• Korean Journal of Food Science and Technology
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• v.38 no.1
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• pp.5-9
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• 2006

Method for separation and quantification of methylxanthins, catechins, and theaflavins in Korean commercial teas (green, oolong, and black teas) was developed using reversed phase high-performance liquid chromatography (HPLC). After extraction with hot water, tea compounds were separated on Inertsil ODS-3v $(5\;{\mu}m)$ column, eluted with gradient of 7% acetonitrile and 93% of 20 mM phosphate buffer mixture for 7 min. Column effluent was monitored at 270 nm. This technique was effective for analyses of m methylxanthins, catechins, and theaflavins in teas and biological samples. In green and oolong teas, two kinds of methylxanthins and 7 of catechins were identified, whereas 4 theaflavins were only identified in black tea. Among seven catechins in green and oolong teas, EGCG showed highest amount, whereas ECG was highest in black tea. (theaflavins were found only in black teas) In all teas, theobromine content was lower than that of caffeine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.154-159
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• 1995

Inhibition of xanthine oxidase by tea extracts obtained from non-fermented tea(steamed green tea and roasted green tea), semi-fermented tea(oolong tea) and fermented tea(black tea) were investigated. The crude catechin fraciton had a hgher inhibitory effect against xanthine oxidase, and the effect was increased with the addition of tea extracts. Their inhibitory effect were hardly influenced until extracted three times with hot water. According to the investigation of catechins in the crude catechin fraction obtained from tea extracts, (-)-epicatechin-(EC), (-)-epicatechin gallate(ECg). (-)-epigallocatechin(EGC) and (-)-epigallocatechin gallate(EGCg) were 80.1$\mu\textrm{g}$/mg 113.5$\mu\textrm{g}$ /mg, 186.3$\mu\textrm{g}$/mg and 367.7$\mu\textrm{g}$/mg in steamed green tea, and 75.6$\mu\textrm{g}$/mg, 114.7$\mu\textrm{g}$/mg, 193.7 $\mu\textrm{g}$/mg and 381.9$\mu\textrm{g}$/mg in roasted green tea, and 69.4$\mu\textrm{g}$/mg, 110.0$\mu\textrm{g}$/mg, 127.1$\mu\textrm{g}$.mg and 464.9$\mu\textrm{g}$/mg in oolong tea, and 78.1$\mu\textrm{g}$/mg, 171.8$\mu\textrm{g}$/mg, 80.7$\mu\textrm{g}$/mg and 51.4$\mu\textrm{g}$/mg in black tea, respectively. Order of the content of these catechins was (-)-EGCg>(-)-EGC>(-)-ECg>(-)-EC in steamed green tea, roasted green tea and oolong tea, and was (-)-ECg>(-)-EGC>(-)-EC>(-)-EGCg in black tea. Also the concentration of catechins was hardly influeced until extracted three times. The inhibition ratio of xanthine oxidase by autherntic catechins was hardly influenced until extracted three times. The inhibition ratio of xanthine oxidase by authentic catechins was 94.9% and 87.6% by addition of 5.0$\mu\textrm{g}$/ml of (-)-EGCg and (-)-ECg, respectively. the inhibitors of xanthine oxidase were supposed to be due to (-)-ECg and (-)-EGCg in tea polyphenol compounds.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.135-140
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• 2007

Antibacterial activities of the major phenolic components from Camellia sinensis L. were investigated against several pathogenic microorganisms including Gram-positive strains like Staphylococcus aureus ATCC 29213 and Streptococcus pyogens 308A; and Gram-negative strains like Escherichia coli ATCC 25922, Escherichia coli 078, Pseudomonas aeruginosa 9027, and Enterobacter cloacae 1321E. The MIC values demonstrate that both (-)-epicatechin and (-)-epigallocatechin were more considerably toxic against Staphylococcus aureus ATCC 29213 than the other two catechins like (-)-epicatechingallate and (-)-epigallocatechin-3-gallate. (-)-Epicatechingallate and (-)-epigallocatechin-3-gallate were most inhibitory against Escherichia coli ATCC 25922. As a result, (-)-epicatechin showed predominant antibacterial activities among tea varieties. The contents of major polyphenolic components such as four catechins, theaflavin, and quercetin were different according to fermentation processes. The total contents of four catechins were ranged from 13.81 to 1.33%, with (-)-epigallocatechin-3-gallate being dominant among tea varieties; theaflavin was found the characteristic pigment in fully-fermented black tea.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1016-1020
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• 2008

Parameters of soluble solids, amino acids, catechins, and color difference of 24 green tea samples from China and Korea were determined. The levels of soluble solids, amino acids, total catechins, and infusion lightness in tea samples from Korea were higher than those from China. Concentrations of epigallocatechin galate and epigallocatechin in teas from China were higher than tea samples from Korea. Geographical origin of teas from the 2 countries was discriminated using parameters of infusion lightness, gallocatechin, and total catechins and applying principal component analysis.

• YAKHAK HOEJI
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• v.45 no.1
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• pp.101-107
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• 2001

Green tea catechins (GTC) and its major component, (-)-epigallocatechin gallate (EGCG) were studied for their protective effects against reactive oxygen species (ROS)-induced oxidative stress. GTC and EGCG skewed the strong antioxidative effects on the lipid peroxidation of ethyl linolate with Fenton's reagent and free radical scavenging effect to DPPH radical generation. They also protected $H_2O$$_2$- or KO$_2$-induced cytotoxicity in CHL cells or mouse splenocytes. These results indicate that GTC and EGCG are capable of protecting the lipid peroxidation, flee radical generation and cytotoxicity induced by ROS. The mechanism of inhibition in ROS-induced cytotoxicity may be due to their antiofidative and free radical scavenging properties. Therefore, GTC and EGCG may be useful chemopreventive agents by protecting the free radical generation which are involved in cancer and aging.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.6
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• pp.775-781
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• 1995

This study was conducted to find out the variation in some medicinal components of Korean green tea by processing recipe and harvesting time in Bongsan-ri(steamroasted green tea) and Buchun-ri(roasted green tea) area. Total chlorophyll content of green tea grown at Bongsan-ri and Buchun-ri was 293mg% and 275mg% and ratio of chlorophyll a to chlorophyll b was 70:30 and 67:33 respectively. The later harvested one had the higher chlorophyll content but the chlorophyll content of the last harvested green tea at Buchun-ri decreased more sharply. Water-soluble pectin of green tea produced at Bongsan-ri and Buchun-ri was 2.05% and 1.84%, respectively. It also increased at the later harvested ones. Total amino acids content of Bongsan-ri and Buchun-ri tea was 2,156mg% and 1,723mg%, respectively. The later harvested tea showed the remarkably decreased. Caffein and catechins of Bongsan-ri and Buchun-ri tea were 2.03%, 11.52% and 2.62%, 14.05%, respectively, Total free catechins content of Bongsan-ri and Buchun-ri tea was 35.59% and 42.73%, and ester type was 58.09% and 44.47%, respectively. Extracted catechins and caffeins of green tea were increased when extracting water temperature was raised from $65^{\circ}C$ to 85$^{\circ}C$ and leaching time was lengthened from 3min. to 9min. About 89% catechins and 97% caffeins of green tea was extracted by nine minutes soaking in 85$^{\circ}C$ water.

• Proceedings of the Korean Society of Life Science Conference
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• 2001.09a
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• pp.38-38
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• 2001

• Textile Coloration and Finishing
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• v.20 no.2
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• pp.75-82
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• 2008

The optimum extraction conditions of green tea used for a bath were investigated for application to textiles. The stability of the extracts and content of active ingredients were analyzed as well. The extraction was more effective in water and methanol than in ethanol. The optimum extraction temperature was determined as $80^{\circ}C$ in water and $60^{\circ}C$ in methanol. The solid extracts were obtained about 7% in water and 9% in methanol on the weight of dry green tea. The extracts were more stable in acid and neutral conditions than in alkaline region. From the analysis of contents of active ingredients, about 20% of effective catechins was appeared to be contained in the extract solid, which was thought to be available for application to textiles.

• Plant Biotechnology Reports
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• v.3 no.1
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• pp.95-101
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• 2009

Tea leaves are major source of catechins—antioxidant flavonoids. Dihydroflavonol 4-reductase (DFR, EC 1.1.1.219) is one of the important enzymes that catalyzes the reduction of dihydroflavonols to leucoanthocyanins, a key ''late'' step in the biosynthesis of catechins. This manuscript reports characterization of DFR from tea (CsDFR) that comprised 1,413 bp full-length cDNA with ORF of 1,044 bp (115-1,158) and encoding a protein of 347 amino acids. Sequence comparison of CsDFR with earlier reported DFR sequences in a database indicated conservation of 69-87% among amino acid residues. In silico analysis revealed CsDFR to be a membrane-localized protein with a domain (between 16 and 218 amino acids) resembling the NAD-dependent epimerase/dehydratase family. The theoretical molecular weight and isoelectric point of the deduced amino sequence of CsDFR were 38.67 kDa and 6.22, respectively. Upon expression of CsDFR in E. coli, recombinant protein was found to be functional and showed specific activity of 42.85 nmol $min^{-1}$ mg $protein^{-1}$. Expression of CsDFR was maximum in younger rather than older leaves. Expression was down-regulated in response to drought stress and abscisic acid, unaffected by gibberellic acid treatment, but up-regulated in response to wounding, with concomitant modulation of catechins content. This is the first report of functionality of recombinant CsDFR and its expression in tea.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.761-769
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• 2013

This study used HPLC to analyze the contents of catechins, alkaloids, theanine, total phenolic compounds and antioxidant activities of commercial Hadong green tea leaves(Uzen, Sezak, Jungzak, Daezak). The content of catechins, alkaloids, theanine, total phenolic compounds were lower by water extracts than by 80% ethanol-water extracts. Total catechin and alkaloid contents in Uzen(172.33 mg/g, 30.80 mg/g) by 80% ethanol extract were the highest. Theanine contents of 80% ethanol-water extracts ranged form 55.36 to 37.48 mg/g of tea leaves. Total phenloic compounds contents of green tea were higher than Uzen. Antioxidative of green tea by DPPH, FTC, TBA method were higher than that Uzen.