harmful effect to smokers and passive smokers due to its rapid conversion to various carcinogenic metabolites. Nitrosamine-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is believed to cause lung cancers among the nicotine-derived carcinogens. Recent studies report that NNK synthesis can be inhibited by the metabolism pathway to produce a stable metabolite cotinine from nicotine. Tea polyphenols have been known to contain factors to prevent cancers and to retard progression of cancers. This study aims to correlate tea polyphenol's potential for cancer prevention with an accelerated formation of cotinine. The conversion from nicotine to cotinine in the presence of tea extracts or three polyphenols (Catechin, epicatechin gallate, epigallocatechin gallate) was measured in established cell lines and in Xenopus oocytes. Among three lines of cell used, PLC/PRF5 and HEK293 cells showed a fast turnover from nicotine to cotinine while HepG2 cell line showed a marginal difference between groups treated and non-treated with tea polyphenols. When Xenopus oocytes were microinjected with nicotine, tea polyphenols appear to accelerate the conversion of nicotine to cotinine. Among the polyphenols tested in this study, (＋)－catechin showed the best efficiency overall in accelerating conversion from nicotine to cotinine both in the cell lines and in the oocytes. In summary, the present study indicated that tea polyphenols have a positive effect on conversion of nicotine to cotinine.

• Integrative Medicine Research
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• v.3 no.1
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• pp.25-33
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• 2014

Background: Green tea contains numerous polyphenols, which have health-promoting effects. The purpose of this study was to evaluate the effect of tannase-converted green tea extract (TGE) formulation on the physical stability and activities of skin-related enzymes. Methods: Physical stability was evaluated by measuring the pH, precipitation, and colors at $25{\pm}2^{\circ}C$ /ambient humidity and at $40{\pm}2^{\circ}C$ \70%${\pm}$5% relative humidity for 4 months. Activities of collagenase, elastase, and tyrosinase as skin-related enzymes were assessed on TGE formulation. Results: The concentrations of epigallocatechin-3-gallate and epicatechin-3-gallate in green tea extract were greatly decreased to the extent of negligible level when treated with tannase. The formulation containing 5% tannase-converted green tea extract showed relatively stable pH, precipitation, and color features for 16 weeks. When TGE was added to the formulation, there was a significant increase in the inhibition of elastase and tyrosinase activities (p<0.05) compared with the formulation containing 5% normal green tea extract. Conclusion: The TGE could be used in cosmetics as skin antiwrinkling or depigmenting agent.

• Journal of the Korean Society of Food Culture
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• v.22 no.4
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• pp.449-453
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• 2007

Using green tea(GT), oolong tea(OT), black tea(BT) and green tea bag(GTB) out of tea products in market, this study quantified polyphenol and catechins as anti-oxidant substances and analyzed their respective anti-oxidant capacities. As a result, more epigallocathechin(EGC) was found in GT and GTB as well as caffein(CAF) in GT and BT. GT contained more epigallocathechin gallate(EGCG) than other tea types. Both FRAP and ORAC, as two methods of analyzing anti-oxidant capacities, showed that GTB had highest anti-oxidant capacities, while OT had lowest of all. By brand, it was found that all the 3 brands of GT had similarly high anti-oxidant capacities, but there were differences in the anti-oxidant activities of GTB and BT depending on brand. Out of catechin components, it was found that epicatechin(EC), epicathechin gallate(ECG) and EGCG were major components affecting anti-oxidant capacities.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.2 s.57
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• pp.117-121
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• 2006

Although many studies have been performed to elucidate the molecular consequence of factors that regulate skin aging, little is known about the effect of green tea catechins except EGCG. The matrix metalloproteinase (MMP), can degrade matrix proteins and results in a collagen deficiency in photodamaged skin, are known to play an important role in photoaging. This study, investigated the effects of green tea catechins on the UVA-induced MMP-1 expression, activity of MMP-2 and synthesis of type I procollagen in human dermal fibroblasts. We examined eight catechins that naturally exist in green tea leaves and compared their efficacies among them. Most of catechins inhibited the expression of MMP-1 in dose dependent manner, and the levels were reduced, especially, 57.4 and 68.2% by treatment with $1{\mu}M$ of epigallocatechin-3-gallate (EGCG) and gallocatechin-3-gallate (GCG), respectively. Also, catechins significantly suppressed the activities of MMP-2. Catechins also induced the expression of type I procollagen, however, they acted only at the concentration below $1{\mu}M$ interestingly. Furthermore, when EGCG:GCG:ECG had the ratio of 0.5:1.5:.1.3, they presented the most effective on procollagen synthesis. Therefore, we concluded that catechins significantly inhibited MMPs and induced collagen synthesis. Taken together, all these results suggested that green tea catechins might be good natural materials act as an anti-photoaging and a skin-aging improving agent.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.10
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• pp.1356-1362
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• 2012

UV-VIS spectrophotometric and high-performance liquid chromatographic (HPLC-DAD) methods were applied in order to identify and quantify the composition of polyphenols in commercial cocoa-containing products. Total polyphenolic contents of cocoa mix, choco-syrup, milk chocolate, and dark chocolate were evaluated using Folin-Ciocalteu's phenol reagent according to a UV-VIS spectrometric method. Antioxidant capacities of cocoa extracts by methanol were evaluated by 2,2'-azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The obtained results show that the polyphenolic contents and antioxidant capacities of cocoa products and chocolates depend on solid cocoa content. Among the tested cocoa products and chocolates, the most abundant phenolic compound was epicatechin.

• Journal of Food Hygiene and Safety
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• v.22 no.3
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• pp.223-230
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• 2007

We have previously reported that green tea catechins(GTC) displayed potent antithrombotic effect, which was due to the antiplatelet activity. In the present study, the antiplatelet activity of each green tea catechin components was compared in vitro. Galloylated catechins including (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG) and (-)-catechin gallate (CG), significantly inhibited collagen $(5{\mu}g/mL)-induced$ rabbit platelet aggregation with $IC_{50}$ values of 79.8, 63.0, 168.2 and $67.3{\mu}M$, respectively. EGCC GCG and CG also significantly inhibited arachidonic acid (AA, $100{\mu}M$)-induced rabbit platelet aggregation with $IC_{50}$ values of 98.9, 200.0 and $174.3{\mu}M$, respectively. However catechins without gallate moiety showed little inhibitory effects against rabbit platelet aggregation induced by collagen or AA compared with galloylated catechins. These observations suggest that the presence of gallate moiety at C-3 position may be essential to the antiplatelet activity of catechins and the presence of B ring galloyl structure may also contribute to the antiplatelet activity of GTC. In line with the inhibition of collagen-induced platelet aggregation, EGCG caused concentration-dependent decreases of cytosolic calcium mobilization, AA liberation and serotonin secretion. In contrast, epigallocatechin (EGC), a structural analogue of EGCG lacking a galloyl group in the 3' position, although slightly inhibited collagen-stimulated cytosolic calcium mobilization, failed to affect other signal transductions as EGCG in activated platelets. Taken together, these observations suggest that the antiplatelet activity of EGCG may be due to inhibition of arachidonic acid liberation and inhibition of $Ca^{2+}$ mobilization and that the antiplatelet of EGCG is enhanced by the presence of a gallate moiety esterified at carbon 3 on the C ring.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.11
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• pp.1501-1506
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• 2011

In this study, we optimized the reaction conditions for the bioconversion of green tea using tannase, and to evaluate its radical scavenging activities. Tea catechins such as (-)-epigallocatechin gallate (EGCG) or (-)-epicatechin gallate (ECG) were hydrolyzed by tannase to produce (-)-epigallocatechin (EGC) or (-)-epicatechin (EC), respectively, and a common product, gallic acid. The bioconversion of tea catechins by tannase was increased as enzyme concentration, substrate concentration and incubation time for enzyme dose. The results indicated the optimum reaction conditions for tannase were tannase 30 U/mL (enzyme concentration) on 1% green tea (substrate concentration) for 1 hr (incubation time for enzyme). Tannase enhanced the radical-scavenging properties of green tea; the 2,2-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging abilities were significantly (p<0.001) greater for the tannase-treated green tea extract compared to the untreated green tea extract. It is reported that ECG has the greatest antioxidant activity among the catechins in green tea, and the release of gallic acid is considered to be beneficial because of its significant antioxidant potency. The results of this study suggest that the tannase-treated green tea increases antioxidant activities under optimum reaction conditions.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.2
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• pp.117-123
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• 2005

A cumulative evidence indicates that consumption of tea catechin, flavan-3-ol derived from green tea leaves, lowers the risk of cardiovascular diseases. However, a precise mechanism for this cardiovascular action has not yet been fully understood. In the present study, we investigated the effects of different green tea catechins, such as epigallocatechin-3 gallate (EGCG), epigallocatechin (EGC), epicatechin-3 gallate (ECG), and epicatechin (EC), on angiotensin II (Ang II)-induced hypertrophy in primary cultured rat aortic vascular smooth muscle cell (VSMC). [$^3H$]-leucine incorporation was used to assess VSMC hypertrophy, protein kinase assay, and western blot analysis were used to assess mitogen-activated protein kinase (MAPK) activity, and RT-PCR was used to assess c-jun or c-fos transcription. Ang II increased [$^3H$]-leucine incorporation into VSMC. However, EGCG and ECG, but not EGC or EC, inhibited [$^3H$]-leucine incorporation increased by Ang II. Ang II increased phosphorylation of c-Jun, extracellular-signal regulated kinase (ERK) 1/2 and p38 MAPK in VSMC, however, EGCG and ECG , but not EGC or EC, attenuated c-Jun phosphorylation increased by Ang II. ERK 1/2 and p38 MAPK phosphorylation induced by Ang II were not affected by any catechins. Ang II increased c-jun and c-fos mRNA expression in VSMC, however, EGCG inhibited c-jun but not c-fos mRNA expression induced by Ang II. ECG, EGC and EC did not affect c-jun or c-fos mRNA expression induced by Ang II. Our findings indicate that the galloyl group in the position 3 of the catechin structure of EGCG or ECG is essential for inhibiting VSMC hypertrophy induced by Ang II via the specific inhibition of JNK signaling pathway, which may explain the beneficial effects of green tea catechin on the pathogenesis of cardiovascular diseases observed in several epidemiological studies.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.8
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• pp.1025-1029
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• 2008

Fresh green tea leaf extracts were prepared by different enzyme treatment conditions, such as concentration, treating time and treating temperature using complex enzyme, Rapidase TF, and then extracted for 30 min at $80^{\circ}C$ to investigate their physicochemical properties. The results showed that free sugar content in every sample tended to increase, especially glucose content was increased up to 7.25 times compared to the control. Total amino acid was barely affected by the enzyme treatment and caffeine content was increased with reaction temperature. Total polyphenol and total catechin content was increased according to the amount of enzyme added and reaction temperature. Regardless of enzyme treatment conditions, composition of catechins were epigallocatechin, epicatechin, epicatechin gallate and epigallocatechin gallate by descending order of the content. Gallic acid content increased up to 0.04% and $45^{\circ}C$ with no further significant changes thereafter. From the results above, we could conclude that a simple and new method to extract green tea materials directly from fresh green tea leaves with improved extract ratio may be introduced by adding $0.08{\sim}0.1%$ of Rapidase TF to heat treated fresh green tea leaves and keeping temperature at $37{\sim}45^{\circ}C$ for $180{\sim}240\;min$ in order to skip existing complicated procedures.