• Korean Journal of Food Science and Technology
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• 제35권4호
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• pp.576-585
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• 2003

An improved method in place of a conventional vanillin spectroscopic method (CVSM) was developed for determination of catechin and its derivatives in extract and oil of grape seeds. For the CVSM, grape seed extracts had relatively high catechin content in the range of $17{\sim}43%$ (g/100g of extract), while grape seed oils had relatively smaller catechin content in the range of $30{\sim}40mg%$ (mg/100g of oil). For the improved vanillin spectroscopic method (IVSM) using a polyamide cartridge, catechin content of grape seed extracts was in the range of $4.0{\sim}7.5%$, while that of grape seed oils was below 5 ppm. Meanwhile, the quantities of catechin and its derivatives were determined by HPLC in the grape seed extracts and oils. Four major catechins [(+)-catechin, procyanidin B2, (-)-epicatechin, and epicatechin gallate] were detected from grape seed extracts, and the ranges of concentrations were as follows: (+)-catechin, $1.35{\sim}2.60%$; procyanidin $B_2$, $0.77{\sim}1.36%$; (-)-epicatechin, $2.35{\sim}4.59%$; (-)-epicatechin gallate, $0.06{\sim}0.30%$. In contrast, four catechins were barely detectable in the grape seed oils. The reproducibility of four major catechins in grape seed extracts, given as coefficient of variation, was below 5%, and the recovery close to above 95%. The achieved detection level of four catechins was $1{\sim}5\;ppm$. Additionally, the contents of catechin compositions in grape seed extract were also determined by HPLC in relation to different cultivars and producing areas. Thus, HPLC method and IVSM using polyamide cartridge can be used as alternative to CVSM for determination of catechin and its derivatives in extract and oil of grape seeds.

• Food Science and Preservation
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• 제16권6호
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• pp.924-928
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• 2009

Green tea has been shown to have multifunctional health-promoting properties including cholesterol level control an antidiabetic effect and anticancer, antioxidant, and antimicrobial properties, inboth in vivo and in vitro experiments.We earlier reported antifungal and antibacterial effects of green tea extract by investigating cell membrane functions. The purpose of the present study was to purify and identify antimicrobial substances from green tea extract. Such materials were extracted from green tea (Camellia sinensis. var. sinensis) and purified by high-performance liquid chromatography. The antimicrobial substances in the extract were identified as epicatechin gallate and epigallocatechin gallate by nuclear magnetic resonance spectrophotometry.

• The Korean Journal of Food And Nutrition
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• 제24권4호
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• pp.720-724
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• 2011

Differences in sensory evaluation, physicochemical properties and antioxidant activities between green tea concentrations and tannase-treated green tea concentrations were measured in this study. The results showed that pH did not differ dependent on tannase treatment but antioxidant ability were slightly increased through tannase treatment without significant($p$ <0.05). However, the turbidity of the tannase-treated green tea concentration had significant difference to the non-treated concentration. The astringency, tested via sensory evaluation, decreased significantly after tannase treatment($p$ <0.05). Traces of epicatechin gallate(ECG) and epigallocatechin gallate(EGCG) also disappeared after the tannase treatment, due to the fact that the ester linkages in the catechin structure were broken by the tannase. It was concluded that tannase treatment of tea products is a very effective process for decreasing astringency and turbidity.

• Korean Journal of Plant Resources
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• 제20권1호
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• pp.38-42
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• 2007

The present study was conducted to investigate the translocation of polyphenols, especially catechin derivatives, from mushroom medium mixed with green tea residues into fruiting body of Pleurotus eryngii. Pleurotus eryngii was grown on the media incorporated by mixing or surface-treated with dry materials including leaf petioles and young stems or leaves of green tea. The dry materials treated in medium did not affect plant height and fresh weight of Pleurotus eryngii body. From the samples of Pleurotus eryngii, the eight main catechin derivatives (-)-gallocatechin(GC), (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), and (-)-catechin gallate (EGCG), and caffeine were analyzed quantitatively by HPLC. The results showed that EGC in Pleurotus eryngii was 45% more detected, when incorporated with the dry materials, than untreated control. Especially, content of EGCG was increased in surface-treated Pleurotus eryngii up to 3.2 ppm, while it was not detected or reduced in control and other treatments. Caffeine content was greatly increased regardless of treatment method, compared with control (0.1ppm), showing 44 fold-amount in Pleurotus eryngii at early growth stage when incorporated with the dry materials into medium. The results indicates that functional catechin derivatives of green tea would be partly translocated into Pleurotus eryngii throught incorporation and surface treatment with residues of green tea plants.

• Journal of Life Science
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• 제18권2호
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• pp.273-278
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• 2008

Various biological resources from plants, animals, mushrooms, microorganisms, and foods were tested for the inhibitory activity against squalene synthase (SQS). Among 32 samples, more than one fourths (9 samples) exhibited significant SQS inhibitory activity. Interestingly, SQS inhibitory activity was detected in the samples such as green tea, fermented soybean paste, and plum juice. The SQS inhibitory activity of green tea was not only high but also stable. Its SQS inhibitors were supposed to be catechin derivatives, which have been known to be main bioactive components in green tea. The galloyl catechins showed higher SQS inhibitory activity compared to the nongalloyl catechins. Especially, (-)-epigallocatechin gallate appeared to be strongest inhibitor against squalene synthase ($IC_{50}=90{\mu}M$).

• Korean Journal of Food Science and Technology
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• 제36권4호
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• pp.542-546
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• 2004

Changes in contents of catechins, caffeine, free amino acids, and minerals in green tea loaves according to harvest periods were compared. Total catechin content increased from 40.61 to 52.04 mg/g, while that of caffeine decreased from 17.56 to 14.61 mg/g according to harvest periods. Regardless of harvest periods, composition of catechins was epigallocatechin (EGC)>epigallocatechin gallate (EGCg)>epicatechin (EC)>gallocatechin (GC)>epicatechin gallate (ECg)>catechin (C)>gallocatechin gallate (GCg)>catechin gallate (Cg). Free amino acid content in green tea leaves was highest in young loaves, and gradually decreased according to harvest periods. Theanine content was markedly decreased with leaf aging, suggesting taste of green tea may be changed from mild to bitter with increasing harvest period. Analyses of mineral elements in green tea leaves showed that Fe, Mn, and Mg increased with leaf aging, while Cu showed opposite trend. Results reveal that content of some chemical compounds in Korean (Posong) green tea was highly dependent on harvest period.

• The Korean Journal of Food And Nutrition
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• 제31권3호
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• pp.416-424
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• 2018

The physiologically advantageous aspects of green tea have been identified recently and green tea has been a favorite drink of many people. Due to the increased awareness of green tea's positive effects on human health, the demand for foods containing green tea has increased. This has led to the development of diverse green tea-related beverages; thereby many companies in Korea have put a wide variety of manufactured green tea beverages on the market. However, the components within green tea beverages have not been examined in Korea yet. In this study, we investigated the contents of the physiologically functional materials found in green tea, such as catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatecin gallate, gallocatechin gallate and caffeine. Fifty-six green tea products purchased from the local grocery stores and cafes were analyzed using high performance liquid chromatography (HPLC) analysis. As a result, all tested products contained catechin and caffeine, although the amount of each component was largely different. The total amount of catechin derivatives in the manufactured green tea beverages purchased from cafes was 263.17 mg/L, while they were 61.99 mg/L in the beverages purchased from the local grocery stores. And, to the almost samples the amount of caffeine was proportional to the amount of catechin.

• Applied Biological Chemistry
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• 제41권1호
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• pp.110-117
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• 1998

Seven kinds of polyphenol compounds having ACE activities were isolated and purified by Sephadex LH-20, MCI-gel CHP-20, ${\um}-Bondapak\;C_{18}$ and Fuji-gel ODS $G_3$ sucessively from cacao bean(Ghana). The chemical structures of each compound were determined and identified using analyzers such as $^1H-NMR$, $^{13}C-NMR$, IR, MS, polarimeter and Elemental Analysis. Inhibition effects of isolated polyphenols on angiotensin converting enzyme (concerned with hypertension) were also observed. The results obtained were as follows,; The compounds isolated and identified were confirmed and determined as compound 1 [(+)-catechin], compound 2 [(-)-epicatechin], compound 3 [procyanidin B-1 : (-)-epicatechin-$(4{\beta}{\rightarrow}8)$-(+)catechin], compound 4 [procyanidin B-2 : (-)-epicatechin-$(4{\beta}{\rightarrow}8)$-(-)-epicatechin], compound 5 [procyanidin B-7 : (-)-epicatechin-$(4{\beta}{\rightarrow}6)$-(+)-catechin], campound 6 (procyanidin B-2,3,3'-O -digallate), compound 7 [cinnamtannin A-2 : (-)-epicatechin-$(4{\beta}{\rightarrow}8)$-(-)-epicatechin-$(4{\beta}{\rightarrow}8)$-(-)-epicatechin-$(4{\beta}{\rightarrow}8)$-(-)-epicatechin]. In the inhibition effect on ACE, procyanidin B-2,3,3'-O-digallate (compound 6) showed a higher value of 94.6% for ACE in $100\;{\um}M$ than other compounds such as (+)-catechin (compound 1), (-)-epicatechin (compound 2), procyanidin B-1 (compound 3), procyanidin B-2 (compound 4), procyanidin B-7 (compound 5) and cinnamtannin A-2 (compound 7) showing 67.9%, 61.9%, 88.6%, 82.5%, 72.2% and 82.3% for ACE, respectively. Inhibition of $4{\beta}{\rightarrow}8$ in coupling bond on the ACE enzyme was more effective than that of $4{\beta}{\rightarrow}6$. Procyanidin containing gallate inhibited more effectively than those containing not any. It was also observed that a lot of hydroxy group in the compounds increased the inhibitory effect.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2222-2226
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• 2011

Amylase is a digestive enzyme that catalyses the starch into sugar. It has been reported that the green tea flavonoid (or polyphenols) (-)-epigallocatechin 3-gallate (EGCG) inhibits human salivary ${\alpha}$-amylase (HSA) and induced anti-nutritional effects. In this study, we performed docking study for seven EGCG-like flavonoids and HSA to understand the interaction mechanism of HSA and EGCG and suggest new possible flavonoid inhibitors of HSA. As a result, EGCG and (-)-epicatechin gallate (ECG) bind to HSA with complex hydrogen bonding interactions. These hydrogen bonding interactions are important for inhibitory activity of EGCG against HSA. We suggested that ECG can be a potent inhibitor of HSA. This study will be helpful to understand the mechanism of inhibition of HSA by EGCG and give insights to develop therapeutic strategies against diabetes.

• Food Science and Biotechnology
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• 제15권5호
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• pp.799-804
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• 2006

Ingestion of green tea has been shown to decrease prostaglandin $E_2$ levels in human colorectum, suggesting that tea constituents modulate arachidonic acid metabolism. In the present study, we investigated the effects of four purified green tea catechins, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epigallocatechin-3-gallate (EGCG), and (-)-epicatechin-3-gallate (ECG), on the catalytic activity of cytosolic phospholipase $A_2$ ($cPLA_2$) and release of arachidonic acid and its metabolites from intact cells. At $50\;{\mu}M$, EGCG and ECG inhibited $cPLA_2$ activity by 19 and 37%, respectively, whereas EC and EGC were less effective. The inhibitory effects of these catechins on arachidonic acid metabolism in intact cells were much more pronounced. At $10\;{\mu}M$, EGCG and ECG inhibited the release of arachidonic acid and its metabolites by 50-70% in human colon adenocarcinoma cells (HT-29) and human esophageal squamous carcinoma cells (KYSE-190 and 450). EGCG and ECG also inhibited arachidonic acid release induced by A23187, a calcium ionophore, in both HT-29 and KYSE-450 cell lines by 30-50%. The inhibitory effects of green tea catechins on $cPLA_2$ and arachidonic acid release may provide a possible mechanism for the prevention of human gastrointestinal inflammation and cancers.