• Journal of Life Science
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• v.26 no.6
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• pp.640-645
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• 2016

Microglial cells are immediately activated in the central nervous system in response to a variety of neuronal environmental changes, such as injuries or inflammation. In addition to the modulation of the intrinsic immune response, a key role of microglial cells is the phagocytosis of dying cells and cellular debris. In this study, the inhibitory effects of epigallocatechine-3-gallate (EGCG), a most abundant and active polyphenol component of green tea, on lipopolysaccharide (LPS)-induced microglial activation are determined. EGCG dose dependently suppressed LPS-induced nitric oxide production and the expression of inducible nitric oxide synthase (iNOS) in BV-2 microglial cells. EGCG are potent LPS-induced inhibitors of several pro-inflammatory cytokine expressions, such as TNF-α and IL-1β, in microglial cells. Furthermore, EGCG generally inhibits the induction of LPS-mediated microglial activation and potently inhibits the phagocytosis of LPS-stimulated BV2 microglia. Although the conditioned media from LPS-stimulated BV-2 cells caused the SN4741 cell death, that from the conditioned media of EGCG pretreated BV-2 cells did not diminish the viability of SN4741 cells. These results suggest EGCG, a green tea polyphenol, could be a promising available molecule for the modulation of harmful microglial activation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.9
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• pp.1328-1332
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• 2011

This study was carried out to investigate changes in epigallocatechin gallate (EGCG) contents and antioxidant activity of duck egg after pressurized soaking in green tea extract. The duck eggs were soaked in different concentrations of green tea extract (10~30%) and subjected to pressures of 0.1~5.0 MPa for 30 min at ambient temperature in a lab model high-pressure rig. After pressured treatment at 5.0 MPa in 30% green tea extract, EGCG content of duck egg white (20 mg/100 g) markedly increased compared to that of untreated sample (0.17 mg/100 g). Moreover, the antioxidant, hepato-protective, and cellular antioxidant activities of duck egg white after pressured treatment at 5 MPa in 30% green tea extract were all higher than those of untreated sample. Our results could have a direct impact on duck egg consumption by increasing consumer awareness of the health benefits of duck eggs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.11
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• pp.1293-1299
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• 2017

Obesity contributes to the development of diseases, such as type II diabetes, hypertension, coronary heart disease, and cancer. In addition, oxidative stress caused by reactive oxygen species (ROS) is recognized widely as a contributing factor in the development of chronic diseases. This study was examined the antioxidant and anti-adipogenic activities of epigallocatechin-3-gallate (EGCG) in 3T3-L1 preadipocytes. 3T3-L1 cells were differentiated with or without EGCG for 6 days. The production of glutathione (GSH) and the activities of the antioxidant enzymes, such as glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) were measured. EGCG inhibited significantly the lipid accumulation and the expression of adipogenic specific proteins including CCAAT/enhancer binding protein ${\alpha}$ and adipocyte fatty acid binding protein. The production of intracellular ROS was decreased significantly by EGCG in 3T3-L1 cells. EGCG increased the GSH production and the activities of GPx, GR, CAT, and SOD. Moreover, EGCG increased the protein expression of glutamate-cysteine ligase and heme oxygenase-1 in 3T3-L1 cells. These results suggest that EGCG increased the activity and expression of antioxidant enzymes and suppressed the lipid accumulation in 3T3-L1 cells. Therefore, the use of phytochemicals that can maintain the GSH redox balance in adipose tissue could be promising for reducing obesity.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.377-382
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• 1998

This study was carried out to measure the contents of moisture, crude ash, crude fat, total amino acid, with amino acid composition, vitamin C, ${\beta}-carotene$, vitamin E, total catechins, EGCG, EGC, ECG, EC, GA, caffeine, theobromine and theophylline of the green tea I, II, III, oolong, and black tea. The content of crude fat of green tea I, II, III, oolong, and black teas was 1.1, 2.5, 4.9, 0.8 and 1.2% respectively, total amino acid content was 0.87, 0.78, 0.60, 0.63 and 1.05% respectively, and theanine content was 0.52, 0.48, 0.31, 0.41 and 0.61%, respectively. Total amino acid content of green tea increased in the order of green tea I> green tea II> green tea III, and among the teas, the content of theanine was the highest in the amino acids present. The content of vitamin C of green teal, II, III, oolong, and black tea was 101.6, 87.5, 95.9, 99.1 and 108.0 mg%, respectively, ${\beta}-carotene$ content was 270, 268, 481, 80 and 181 ppm, respectively. Among the ${\alpha}-,\;{\beta}-,\;{\gamma}-\;and\;{\delta}-tocopherol$, the content of ${\alpha}-tocopherol$ was the highest in vitamin E present, and ${\beta}-\;and\;{\delta}-tocopherol$ were not detected in the samples of green teal, II, III, oolong, and black teas. The total catechins of green teal, II, III, oolong, and black teas was 10.5, 10.4, 7.2, 8.4 and 1.8% respectively, and among them, EGCG content was the highest. The content of EGC increased in the order of green tea I > green tea III > green tea II > oolong tea> black tea. The contents EGCG and ECG increased in the order of oolong tea> green tea I > green tea II> green tea III> black tea, and the highest contents of EGCG and ECG were observed in the samples of oolong tea. The content of GA was 0.01, 0.02, 0.05, 0.13 and 0.31%, respectively, and the highest contents of GA, caffeine and theobromine were observed in the sample of black tea. The highest content of theophylline, however, was observed in the sample of green tea I.

• KSBB Journal
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• v.16 no.5
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• pp.442-445
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• 2001

Catechin compounds as anticancer and antioxidant were target materials from Korean Green Tea in this work. The methodologies of solvent extraction and partition were utilized to recover catechin compounds from green tea and the optimal experimental conditions were found by comparing the degree of recovery as slovent. extraction times and operating temperatures. The extract was partitioned with chloroform, which was best fit to remove caffeine after the extraction of green tea with 80$^{\circ}C$ water for 40 min. Further, the resulting extract was partitioned in ethyl acetate layer to purify the catechin compounds of EGC, EC EGCG and ECG. This experimental result could be extended to preparative HPLC to obtain EGCG on a commercial scale.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.370-376
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• 1998

The extraction yield of MeOH extract of green teas, oolong tea and black tea were 3 to 5, 4 to 5, and 5 to 7 fold higher than those of EtOH and EtAC extract, respectively. The amount of total catechins of EtAC extract of the black tea, and of the green teas and oolong tea were three- and two-fold higher than that of EtOH or MeOH extract of the corresponding teas, respectively. The antioxidative activities of EtOH, MeOH and EtAc extract were considerably higher than that of BHT and $dl-{\alpha}-tocopherol$ at 200 ppm level. The antioxidative activities of EtOH and MeOH extract at 200 and 500 ppm level, and of EtAc extract at 200 ppm level varied depending on the type of tea as follows : green tea I > green tea II > green tea III > oo-long tea> black tea. The antioxidative activity increased as the content of EGC increased. But the antioxidative activity of MeOH extract at 1000 ppm level, and of EtAc extract at 500 and 1000 ppm level were not affected by the content of EGC and EGCG.

• 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.33 no.7
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• pp.1079-1084
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• 2004

The present study was conducted to compare antioxidant activity of green teas, fermented teas and other related common teas by examining radical scavenging activity using DPPH (2,2 diphenyl l-picryl hydrazyl). Scavenging activity ($SC_{50}$/) of epigallocatechin gallate (EGCG) for 0.1 mM DPPH radical was 5.5 $\mu$M or 4.2 mg/L by weight, then catechin, 14 $\mu$M or 2.5 mg/L and vitamin C, 22 $\mu$M or 3.9 mg/L, respectively. Kyokuro tea (okro) powder of 24.2 mg/L or green tea powder of 25.2 mg/L was used to reach $SC_{50}$/ for 0.1 mM DPPH. One serving of 2 g green tea provides antioxidant activity equivalent to 109∼147 mg EGCG, 145∼185 mg catechin or 131∼168 mg vitamin C. Teas from the first harvest had the highest radical scavenging activity when compared with later harvest green teas grown in the same region, but there is virtually no difference by the harvest time. A Chinese green tea, Dragon well had the highest antioxidant activity among other green teas tested providing antioxidant capacity equivalent to 168 mg EGCG or 188 mg vitamin C per 2 g serving, but partially fermented Chinese teas had much lower antioxidant activity than any green tea tested. Black tea which is fully fermented showed as strong antioxidant activity as green teas (76.3 mg vs 86.7∼67.6 mg per tea bag). One tea bag of green teas from market provided antioxidant capacity equivalent to 52∼86 mg EGCG, 70∼105 mg catechin or 63-96 mg vitamin C. Teas made of persimmon leaf, pine needle, mulberry leaf had comparatively low anti-oxidant activity equivalent to 2.5∼4.8 mg EGCG or 15∼21 mg vitamin C per teabag. The third brewed green tea still had enough antioxidant activity, while tea from tea bag brewed for 3 min or 5 min did not have any difference in their antioxidant activity. More systemic studies are needed to clarify the relationship between tea catechins and antioxidant capacity focusing on how growing, harvest time, fermentation and other processes can influence on this.

• Journal of Nutrition and Health
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• v.44 no.3
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• pp.196-202
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• 2011

Epigallocatechin gallate (EGCG), or epigallocatechin 3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin. EGCG may be therapeutic for many disorders including diabetics and some types of cancer. However it is unknown whether EGCG can induce transdifferentiation of pancreatic cells in pancreatitis. The aim of this study was to investigate the effects of EGCG on the expression of pancreatic regenerating related markers in pancreatic AR42J cells, a model of pancreatic progenitor cells. AR42J cells, differentiated with betacellulin and activin A, were cultured with/without EGCG in a time-dependent manner. Cell growth rate, levels of mRNA, and protein expression were examined with the MTT assay, quantitative PCR, and Western blots, respectively. The results showed that AR42J cell growth rates were inhibited by EGCG in a dose-dependent manner. mRNA and protein expression of amylase, insulin and neurogenin 3 (ngn 3) increased in AR42J cells treated with EGCG. Additionally, we demonstrated that the signal transduction pathway of mitogen-activated protein (MAP) kinase is active in EGCG-treated AR42J cells. ERK and JNK phosphorylation decreased in cells treated with EGCG but not p38 phosphorylation. Activation of the p38 MAP kinase pathway was confirmed by specific MAP kinase pathways inhibitors: U0126 for ERK, SP600126 for JNK, and SB203580 for p38. Activated p38 phosphorylation was inhibited by the specific p38 inhibitor SB203580 but p38 phosphorylation was inhibited with increased EGCG treatment. The ERK and JNK MAP kinase pathways were not affected by EGCG treatment. Although further studies are needed, these results suggest that EGCG affects the induction of pancreatic cell regeneration by increasing the ngn 3 protein and mRNA expression and activating the p38 MAP kinase pathway.

• Journal of Life Science
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• v.14 no.6 s.67
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• pp.920-924
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• 2004

The beneficial effects of green and fermented tea are generally attributed to some antioxidant activities including superoxide dismutase (SOD)-like ability and scavenging activity originated from their phenolic compounds and flavonoids. Content of total flavonoid of green tea $(413.3\;{\mu}g/g)$ was similar to those of fermented tea $(405.7\;{\mu}g/g)$. Content of total phenol of green tea $(46.8\;{\mu}g/g)$ was higher than those of fermented tea $(23.5\;{\mu}g/g)$. Major catechin compounds of hot water extract in green tea was EGCG, including EGC, Gc, catechin and catechol. EGCG was not detected .in fermented tea. SOD-like ability was increased in proportional to added concentration of hot water extract. The scavenging activities of hydroxyl radical at $3000\;{\mu}g/ml$ of green and fermented teas were found up to $60\%$. Hot water extract of green tea was more effective in scavenging activity than that of fermented tea.