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PubMed2005

Polyphenolic compounds from red grapes acutely improve endothelial function in patients with coronary heart disease.

BACKGROUND: It has been shown that acute intake of red wine improves endothelial-dependent vasodilatation. It is not clear, however, which constituents of red wine are responsible for this effect. We examined whether acute intake of a red grape polyphenol extract has a positive effect on brachial artery flow-mediated dilatation. METHODS: We recruited 30 male patients with coronary heart disease. They were randomly assigned either to a red grape polyphenol extract (600 mg) dissolved in 20 ml of water (n = 15) or 20 ml of water (placebo) (n = 15). The extract of grapes contained 4.32 mg epicatechin, 2.72 mg catechin, 2.07 mg gallic acid, 0.9 mg trans-resveratrol, 0.47 mg rutin, 0.42 mg epsilon-viniferin, 0.28 mg, p-coumaric acid, 0.14 mg ferulic acid and 0.04 mg quercetin per gram. Flow-mediated dilatation of the brachial artery was evaluated after reactive hyperemia induced by cuff obstruction of the forearm, using high-resolution ultasonography. Particularly, flow-mediated dilatation was measured after fasting and 30, 60 and 120 min after the intake of the grape extract or placebo. RESULTS: Intake of the red grape polyphenol extract caused an increase in flow-mediated dilatation, peaking at 60 min, which was significantly higher than the baseline values (4.52+/-1.34 versus 2.6+/-1.5%; P < 0.001) and the corresponding values at 60 min after the intake of placebo (4.52+/-1.34 versus 2.64+/-1.8%, P < 0.001). There was no change in FMD values after the intake of placebo throughout the whole duration of the study. CONCLUSION: Polyphenolic compounds from red grapes acutely improve endothelial function in patients with coronary heart disease. These results could probably, at least partly, explain the favorable effects of red wine on the cardiovascular system.

Blood Flow Velocity↗
PubMed2006

Relationships between optically assessed polyphenols and chlorophyll contents, and leaf mass per area ratio in woody plants: a signature of the carbon-nitrogen balance within leaves?

Chlorophyll (Chl) and epidermal polyphenol (EPhen) contents were estimated in vivo using two optical leaf-clips, SPAD-502 and Dualex, respectively. The area-based measurements were transformed into mass-based data by taking into account the leaf dry mass per area (LMA). Measurements were performed on forest trees and on saplings grown under controlled conditions. While LMA increased with irradiance along a vertical transect in a beech canopy or in saplings grown under different and increasing irradiance levels, mass-based EPhen (EPhen(m)) increased, whereas mass-based Chl (Chl(m)) decreased. This was a signature of a gradual switch of investment from protein into polyphenol production. A similar signature was obtained in saplings grown on nitrogen-deficient soil with respect to fertilized controls. However, nitrogen effects remained moderate compared to irradiance-induced effects. EPhen(m) and Chl(m) both declined with plant ageing-induced increases in LMA, under all tested growth conditions. This was a signature of an accumulation of dry matter that diluted Chl and EPhen. The described competition between Chl and EPhen in leaves fits well with the predictions of the Protein Competition Model (PCM), that is, that the total leaf mass-based polyphenols content (Phen(t)) is controlled by the competition between protein and polyphenol biosynthetic pathways and its metabolic regulation.

Carbon↗
PubMed1997

Effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells: the structure-inhibitory activity relationship.

We studied the effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells. Among tea polyphenols, (-)- epigallocatechin gallate (EGCG) most strongly and dose-dependently inhibited histamine release from cells stimulated with a calcium ionophore, A23187. (-)-Epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) with a triphenol residue moderately inhibited histamine release, whereas diphenolic (+)-catechin (C) and (-)-epicatechin (EC) did not. The magnitude of the inhibitory effect was in the order EGCG > ECG > EGC. Among simple polyphenols, the triphenol compounds, pyrogallol (PG) and gallic acid (GA) exerted inhibitory activity, but the diphenols, pyrocatechol, hydroquinone, and resorcinol did not. In addition, the mixture of PG and GA inhibited histamine release as strongly as EGCG with two triphenol residues. Similarly, they inhibited histamine release induced by IgE-antigen complex stimulation more efficiently than that induced by A23187 stimulation. EGCG did not inhibit the increase of intracellular Ca2+ in RBL-2H3 cells stimulated with A23187 or IgE antigen. These results indicate that the triphenol structure plays an important role in the inhibitory activity of tea polyphenols. Their activity seemed to be exerted through the metabolic events occurring after the elevation of intracellular Ca2+ concentration.

Animals↗
PubMed2004

Ellipsometry analysis of the in vitro adsorption of tea polyphenols onto salivary pellicles.

The adsorption of components from black tea and of purified tea polyphenols onto a whole unstimulated salivary pellicle-like protein layer, formed in vitro on hydroxyapatite discs, was studied by in situ ellipsometry. It was found that components from black tea and the purified polyphenols epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG) and theaflavin readily adsorbed onto the pellicle. Further investigations showed that under the experimental conditions of this study, no black tea- or purified polyphenol-modified pellicles were eluted by either phosphate buffer or sodium dodecyl sulphate rinses. Therefore, black tea and its polyphenol components are indicated to have a profound effect on in vitro pellicle modification. Similar effects were observed for tannic acid.

Adsorption↗
PubMed2006

Inhibition of amyloid fibril formation by polyphenols: structural similarity and aromatic interactions as a common inhibition mechanism.

The formation of well-ordered fibrillar protein deposits is common to a large group of amyloid-associated disorders. This group consists of several major human diseases such as Alzheimer's disease, Parkinson's disease, prion diseases, and type II diabetes. Currently, there is no approved therapeutic agent directed towards the formation of fibrillar assemblies, which have been recently shown to have a key role in the cytotoxic nature of amyloidogenic proteins. One important approach in the development of therapeutic agents is the use of small molecules that specifically and efficiently inhibit the aggregation process. Several small polyphenol molecules have been demonstrated to remarkably inhibit the formation of fibrillar assemblies in vitro and their associated cytotoxicity. Yet, the inhibition mechanism was mostly attributed to the antioxidative properties of these polyphenol compounds. Based on several observations demonstrating that polyphenols are capable of inhibiting amyloid fibril formation in vitro, regardless of oxidative conditions, and in view of their structural similarities we suggest an additional mechanism of action. This mechanism is assuming structural constraints and specific aromatic interactions, which direct polyphenol inhibitors to the amyloidogenic core. This proposed mechanism is highly relevant for future de novo inhibitors' design as therapeutic agents for the treatment of amyloid-associated diseases.

Amyloid beta-Peptides↗
PubMed2003

Effect of polyphenolic compounds on the renal Na(+),K(+)-ATPase during the restoration of normotension after experimentally induced hypertension in rats.

It is commonly known that consumption of foods and beverages rich in polyphenols is associated with a lower incidence of cardiovascular disease. The purpose of this study was to assess whether the application of red wine polyphenols influences the kinetic properties of renal Na(+),K(+)-ATPase in rats in which hypertension has been experimentally induced by the nitric oxide synthase inhibitor L-NAME. Treatment with polyphenols during the recovery from hypertension to normotension resulted in the complete revival of the functional properties of the Na(+),K(+)-ATPase, as indicated by the total restoration of K(m), K(Na) (concentration of Na(+) necessary to achieve half-maximal reaction velocity) and V(max) for enzyme activation by ATP and/or Na(+) to pre-hypertension values. Two positive effects of polyphenols during the recovery period are indicated: a restoration of the affinity of the ATP and Na(+) binding sites to control values and a probable increase in the number of Na(+),K(+)-ATPase molecules to a level comparable to that in control conditions, as suggested by the complete renewal of V(max).

Adenosine Triphosphate↗
PubMed2006

Specific plasma membrane binding sites for polyphenols, including resveratrol, in the rat brain.

Using [3H]resveratrol (3,5,4'-trihydroxy-trans-stilbene) as radioligand, we investigated the possible existence of specific polyphenol binding sites at the level of the cellular plasma membrane in rat brain. Specific [3H]resveratrol binding sites were found to be enriched in the plasma membrane pellet with lower levels in the nuclear and cell debris fraction. Specific [3H]resveratrol binding to the plasma membrane fraction was sensitive to trypsin digestion and protein denaturation but not to DNase and RNase treatment. Saturation binding experiments revealed that specific [3H]resveratrol recognized a single class of sites with an apparent affinity (KD) of 220+/-45 nM and a maximal capacity (Bmax) of 1060+/-120 fmol/mg protein. Various polyphenols and resveratrol derivatives competed against specific [3H]resveratrol binding in rat brain plasma membrane homogenates with the tea catechin gallates (epigallocatechin gallate and epicatechin gallate) displaying the highest affinities (Ki=25-45 nM) followed by resveratrol (Ki=102 nM). Quantitative autoradiographic studies revealed that specific [3H]resveratrol binding sites are broadly distributed in the rat brain, with highest levels of labeling seen in the choroid plexus and subfornical organ. Finally, the potency of various polyphenols and resveratrol analogs in protecting hippocampal cells against beta-amyloid-induced toxicity correlated well (r=0.74) with their apparent affinity in the [3H]resveratrol binding assay. Taken together, these results suggest that the neuroprotective action of various polyphenols and resveratrol analogs could be mediated by the activation of common "receptor" binding sites particularly enriched at the level of the cellular plasma membrane in the rat brain.

Animals↗
PubMed2003

Polyphenols from Camellia sinenesis attenuate experimental cholestasis-induced liver fibrosis in rats.

Accumulation of hydrophobic bile acids during cholestasis leads to generation of oxygen free radicals in the liver. Accordingly, this study investigated whether polyphenols from green tea Camellia sinenesis, which are potent free radical scavengers, decrease hepatic injury caused by experimental cholestasis. Rats were fed a standard chow or a diet containing 0.1% polyphenolic extracts from C. sinenesis starting 3 days before bile duct ligation. After bile duct ligation, serum alanine transaminase increased to 760 U/l after 1 day in rats fed a control diet. Focal necrosis and bile duct proliferation were also observed after 1-2 days, and fibrosis developed 2-3 wk after bile duct ligation. Additionally, procollagen-alpha1(I) mRNA increased 30-fold 3 wk after bile duct ligation, accompanied by increased expression of alpha-smooth muscle actin and transforming growth factor-beta and the accumulation of 4-hydroxynenonal, an end product of lipid peroxidation. Polyphenol feeding blocked or blunted all of these bile duct ligation-dependent changes by 45-73%. Together, the results indicate that cholestasis due to bile duct ligation causes liver injury by mechanisms involving oxidative stress. Polyphenols from C. sinenesis scavenge oxygen radicals and prevent activation of stellate cells, thereby minimizing liver fibrosis.

Actins↗
PubMed2005

Mechanism of potentiation by polyphenols of contraction in human vein-engineered media.

The potential of natural dietary polyphenols in the treatment of vascular diseases originating from veins has been suggested in the literature. However, the mechanisms involved to explain the effects of polyphenols are not yet elucidated. Therefore, the aim of this study was to investigate the mechanisms by which polyphenols from red wine (Provinols) modulated contraction in human veins. We took advantage of a human model previously reported as a new tool for pharmacological research, using tissue-engineered techniques allowing the production of vascular media based exclusively on human smooth muscle cells. Thus human tissue-engineered vascular media (TEVM) were produced with cells originating from umbilical cord vein. TEVM were treated with either vehicle or Provinols. Results showed that treatment of TEVM with Provinols significantly potentiated the contractile responses induced by histamine and bradykinin. The potentiating effect of Provinols was not associated with an enhancement of histamine-induced increase in cytosolic calcium; rather, it implied the presence of a Ca(2+)-independent signaling pathway. Pharmacological studies indicated that action of Provinols took place at the level of phospholipase A(2)-Rho-kinase pathway and was associated with an enhancement of myosin light chain kinase activity. These results, obtained using the human TEVM, bring new insights to explain the regulation of venous contraction by polyphenols.

Calcium↗
PubMed1993

Oolong tea polyphenols inhibit experimental dental caries in SPF rats infected with mutans streptococci.

An extract of oolong tea (semifermented tea leaves of Camellia sinensis) and its chromatographically isolated polyphenolic compound was examined for in vitro inhibitory effects on glucosyltransferases (GTases) of mutans streptococci and on caries development in Sprague-Dawley rats infected with mutans streptococci. The samples showed no detectable effect on the growth of mutans streptococci. However, insoluble glucan synthesis from sucrose by the GTases of Streptococcus mutans MT8148R and Streptococcus sobrinus 6715 was markedly inhibited, as was sucrose-dependent cell adherence of these mutans streptococci. The administration of the oolong tea extract and the isolated polyphenol compound into diet 2000 and drinking water resulted in significant reductions in caries development and plaque accumulation in the rats infected with mutans streptococci. The active components in the oolong tea extract were presumptively identified as polymeric polyphenols which were specific for oolong tea leaves. These results indicate that the oolong tea polyphenolic compounds could be useful for controlling dental caries.

Animals↗
PubMed2002

Red wine polyphenols enhance endothelial nitric oxide synthase expression and subsequent nitric oxide release from endothelial cells.

BACKGROUND: Population-based studies suggest a reduced incidence of morbidity and mortality from coronary heart disease caused by moderate and regular consumption of red wine. Endothelial nitric oxide (NO) is a pivotal vasoprotective molecule. This study examines the influence of red wine polyphenols on the regulation of endothelial nitric oxide synthase (eNOS) expression and subsequent NO synthesis, focusing on the putative long-lasting antiatherosclerotic effects of red wine. METHODS AND RESULTS: Treatment (20 hours) of human umbilical vein endothelial cells (HUVECs) and of the HUVEC-derived cell line EA.hy926 with a alcohol-free red wine polyphenol extract (RWPE) led to a concentration-dependent (100 to 600 microg/mL), significant increase in NO release (up to 3.0-fold/HUVEC and 2.0-fold/EA.hy926) as shown by use of the fluorescent probe DAF-2. This effect was corroborated by the [14C]L-arginine/L-citrulline conversion assay in intact EA.hy926 cells. RWPE (20 hours, 100 to 600 microg/mL) also significantly increased eNOS protein levels up to 2.1-fold. Furthermore, we found an increased human eNOS promotor activity (up to 2-fold) in response to red wine polyphenols (18 hours, 100 to 600 microg/mL), as demonstrated by a luciferase reporter gene assay. CONCLUSION: We provide conclusive data showing for the first time that a RWPE increases eNOS expression and subsequent endothelial NO release. Increased active eNOS levels may antagonize the development of endothelial dysfunction and atherosclerosis, a hypothesis that supports the view that red wine indeed may have long-term protective cardiovascular properties mediated by its polyphenols.

Cells, Cultured↗
PubMed2000

Red wine polyphenols inhibit proliferation of vascular smooth muscle cells and downregulate expression of cyclin A gene.

BACKGROUND: Red wine polyphenols have been shown to contribute to the "French paradox" phenomenon, which consists of lower morbidity and mortality from coronary heart disease in the French population. Although vascular smooth muscle cell (VSMC) proliferation plays an important role in the progression of atherosclerotic lesions, the effects of red wine polyphenols on VSMC proliferation have not been elucidated. METHODS AND RESULTS: We extracted the total polyphenolic fraction from red wine (RW-PF) by column chromatography. Treatment with RW-PF showed a potent inhibitory effect on the proliferation and DNA synthesis of cultured rat aortic smooth muscle cells (RASMCs). In contrast, the inhibitory effect of RW-PF on the proliferation of bovine carotid endothelial cells was observed only at much higher concentrations. To elucidate the molecular mechanisms of this antiproliferative effect of RW-PF on RASMCs, we investigated the effects of RW-PF on cell cycle regulation. RW-PF downregulated the expression of cyclin A mRNA and cyclin A promoter activity. In addition, RW-PF decreased the binding of nuclear proteins to the activating transcription factor (ATF) site in the cyclin A promoter and downregulated the mRNA levels of transcription factors, cAMP-responsive element-binding protein (CREB), and ATF-1. CONCLUSIONS: These results suggest that the downregulation of cyclin A gene expression may contribute to the antiproliferative effect of red wine polyphenols on RASMCs through the inhibition of transcription factor expression.

Animals↗
PubMed1999

Plant polyphenols inhibit benzoyl peroxide-induced superoxide anion radical production and diacylglyceride formation in murine peritoneal macrophages.

Naturally occurring plant polyphenols, which include ellagic acid (EA), tannic acid (TA), caffeic acid (CA), and ferulic acid (FA), were tested for their superoxide anion radical (SOR)-scavenging activities. SOR were produced by interaction of the tumor promoter benzoyl peroxide (BPO) with murine peritoneal macrophages in vitro. The levels of SOR were assessed microscopically by counting the number of formazan-positive cells per 250 cells produced by the reduction of nitro blue tetrazolium. BPO at a concentration of 15 micrograms/1.85 x 10(6) cells/0.5 ml induced maximum formation of SOR in resident and thioglycollate-elicited cells. All the tested polyphenols were able to inhibit the formation of SOR induced by the tumor promoter to a variable degree. Inhibition of BPO-induced SOR formation by polyphenols was in the following order: FA > TA > CA > EA. BPO stimulated the accumulation of diacylglycerol (DAG) in resident and elicited macrophages with concurrent release of choline equivalents from macrophages. Polyphenols inhibited DAG accumulation, which paralleled the inhibition of choline equivalent release. FA was observed to be the most effective and EA the least effective inhibitor of SOR formation, DAG accumulation, and release of choline equivalents. It is likely that inhibition of SOR formation might be due to some interference in the cellular lipid metabolism and phospholipid equivalent deacylation and choline release.

Animals↗
PubMed2003

Screening of chemopreventive tea polyphenols against PAH genotoxicity in breast cancer cells by a XRE-luciferase reporter construct.

Polycyclic aromatic hydrocarbons (PAHs) are established cancer initiators that can be found in our food and environment. Some dietary plant polyphenols are strong inhibitors to PAH-induced mutagenesis, whereas others may not be as effective. To identify the chemopreventive compounds from a huge volume of dietary components, the development of an efficient screening method is required. In this study, a xenobiotic response element (XRE)-luciferase reporter plasmid was constructed to screen for some potential chemopreventive agents in tea against PAH-induced DNA damage. Tea is one of the most consumed beverages worldwide, and its beneficial effects on health have been documented. Previous studies have claimed that tea polyphenols could be protective against various cancers, and the rich database can be a source for comparison. Among the green and black tea polyphenols, the XRE-luciferase reporter assays suggested that only epigallocatechin gallate (EGCG) was effective in reducing XRE-driven luciferase assay in MCF-7 cells at the concentrations tested. Further study indicated EGCG could reduce CYP1A1 and CYP1B1 mRNA abundances and decrease the DMBA-DNA lesions. The results of DNA covalent binding of all tea polyphenols tested were consistent with the XRE-reporter assays. This study illustrated that the XRE-reporter assay was a viable screening test for dietary chemopreventive agents against PAH-initiated breast mutagenesis. It has the advantages of shorter sample processing time and producing no radioactive waste over directly measuring the CYP1A1/1B1 expressions, DNA lesion, or gel mobility shift assay.

Analysis of Variance↗
PubMed2003

Inhibitory effect of water-soluble derivative of propolis and its polyphenolic compounds on tumor growth and metastasizing ability: a possible mode of antitumor action.

Polyphenolic compounds are widely distributed in the plant kingdom and display a variety of biological activities, including chemoprevention and tumor growth inhibition. Propolis is made up of a variety of polyphenolic compounds. We compared how the routes of administration of polyphenolic compounds deriving from propolis and of propolis itself affect the growth and metastatic potential of a transplantable mammary carcinoma (MCa) of the CBA mouse. The influence of tested compounds on local tumor growth was also studied. Metastases in the lung were generated by 2 x 10(5) tumor cells injected intravenously (IV). A water-soluble derivative of propolis (WSDP) and polyphenolic compounds (caffeic acid, CA, and CA phenethyl ester, CAPE) were given to mice per os (PO) or intraperitoneally (IP) before or after tumor cell inoculation. Tested compounds significantly decreased the number of lung colonies. When mice were inoculated with 10(5) MCa cells in the exact site of subcutaneous injection of different doses of WSDP, CA, or CAPE, tumor growth was inhibited, and survival of treated mice was prolonged. Antitumor activity, according to the results obtained, is mostly related to the immunomodulatory properties of the compounds and their capacity to induce apoptosis and necrosis. In conclusion, results presented here indicate that WSDP, CA, and CAPE could be potential useful tools in the control of tumor growth in experimental tumor models when administrated PO; because PO administration is the easiest way of introducing a compound used for prevention and/or cure of any disease, it is likely that this article has reached the goal of the investigation.

Administration, Oral↗
PubMed2006

Inhibition of IL-8 production by green tea polyphenols in human nasal fibroblasts and A549 epithelial cells.

The attraction of leukocytes to tissues is essential in order for inflammation and the host response to infection to occur. Airway inflammation is a very common cause illness with a substantial impact on health care. Neutrophils play an essential role in the host defense and in inflammation, but the latter may trigger and sustain the pathogenesis of a range of acute and chronic diseases. Infiltration of neutrophils occurs as a response to chemoattractant molecules by resident tissue cells. The recruitment of neutrophils in airway inflammation may account for the generation of IL-8. To evaluate the effectiveness of green tea polyphenols in the modulation of airway inflammation through the blocking of neutrophil chemokine production, nasal mucosal fibroblasts and A549 bronchial epithelial cells were analyzed for the production of IL-8. Both nasal mucosal fibroblasts and bronchial epithelial cells produced significant amounts of IL-8 through stimulation of IL-1beta. Tea polyphenols were very effective in the inhibition of IL-8 production. Among the polyphenols tested, EGCG and ECG showed strong inhibitory activity in dose-dependent manners. EGC and EC showed moderate inhibition at 48 h culture, whereas (-)catechin was not effective. Production of IL-8 after stimulation by proinflammatory cytokines in both nasal fibroblasts and bronchial epithelial cells was significantly blocked by pretreatment with green tea polyphenols.

Blotting, Western↗
PubMed2001

Relationship between the enzymatic browning and phenylalanine ammonia-lyase activity of cut lettuce, and the prevention of browning by inhibitors of polyphenol biosynthesis.

Cut lettuce stored at 4 degrees C gradually turned brown on the cut section after several days of storage. Three factors for enzymatic browning, the polyphenol content, polyphenol oxidase activity, and phenylalanine ammonia-lyase (PAL) activity, were examined during the cold storage of cut lettuce. A relationship between the browning and PAL activity was apparent. We tried to prevent this browning by using the two enzyme inhibitors, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the phenylpropanoid pathway, and glyphosate, an inhibitor of the shikimate pathway. AIP and glyphosate significantly inhibited the browning of cut lettuce. The polyphenol content and PAL activity were both reduced by the treatment with AIP. These results show that regulating the biosynthesis of polyphenols is essential to prevent the browning of cut lettuce.

Catechol Oxidase↗
PubMed1995

Effect of tea polyphenols on fecal flora and fecal metabolic products of pigs.

The effects of tea polyphenols on fecal flora and fecal metabolic activities were studied in eight 30-day-old pigs fed a basal diet (control) or the diet supplemented with 0.2% of tea polyphenols for 2 weeks. During tea polyphenol administration compared to before administration, the levels of lactobacilli were increased significantly (P < 0.05 and P < 0.01 on days 7 and 14 of administration, respectively), whereas the levels of total bacteria (P < 0.01) and bacteroidaceae (P < 0.01 and P < 0.001 on days 7 and 14 of administration, respectively) were decreased significantly. The detection rate of lecithinase positive clostridia including Clostridium perfrigens showed a tendency to decrease during administration. No detectable change occurred in the levels of other organisms throughout the experimental period. Fecal concentrations of ammonia were decreased significantly (P < 0.05 and P < 0.01 on days 7 and 14 of administration, respectively). Fecal phenol (P < 0.001), p-cresol (P < 0.05), and skatol (P < 0.01) were reduced significantly on day 14 of administration compared to before administration. The amounts of fecal short chain fatty acids, acetic acid (P < 0.05) and lactic acid (P < 0.05) were increased significantly on day 14 of administration. The pH values were decreased slightly during administration. The odour of the feces was reduced remarkably during tea polyphenol administration.

Animals↗