Research Database

Author: A.J. Pham⁎ and J.B. Williams and A.C. Tolentino and J.L. Silva and M.W. Schilling

 

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Author: A.J. Pham and J.B. Williams and S. Kin and Y.L. Xiong and M.W. Schilling

 

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Author: Prakitpunthu Tomtitchong and Jean E. Crabtree

Introduction: Epidemiological studies suggest epigallocatechin-3-gallate (EGCG), a natural product from green tea, may have a role in prevention of gastric atrophy and gastric cancer in Asian populations. Anyway, the diversity of results from in vivo studies was observed. Our group reported that EGCG inhibits H. pylori-induced upregulation of COX-2, EGF- related ligand and ADAMs transcripts, ERK phosphorylation and IL-8 activation in gastric and non-gastric epithelial cells. But we have simultaneously observed that EGCG can be a stimulator in some conditions. Recently, an EGCG specific receptor has been identified which is the 67 kDa laminin receptor (LR). We postulate that varying levels of the EGCG receptor, the 67 kDa LR, on different cell lines may modify the in vitro results determining the inhibitory effects of EGCG on cell signaling pathways. Methods: MKN28, MGEC, L5F11 and A431 epithelial cells were incubated with MLuC5 mouse monoclonal IgM before incuba- tion with TRITC-conjugated goat anti-mouse expression of the EGCG receptor. The 67 kDa laminin receptor (LR) or EGCG receptor was evident by immunofluorescence. Expression levels of EGCG receptor were compared with the different responses to EGCG among the four cell lines. Results: Strong expression of the EGCG receptor was evident on MKN28 cells but reduced levels were observed on L5F11 and A431 cells. MGEC cells show no expression of 67 kDa LR. Conclusions: Varying levels of the laminin or EGCG receptor may explain the different responses of the cell lines to EGCG and might explain variation of a role EGCG in prevention of H. pylori-induced gastric carcinogenesis.

 

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Author: S. Yamada and S. Misaka and K. Tanabe and A. Osano and K. Takeuchi and J.P. Werba and H. Watanabe

Background and purpose: Green tea has been reported to have various health benefits including cancer prevention and antiox- idative effect. Catechins, the main flavonoids in green tea, are considered to be potential components of these effects. Recently, a case report suggested that the consumption of catechin-rich green tea is associated with simvastatin intolerance. The present study aimed to evaluate the effect of catechin-rich green tea consumption on the pharmacokinetics of simvastatin lactone (SIM) and simvas- tatin acid (SVA), which are a prodrug and an active metabolite of simvastatin, respectively. Methods: In an open-label, two-way crossover study with 14 days washout, a single oral dose of 10mg SIM was administered to 12 healthy Japanese male volunteers (23–26 years old; body weight, 65.1±2.4 kg) after drinking of green tea (700mL/day, total catechinsof1080mg)orwater for2weeks. Bloodsampleswerecol- lected up to 24h after the administration. Plasma concentrations of SIM and SVA were determined using LC/MS/MS. Pharmacokinetic parameters were estimated by noncompartmental analysis. Results and discussion: Chronic consumption of catechin- rich green tea led to increases in the area under the plasma concentration-time curve (AUC0–∞) andmaximum concentration (Cmax) of SIM by 1.6- and 1.3-folds, respectively, as compared to water. No change was observed in the elimination half-life of SIM between green tea andwater, indicating that catechinsmainlymay inhibit SIMmetabolism in the intestine. In addition, green tea con- sumption significantly increased AUC0–∞ and Cmax of SVA by 1.5 and 1.6-folds, respectively, suggesting that green teamay affect not only the pharmacokinetics, but also the pharmacodynamics of SVA. Conclusion: The chronic consumption of catechin-rich green tea may cause the clinically relevant interaction with simvastatin.

 

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Author: Saeed Masoum and Mohsen Behpour and Fatemeh Azimi and Mohammad Hassan Motaghedifard

Differential pulse voltammetry technique assisted by chemometric methods such as multivariate curve resolution-alternating least squares (MCR-ALS) has been proposed as a valuable approach for (+)-catechin determination in the presence of gallic acid at the surface of multiwalled carbon nanotube paste electrode. Central composite design and response surface methodology were used to optimize the influencing parameters. To determine (+)-catechin in the presence of unexpected electroactive interference with a very high degree of overlapping, second-order electrochemical data were generated by changing the pulse height as an instrumental parameter. After potential shift correction, MCR-ALS results show that second-order calibration could be applied with great success for electroanalytical determination of highly overlapped electroactive species. The linear least-squares calibration curve based on the area under concentration profile was provided over the range of 0.10–2.69 μM for (+)-catechin, whereas detection limit was found to be 0.017 μM. Also in this study, the effect of rotational ambiguity associated with a particular MCR solution under a set of constraints was investigated.

 

 

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Author: Sofia Benyahya and Chahinez Aouf and Sylvain Caillol and Bernard Boutevin and Jean Pierre Pascault and Hélène Fulcrand

Phenolic extract from the green tea leaves was used for the production of thermoset epoxy resins. The commercial green tea extract (GTE) was functionalized by the reaction with epichlorohydrin in the presence of phase transfer catalyst. The glycidyl ether derivative of the green tea extract (GEGTE) obtained with a good yield was cured in epoxy polymer with isophorone diamine (IPD) and the resulting network was compared to catechin-IPD and diglycidyl ether of bisphenol A (DGEBA-IPD) systems. The thermal and mechanical analyses of this bio-based epoxy polymer showed its high reactivity associated with a high crosslinking density (Tg: 140–190 °C), a high thermal resistance and interesting mechanical properties.

 

 

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Author: G. Balaji and M. Chalamaiah and P. Hanumanna and B. Vamsikrishna and D. Jagadeesh Kumar and V. Venu babu

Green tea (Camellia sinensis) is one of the most popular and widely consumed beverages in the world. In the current study, aqueous extract of green tea (C. sinensis) was evaluated for mast cell stabilizing and anti-anaphylactic activities. Green tea extract (11, 13, 15 mg/ml) significantly (P < 0.05) inhibited compound 48/80-induced rat mesentric mast cell degranulation in a dose dependent manner. Anti-anaphylactic activity of green tea extract was performed in female mice. At a dose of 400, 500, 600 mg/kg BW, green tea extract showed significant reduction in the mortality of mice subjected to anaphylactic shock by compound C48/80. Ketotifen was used for comparison. In addition, IR and UV–Visible spectroscopy analysis of green tea extract revealed the presence of functional groups of bioactive compounds. These results suggest that green tea could be useful in the treatment of asthma and allergic rhinitis.

 

 

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Author: Ke-Wang Luo and Chun-Hay Ko and Grace Gar-Lee Yue and Julia Kin-Ming Lee and Kai-Kai Li and Michelle Lee and Gang Li and Kwok-Pui Fung and Ping-Chung Leung and Clara Bik-San Lau

Green tea (Camellia sinensis, CS), a kind of Chinese tea commonly consumed as a healthy beverage, has been demonstrated to have various biological activities, including antioxidation, antiobesity and anticancer. Our study aims to investigate the antitumor, antimetastasis and antiosteolytic effects of CS aqueous extract both in vitro and in vivo using metastasis-specific mouse mammary carcinoma 4T1 cells. Our results showed that treatment of 4T1 cells with CS aqueous extract resulted in significant inhibition of 4T1 cell proliferation. CS extract induced 4T1 apoptosis in a dose-dependent manner as assessed by annexin-V and propidium iodide staining and caspase-3 activity. Western blot analysis showed that CS increased the expression of Bax-to-Bcl-2 ratio and activated caspase-8 and caspase-3 to induce apoptosis. CS also inhibited 4T1 cell migration and invasion at 0.06–0.125 mg/ml. In addition, CS extract (0.6 g/kg, orally fed daily for 4 weeks) was effective in decreasing the tumor weight by 34.8% in female BALB/c mice against water treatment control (100%). Apart from the antitumor effect, CS extract significantly decreased lung and liver metastasis in BALB/c mice bearing 4T1 tumors by 54.5% and 72.6%, respectively. Furthermore, micro-computed tomography and in vitro osteoclast staining analysis suggested that CS extract was effective in bone protection against breast cancer-induced bone destruction. In conclusion, the present study demonstrated that the CS aqueous extract, which closely mimics green tea beverage, has potent antitumor and antimetastasis effects in breast cancer and could protect the bone from breast cancer-induced bone destruction.

 

 

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Author: David Méndez Sevillano and Luuk A.M. van der Wielen and Nasim Hooshyar and Marcel Ottens

This work focuses on the rapid selection of a resin from a defined set of macroporous polymeric resins for the decaffeination of catechins from green tea. High-throughput experimentation and design of experiments are used in order to retrieve as much information as possible from a small set of experiments on the interaction of components with the resins. A multicomponent Langmuir isotherm model is used to describe the adsorption and parameters are regressed with high accuracy. These parameters are subsequently used for the definition of criteria to calculate a weighted resin score. The optimal resin is Diaion 20HP with a score of 90.50%, mainly due to its good selectivity for caffeine over catechin (3).

 

 

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Author: Piwen Wang and Jaydutt V. Vadgama and Jonathan W. Said and Clara E. Magyar and Ngan Doan and David Heber and Susanne M. Henning

The chemopreventive activity of green tea (GT) is limited by the low bioavailability and extensive methylation of GT polyphenols (GTPs) in vivo. We determined whether a methylation inhibitor quercetin (Q) will enhance the chemoprevention of prostate cancer in vivo. Androgen-sensitive LAPC-4 prostate cancer cells were injected subcutaneously into severe combined immunodeficiency (SCID) mice one week before the intervention. The concentration of GTPs in brewed tea administered as drinking water was 0.07% and Q was supplemented in diet at 0.2% or 0.4%. After 6-weeks of intervention tumor growth was inhibited by 3% (0.2% Q), 15% (0.4% Q), 21% (GT), 28% (GT+0.2% Q) and 45% (GT+0.4% Q) compared to control. The concentration of non-methylated GTPs was significantly increased in tumor tissue with GT+0.4% Q treatment compared to GT alone, and was associated with a decreased protein expression of catechol-O-methyltransferase and multidrug resistance-associated protein (MRP)-1. The combination treatment was also associated with a significant increase in the inhibition of proliferation, androgen receptor and phosphatidylinositol 3-kinase/Akt signaling, and stimulation of apoptosis. The combined effect of GT+0.4% Q on tumor inhibition was further confirmed in another experiment where the intervention started prior to tumor inoculation. These results provide a novel regimen by combining GT and Q to improve chemoprevention in a non-toxic manner and warrant future studies in humans.

 

 

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