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PubMed2005

[Effect of tea polyphenols on alcoholic liver injury].

OBJECTIVE: To reproduce an experimental model of alcoholic liver disease in rats and to investigate the preventive and treatment effects of tea polyphenols on alcoholic liver disease. METHODS: 68 male Sprague-Dawley rats were randomly divided into 3 groups: alcohol group (gastrically infused with 56% of ethanol once a day with a dose of 7 g/kg body weight for 4, 12 and 24 weeks), tea polyphenols group (gastric infusion with alcohol same as in the alcohol group and with tea polyphenols at 0.25 g/kg bw) and control group (gastric infusion with normal saline). At the end of 4, 12 and 24 weeks, blood samples were collected and then the rats were sacrificed. Liver samples were obtained for routine histological examination and the degree of hepatic steatosis and alcoholic hepatitis were examined. Blood specimens were used for evaluation of alanine transaminase (ALT) and aspartate aminotransferase (AST). RESULTS: (1) The levels of the two transaminases were elevated with the increase of the duration of ethanol feeding and the difference is significant. TP significantly mitigated the increase of ALT and AST activities induced by the alcohol. (2) Histological changes of the liver injury indicated that piecemeal or focal necrosis of hepatocytes was present in the centrilobular area. As fibrosis advanced, broader septa were formed with central-central and centra-portal bridging necrosis. In the TP infusion group, the severity of the pathological changes was significantly milder. CONCLUSION: The results of this study revealed that TP mitigated the development of alcoholic liver disease, and TP may be a potential drug for treatment of alcoholic liver disease.

Animals↗
PubMed2005

[Effects of tea polyphenols and tea pigments on apoptosis in HepG2 cell line].

OBJECTIVE: To investigate the effect of tea polyphenols and tea pigments on apoptosis in HepG2 cells. METHODS: HepG2 cells were seeded at a density of 5 x 10(5)/well in six-well culture dishes. The cells were then treated with 50 or 100 mg/L tea pigments and harvested at 48h by trypsinization. Agrose electrophoresis was applied to investigate DNA-LADDER, Bcl-2 and Bax protein expression were detected by Western blot. RESULTS: Tea polyphenols and tea pigments induced the appearance of DNA-LADDER; Western blot analysis demonstrated that Bcl-2 expression was significantly inhibited and the expression of Bax was significantly induced by tea polyphenols and tea pigments. CONCLUSION: Induction of apoptosis may be an important mechanism of cancer chemoprevention by tea.

Antineoplastic Agents, Phytogenic↗
PubMed2005

The effects of tea polyphenolic compounds on hair loss among rodents.

The objective of this study was to examine the effects of polyphenolic compounds, present in noncommercially available green tea, on hair loss among rodents. In an experimental study, we randomly assigned 60 female Balb/black mice, which had developed spontaneous hair loss on the head, neck and dorsal areas into two equal groups; A (experimental) and B (control). Group A received 50% fraction of polyphenol extract from dehydrated green tea in their drinking water for six months. Group B received regular drinking water. Both groups were fed regular rodent diets (Purina Rodent Chow 5001) and housed individually in polycarbonate cages. The results showed that 33% of the mice in experimental Group A, who received polyphenol extract in their drinking water, had significant hair regrowth during six months of treatment (p = 0.014). No hair growth was observed among mice in the control group, which received regular water.

Alopecia↗
PubMed2005

The effects of tea polyphenolic compounds on hair loss among rodents.

The objective of this study was to examine the effects of polyphenolic compounds, present in noncommercially available green tea, on hair loss among rodentts. In an experimental study, we randomly assigned 60female Balb/black mice, which had developed spontaneous hair loss on the head, neck and dorsal areas into two equal groups; A (experimental) and B (control). Group A received 50% fraction of polyphenol extract from dehydrated green tea in their drinking water for six months. Group B received regular drinking water. Both groups were fed regular rodent diets (Purina Rodent Chow 5001) and housed individually in polycarbonate cages. The results showed that 33% of the mice in experimental Group A, who received polyphenol extract in their drinking water, had significant hair regrowth during six months of treatment (p = 0.014). No hair growth was observed among mice in the control group, which received regular water.

Alopecia↗
PubMed2005

Polyphenols as potential therapeutical agents against cardiovascular diseases.

Increasing evidence suggests that polyphenols from fruits, vegetables and beverages such as wine and tea may exert protective effects on the cardiovascular system. Indeed, research in the field of polyphenols points out their antioxidant and free radical scavenging properties, leading to lower low-density lipoprotein (LDL) oxidation and platelet aggregation. These compounds are also able to modulate the generation of nitric oxide (NO) from vascular endothelium and to interfere with the mechanisms leading to inflammation and endothelial apoptosis, contributing to the prevention of the endothelial dysfunction, known to play a central role in the pathogenesis of cardiovascular diseases. This article reviews the potential targets of polyphenols involved in the complex pathophysiological events occurring in cardiovascular diseases, such as hypertension, atherosclerosis and stroke.

Animals↗
PubMed2006

Methylation of green tea polyphenols affects their binding to and inhibitory poses of the proteasome beta5 subunit.

Previously, we showed that ester carbon-containing tea polyphenols, including (-)-epigallocatechin gallate [(-)-EGCG] and (-)-epicatechin-3-gallate [(-)-ECG], potently inhibit proteasomal chymotrypsin-like activity. In addition, our in silico docking study suggested that a particular pose of (-)-EGCG could lead to potential covalent modification of the N-terminal threonine (Thr 1) of the proteasome beta5 subunit in the chymotrypsin-like active site. It has been suggested that some major biotransformation reactions, such as methylation, could result in reduced biological activity of (-)-EGCG in vivo. We hypothesize that methylation reduces binding of (-)-EGCG to the beta5 subunit of the proteasome and, therefore, decreases its proteasomal chymotrypsin-like-inhibitory potency. Here, we report that, while methylation has no effect on nucleophilic susceptibility of (-)-EGCG and (-)-ECG, it may disrupt the ability of these polyphenols to interact with Thr 1 of the proteasome beta5 subunit. In silico docking shows that methylation results in the tea polyphenols' ester carbon being moved away or blocked entirely from Thr 1. Additionally, methylation impairs the ability of (-)-EGCG and (-)-ECG to dock in a consistent low energy pose. These observations, no change in nucleophilic susceptibility, moving or blocking the ester carbon from Thr 1, and lack of a consistent docking pose, suggest that methylation disrupts the ability of (-)-EGCG and (-)-ECG to bind to the proteasome beta5 subunit, which may then diminish their proteasomal chymotrypsin-inhibitory and, therefore, other biological activities.

Catechin↗
PubMed1996

Antimutagenic effects of polyphenols isolated from Terminalia bellerica myroblan in Salmonella typhimurium.

Antimutagenic effect of 2 polyphenolic fractions isolated from T. bellerica in TA98 and TA100 strains of S. typhimurium against 2AF, NPD and 4NQNO has been characterized. Both the fractions were significantly effective against S9-dependent 2AF; less effective against NPD and almost not effective against 4NQNO in TA100 strain. Using 13C-NMR spectral analysis, the TB-3 fraction, which was significantly more effective against 2AF compared to TB-4, was found to be a mixture of 3 tannins while TB-4 was non-tannin fraction. Interaction of polyphenols with S9 proteins may be the probable cause of inhibitory effect of these polyphenols, though the possibility of other mechanisms cannot be ruled out.

Antimutagenic Agents↗
PubMed1996

Negative ion electrospray mass spectrometry of polyphenols, catecholamines and their oxidation products.

Polyphenols, catecholamines and their oxidation products have a variety of physiological effects and are key components of insect cuticle and other biological structures. Three dihydroxybenzene isomers were easily differentiated using negative ion electrospray mass spectrometry (ESMS) or tandem mass spectrometry (MS/MS). Ions at m/z 107-109 were diagnostic for more complex polyphenols and catecholamines with a dihydroxybenzene moiety. The product ion spectra of other compounds including 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylalanine (DOPA) and N-acetyldopamine (NADA) had product ions at m/z 121-123 corresponding to methylene homologues of dioxygenated benzene. Oxidation of DOPA using tyrosinase, Ag2O or NaIO4 could be followed using ESMS and several proposed intermediates proceeding from DOPA through a quinone methide intermediate, 5,6-dihydroxyindole and dihydroxyindole quinone were confirmed using negative ion ESMS/MS. Spectra of the NaIO4 oxidation products of 1,2,3-trihydroxybenzene (pyrogallol) were consistent with tetrahydroxybenzene, two non-cyclic tetraoxygenated derivatives and a bicyclic polymerization product, purpurogallin. ESMS can be used to analyse complex polyphenolic conjugates commonly encountered in biological specimens.

Catecholamines↗
PubMedDate not supplied

A modified method for determining protein binding capacity of plant polyphenolics using radiolabelled protein.

A modified radiochemical protein binding method for determining the protein binding capacity of plant polyphenolics (tannins) is described. Purified tannin or unfractionated plant extracts were immobilised on filter paper discs and incubated with the 125I-labelled bovine serum albumin. Protein bound to the disc was proportional to the amount of tannin applied to the disc, although at high concentrations of polyphenolics the discs became saturated and the relationship was no longer applicable. The method was validated using purified procyanidin from Sorghum grain and has been applied to crude polyphenolic extracts from maple, white oak, black oak, walnut and tulip poplar leaves. Specific chemical assays for the determination of proanthocyanidins (acid butanol method) and hydrolysable tannins (modified potassium iodate method) were employed to validate the new protein binding method with the complex plant extracts.

Chemical Precipitation↗
PubMed1997

Inhibition of peroxynitrite-mediated tyrosine nitration by catechin polyphenols.

Peroxynitrite is a cytotoxic species generated by the reaction between superoxide and nitric oxide. The ability of catechins and their gallate esters to decrease peroxynitrite-induced nitration of tyrosine and to limit surface charge alteration of low density lipoprotein (LDL) was investigated. All compounds tested were found to be potent peroxynitrite scavengers preventing the nitration of tyrosine. The ability of the catechin polyphenols at 10 microM to minimise tyrosine nitration induced by peroxynitrite (500 microM) was ECG (38.1 +/- 3.6%) approximately EGCG (32.1 +/- 7.5%) approximately gallic acid (32.1 +/- 1.9%) > catechin (23.9 +/- 5.4%) approximately epicatechin (22.9 +/- 3.3%) approximately EGC (19.9 +/- 2.0%). Trolox (10 microM) was used as the standard for comparative purposes and was found to be less effective than the polyphenols in inhibiting tyrosine nitration (13.6 +/- 2.9%). The catechin polyphenols were also found to offer protection from peroxynitrite-induced modification of critical amino acids of apolipoprotein B-100 of LDL which contribute towards its surface charge.

Catechin↗
PubMed1978

[Polyphenols in brewing (author's transl)].

Analytical methods for the determination of polyphenols of malt, barley, hop, wort, and beer are described. Malt or barley tannins has hitherto not received as much study as hop tannin. Polyphenols or tannins are classified. Studies on non-biological hazes are discussed in relation to the haze problem in brewing. The leucoanthocyanins of malt differ from those of hops in ability to form hazes. Subfractionation of polyphenol concentrates on sephadex columns allows isolation of individual tannins.

Anthocyanins↗
PubMed1994

Inhibitory Effects of Polyphenolic Catechins from Chinese Green Tea on HIV Reverse Transcriptase Activity.

Three polyphenolic catechins, epigallocatechin (1), epicatechin-3-O-gallate (2) and epigallocatechin-3-O-gallate (3), were isolated from Chinese green tea, Ti-Kaun-Yin (Camellia sinensis) and demonstrated as a new class of human immunodeficiency virus-reverse transcriptase (HIV-RT) inhibitor. The concentrations required for 50% inhibition for the compounds (1), (2) and (3) were 7.80, 0.32 and 0.68 &mgr;M, respectively. The polyphenolic catechins with a galloyl group at the 3 position were potent inhibitors of HIV-RT. Kinetic analysis indicated that the polyphenolic catechins were competitive inhibitors with respect to the template-primer (rA)(n)(dT)(12-18) and noncompetitive inhibitors to dTTP. Copyright 1994 S. Karger AG, Basel

Journal Article↗
PubMed2000

Activation of antioxidant-response element (ARE), mitogen-activated protein kinases (MAPKs) and caspases by major green tea polyphenol components during cell survival and death.

Green tea polyphenols (GTP) have been demonstrated to suppress tumorigenesis in several chemical-induced animal carcinogenesis models, and predicted as promising chemopreventive agents in human. Recent studies of GTP extracts showed the involvement of mitogen-activated protein kinases (MAPKs) in the regulation of Phase II enzymes gene expression and induction of apoptosis. In the current work we compared the biological actions of five green tea catechins: (1) induction of ARE reporter gene, (2) activation of MAP kinases, (3) cytotoxicity in human hepatoma HepG2-C8 cells, and (4) caspase activation in human cervical squamous carcinoma HeLa cells. For the induction of phase II gene assay, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate (ECG) potently induced antioxidant response element (ARE)-mediated luciferase activity, with induction observed at 25 microM with EGCG. The induction of ARE reporter gene appears to be structurally related to the 3-gallate group. Comparing the activation of MAPK by the five polyphenols, only EGCG showed potent activation of all three MAPKs (ERK, JNK and p38) in a dose- and time-dependent manner, whereas EGC activated ERK and p38. In the concentration range of 25 microM to 1 mM, EGCG and ECG strongly suppressed HepG2-ARE-C8 cell-growth. To elucidate the mechanisms of green tea polyphenol-induced apoptosis, we measured the activation of an important cell death protein, caspase-3 induced by EGCG, and found that caspase-3 was activated in a dose- and time-dependent manner. Interestingly, the activation of caspase-3 was a relatively late event (peaked at 16 h), whereas activation of MAPKs was much earlier (peaked at 2 h). It is possible, that at low concentrations of EGCG, activation of MAPK leads to ARE-mediated gene expression including phase II detoxifying enzymes. Whereas at higher concentrations of EGCG, sustained activation of MAPKs such as JNK leads to apoptosis. These mechanisms are currently under investigation in our laboratory. As the most abundant catechin in GTP extract, we found that EGCG potently induced ARE-mediated gene expression, activated MAP kinase pathway, stimulated caspase-3 activity, and induced apoptosis. These mechanisms together with others, may contribute to the overall chemopreventive function of EGCG itself as well as the GTP

Antioxidants↗
PubMed2004

Chemometric characterisation of Basque and French ciders according to their polyphenolic profiles.

Polyphenolic compositions of Basque and French ciders were determined by HPLC-DAD following thiolysis, in order to characterise and differentiate these beverages and then develop a classification system capable of confirming the authenticities of both kinds of cider. A data set consisting of 165 cider samples and 27 measured features was evaluated using multivariate chemometric techniques, such as cluster analysis and principal component analysis, in order to perform a preliminary study of data structure. Supervised pattern recognition techniques such as linear discriminant analysis (LDA), K-nearest neighbours (KNN), soft independent modelling of class analogy (SIMCA), and multilayer feed-forward artificial neural networks (MLF-ANN) attained classification rules for the two categories using the chemical data, which produced satisfactory results. Authentication systems obtained by combining two of these techniques were proposed. We found that SIMCA and LDA or KNN models achieved 100% hit-rates, since LDA and KNN permit the detection of every Basque cider and SIMCA provides a model for Basque cider that excludes all French ciders. Polyphenolic profiles of the ciders provided enough information to be able to develop classification rules for identifying ciders according to their geographical origin (Basque or French regions). Chemical and organoleptic differences between these two types of cider are probably due to the original and distinctive cidermaking technologies used for their elaboration. Using polyphenic profiles, about 80% of French ciders could be distinguished according to their region of origin (Brittany or Normandy). Although their polyphenolic profiles did not provide enough information to achieve an authentication system for Breton and Norman ciders.

Journal Article↗
PubMed1999

Changes in the location of polyphenol oxidase in potato (Solanum tuberosum L.) tuber during cell death in response to impact injury: comparison with wound tissue.

In order to elucidate the nature of the response of potato to impact injury at the biochemical level, changes in the location of the enzyme responsible for the discoloration, polyphenol oxidase, were determined using immunogold location with an antibody specific for potato tuber polyphenol oxidase. Tissue printing revealed that the enzyme was distributed throughout the tuber. Following impact injury, both tissue printing and quantitative electron microscopy indicated that there was no increase in the level of the enzyme although there was subcellular redistribution of polyphenol oxidase. This redistribution was first apparent at 12 h after impact, as determined by the use of confocal immunolocation, and coincided with loss of membrane integrity. These changes were examined in parallel with a number of stress-related parameters in both impact and wound responses. Wounding was accompanied by active gene expression and protein synthesis, leading to metabolic activity and tissue repair. In contrast, the bruising response was characterised by a limited active response and vital-staining methods indicated that after 16 h the tissue undergoes cell death.

Catechol Oxidase↗
PubMed1989

The effect of some of the polyphenolic compounds on sperm motility in vitro: a structure-activity relationship.

Many of the common polyphenolic compounds which are naturally present in abundance in plant extracts, exercise inhibitory effects on mammalian sperm motility in vitro, which could be the cause of the antifertility effects of the crude plant extracts. The action of these polyphenolic compounds seems to be structure-dependent. Their activity was found to be dependent on the positions of hydroxyl groups and modulated by the positions of methyl groups on the benzene ring. Carbon-carbon double bond on the side chain of cinnamic acid series compounds was essential for their activity. One of the plausible actions of polyphenols on spermatozoa seems to be the augmentation of the generation of superoxide radicals by them, which might be involved in the inhibition of their motility in vitro.

Animals↗
PubMed1992

Antimutagenic effects of polyphenolic compounds.

Smokers expose themselves to potent carcinogens daily. One of them is the nicotine-derived nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Since estimates are that humans consume 1 g of phenolic compounds/day, we investigated the inhibitory effects of five structurally related polyphenolic compounds on the mutagenicity of NNK in Salmonella typhimurium TA1535. NNK at a concentration of 80 mM was activated by hamster liver microsomes. The antimutagenic efficacies were dose-related between the non-toxic concentrations of 0.1 and 0.5 mmol/dish in the following order: esculetin > ellagic acid > (+)-catechin > propyl gallate > (-)esculin. At the highest non-toxic dose tested (0.5 mmol/dish), these polyphenolics inhibited mutagenesis in TA1535 by 77%, 67%, 62%, 59% and 53%, respectively. The results of this study demonstrated that polyphenolic compounds may inhibit the activation of NNK.

Animals↗
PubMed2006

Decolorization and removal of textile and non-textile dyes from polluted wastewater and dyeing effluent by using potato (Solanum tuberosum) soluble and immobilized polyphenol oxidase.

Celite bound potato polyphenol oxidase preparation was employed for the treatment of wastewater/dye effluent contaminated with reactive textile and non-textile dyes, Reactive Blue 4 and Reactive Orange 86. The maximum decolorization was found at pH 3.0 and 4.0 in case of Reactive Blue 4 and Reactive Orange 86, respectively. Immobilized potato polyphenol oxidase was significantly more effective in decolorizing the individual dye and complex mixtures of dyes as compared to soluble enzyme. The absorption spectra of the treated and untreated dye mixture and dyeing effluent exhibited a marked difference in the absorption value at various wavelengths. The polluted water contaminated with an individual dye or mixtures of dyes treated with soluble and immobilized potato polyphenol oxidase resulted in the remarkable loss in total organic carbon.

Biodegradation, Environmental↗