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Red wine polyphenolics suppress the secretion and the synthesis of Apo B48 from human intestinal CaCo-2 cells.

Epidemiological studies suggest that the red wine consumption may reduce the risk factor of cardiovascular disease. However, the mechanisms of how the red wine phenolic components reduce the risk of cardiovascular disease is currently unknown. Our previous study demonstrated that red wine polyphenolics suppress the secretion of pro-atherogenic lipoproteins (very low density lipoproteins) from human hepatic HepG2 cells. Therefore, in this study we hypothesize that red wine polyphenolics will also attenuate the production and secretion of another pro-atherogenic lipoprotein (chylomicrons) from human intestinal CaCo-2 cells. Cultured CaCo-2 cells were incubated in the presence of dealcoholized red wine, alcoholized red wine and atorvastatin for 24 h. The apo B48 protein (marker of intestinal chylomicrons) was quantified on Western blotting and the enhanced chemiluminescence. Apo B48 levels in the cells and that secreted into the media were significantly reduced by 29% in the cells incubated with dealcoholized red wine compared with control cells. Also the similar effect was shown in the cells incubated with alcoholized red wine. The cells incubated with atorvastatin shown the significant reduction of apo B48 production compared to control cells. Collectively, this study suggests that red wine polyphenolics down regulate the production of chylomicron in intestinal CaCo-2 cells.

Apolipoprotein B-48↗

Effect of the walnut polyphenol fraction on oxidative stress in type 2 diabetes mice.

We examined the in vivo antioxidative effect of a polyphenol-rich walnut extract on oxidative stress in mice with type 2 diabetes. C57BL/KsJ-db/db mice were used as an accelerated oxidative animal model. The oral administration of the walnut polyphenol fraction at 200 mg/kg body weight for 4 weeks caused a significant decrease in the level of urinary 8-hydroxy-2'-deoxyguanosin, which is an in vivo marker of oxidative stress. These results imply that walnut polyphenols have both in vitro and in vivo antioxidant effects.

Animals↗

Urinary biomarkers of tea polyphenols and risk of colorectal cancer in the Shanghai Cohort Study.

There have been no studies on specific tea polyphenol biomarkers and risk of colorectal cancer in humans. We prospectively examined the associations between validated biomarkers of specific tea polyphenols and risk of developing colorectal cancer among a cohort of 18,244 men in Shanghai, China, with 16 years of follow-up. Epigallocatechin (EGC), 4'-O-methyl-epigallocatechin (4'-MeEGC) and epicatechin, and their metabolites in baseline urine samples were measured on 162 incident colorectal cancer cases and 806 matched controls. Individuals with high prediagnostic urinary EGC levels had a lower risk of colon cancer. Compared with undetectable EGC, odds ratios (95% confidence interval) for colon cancer in the lowest, intermediate and highest tertile of detectable EGC were 0.64 (0.33-1.24), 0.60 (0.30-1.20) and 0.40 (0.19-0.83), respectively (p for trend = 0.02). A similar inverse relation between 4'-MeEGC and colon cancer also was observed. Compared with the lowest quartile, odds ratios (95% confidence intervals) for colon cancer in the 2nd, 3rd and 4th quartiles of urinary 4'-MeEGC were 0.49 (0.25-0.96), 0.32 (0.16-0.67) and 0.41 (0.20-0.84), respectively (p for trend = 0.006). The strongest protective effect was seen for regular tea drinkers who showed high levels of urinary EGC and 4'-MeEGC. No association between urinary levels of epicatechin or its metabolite and colon cancer risk was observed. Urinary levels of tea polyphenols and their metabolites were not associated with rectal cancer risk. The present study supports the notion of tea catechins as chemopreventive agents against the development of colon cancer in humans.

Biomarkers↗

Dietary polyphenols (-)-epicatechin and chrysin inhibit intestinal glucuronidation metabolism to increase drug absorption.

The effect of dietary polyphenols on the intestinal glucuronidation and absorption of a model phenolic drug, alpha-naphthol (alpha-NA), was studied in isolated rat small intestine. (-)-Epicatechin significantly inhibited the glucuronidation of alpha-NA. Chrysin, (-)-epigallocatechin galleate (EGCG), and quercetin decreased the rate of glucuronidation, although not significantly. Baicalin did not affect the glucuronidation. The rate of absorption of alpha-NA in the presence of these polyphenols also varied. The absorption clearance (CLabs) and the metabolic clearance (CLmet) were inversely correlated, and this relationship was well explained in the metabolic inhibition model with kinetic parameters (knowledge-based prediction) which characterizes the relationship between the CLabs and CLmet of alpha-NA (Biochim Biophys Acta 1998, 1425, 398.). These results indicate that the concomitant intake of some polyphenols can increase the absorption of a phenolic drug, and the effect is predictable. (-)-Epicatechin and chrysin are effective for the inhibition of glucuronidation and promotion of intestinal drug absorption.

Animals↗

Hibiscus polyphenol-rich extract induces apoptosis in human gastric carcinoma cells via p53 phosphorylation and p38 MAPK/FasL cascade pathway.

In view of the continuing need for effective anticancer agents, and the association of diet with reduced cancer risk, edible plants are increasingly being considered as sources of anticancer drugs. Hibiscus sabdariffa Linne (Malvaceae), an attractive plant believed to be native to Africa, is cultivated in the Sudan and Eastern Taiwan. Polyphenols had been demonstrated previously to possess antioxidative and antitumor promoting effects. In this study, investigations were conducted to examine the mechanism of the anticancer activity of H. sabdariffa L., Hibiscus polyphenol-rich extracts (HPE). Using HPLC assay, HPE was demonstrated to contain various polyphenols. HPE induced cell death of eight kinds of cell lines in a concentration-dependent manner. Among them human gastric carcinoma (AGS) cells were the most susceptible to HPE (0.95 mg/mL HPE inhibited its growth by 50%). Our results revealed that AGS cells underwent DNA fragmentation, and had an increase in the distribution of hypodiploid phase (apoptotic peak, 52.36%) after a 24-h treatment with HPE (2.0 mg/mL). This effect of HPE in AGS cells might be mediated via p53 signaling and p38 MAPK/FasL cascade pathway, as demonstrated by an increase in the phosphorylation of p53 and the usage of a specific p38 inhibitor, SB203580. Thus, our data present the first evidence of HPE as an apoptosis inducer in AGS cells and these findings may open interesting perspectives to the strategy in human gastric cancer treatment.

Apoptosis↗

Molecular targets for the cancer preventive activity of tea polyphenols.

Inhibition of carcinogenesis by tea and tea polyphenols has been demonstrated in many animal models. The mechanisms of action have been extensively investigated mostly in cell culture systems with (-)-epigallocatechin-3-gallate (EGCG), the most active and major polyphenolic compound from green tea. However, the mechanisms of cancer preventive activity by tea and tea polyphenols are not clearly understood. This article discusses some of the reported mechanisms and possible targets for the action of EGCG. The difficulties and major issues in extrapolating data from studies in cancer cell lines to cancer prevention mechanisms are discussed. Activities observed in cell culture with high concentrations of EGCG may not be relevant because of the limited systemic bioavailability of EGCG. In addition, possible artifacts due to the auto-oxidation of EGCG may complicate this issue. Some recent studies revealed high-affinity EGCG binding proteins as possible direct targets for the action of EGCG. Validating the related cancer preventive mechanisms found in in vitro studies in animal models and human samples would be exciting.

Animals↗

Beneficial effects of tea and its polyphenols against prostate cancer.

Tea, next to water, is the most widely consumed beverage in the world. Depending upon the level of fermentation, tea can be categorized into three types: green (unfermented), oolong (partially fermented), and black (highly to fully fermented). In general, green tea has been found to be superior to black and oolong tea in terms of antioxidant and health promoting benefits owing to the higher content of (-)-epigallocatechin-3-gallate. Tea polyphenols comprise about one-third of the weight of the dried leaf, and they exhibit biochemical and pharmacological activities including antioxidant activities, inhibition of cell proliferation, induction of apoptosis, cell cycle arrest and modulation of carcinogen metabolism. Several studies demonstrate that most tea polyphenols exert their effects by scavenging reactive oxygen species (ROS) since excessive production of ROS has been implicated in the development of a variety of ailments including cancer of the prostate gland (CaP). Using cell culture and animal model systems, molecular targets for these remarkable beneficial effects of green tea drinking on CaP prevention and therapy have been defined. Geographical and case-control studies are showing that green tea drinking could afford CaP chemopreventive effects in human population. In this review we attempt to summarize the experimental as well as the epidemiological basis for the possible role of tea and its polyphenols for chemoprevention and chemotherapy of CaP.

Androgens↗

Polyphenolic apple juice extracts and their major constituents reduce oxidative damage in human colon cell lines.

Apple juice containing high amounts of antioxidative polyphenols might protect the intestine against oxidative cell damage. We investigated the preventive effectiveness of polyphenolic juice extracts of different origins (cider and table apples) in comparison to their major constituents in human colon cell lines (Caco-2, HT29). Parameters studied were (oxidative) DNA damage (Comet assay), glutathione level (photometric kinetic assay), cellular redox status (dichlorofluorescein assay) and antioxidant capacity. The extracts (50-250 microg/mL) modulated DNA damage and redox status in a concentration-dependent manner at 24-h incubation. The pomace extraction technology, applied for juice preparation, and the preferential selection of cider apple varieties influenced the polyphenolic pattern and increased the biological effectiveness of the extracts. The preventive potential of major juice constituents (1-100 microM, 24 h) strongly differed: rutin, epicatechin and caffeic acid clearly reduced (oxidative) DNA damage (Caco-2), chlorogenic acid efficiently decreased cellular reactive oxygen species level (HT29, Caco-2). The aglyca quercetin and phloretin exhibited the highest preventive/antioxidant capacity in all assays. The stability of the compounds inversely correlated with their preventive effectiveness and might contribute to the observed cell specific sensitivities. In conclusion, apple juice extracts distinctly reduce oxidative cell damage in human colon cell lines, an effect, which in part can be accounted for by their major constituents.

Beverages↗

Solvent effects on focused microwave assisted extraction of polyphenolic acids from Eucommia ulmodies.

An open microwave-assisted extraction system was used to extract gallic acid, protocatechuic acid, chlorogenic acid and caffeic acid from Eucommia ulmodies. The effect of extraction variables, especially solvent, on the recoveries of these polyphenolic compounds was investigated using factorial design. As extracting solvent for these compounds, methanol produced a higher recovery than pure water. For straight chain alcohol solvents, the lower the carbon number, the higher the recoveries of the polyphenolic acids. The optimal ratio of methanol:water:glacial acetic acid in the solvent mixture used in microwave-assisted extraction was 2:8:0.3 (v/v) and this solvent could be directly used as the mobile phase in HPLC separation without additional intermittent treatment as reported in literature. The extraction under the condition of 50% microwave power and 30 s irradiation at a solvent:sample ratio of 10 (mL/g) was found to be the most advantageous. The repeatability test of extraction and chromatographic analysis was satisfactory for the analysis of these polyphenolic compounds.

Chemistry Techniques, Analytical↗

An analytical survey of the polyphenols of seeds of varieties of grape (Vitis vinifera) cultivated in Greece: implications for exploitation as a source of value-added phytochemicals.

Seed samples from 12 white and 25 red international and Hellenic native grape varieties (Vitis vinifera) were screened for their polyphenolic composition. The polyphenols determined were mainly of low molecular weight, including gallic acid, catechin, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate and the procyanidins B1 and B2. Average values of total content for white and red varieties (376 and 388 mg/100 g seeds, respectively) were very similar. Comparable results were observed with respect to the individual polyphenol content with seeds from red varieties being, in general, slightly richer. The predominant flavanol monomer in white and red varieties was catechin (which accounted for 50.5 and 49.3%, respectively, of the total content), whilst gallic acid and epigallocatechin were the constituents showing the lowest content, respectively. The data obtained are discussed with regard to the exploitation of grape seeds as a low-cost source of value-added phytochemicals.

Flavonoids↗

Antimutagenic effects of black tea (World Blend) and its two active polyphenols theaflavins and thearubigins in Salmonella assays.

Almost two thirds of the world population consume tea everyday. Tea is processed differently in different parts of the world to give green (20%), black (78%) or oolong tea (2%). The antimutagenic and anticarcinogenic activities of green tea were extensively investigated compared with those of black tea. Considering the potent antimutagenic effects of green tea we recognized the need to evaluate the antimutagenic effects of black tea (World Blend Tea, Southern Tea Co., Marietta, GA) in Salmonella strains TA97a, TA98, TA100 and TA102 in preincubation tests, both with and without S9 activation. Attempts have also been made to compare the results of the tea extracts with their two active polyphenols theaflavins and thearubigins. Antimutagenicity assays were carried out in bacterial plates treated with different concentrations (1%, 2.5%, 5%, 10% and 20%) of tea extracts against known bacterial mutagens sodium azide, 4-nitro-o-phenylenediamine, cumine hydroperoxide, 2-aminofluorene and danthron. A significant decrease in the number of revertant colonies was observed in the plates treated with 1% to 20% of tea extract plus positive mutagen when compared with positive mutagen only. Both the active polyphenols theaflavins and thearubigins extracted from the black tea (World blend) also showed significant antimutagenic effects against known positive compounds in these strains. In the experiments with S9 activation, the antimutagenic effects were significantly higher. These results indicate that black tea and its two polyphenols have significant antimutagenic effects in Ames Salmonella assays.

Animals↗

Polyphenols in chocolate, which have antioxidant activity, modulate immune functions in humans in vitro.

We studied the effects of antioxidants from chocolate, cacao liquor polyphenol (CLP), on human immune functions in vitro. CLP is an enriched polyphenol fraction purified from cacao liquor that is a major component of chocolate. It has been shown that polyphenols have antioxidant activity, and reactive oxygen species (ROS) are involved in immune responses. CLP inhibited both hydrogen peroxide and superoxide anion, typical ROS, production by phorbol myristate acetate-activated granulocytes. CLP also inhibited menadione-induced production of both hydrogen peroxide and superoxide anion in normal human peripheral blood lymphocytes (PBL). CLP treatment of normal PBL in vitro inhibited mitogen-induced proliferation of T cells and polyclonal Ig production by B cells in a dose-dependent manner. CLP treatment inhibited both IL-2 mRNA expression of and IL-2 secretion by T cells. These results suggest that antioxidant CLP has immunoregulatory effects.

Adult↗

Black tea, green tea, and tea polyphenols. Effects on trace element status in weanling rats.

Previous studies have shown that tea consumption can impair trace element metabolism, particularly iron status, and increase the risk of anemia in humans and animals. More recently, however, evidence has been accumulating to show that, in animals, consumption of green tea or its polyphenols is associated with a reduction of the incidence and severity of a variety of experimentally induced cancers. In this study we have monitored the growth, trace element status, including hematological parameters of weanling rats given either (1) water, (2) 1% black tea, (3) 1% green tea, or (4) 0.2% crude green tea extract as their sole drinking fluid while consuming diets containing either adequate or low amounts of iron. With the exception of manganese, none of the trace elements studied (iron, copper, zinc, and manganese) or the hematological indices measured were affected by the type of beverage supplied, even though the polyphenol extract was shown to chelate metals in vitro and all the animals fed the low iron diet were shown to be anemic. There appeared to be an effect of black and green teas on manganese balance in both the first and last weeks of the study. A lower level of brain manganese was associated with green tea consumption, and a higher level of this element in the kidneys of animals fed black tea. The results demonstrate that both black and green teas and a green tea polyphenol extract do not represent a risk to animals consuming the beverages as their sole fluid intake with respect to iron availability, although the interactions with manganese deserve further study.

Animals↗

Antioxidative properties of brown algae polyphenolics and their perspectives as chemopreventive agents against vascular risk factors.

Several polyphenolic compounds and complex mixtures were isolated from brown algae species. The 1,1-diphenyl-2-picryhydarzyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) of these compounds were evaluated to determine their physiological usefulness as antioxidants for vascular protection. The antioxidative protection of low-density lipoprotein (LDL) was also evaluated and compared with that of catechin, because the generation of oxidized LDL is one of the most active and specific risk factors contributing to atherogenesis. Oral administration to rats of a commercially available sample (VNP) containing 30% of these polyphenolic compounds and 70% dietary fiber revealed that the serum reducing capacity measured in terms of FRAP value was significantly elevated 30 min after the treatment, but declined rather quickly thereafter, indicating the good oral absorption of the compounds and their fast binding to the lumenal surface of the blood vessels. An eight-week, human, clinical trial (n=31) of VNP showed significant improvement in erectile function measured by IIEF (international index of erectile function) score. These results collectively demonstrated the usefulness of these polyphenolic compounds as fundamental chemopreventive agents against vascular risk factors originating from oxidative stress.

Animals↗

Antioxidant and radical scavenging properties in vitro of polyphenolic extracts from red wine.

BACKGROUND & AIMS: Red wine polyphenols inhibit chemically-induced oxidative DNA damage in vivo in experimental animals through a mechanism which is still unclear. On this basis, we tried to clarify the mechanisms of inhibition of DNA oxidation in vitro by wine extracts containing monomeric and polymeric phenols (WE) and monomer-free complex polyphenols and tannins (WCPT) from red wine. METHODS: Oxidative DNA damage was induced by incubating DNA with GSH/Fe3+ or cumene hydroperoxide (CumOOH) in vitro and using 8-OH-2-deoxyguanosine (8-OHdG) levels as a measure of DNA oxidation. Levels of 8-OHdG were determined by HPLC coupled with electrochemical detector (ESA). RESULTS AND CONCLUSIONS: WCPT and WE, at microM concentrations, reduced concentration-dependently oxidative DNA damage induced by GSH/Fe3+. WCPT and WE also reduced DNA oxidation by CumOOH. In conclusion, complex polyphenols and tannin extracts from red wine, with or without small molecular phenols, prevent oxidative DNA damage through a dual mechanism, iron binding and direct free radical scavenging.

Animals↗

Protective effects upon experimental inflammation models of a polyphenol-supplemented virgin olive oil diet.

OBJECTIVE AND DESIGN: The aim of the present study was to examine the effect of a virgin olive oil enriched diet in acute and chronic inflammation models in rats and to determine the effect of supplementing this oil with a higher content of its polyphenolic fraction. The response was compared to oils rich in monounsaturated fatty acids (high oleic sunflower oil and palm olein) and rich in polyunsaturated fatty acids (fish oil). DIETS: Groups of 6-8 male Wistar rats were fed from weaning on six purified diets differing in type of oil: 2% corn oil (basal diet, BD), 15% high oleic sunflower oil (HOSO), 15% virgin olive oil (VOO), 15% virgin olive oil supplemented with 600 p.p.m. polyphenols from this oil (PSVOO), 15% palm olein (POL), and 15% fish oil (FO). MATERIALS AND METHODS: Rats were fed for 8 weeks with BD, HOSO, VOO, PSVOO, POL and FO diets before injecting carrageenan. Rats were fed for 3 weeks with BD, PSVOO and FO diets before induction of adjuvant arthritis. Dietary treatment with or without indomethacin continued during 3 weeks. The data were evaluated using an analysis of variance (ANOVA) followed by the least-significant differences. RESULTS: In carrageenan oedema test, the inflammation indices of animals fed on a diet rich in olive oil (VOO) were lower compared to animals fed with oils high in oleic acid (HOSO, POL) and polyunsaturated fatty acids (FO), and markedly diminished in the group fed on PSVOO. In established adjuvant arthritis, the PSVOO diet was even more effective than FO diet in the prevention of inflammation. Both groups of animals showed an increase in weight during the latter days of the experiment compared to the BD. Indomethacin administered to every diet group, exerted a strong inhibitory effect on the inflammatory process throughout which was augmented by the PSVOO and FO diets. CONCLUSIONS: This study demonstrates that virgin olive oil with a higher content of polyphenolic compounds, similar to that of extra virgin olive oil, shows protective effects in both models of inflammation and improves the disease associated loss of weight. This supplementation also augmented the effects of drug therapy.

Animals↗

Determination of polyphenols in wines by reaction with 4-aminoantipyrine and photometric flow-injection analysis.

A new flow-injection analytical procedure is proposed for the determination of the total amount of polyphenols in wines; the method is based on the formation of a colored complex between 4-aminoantipyrine and phenols, in the presence of an oxidizing reagent. The oxidizing agents hexacyanoferrate(III), peroxodisulfate, and tetroxoiodate(VII) were tested. Batch trials were first performed to select appropriate oxidizing agents, pH, and concentration ratios of reagents, on the basis of their effect on the stability of the colored complex. Conditions selected as a result of these trials were implemented in a flow-injection analytical system in which the influence of injection volume, flow rate, and reaction-coil length, was evaluated. Under the optimum conditions the total amount of polyphenols, expressed as gallic acid, could be determined within a concentration range of 36 to 544 mg L(-1), and with a sensitivity of 344 L mol(-1) cm(-1) and an RSD <1.1%. The reproducibility of analytical readings was indicative of standard deviations <2%. Interference from sugars, tartaric acid, ascorbic acid, methanol, ammonium sulfate, and potassium chloride was negligible. The proposed system was applied to the determination of total polyphenols in red wines, and enabled analysis of approximately 55 samples h(-1). Results were usually precise and accurate; the RSD was <3.9% and relative errors, by the Folin-Ciocalteu method, <5.1%.

Ampyrone↗

Agrobacterium-mediated genetic transformation of tea leaf explants: effects of counteracting bactericidity of leaf polyphenols without loss of bacterial virulence.

Tea is one of the major crops in Asia and Africa, and its improvement by genetic modification is important for economy of many tea-producing regions. Although somatic embryos derived from cotyledon explants have been transformed with Agrobacterium, the leaves of several commercially important tea cultivars have remained recalcitrant to transformation, largely due to bactericidal effect of polyphenols that are exuded by tea leaves in vitro. Moreover, the commonly used polyphenol adsorbents and antioxidants cannot overcome this problem. Leaf explants, however, are more desirable than cotyledon-derived somatic embryos, especially when it is necessary to further improve a selected elite and also retain its superior traits. Thus, we developed a procedure for Agrobacterium-mediated genetic transformation of tea leaf explants which is based on the presence of L-glutamine in the co-cultivation medium. We then showed that the transformation process is facilitated via a protective action of L-glutamine against bactericidal effects of leaf polyphenols without affecting the bacterial virulence (vir) gene expression.

Anti-Bacterial Agents↗