Research Database

Author: Rajesh L. Thangapazham and Anoop K. Singh and Anuj Sharma and James Warren and Jaya P. Gaddipati and Radha K. Maheshwari

Tea [Camellia sinensis (Theaceae)] intake is second only to water in terms of worldwide popularity as a beverage. The Green tea polyphenols have been shown to have a protective effect in prostate cancer in various pre-clinical animal models and has been reported to be effective in several other cancer types as well. An inverse association between the risk of breast cancer and the intake of green tea has also been reported in Asian Americans. Several epidemiological studies have shown that breast cancer progression is delayed in the Asian population that consumes green tea on regular basis. In this study, we report the effectiveness of green tea polyphenols (GTP) and its constituent Epigallocatechin Gallate (EGCG) in tumor regression using both in-vitro cell culture models and in vivo athymic nude mice models of breast cancer. The anti-proliferative effect of GTP and EGCG on the growth of human breast cancer MDA-MB-231 cell was studied using a tetrazolium dye-based (MTT) assay. Both GTP and EGCG treatment had the ability to arrest the cell cycle at G1 phase as assessed by flow cytometry. The expression of Cyclin D, Cyclin E, CDK 4, CDK 1 and PCNA were down regulated over the time in GTP and EGCG treated experimental group, compared to the untreated control group as evaluated by western blot analysis for cell cycle proteins, which corroborated the G1 block. Nude mice inoculated with human breast cancer MDA-MB-231 cells and treated with GTP and EGCG were effective in delaying the tumor incidence as well as reducing the tumor burden when compared to the water fed and similarly handled control. GTP and EGCG treatment were also found to induce apoptosis and inhibit the proliferation when the tumor tissue sections were examined by immunohistochemistry. Our results suggest that GTP and EGCG treatment inhibits proliferation and induce apoptosis of MDA-MB-231 cells in-vitro and in-vivo. All together, these data sustain our contention that GTP and EGCG have anti-tumor properties.

 

 

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Author: Sung I. Koo and Sang K. Noh

Author: S. Mahaboob Khan and Gurjot Kour

This paper reports the effect of green tea administration following subacute toxicity caused by exposure to organophosphorus pesticide chlorpyriphos in liver of rats. Four groups containing five male Sprague–Dawley rats each were selected. Group I served as control. Group II rats were permitted free access to solubilised crude extract of green tea (1.5%w/v in water) as the sole drinking fluid. Group III rats were given a single daily oral dose of chlorpyriphos (30 mg/kg bodyweight in corn oil). Group IV rats received oral dose of pesticide and green tea extract simultaneously. All rats were sacrificed after 15 days. Significant damage to liver was observed via increased serum levels of transaminases and alkaline phosphatase. Lipid peroxidation showed a 5-fold increase in pesticide exposed rats compared to control. In contrast, levels of antioxidant GSH, glutathione-dependent enzymes like glutathione peroxidase (GPx), glutathione S-transferase (GST) and free radical scavengers like catalase (CAT) and superoxide dismutase (SOD) were significantly lower than those of the control group reinforcing oxidative damage. The use of green tea extract appeared to be beneficial to rats, although not to a great extent in significantly reducing and reversing the damage sustained by pesticide exposure and favors recovery.

 

 

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Author: Huiling Liang and Yuerong Liang and Junjie Dong and Jianliang Lu and Hairong Xu and Hui Wang

Hot water treatment was used to decaffeinate fresh tea leaf in the present study. Water temperature, extraction time and ratio of leaf to water had a statistically significant effect on the decaffeination. When fresh tea leaf was decaffeinated with a ratio of tea leaf to water of 1:20 (w/v) at 100 °C for 3 min, caffeine concentration was decreased from 23.7 to 4.0 mg g−1, while total tea catechins decreased from 134.5 to 127.6 mg g−1; 83% of caffeine was removed and 95% of total catechins was retained in the decaffeinated leaf. It is considered that the hot water treatment is a safe and inexpensive method for decaffeinating green tea. However, a large percentage of tea catechins was lost if rolled leaf and dry tea were decaffeinated by the hot water treatment and so the process is not suitable for processing black tea.

 

 

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Author: Hyong Seok Park and Hee Jin Lee and Min Hye Shin and Kwang-Won Lee and Hojoung Lee and Young-Suk Kim and Kwang Ok Kim and Kyoung Heon Kim

Due to the adverse effects of the caffeine in a variety of plant products, many methods have been explored for decaffeination, in efforts to remove or reduce the caffeine contained in plant materials. In this study, in order to remove caffeine from green tea (Camellia sinensis) leaves, we have employed supercritical carbon dioxide (SC–CO2), which is known to be an ideal solvent, coupled with a cosolvent, such as ethanol or water. By varying the extraction conditions, changes not only in the amount of caffeine, but also in the quantities of the principal bioactive components of green tea, including catechins, such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC), were determined. The extraction conditions, including temperature, pressure and the cosolvent used, were determined to affect the efficacy of caffeine and catechin extraction. In particular, the type and concentration of a cosolvent used constituted critical factors for the caffeine removal, combined with minimal loss of catechins, especially EGCG. When the dry green tea leaves were extracted with SC–CO2 modified with 95% (v/v) ethanol at 7.0 g per 100 g of CO2 at 300 bar and 70 °C for 120 min, the caffeine content in the decaffeinated green tea leaves was reduced to 2.6% of the initial content. However, after the SC–CO2 extraction, a substantial loss of EGCG, as much as 37.8% of original content, proved unavoidable.

 

 

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Author: Min-Jer Lu and Chinshuh Chen

In vitro experiments were performed to test inhibition of nitrite-mediated N-nitrosation by individual catechins, green tea, and tannase-treated green tea extracts. The extent of inhibition was measured via nitrosamine formation. Green tea with or without tannase treatment was examined to study nitrosation inhibition in order to evaluate the inhibitory activities with the structural changes of catechins present in the extracts. The results showed that the tannase-treated green tea had a greater ability to inhibit the nitrosation than green tea and ascorbic acid did. The tannase-treated green tea strongly inhibited the formation of N-nitrosodimethylamine (NDMA). Among four major catechins tested, epigallocatechin blocked the N-nitrosation efficiently, and epigallocatechin gallate was more unstable than epigallocatechin at pH 2.0 or 8.0. These results suggest that the consumption of tannase-treated green tea can reduce NDMA formation.

 

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Author: Naghma Khan and Hasan Mukhtar

People have been consuming brewed tea from the leaves of the Camellia sinensis plant for almost 50 centuries. Although health benefits have been attributed to tea, especially green tea consumption since the beginning of its history, scientific investigations of this beverage and its constituents have been underway for less than three decades. Currently, tea, in the form of green or black tea, next to water, is the most widely consumed beverage in the world. In vitro and animal studies provide strong evidence that polyphenols derived from tea may possess the bioactivity to affect the pathogenesis of several chronic diseases. Among all tea polyphenols, epigallocatechin-3-gallate has been shown to be responsible for much of the health promoting ability of green tea. Tea and tea preparations have been shown to inhibit tumorigenesis in a variety of animal models of carcinogenesis. However, with increasing interest in the health promoting properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and health benefits of tea with special reference to cancer and cardiovascular diseases.

 

 

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Author: Shuhong Guo and Jingqi Yan and Tangbin Yang and Xianqiang Yang and Erwan Bezard and Baolu Zhao

Author: Emily D. Niemeyer and Jennifer S. Brodbelt

Hydrogen/deuterium exchange reactions in a quadrupole ion trap mass spectrometer are used to differentiate galloylated catechin stereoisomers (catechin gallate and epicatechin gallate; gallocatechin gallate and epigallocatechin gallate) and the nongalloylated analogs (catechin and epicatechin, gallocatechin and epigallocatechin). Significant differences in the hydrogen/deuterium exchange behavior of the four pairs of deprotonated catechin stereoisomers are observed upon reaction with D2O. Interestingly, the nongalloylated catechins undergo H/D exchange to a much greater extent than the galloylated species, incorporating deuterium at both aromatic/allylic and active phenolic sites. Nongalloylated catechin isomers are virtually indistinguishable by their H/D exchange kinetics over a wide range of reaction times (0.05 to 10 s). Our experimental results are explained using high-level ab initio calculations to elucidate the subtle structural variations in the catechin stereoisomers that lead to their differing H/D exchange kinetics.

 

 

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Author: Mansour Rahimi and Nader Moinfar and Afsaneh Ashrafi

 

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