Research Database

Author: Jun Xi and Deji Shen and Shou Zhao and Bingbing Lu and Ye Li and Rui Zhang

Author: Soon-Mi Shim and Mario G. Ferruzzi and Young-Cheul Kim and Elsa M. Janle and Charles R. Santerre

The effects of phytochemical-rich foods on bioaccessibility of mercury in fish tissue (the amount of mercury that is released from fish into gastrointestinal tract fluid following a simulated digestion) were investigated using an in vitro digestion. Total mercury in the aqueous phase following a simulated digestion of fish with added food treatments was used to measure mercury bioaccessibility. Green tea extract (31–2000 mg), black tea extract (31–2000 mg), and soy protein (50–100 mg) significantly reduced mercury bioaccessibility by 82–92%, 88–91%, and 44–87%, respectively. Grapefruit juice (0.5–10 ml) did not reduce mercury in the aqueous phase. Wheat bran (50–1000 mg) decreased mercury bioaccessibility (84%); oat bran and psyllium reduced bioaccessibility (by 59–75%, 15–31%, respectively) at amounts greater than 500 mg. We therefore suggest that co-consumption of foods containing phytochemicals at the same time as fish that contains mercury may potentially reduce mercury absorption compared to eating fish alone.

 

 

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Author: H. Aoshima and S. Ooshima

Shoyu is the Japanese name for soy sauce and the most popular liquid condiment (seasoning) used in Japanese cuisine as well as in cuisines of other oriental countries. Shoyu is prepared by digesting mold-cultured soybeans and wheat seeded with an aspergillus (koji in Japanese) in the presence of sodium chloride. Gyoshoyu is produced when the soybeans and wheat are replaced with fish. Both Shoyu and Gyoshoyu have high level of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Hydrogen peroxide is produced in green tea after exposure to air. To find a safe and economical method of preventing the production of H2O2 in green tea, effects of Shoyu and Gyoshoyu on H2O2 level in bottled green tea were examined. Both Shoyu and Gyoshoyu suppressed the production of H2O2. Gyoshoyu decomposed H2O2 possibly because of the presence of a thermostable catalase, while Shoyu did not. Some components of Shoyu and Gyoshoyu may be useful to suppress the production of H2O2 in green tea.

 

 

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Author: Zhou Danrong and Chen Yuqiong and Ni Dejiang

Green tea extracts (GTEs) were prepared with tap water (TW), activated carbon adsorbed water (AC), deionized water (DI), distilled water (DW), reverse osmosis water (RO) and ultra-pure water (UP). Their nutritional components were determined by chemical methods. Deoxyribose assay and the xanthine oxidase method were applied to test the antioxidant activities of GTE in vitro. The results indicated that there were statistically significant differences (P < 0.05) in the yield rate, the contents of polyphenols, catechins, caffeine, copper, lead and fluorine. Among them, DI gave the greatest yield rate and polyphenols, with low caffeine, DW increased the contents of non-ester catechins and AC enhanced the concentrations of ester catechins. The contents of copper and lead in GTEs were highly correlated with those of the tested water (r = 0.767 and 0.871, respectively). Fluorine contents in all GTEs were above 6.0 g kg−1. GTEs prepared with RO displayed the highest antioxidant activities among the six GTEs.

 

 

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Author: Haim Shapiro and Shaul Lev and Jonathan Cohen and Pierre Singer

Sepsis is the overwhelming systemic response to infection of a normally sterile body compartment. Despite advances in elucidating its pathophysiology, severe sepsis remains a leading cause of death in the critically ill. Polyphenols are a family of chemicals found in food and beverages derived from plants, such as cocoa, green tea, turmeric, and soya, as well as in medicinal herbs. These phytochemicals exhibit anti-inflammatory and vasculoprotective properties in clinical and preclinical studies. The oral or systemic administration of polyphenols protects rodents from endotoxinemia and microbial sepsis. Under these circumstances, polyphenols reproducibly attenuate microvascular hyperpermeability, tissue infiltration by leukocytes, oxidative and nitrosative stress, tissue injury, organ dysfunction, shock and vasoplegia, lactate production, and mortality. Importantly, efficacy is maintained in some cases even when treatment is initiated hours after the onset of sepsis. The inhibition of nuclear factor–κB activation and subsequent expression of inducible nitric oxide synthase, adhesion molecules, and tumor necrosis factor–α by polyphenols is operative in ameliorating the sequelae of sepsis. Enhancement of the endogenous antioxidant capacity probably also contributes to the effectiveness of the polyphenols. Because several of the polyphenols reviewed in this article appear to be safe and to exert anti-inflammatory effects in humans, clinical trials assessing their efficacy in the critically ill are indicated. Whether delivered alone or in combination with nutritional formulas, polyphenols may help to prevent and treat sepsis.

 

 

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Author: Soichiro Kori and Hideo Namiki and Kingo Suzuki

Green tea polyphenols have been reported to have anti-inflammatory activities, although the molecular mechanisms responsible for this effect remain unclear. In the present study, we examined the effect of green tea extract and a variety of polyphenolic compounds on spreading of peripheral blood polymorphonuclear leukocytes (PMNs) over fibrinogen-coated surfaces. Green tea extract exerted a biphasic effect on PMN spreading; it induced or suppressed spreading at low and high concentrations, respectively. We also found that pyrogallol-bearing compounds have spreading induction activity. Among the compounds tested, tannic acid (TA) had the strongest activity; the concentrations required for induction of maximal spreading were 2 µM for TA, 200 µM for (−)-epigallocatechin gallate, and 2000 µM for the other active compounds. Furthermore, TA was the only compound showing a biphasic effect similar to that of green tea extract; TA at 20 or 200 µM suppressed spreading. The spreading-stimulatory signal was still latent during PMN exposure to TA at concentrations that inhibited spreading, because the pre-exposed PMNs underwent spreading when plated after removal of free TA by centrifugation. The spreading-inhibitory effect of TA at high concentrations overcame the induction of spreading by other stimuli, including phorbol 12-myristate 13-acetate, hydrogen peroxide, denatured fibrinogen surfaces, and naked plastic surfaces. These results suggest that TA as well as green tea extract is bi-functional, having pro-inflammatory and anti-inflammatory effects at low and high concentrations, respectively. Pharmacological use of TA may thus provide new strategies aimed at regulation of PMN spreading for control of inflammation.

 

 

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Author: Yoshiharu Mukai and Kazuko Kamijo and Yukio Hirata and Toshio Teranaka

The purpose of this study was to evaluate the influence of a bottled green tea beverage on dentin demineralization with a demineralization gel system in vitro. Samples were cut from bovine root dentin. Each sample was immersed in 8% methylcellulose gel onto which a layer of green tea beverage was placed. For comparison, sugar-free coffee beverage, deionized water, and 0.8-ppm F solutions were used. After two weeks, the treatment solutions were replaced with demineralization solution. The mineral profiles and mineral loss values of the lesions were obtained by transversal microradiography (TMR) after one-week demineralization. The green tea, coffee, and fluoride solution treatments induced a significantly thicker surface layer when compared with the deionized water treatment. In particular, the mineral volume % of the demineralized dentin specimens treated with green tea was approximately seven times higher than that of the de-ionized water treatment. The green tea treatment showed significantly lower mineral loss than the other three treatments. TMR measurements clearly showed that the sugar-free bottled green tea beverage inhibited dentin lesion progression, presumably due to the effect of sub-ppm fluoride levels.

 

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Author: Naping Tang and Yuemin Wu and Bo Zhou and Bin Wang and Rongbin Yu

Studies investigating the association of green tea and black tea consumption with lung cancer risk have reported inconsistent findings. To provide a quantitative assessment of this association, we conducted a meta-analysis on the topic. Studies were identified by a literature search in PubMed from 1966 to November 2008 and by searching the reference lists of relevant studies. Summary relative risk (RR) estimates and their corresponding 95% confidence intervals (CIs) were calculated based on random-effects model. Our meta-analysis included 22 studies provided data on consumption of green tea or black tea, or both related to lung cancer risk. For green tea, the summary RR indicated a borderline significant association between highest green tea consumption and reduced risk of lung cancer (RR = 0.78, 95% CI = 0.61–1.00). Furthermore, an increase in green tea consumption of two cups/day was associated with an 18% decreased risk of developing lung cancer (RR = 0.82, 95% CI = 0.71–0.96). For black tea, no statistically significant association was observe through the meta-analysis (highest versus non/lowest, RR = 0.86, 95% CI = 0.70–1.05; an increment of two cups/day, RR = 0.82, 95% CI = 0.65–1.03). In conclusion, our data suggest that high or an increase in consumption of green tea but not black tea may be related to the reduction of lung cancer risk.

 

 

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Author: Joyce Ferreira Severino and Bernard A. Goodman and Christopher W.M. Kay and Klaus Stolze and Daniel Tunega and Thomas G. Reichenauer and Katharina F. Pirker

Electron paramagnetic resonance spectroscopy and density functional theory calculations have been used to investigate the redox properties of the green tea polyphenols (GTPs) (−)-epigallocatechin gallate (EGCG), (−)-epigallocatechin (EGC), and (−)-epicatechin gallate (ECG). Aqueous extracts of green tea and these individual phenols were autoxidized at alkaline pH and oxidized by superoxide anion (O2−) radicals in dimethyl sulfoxide. Several new aspects of the free radical chemistry of GTPs were revealed. EGCG can be oxidized on both the B and the D ring. The B ring was the main oxidation site during autoxidation, but the D ring was the preferred site for O2− oxidation. Oxidation of the D ring was followed by structural degradation, leading to generation of a radical identical to that of oxidized gallic acid. Alkaline autoxidation of green tea extracts produced four radicals that were related to products of the oxidation of EGCG, EGC, ECG, and gallic acid, whereas the spectra from O2− oxidation could be explained solely by radicals generated from EGCG. Assignments of hyperfine coupling constants were made by DFT calculations, allowing the identities of the radicals observed to be confirmed.

 

 

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Author: Benno F. Zimmermann and Menelaos Papagiannopoulos and Sonja Brachmann and Mario Lorenz and Verena Stangl and Rudolf Galensa

This paper describes a new and straightforward method for determination of the green tea catechins epicatechin, epicatechin gallate, epigallocatechin, and epigallocatechin gallate in human plasma. Sample preparation includes addition only of dimethylformamide and trichloroacetic acid. After centrifugation, the supernatant can be injected into the HPLC. If required, the glucuronides and sulphates of the catechins can be enzymatically hydrolysed before extraction. Recovery ranges from 92.9 to 98.2%; limits of detection, from 2.4 to 5.0 ng/mL; and relative standard deviations, from 3.1 to 8.6%. Twelve samples can be processed within 45 min, and are then ready to be injected into the HPLC. The method was successfully applied to human plasma. This method is suitable for studies on absorption, bioavailability, and kinetics of green tea catechins in plasma. Since manual work and time consumption are minimal, the procedure is especially useful for large numbers of samples.

 

 

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