• Journal of Nutrition and Health
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• v.33 no.6
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• pp.632-638
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• 2000

This study was designed to observe the effect of green tea on colon tumor incidence and biomarkers of colon carcinogenesis in 1, 2-dimethlhydrazine-treated rats. Male Sprague Dawley rats at 7 weeks of age were divided into two groups: control and green tea(GT) groups. Control rats had distilled water as drinking water but GT group received green tea extracts(2.5%, w/v water) as drinking water throughout the experiment periods. All rats were fed the experimental diet containing 15% fat by weight for 20 weeks. and were i.m. injected with DMH for 6 weeks to give total dose of 180mg/kg body weight. Tumor incidence was reduced in GT group (39%) compared with control group (56%) Green tea significantly reduced cell proliferation (total cells per crypt, crypt length and proliferative zone) in colonic mucosa and also significantly reduced the levels of preformed prostalandin E2(PGE2) and thromboxance B2(TXB2) in colonic mucosa but the fatty acid profile of total lipid in colonic mucosa was not significantly influenced by green tea. However the relative percent of C20:4 and the levels f preformed PGE2 and TXB2. were significantly higher in tumor tissue compared with normal surrounding mucosa.Green tea increased the fecal excretion of total bile acid but not scondary bile acid which is known as one of promoters for colon cancer,. These results suggest that green tea could have preventive effect against colon cancer when consumed daily by influencing on antioxidant effect and the metabolism of arachidonic acid.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.327-331
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• 2002

Tea is a pleasant, popular and safe beverage in the world. During the past decade, epidemiological studies have shown that tea catechins intake is associated with lower risk of cardiovascular disease. Tea provides a dietary source of health-promoting components to help humans reduce a wide variety of cancer risks and chronic diseases. The antioxidative activity of tea-derived catchins has been extensively studied. The antioxidant effect is a synergistic action between catechins e.g. EGCG, EGC, ECG, EC, pheophytins a and b, and other components in tea leaves, which aye more bioavailable for human body. Green tea has a Higher content of catechins than other kinds of tea. Green tea extract with hot water has high potential and more efficiency to reduce cancer risk than any other tea products or pure EGCG. Protein, iyon, and other food components may interfere with the bioavailability of ten catechins. Interaction of catechins with drug affects the cancer-preventive activity of some cancer-fighting medication. Further studies are required to determine the bioavailability of tea catechins and cancer-preventive functionality.

• Korean Journal of Veterinary Research
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• v.42 no.4
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• pp.475-483
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• 2002

We performed this study to determine the effect of Korean favorite teas (green tea, ginseng tea, coffee and barley tea) on jejunal crypt survival, endogenous spleen colony formation and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of ${\gamma}$-radiation. Jejunal crypts were protected by pretreatment of green tea (P.O.: 1.25% water extract, for 7 days before irradiation., I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.01) or ginseng (I.P.: 50 mg/kg of body weight, at 12 and 36 hours before irradiation, p<0.05). Green tea (p<0.05) or ginseng (p<0.05) administration before irradiation (I.P. at 12 and 36 hours before irradiation) resulted in an increase of t formation of endogenous spleen colony. The frequency of radiation-induced apoptosis was also reduced by pretreatment of green tea (P.O.: p<0.005, I.P.: p<0.05), pretreatment of ginseng (P.O.: p<0.005, I.P.: p<0.005) or posttreatment of ginseng (I.P.: 50 mg/kg of body weight, at 30 minutes after irradiation, p<0.05). Treatment with coffee or barley tea showed no significant modifying effects on the radiation-induced damages. These results indicated that green tea and ginseng might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of green tea, ginseng and its components.

• 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.

• Advances in Traditional Medicine
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• v.5 no.2
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• pp.137-143
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• 2005

Doxorubicin induces oxidative stress leading to cardiotoxicity causing electrocardiogram abnormalities and increases in biomarkers associated with toxicity. Green tea extract (GTE) is reported to possess antioxidant activity mainly via its polyphenolic constituent, catechins. This study was intended to determine the effect of various doses of GTE (25, 50 and 100 mg/kg/day p.o. for 30 days) on doxorubicin-induced electrocardiographic and biochemical changes in rat heart. The latter included lactate dehydrogenase, creatine kinase, and glutamic oxaloacetate transaminase in serum and superoxide dismutase, catalase, and reduced glutathione, as well as membrane bound enzymes like $Na^+K^+ATPase,\;Ca^{2+}ATPase,\;Mg^{2+}ATPase$ and decreased lipid peroxidation in heart tissue Results demonstrated that rats which received GTE were less susceptible to such changes indicating protection afforded by GTE.

• Preventive Nutrition and Food Science
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• v.7 no.2
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• pp.151-156
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• 2002

Antioxidant activity or green tea extracts (GTE) was evaluated in soybean oil (SBO), rice bran oil (RBO) and winterized rice bran oil (WRBO) stored at 63$^{\circ}C$ for 36 days. Lipid oxidation of the oils was determined using the active oxygen method (AOM), peroxide value (POV), change in unsaturated free fatty acid concentrations and by sensory evaluation. SBO had a higher concentration of the polyunsaturated fatty acids, linoleic and linolenic acid than RBO and WRBO. WRBO and RBO were more stable against lipid oxidation than SBO. Addition of GTE (200 ppm) to the stored oils, increased the induction period (IP) in AOM, reduced the increase in POV, and lessened the change in unsaturated fatty acids. Furthermore, GTE prevented the development of rancid flavors resulting from storage, all of which demonstrate the protective antioxidative activity of GTE. However, oil color became darker in the GTE treated oils. The antioxidant protection of GTE was most effective in RBO.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.273-276
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• 2000

In the course of surveying the anti-plaque agents for dental caries prevention, the extract of Korean green tea leaves (KGTL) was tested for inhibitory activity against Streptococcus mutans adhering to glass surfaces in the presence of crude glucosyltransferase (GTase). The extracts of KGTL showed a positive inhibitory activity against GTase. The active compound was purified through Sephadex LH-20 and MCI gel CHP-20P columns. A positive reaction was shown in the anisaldehyde-$H_2SO_4$ test, which confirmed the condensed tannin. The inhibitory compound was identified as 3-galloylprocyanidin $B_3$ through IR, negative FAB-mass, and $^{1}H$-NMR spectroscopic analyses. Acetone extract and 3- galloylprocyanidin $B_3$ of KGTL showed inhibitory effect against GTase. The percent of inhibition was determinated to be 71.84% (P<0.01) with 10 mM 3-galloylprocyanidin B3. The 3-galloylprocyanidin $B_3$, which possessed a galloyl, showed a higher inhibitory activity against glucosyltransferase than monomeric (+)-catechin and procyanidine $B_3$ which had no galloyl group.

• Journal of Food Hygiene and Safety
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• v.29 no.3
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• pp.211-216
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• 2014

Bacillus cereus was isolated in 155 of 4,318 food samples from 2012 to 2013. Of the isolates, 140 isolates were performed antimicrobial disk test against garlic, cinnamon, ginger, and green tea extracted at two different temperature, $25^{\circ}C$ and $70^{\circ}C$. The isolates from Powdered Red Pepper showed frequently to 48.65%, and followed by Agriculture Products (31.08%) and Kimchi (25.61%). The isolation rate of Cooked Foods in the Restaurant supposed to causing food poison was 1.17%. Analysis of antimicrobial activity showed that $25^{\circ}C$ garlic extract, $25^{\circ}C$ green tea extract, and $70^{\circ}C$ green tea extract resisted against all 140 isolates and the others resisted against some isolates. Antimicrobial activity was depended on the temperature; garlic > green tea > cinnamon in $25^{\circ}C$ and green tea > garlic > cinnamon in $70^{\circ}C$. The correlation analysis of each extracts showed that geen tea extract was different significantly with garlic and cinnamon extracting in $25^{\circ}C$ and with only garlic extracting in $70^{\circ}C$ at p < 0.05.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1382-1388
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• 2008

Antimicrobial activities of green tea extracts used for coarse tea were investigated by disc diffusion method using eight different bacteria. Among the green tea extracts, the 70% ethanol extract demonstrated the strongest antimicrobial activities against Vibrio parahemolyticus (V. parahemolyticus) and Staphylococcus aureus (S. aureus) and thus was further fractionated. Among these fractions, the ethyl acetate fraction showed the strongest antimicrobial activities against V. parahemolyticus, S. aureus, Bacillus subtilis (B. subtilis), and Streptococcus mutans (S. mutans). These activities exceeded that of all extracts and fractions tested in this study. Interestingly, although green tea extracts showed significant antimicrobial activity against Micrococcus luteus (M. luteus), once fractionated, the ethyl acetate fraction did not show any antimicrobial activity against M. luteus. MICs of the ethyl acetate fraction were $5\;\;{\mu}L$/disc against B. subtilis and $3\;{\mu}L$/disc against S. aureus, S. mutans and V. parahaemolyticus. 90% inhibition of B. subtilis was observed with 0.05% ethyl acetate fraction but S. mutans needed over 0.1% ethyl acetate fraction to exhibit the same inhibition as B. subtilis. Antimicrobial activities of ethyl acetate fractions were reduced around 10% by thermal treatment at $121^{\circ}C$ for 20 min. All the results suggest that the 70% ethanol extract as well as the ethyl acetate fraction from green tea used for coarse tea could be further developed into a natural antimicrobial agent.