• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.53 no.2
• /
• pp.224-232
• /
• 2008

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. The contents of catechins and caffeine in green tea are considered as a standard of quality evaluation of green tea. Therefor, the purpose of this study was to investigate the most suitable HPLC condition for simultaneous determination of catechins and caffeine in green tea extracts. The efficient HPLC analytical condition of catechins and caffeine contained green tea extracts was developed. The gradient elution employed a $250\;mm\;{\times}\;4.6\;mm$ i.d. YMC-pak ODS-AM 303 column. The gradient system was used two mobile phases. A gradient elution was performed with mobile phase A, consisting of 0.1% aqueous phosphoric acid, and mobile phase B, comprising 100% MeOH, and delivered at a flow rate of 1 mL/min as follows: $0{\sim}25\;min$, 80% A; $26{\sim}50\;min$, $80{\sim}70%$ A; 51 min, 80% A. $51{\sim}55\;min$, 80% A. The UV detection wavelength was set at 280 nm. The limit of detection (LOD) for catechins and caffeine standards were under 50 ng/mL.

• Food Science and Preservation
• /
• v.12 no.1
• /
• pp.36-42
• /
• 2005

The purpose of this study was to investigate the component and quality characteristics of green tea. Four kinds of green tea powder obtained from Hwagae area were evaluated the component of carbohydrates, protein crude fat and crude ash. Also the content of ascorbic acid, minerals and polyphenols in green tea powder were evaluated. Quality characteristics of green tea powder was evaluated by Hunter's colur value and sensory evaluation. Green tea was composed of $9.2\~11.8\%$ of moisture, $4.9\~6.1\%$ of crude ash, $5.2\~6.1\%$ of crude fat, $22.5\~26.4\%$ of protein and $50.4\~55.1\%$ of cabohydrates. The content of total ascorbic acid in green tea powder was $312\~392mg/100g$ and dehydiuascorbic acid was $157\~176mg/100g$. The contents of minerals in green tea powder sodium was $340\~580mg/100g$, magnesium was $242\~320mg/100g$, potassium $223\~278mg/100g$ me calcium $145.7\~238.7mg/100g$. Polyphenol content of green tea powder was $7.8\~9.3\%$ which was the highest in A and the lowest in B. Hunters color values of green tea, lightness(L) was $52.3\~69.6$, redness(a) was $0.11\~-5.61$, yellowness(b) was $14.23\~23.34$, which were better in green tea C and D than green tea A and B. From sensory evaluation of green tea powders, green tea D obtained the significant highest scores in color, flavor and overall quality(p<0.05) and followed by green tea C, Green tea powder C and D which have high levels of protein and ascorbic acid were evaluated as good quality in color and sensory evaluation.

• Food Science and Preservation
• /
• v.14 no.6
• /
• pp.709-715
• /
• 2007

Korean green tea has been claimed to have health-promoting effects, which may be related to the antioxidant activity in vitro. Korean green teas (Woojeon, WJ ; Sejak, SJ ; Jungjak, JJ ; Daejak, DJ) were subjected to different harvested times and yet little research has examined their bioactive compounds. To assess the effect of this different harvested times on nutritional and health-related properties such as Korean green tea polyphenols, flavonoids, theanine and free amino acids, antioxidant activities and radical scavenging activities were determined. Total polyphenols in JJ (37.16 mg/g) was higher than in other products (WJ, 19.55 ; SJ 24.65 ; DJ, 23.28 mg/g). Contents of flavonol and flavone glycosides were the highest at DJ (350.83 mg%) as compared to WJ (220.81), SJ (256.88) and JJ (270.36 mg%). Contents of theanine and total free amino acids were the highest at WJ (14.11, 23.62 mg/g, respectively), but decreased thereafter. Antioxidant activities were higher in JJ and DJ, using the linoleic acid peroxidation, DPPH and ABTS free radical-scavenging activities. However, WJ and SJ had less active antioxidant activity and free radical-scavenging activity. Reducing powers were increased depend on the concentration of extracts. Antioxidant activity and free radical-scavenging activity of JJ and DJ seemed to relate with total polyphenol and flavonoid contents.

• Molecules and Cells
• /
• v.39 no.6
• /
• pp.508-513
• /
• 2016

To investigate the potential therapeutic effects of polyphenols in treating Pb induced renal dysfunction and intoxication and to explore the detailed underlying mechanisms. Wistar rats were divided into four groups: control groups (CT), Pb exposure groups (Pb), Pb plus Polyphenols groups (Pb+PP) and Polyphenols groups (PP). Animals were kept for 60 days and sacrificed for tests of urea, serum blood urea nitrogen (BUN) and creatinine. Histological evaluations were then performed. In vitro studies were performed using primary kidney mesangial cells to reveal detailed mechanisms. Cell counting kit-8 (CCK-8) was used to evaluate cell viability. Pb induced cell apoptosis was measured by flow cytometry. Reactive oxygen species (ROS) generation and scavenging were tested by DCFH-DA. Expression level of tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-1-${\beta}$ (IL-1-${\beta}$) and IL-6 were assayed by ELISA. Western blot and qPCR were used to measure the expression of ERK1/2, JNK1/2 and p38. Polyphenols have obvious protective effects on Pb induced renal dysfunction and intoxication both in vivo and in vitro. Polyphenols reduced Pb concentration and accumulation in kidney. Polyphenols also protected kidney mesangial cells from Pb induced apoptosis. Polyphenols scavenged Pb induced ROS generation and suppressed ROS-mediated ERK/JNK/p38 pathway. Downstream pro-inflammatory cytokines were inhibited in consistency. Polyphenol is protective in Pb induced renal intoxication and inflammatory responses. The underlying mechanisms lie on the antioxidant activity and ROS scavenging activity of polyphenols.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2001.10a
• /
• pp.41-42
• /
• 2001

The chemopreventive effect of tea against 2-amino-l-methyl-6-phenylimidazo［4, 5-b ］pyridine (PhIP)-DNA adduct formation and its mechanism were studied. Rats were exposed to freshly prepared aqueous extracts of green tea (3% w/v) as the sole source of drinking water for 10 days prior to administration with a single dose of PhIP (10 mg/kg body wt) by oral gavage. PhIP-DNA adducts in the liver, colon, heart, and lung were measured using the $^{32}$ P-postlabelling technique.(omitted)

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.6
• /
• pp.765-770
• /
• 2017

Green tea (Camellia sinensis L.) is consumed as a popular beverage worldwide, particularly in Asia. In this study, the effects of green tea powder addition on the antioxidant activities and texture properties of cooked rice were investigated. Texture analysis was carried out by texture profile analysis. Total polyphenols and total flavonoids were determined using spectrophotometric methods, and antioxidative activities were determined based on DPPH and ABTS radical scavenging activities, reducing power, and lipid peroxidation inhibitory activity. Antioxidant contents and antioxidative activities increased with a higher amount of green tea powder. However, there was no difference in texture properties between cooked rice with green tea powder and the control group. In conclusion, addition of green tea powder to cooked rice would be useful to increase antioxidant contents and antioxidative activities without alteration of texture properties.

• Korean Journal of Food Science and Technology
• /
• v.43 no.5
• /
• pp.641-647
• /
• 2011

Polyphenols in green tea are biologically active and may interact with commonly-consumed over-the-counter (OTC) drugs in the body. In this study, modulation of cytotoxicity of polyphenon 60 (PPE, tea polyphenol mixture) with co-treatment of several OTC drugs, including ibuprofen (Ibu), acetaminophen (AAP), and aspirin was investigated in intestinal cells. PPE showed more potent cytotoxic effects on colon cancer HCT 116 cells than on normal intestinal INT 407 cells. Ibu had the strongest cytotoxic effects on both cell types. Cytotoxicity of PPE on HCT 116 and INT 407 cells was not markedly altered by co-treated OTC drugs. Cytotoxicity of the OTC drugs was not affected by PPE. When HCT 116 cells were incubated with AAP before or after PPE treatment, cytotoxicity was slightly enhanced more than their additive effect. The present study may provide basic information of possible toxicity due to interaction of the polyphenols and the OTC drugs.

• Food Science and Preservation
• /
• v.13 no.4
• /
• pp.421-426
• /
• 2006

Preservation stability of the extract from dried green tea produced in Jeju, extracted at $55^{\circ}C$ for 15 min and bottled in PET container after filtration and then settled at $4^{\circ}C$, indoor at room temperature and outdoor, respectively, was estimated. Color L-value was almost constant but color of the extract became darkened during storage, especially in indoor storage. Main catechins of green tea extract were (-)-epigallocatechin, (-)-epigallocatechin gallate, epicatechin, (+)-catechin, epicatechin gallate in order, and the content of epigallocatechin was 53.8%. Nevertheless total catechin content was not changed in cold storage, and $4.7\sim10%$ of total catechins were reduced in outdoor or indoor storage after 14 weeks. Caffeine content were increased but total polyphenols were not changed largely during storage. Election donating abilities (EDA) showed more than 60% without influence of storage conditions and periods. Nitrite scavenging abilities (NSA) showed more than 90% at pH 1.2, but those were decreased gradually as pH increased, and then disappeared at pH 6.0. Color, polyphenols, antioxidant activities of extract were not so changed for more than 3 months. Microbial growth was not shown during same periods, due to heat treatment of the extracts at $95^{\circ}C$ for 10 min.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2001.10a
• /
• pp.45-45
• /
• 2001

Heterocyclic aromatic amines (HCAs) are established genotoxic human cancer risks, that display their activity also in a number of animal models and in vitro. They are formed during the trying or broiling of creatinine-containing foods, mainly fish or meat. We established that mixing soy protein with ground meat blocks the formation of HCAs. we also observed that coating the surface of meat with polyphenols green or from black tea gives a dose - related reduction of the formation of HCAs.(omitted)

• Microbiology and Biotechnology Letters
• /
• v.38 no.2
• /
• pp.198-206
• /
• 2010

The aim of this work was to investigate the synergically bactericidal effects and cellular responses of tea polyphenols (TPP) and imipenem on imipenem-resistant Pseudomonas aeruginosa. Imipenem-resistant Ps. aeruginosa was isolated from patient in hospital. The bactericidal effects of TPP and imipenem were evaluated on the basis of its minimum inhibitory concentrations (MIC). The combined use of TPP and imipenem resulted in 16-fold and 8-fold reductions in the MICs of imipenem for the imipenem-susceptible and imipenem-resistant Ps. aeruginosa, respectively. The bactericidal effects of the imipenem and TPP against the Ps. aeruginosa was evaluated using the time-kill assay. The synergetic effects of the combinations of TPP and imipenem against Ps. aeruginosa were confirmed. Western blot using anti-DnaK and anti-GroEL monoclonal antibodies was performed to investigate the expression of stress shock proteins (SSPs) in imipenem-susceptible and imipenem-resistant strains exposed to TPP. The amount of SSPs were induced as the exposure time increased and decreased. The molecular weights of DnaK and GroEL were 70 kDa and 60 kDa, respectively. SDS-PAGE with silver staining revealed that the amount of lipopolysaccharides (LPS) increased or decreased in the strain treated to different concentrations and exposing periods of TPP. Scanning electron microscopic analysis demonstrated the presence of umblicated and wrinkled surfaces for cells treated with TPP or imipenem.