Research Database

Author: Qiong Li and Haifeng Zhao and Ming Zhao and Zhaofeng Zhang and Yong Li

As the organism ages, production of reactive oxygen species (ROS) increases while antioxidants defense capability declines, leading to oxidative stress in critical cellular components, which further enhances ROS production. In the brain, this vicious cycle is more severe as brain is particularly vulnerable to oxidative damage. In our study, 14-month-old female C57BL/6J mice were orally administered 0.05% green tea catechins (GTC, w/v) in drinking water for 6 months. We found that GTC supplementation prevented the decrease in total superoxide dismutase and glutathione peroxidase activities in serum as well as reduced the thiobarbituric acid reactive substances and protein carbonyl contents in the hippocampus of aged mice. The activation of transcriptional factor nuclear factor-kappa B and lipofuscin formation in pyramidal cells of hippocampal CA1 region, which are all related to oxidative stress, was also reduced after GTC treatment. We also found that long-term GTC treatment prevented age-related reductions of two representative post-synaptic proteins post-synaptic density 95 and N-methyl-d-aspartate receptor 1 in the hippocampus. These results demonstrated that chronic 0.05% green tea catechins administration may prevent oxidative stress related brain aging in female C57BL/6J mice.

 

 

Get the whole article here

Author: Shigeki Yanagi and Kazuaki Matsumura and Akira Marui and Manabu Morishima and Suong-Hyu Hyon and Tadashi Ikeda and Ryuzo Sakata

Objective Ischemia–reperfusion injury is among the most serious problems in cardiac surgery. Epigallocatechin-3-gallate, a major polyphenolic component of green tea, is thought to be cardioprotective through its antioxidant activities. We investigated cardioprotective effects of oral epigallocatechin-3-gallate pretreatment against ischemia–reperfusion injury in isolated rat hearts and considered possible underlying mechanisms. Methods Rats were given epigallocatechin-3-gallate solution orally at 0.1, 1, or 10 mmol/L (n = 12 per group) for 2 weeks; controls (n = 12) received tap water alone for 2 weeks. Subsequently, Langendorff-perfused hearts were subjected to global ischemia for 30 minutes, followed by 60 minutes of reperfusion. Results Recoveries at 60 minutes after reperfusion of left ventricular developed pressure and maximum positive and minimum negative first derivatives of left ventricular pressure were significantly higher in 1-mmol/L group than in 0.1-mmol/L (P < .0001), 10-mmol/L (P < .05), and control (P < .0001) groups. Oxidative stress after reperfusion, as reflected by 8-hydroxy-2′-deoxyguanosine index, was lower in 1-mmol/L group than in control (P < .01) and 0.1-mmol/L (P < .05) groups. Western blot analysis after reperfusion showed p38 activation and active caspase-3 expression to be lower in 1-mmol/L group than in control group (P < .05). Conclusions Oral pretreatment with epigallocatechin-3-gallate preserved cardiac function after ischemia–reperfusion, an effect that may involve its antioxidative, antiapoptotic properties, although a high dose did not lead to dramatic improvement in cardiac function. Oral epigallocatechin-3-gallate pretreatment may be a novel and simple cardioprotective method for preventing perioperative cardiac dysfunction in cardiac surgery.

 

Get the whole article here

Author: Yoon Woo Koh and Eun Chang Choi and Sung Un Kang and Hye Sook Hwang and Mi Hye Lee and JungHee Pyun and RaeHee Park and YoungDon Lee and Chul-Ho Kim

Hepatocyte growth factor (HGF) and c-Met have recently attracted a great deal of attention as prognostic indicators of patient outcome, and they are important in the control of tumor growth and invasion. Epigallocatechin-3-gallate (EGCG) has been shown to modulate multiple signal pathways in a manner that controls the unwanted proliferation and invasion of cells, thereby imparting cancer chemopreventive and therapeutic effects. In this study, we investigated the effects of EGCG in inhibiting HGF-induced tumor growth and invasion of oral cancer in vitro and in vivo. We examined the effects of EGCG on HGF-induced cell proliferation, migration, invasion, induction of apoptosis and modulation of HGF/c-Met signaling pathway in the KB oral cancer cell line. We investigated the antitumor effect and inhibition of c-Met expression by EGCG in a syngeneic mouse model (C3H/HeJ mice, SCC VII/SF cell line). HGF promoted cell proliferation, migration, invasion and induction of MMP (matrix metalloproteinase)-2 and MMP-9 in KB cells. EGCG significantly inhibited HGF-induced phosphorylation of Met and cell growth, invasion and expression of MMP-2 and MMP-9. EGCG blocked HGF-induced phosphorylation of c-Met and that of the downstream kinases AKT and ERK, and inhibition of p-AKT and p-ERK by EGCG was associated with marked increases in the phosphorylation of p38, JNK, cleaved caspase-3 and poly-ADP-ribose polymerase. In C3H/HeJ syngeneic mice, as an in vivo model, tumor growth was suppressed and apoptosis was increased by EGCG. Our results suggest that EGCG may be a potential therapeutic agent to inhibit HGF-induced tumor growth and invasion in oral cancer.

 

 

Get the whole article here

Author: Karl J. Siebert and Atsushi A. Maekawa and P.Y. Lynn

Samples of dilute HCl intended to result in mixtures with saliva with pH levels below, near and above the level of maximum protein–polyphenol interaction were presented to panelists. Significant differences in astringency were seen, but no evidence of a decline in astringency with stronger acid. Panelists abstained from tea drinking for some time, then drank two or more cups of green tea per day for some days, and finally omitted tea drinking for a period. Salivary polyphenol levels were determined throughout the experiment. Drinking green tea resulted in a highly significant (p < 0.01) increase in salivary polyphenol levels that persisted for some days. Very dilute HCl solutions (0, 0.005, 0.006 and 0.007 N) were presented to panelists before, during and after the period of tea drinking and rated for astringency and sourness. Astringency and sourness intensity ratings increased significantly (p < 0.01) during the period of tea drinking. It appears that there is a metabolic pool of polyphenol that is influenced by dietary habits. It appears likely that the salivary polyphenol level influences perception of astringency caused by acids.

 

Get the whole article here

Author: Dominik Kmiecik and Józef Korczak and Magdalena Rudzińska and Joanna Kobus-Cisowska and Anna Gramza-Michałowska and Marzanna Hęś

Author: Giselle Lehrke and Laura Hernaez and Sandra L. Mugliaroli and Mariana von Staszewski and Rosa J. Jagus

Acid tolerance of two strains of Listeria innocua as single strain culture and co-culture, were evaluated in liquid cheese whey after exposure to nisin, Microgard™ and green tea. Inorganic and organic acids were applied after natural antimicrobials treatments and microbial counts were made to analyze the bacterial response. The results have demonstrated that natural antimicrobials like nisin, Microgard™ and green tea, present in the liquid cheese whey, did not produce any cross-protection effects. On the contrary, in most of the cases, the antimicrobial treatment increased the susceptibility of L. innocua to acid stress, particularly in the treatment with nisin or green tea extract and organic acids. These results were corroborated by different techniques, including transmission electron microscopy.

 

 

Get the whole article here

Author: Mark E. Stearns and Min Wang

We have examined whether epigallocatechin-3-gallate (EGCG), and extract of green tea, in combination with taxane (i.e., paclitaxel and docetaxel), exerts a synergistic activity in blocking human prostate PC-3ML tumor cell growth in vitro and in vivo. Growth assays in vitro revealed that the IC50 values were ∼30 μM, ∼3 nM, and ∼6 nM, for EGCG, paclitaxel and docetaxel, respectively. Isobolograms generated from the data clearly indicated that EGCG in combination with paclitaxel or docetaxel had an additive effect in blocking tumor cell growth. EGCG combined with taxane also had an additive effect to increase the expression of apoptotic genes, (p53, p73, p21, and caspase 3) and the percent apoptosis observed in vitro and in tumor modeling studies in severe combined immunodeficient mice. The tumor modeling studies clearly showed that EGCG plus taxane injected intraperitoneally (i.p.) induced a significant increase in apoptosis rates (TUNEL assays) and eliminated preexisting tumors generated from PC-3ML cells implanted i.p., increasing disease-free survival rates to greater than 90%. More importantly, the combination therapy (i.p. biweekly) blocked metastases after intravenous injection of PC-3ML cells through the tail vein. In mice treated with EGCG plus taxane, the disease-free survival rates increased from 0% (in untreated mice) to more than 70% to 80% in treated mice. Taken together, these data demonstrate for the first time that EGCG in combination with taxane may provide a novel therapeutic treatment of advanced prostate cancer.

 

Get the whole article here

Author: Radomir V. Malbaša and Eva S. Lončar and Jasmina S. Vitas and Jasna M. Čanadanović-Brunet

This paper investigates the influence of starter cultures, obtained from kombucha isolates, on the antioxidant activity of kombucha beverages. Three starter cultures were used as follows: (1) mixed culture of acetic bacteria and Zygosaccharomyces sp. (SC1); (2) mixed culture of acetic bacteria and Saccharomyces cerevisiae (SC2); as well as (3) native local kombucha. The starter cultures were added to black and green tea sweetened with 7% of sucrose. Fermentation was carried out at 28 °C for 10 days. Antioxidant activity to hydroxyl and DPPH radicals was monitored. Kombucha beverage on black tea has shown the highest antioxidant activity to both types of radicals with starter SC1, while the green tea beverage has shown the highest activity with native kombucha. The main reason for the different antioxidant activities, beside tea composition, was ascribed to differing production of both vitamin C and total organic acids in the investigated systems.

 

 

Get the whole article here

Author: Atsuo Miyagishima and Sadahiro Fujiki and Aya Okimura and Sakae Arahata and Shinsuke Inagaki and Yasunori Iwao and Shigeru Itai

We have recently succeeded in manufacturing low-caffeine tea (LCT) by employing a special picking method in the 3rd leaf period and shortening the leaf-rolling process. In the present study, the effect of this special method on the content of other physiologically active substances, such as catechins, theanine, and vitamin C, as well as the mechanism of reduction of caffeine content in the LCT were investigated using capillary electrophoresis. By comparing the various components of tea leaves at different picking periods with or without shortening of the rolling process, it was found that the delayed leaf picking period and shortening of the rolling process used in the manufacture of LCT selectively reduced the caffeine content while retaining catechins, theanine, and vitamin C at a sufficient level. Therefore, our study demonstrated that this modified method may be useful in the manufacture of decaffeinated green tea.

 

Get the whole article here

Author: Anna Hsu and Richard S. Bruno and Christiane V. Löhr and Alan W. Taylor and Rodrick H. Dashwood and Tammy M. Bray and Emily Ho

Chronic inflammation and nuclear factor-kappa B (NFκB) have been implicated in prostate cancer development; thus, dietary factors that inhibit NFκB may serve as effective chemo-preventative agents. Prostate cancer risk is significantly lower in Asian countries compared to the United States, which has prompted interest in the potential chemopreventative action of Asian dietary components such as soy and green tea. This study examined the effects of dietary soy and tea on NFκB activation and inflammation in vivo using a hormone-induced rat model for prostate cancer. Male Noble rats implanted with estradiol and testosterone were divided into 4 dietary groups: control, soy, tea, or soy+tea. NFκB activation and inflammatory cytokines were measured post implantation. The combination of soy and tea suppressed NFκB p50 binding activity and protein levels via induction of IκBα. Soy and tea also decreased prostate inflammatory infiltration, increased Bax/BcL2 ratio and decreased protein expression of tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1β compared to control. Soy and tea attenuated prostate malignancy by decreasing prostate hyperplasia. These effects were not apparent in groups treated with soy or tea alone. The ongoing in vivo studies thus far suggest that combination of foods, such as soy and tea, may inhibit hormone-induced proinflammatory NFκB signals that contribute to prostate cancer development.

 

 

Get the whole article here