Compound In Green Tea Research Articles

Epigallocatechin 3-gallate attenuates neuronal damage induced by 3-hydroxykynurenine.

3-Hydroxykynurenine (3-HK), which is an endogenous metabolite of tryptophan in the kynurenine pathway, is a potential neurotoxin in several neurodegenerative disorders. Epigallocatechin 3-gallate (EGCG), a major compound of green tea, is recognized as a promising natural substance for protection against neuronal diseases. This study investigated the possible protective roles and mechanism of EGCG, against 3-HK-induced cell death. It was found that 3-HK induces neuronal cell death in the human neuroblastoma SH-SY5Y cell line. The reduced cell viability produced characteristic features such as cell shrinkages, plasma membrane blebbing, chromatin condensation, and nuclear fragmentation. The cells treated with 3-HK showed an increase in the concentration of reactive oxygen species (ROS) as well as in caspase activity. In addition, both are involved in the 3-HK-induced apoptosis. EGCG attenuated the cell viability reduction by 3-HK in both a dose- and time-dependent manner. Optical microscopy showed that EGCG inhibited the cell morphological features in the 3-HK-treated cells. Furthermore, the increase in the ROS concentration and the caspase activities by 3-HK were also attenuated by EGCG. These results showed that EGCG has a protective effect on the 3-HK induced cell death by inhibiting ROS production and caspase activity. The results suggest that EGCG might be a promising protective substance against the neuronal degenerative diseases.

Evaluation of Japanese Green Tea Extract Using GC/O with Original Aroma Simultaneously Input to the Sniffing Port Method (OASIS)

Recent studies of natural aromas have focused on only the lowest odor threshold compounds. In this study, we evaluated the volatile compounds of Japanese green tea, comparing the original aroma simultaneously input to the sniffing port method (OASIS) with the aroma extract dilution analysis method (AEDA). Geraniol, indole and linalool were classified in the low odor threshold by AEDA. Using OASIS, geraniol showed enhancement of the green character and indole showed strengthening the overall green tea odor, but linalool gave the same result as AEDA. On the other hand cis-3-hexenol, decanal and β-ionone were classified in the high odor threshold by AEDA, OASIS showed enhancement of the green, tea-leafy, and sweet characters respectively. We added these compounds to a Japanese green tea infusion and evaluated it. The results showed great similarity to the OASIS results. In conclusion, OASIS is an effective technique by which to evaluate mixtures of volatile compounds with original aromas.

Regulation of IGFBP-5 expression during tumourigenesis and differentiation of oral keratinocytes.

To identify molecular events involved in the pathogenesis of oral squamous cell carcinoma (OSCC), genes differentially expressed in OSCC and non-cancerous matched tissue (NCMT) samples were analysed using a subtractive hybridization strategy. NCMT-enriching clones that have been linked to suppressor pathway in previous studies were subjected to advanced analyses. Complete absence of insulin-like growth factor binding protein-5 (IGFBP-5) expression at both the mRNA and the protein level was identified in nearly all (5/6) OSCC cell lines with the exception of the SCC25 cell line, which exhibited high IGFBP-5 expression. However, this protein is consistently present in cultured normal human oral keratinocytes (NHOKs). Immunohistochemistry revealed moderate to strong cytoplasmic immunoreactivity of IGFBP-5 in the stratum spinosum and stratum granulosum in the vast majority of NCMT samples. A remarkable reduction in IGFBP-5 immunoreactivity was detected in 56% (26/46) of OSCC samples, compared with the corresponding NCMT (p < 0.0001). Induction of differentiation in both NHOKs and SCC25 up-regulated IGFBP-5 expression. Administration of a green tea compound with anti-cancer properties, (-)-epigallocatechin 3-gallate, at a concentration of 5-20 micro g/ml also up-regulated IGFBP-5 expression in NHOKs in a dose-dependent manner. The findings suggest that IGFBP-5 may be an important factor in the differentiation of oral keratinocytes and that down-regulation of IGFBP-5 may be involved in the neoplastic transformation of oral keratinocytes.

Green tea: Biochemical and biological basis for health benefits

Publisher Summary Green tea beverages originated many thousands of years ago as a medicinal tonic. The historically long use of many folk remedies does not necessary prove their medical usefulness. However, recent evidence based on modern scientific evaluations of green tea appears to support the possibility that green tea compounds, especially catechins, are medically valuable. The chapter focuses on green tea and green tea catechins rather than on fermented teas or catechin by-products that are produced during fermentation. Theaflavins and thearubigins, a complex mixture of catechin condensation products with a heterogeneous molecular weight distribution, are major fermentation products in black tea, which, like catechins, have antioxidant and antitumorigenic activities. Experimental studies on the physiological effects of some polyphenolic tannins from other plants indicate that they also may be beneficial for decreasing serum lipids, reducing blood pressure, and modulating immune responses and for use as antitumorigenic and antibacterial agents and use in food preservation. The chapter discusses that tea polyphenols are widely used as natural antioxidants for prevention of oxidation of edible oils or discoloring of foods.

Effect of packing size on chomatographic separation of catechin compounds in Green Tea

EGCG (Epigallocatechin Gallate), one of the catechin compounds abundant mainly in green tea, has chemopreventive effects against carcinogenesis. The extract at 50 ‡C water from the powder of green tea was partitioned with chloroform and ethyl acetate. The resulting solution was further purified on three different columns, 4.6x250 mm (40/63 mm), 4.6x250 mm (15 mm), 3.9x300 mm (10 mm), in order to separate EGCG among catechin compounds from green tea. In a given packing size, the composition of the binary mobile phase, water and acetonitrile, with 0.1% acetic acid was changed to operate in optimized experimental conditions. In a packed column of 40/63 mm packing, catechin compounds were not well separated. With packing sizes of 15 and 10 mm, the resolution of EGCG among catechin compounds was better, and maximum injection volume to separate EGCG purely was 100 and 480 ml, respectively. The study on the effect of packing size may be utilized for preparative chromatographic separation.

Green tea compounds inhibit tyrosine phosphorylation of PDGF β-receptor and transformation of A172 human glioblastoma

The effect of the green tea compounds 2-(3,4-dihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3,5,7-triol (catechin), epicathechin (EC), epigallocathechin-3 gallate (EGCG), epicathechin-3 gallate (ECG) and catechin-3 gallate (CG) on the tyrosine phosphorylation of PDGF β-receptor (PDGF-Rβ) and on the anchorage-independent growth of A172 glioblastoma cells in semisolid agar has been investigated. Treatment of A172 glioblastoma with 50 μM CG, ECG, EGCG and 25 μM Tyrphostin 1296 resulted in an 82±17%, 77±21%, 75±8% and 55±11%, respectively (mean±S.D., n=3) inhibition of the PDGF-BB-induced tyrosine phosphorylation of PDGF-Rβ. The PDGF-Rβ downstream intracellular transduction pathway including tyrosine phosphorylation of phospholipase C-γ1 (PLC-γ1) and phosphatidylinositol 3′-kinase (PI 3′-K) was also inhibited. Spheroid formation was completely inhibited by 50 μM ECG, CG, EGCG and by 25 μM Tyrphostin 1296. We conclude that catechins of the green tea possessing the gallate group in their chemical structure act as anticancer agents probably partly via their ability to suppress the tyrosine kinase activity of the PDGF-Rβ.

Anti-genotoxic compounds in green tea

Anti-genotoxic compounds in green tea

Green tea and leukoplakia

BACKGROUND: A feasibility chemoprevention trial of green tea and oral leukoplakia has been conducted. The purpose is to demonstrate the success and pitfalls of conducting such a population-based trial within Indian rural villages.METHODS: Two dosages of green tea were utilized: 3.6 g per day and 5.4 g per day. Compliance was measured using tea package counts and by measuring the blood concentration of the active anticancer compound in green tea, (-)-epigallo-catechin-3-gallate (EGCG).RESULTS: Following a 3-year planning period, 13 villages were visited, and 1,203 tobacco users were interviewed in order to identify 64 participants suitable for trial inclusion. Of the subsequently 28 consenting individuals entered, 23 remained on protocol for the entire 6-month duration, Overall compliance was excellent, with participants consuming approximately 80% of prescribed packets.CONCLUSIONS: These results provide a basis for continuing international collaborative efforts in conducting population-based chemoprevention trials against head and neck cancer. (C) 1997 by Excerpta Medics, Inc.

Tea and cancer.

Tea is one of the most popular beverages consumed worldwide. The relationship between tea consumption and human cancer incidence is an important concern. This topic has been studied in different populations by many investigators, but no clear-cut conclusion can be drawn. Whereas some studies have shown a protective effect of tea consumption against certain types of cancers, other studies have indicated an opposite effect. Our purpose is to provide a critical review of this topic, covering basic chemistry and biochemical activity of tea, epidemiologic investigations, and laboratory studies, as well as possible directions for future research. Studies have demonstrated either a lack of association between tea consumption and cancer incidence at specific organ sites or inconsistent results. On the other hand, many laboratory studies have demonstrated inhibitory effects of tea preparations and tea polyphenols against tumor formation and growth. This inhibitory activity is believed to be mainly due to the antioxidative and possible antiproliferative effects of polyphenolic compounds in green and black tea. These polyphenolics may also inhibit carcinogenesis by blocking the endogenous formation of N-nitroso compounds, suppressing the activation of carcinogens, and trapping of genotoxic agents. The effect of tea consumption on cancer is likely to depend on the causative factors of the specific cancer. Therefore, a protective effect observed on a certain cancer with a specific population may not be observable with a cancer of a different etiology. On the basis of this concept, we suggest future laboratory and epidemiologic studies to elucidate the relationship between tea consumption and human cancer risk.

Inhibitory effect of topical application of a green tea polyphenol fraction on tumor initiation and promotion in mouse skin.

A green tea polyphenol fraction was evaluated for its ability to inhibit tumor initiation by polycyclic aromatic hydrocarbons and tumor promotion by a phorbol ester in the skin of CD-1 mice. Topical application of the green tea polyphenol fraction inhibited benzo[a]pyrene- and 7,12-dimethylbenz[a]-anthracene-induced tumor initiation as well as 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor promotion. Topical application of the green tea polyphenol fraction also inhibited TPA-induced inflammation, ornithine decarboxylase activity, hyperplasia and hydrogen peroxide formation. Studies with individual polyphenolic compounds in green tea indicated that topical application of (-)-epigallocatechin gallate, (-)-epigallocatechin and (-)-epicatechin gallate inhibited TPA-induced inflammation in mouse epidermis.

Bound flavour compounds in plants 2. Part. Free and bound flavour compounds in green and black tea

In grunem (Taiwan Gunpowder) und schwarzem (Ceylon high OP) Tee sind betrachtliche Mengen an Aromastoffen in glykosidischer Bindung vorhanden; ihr Anteil ist sogar hoher als der an freien Aromastoffen. Hauptkomponenten sind in beiden Teesorten cis-3-Hexen-1-ol, Benzylalkohol und 2-Phenylethanol in gebundener Form, dazu im Schwarztee Linalool und im grunen Tee Geraniol. Die unterschiedlichen Anteile dieser beiden Terpenalkohole spiegeln die unterschiedlichen Tee-Varietaten wieder, denen die untersuchten Teesorten angehoren: der Ceylon-Tee ist der Varietatassamica zuzuordnen, der Tee aus Taiwan der Varietatsinensis. Die Zusammensetzung der aus gebundenen Formen freisetzbaren Aromastoffe war ahnlich komplex wie die der freien Aromastoffe, wobei die Unterschiede zwischen den beiden Teesorten auf den verschiedenen Herstellungsverfahren beruhen. Das Auftreten gebundener Formen solcher Aromastoffe, die nicht originar vorhanden sind, sondern erst wahrend der Welk- oder der Fermentationsphase gebildet werden, impliziert das Vorhandensein glykosidierender Aktivitaten im Teeblatt noch in relativ spaten Stadien der Schwarzteeherstellung. Die Untersuchung der gebundenen Anteile an Aromastoffen tragt neben der Analyse der freien Aromastoffe wesentlich zum Verstandnis der Reaktionen im Teeblatt wahrend der verschiedenen Produktionsstadien bei.

The Effect of Green Tea and Related Substances on the Gastrointestinal Absorption of Strontium 90

The effect of green tea and related compounds against Sr-90 absorption through the intestine was examined by using Wistar strain rats. It was concluded that green tea acts inhibitorily on the absorption of Sr-90 through the intestine and that the effect is partly due to the astringent action and the reduction of the intestinal movement by green tea.