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At least 973 records · Page 54Linked to original sources
PubMed2004

Novel epicatechin derivatives with antioxidant activity modulate interleukin-1beta release in lipopolysaccharide-stimulated human blood.

We examine the potential antioxidant activity and the immune function of new epicatechin conjugates obtained by depolymerization of grape polymeric flavanols in the presence of cysteamine or cysteine. When incubated with an erythrocyte suspension, flavanols protected the erythrocyte membrane from hemolysis induced by 2,2'-azo-bis(2-amidinopropane)dihydrochloride (AAPH), an azo free radical initiator. The inhibitory effect was concentration-dependent and the IC50 was 119.8 microM for epicatechin, and 74.9 and 89.4 microM for the cysteine and cysteamine derivatives, respectively. These compounds were tested for their antioxidant activity and their capacity to modulate interleukin-1beta (IL-1beta), which is currently considered to be the major cytokine factor influencing the acute phase of the inflammatory response. At concentrations up to 20 microM, epicatechin and its derivatives inhibited the production of IL-1beta in whole blood incubated in the presence of E. coli lipopolysaccharide (LPS), in a concentration-dependent manner. The most active compound was the cysteamine derivative.

Antioxidants↗
PubMed2006

Grape seed flavanols, but not Port wine, prevent ethanol-induced neuronal lipofuscin formation.

Lipofuscin is an end-product of lipid peroxidation which dramatically increases following ethanol consumption, as we have shown in hippocampal and cerebellar neurons. In this work, we corroborated observations indicating that supplementation of ethanol with 200 mg/l of grape seed flavanols prevents increased lipofuscin formation, an action that has been ascribed to the antioxidant properties of the flavanols. Because wine is an alcoholic beverage naturally rich in flavanols, we decided to study the effect of chronic ingestion of Port wine (PW), which also contains 20% ethanol and approximately 200 mg/l of flavanol oligomers, upon lipofuscin accumulation in the hippocampal CA1 and CA3 pyramidal neurons and in the cerebellar Purkinje cells. Six months old rats were fed with PW and results were compared with those obtained in ethanol-treated groups and pair-fed controls. After 6 months of treatment, the volume of lipofuscin per neuron was estimated using unbiased stereological methods. Treatment with PW resulted in an increase of lipofuscin in all neuronal populations studied when compared to controls and to rats treated with ethanol supplemented with flavanols. No differences were observed when comparisons were made with ethanol drinking rats. We conclude that PW, despite containing 20% ethanol and flavanols, does not prevent ethanol-induced lipofuscin formation as previously found in animals drinking ethanol plus flavanols. The reduced antioxidant capacity of PW might depend on the type and amount of flavanols present and on its content in sugars.

Alcohol-Induced Disorders, Nervous System↗
PubMed2005

Grape seed extract suppresses lipid peroxidation and reduces hypoxic ischemic brain injury in neonatal rats.

Oxygen radicals play a crucial role in brain injury. Grape seed extract is a potent anti-oxidant. Does grape seed extract reduce brain injury in the rat pup? Seven-day-old rat pups had the right carotid arteries permanently ligated followed by 2.5 h of hypoxia (8% oxygen). Grape seed extract, 50 mg/kg, or vehicle was administered by i.p. 5 min prior to hypoxia and 4 h after reoxygenation and twice daily for 1 day. Brain damage was evaluated by weight deficit of the right hemisphere at 22 days following hypoxia and by histopathology. Grape seed extract reduced brain weight loss from 20.0+/-4.4% S.E.M. in vehicle pups (n=21) to 3.1+/-1.6% in treated pups (n=20, P<0.01). Grape seed extract improved the histopathologic brain score in cortex, hippocampus and thalamus (P<0.05 versus vehicle). Concentrations of brain 8-isoprostaglandin F2alpha and thiobarbituric acid reacting substances significantly increased due to hypoxic ischemia. Grape seed extract reduced this increase. Treatment with grape seed extract suppresses lipid peroxidation and reduces hypoxic ischemic brain injury in neonatal rat.

Animals↗
PubMed2004

Inhibition of metalloproteinase activity by fruit extracts.

While the metalloproteinase enzymes are essential for development and remodeling of tissues, aberrant over expression of these enzymes contributes to several pathologic conditions. In particular, metalloproteinase over expression in cancer plays a significant role in metastasis by providing a mechanism for invasion and spread. The data presented here indicate that water extracts of raspberries, blackberries and muscadine grapes inhibit the activities of metalloproteinases 2 and 9. This inhibition could contribute to the suppression of carcinogenesis by diets high in fruit content.

Anticarcinogenic Agents↗
PubMed2006

Purple grape juice inhibits 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and in vivo DMBA-DNA adduct formation.

There has been considerable interest in identifying specific foods and phytochemicals that may have breast cancer preventive properties. Concord grapes are rich in polyphenolic chemicals and anthocyanin pigments that may have biological properties which could suppress cancer such as having antioxidant, antiproliferative, and proapoptotic actions. To determine the potential breast cancer protective action of purple grape juice, we examined the effect of grape juice consumption on the initiation stage of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumorigenesis and on the in vivo formation of rat mammary DNA adducts in female Sprague-Dawley rats. Consumption of grape juice significantly inhibited mammary tumor mass at termination and the growth of tumors for the first 5 weeks of detectable tumor development. Consumption of grape juice phenolics by rats also significantly inhibited in vivo mammary DMBA-DNA adduct formation by 34 and 56% for animals fed phenolics at 346 and 692 mg/dL, respectively, compared to controls. Mammary 8-oxo-deoxyguanosine (8-oxo-dG) levels decreased by 25 and 37%, respectively, but the differences were not statistically significant. Liver DMBA-DNA adducts decreased by 10-30%, while 8-oxo-dG adducts remained unchanged, following grape juice intake. Liver glutathione S-transferase activity was significantly increased following grape juice consumption, but only at the highest level of intake. In addition, liver activities of catalase increased and xanthine oxidase decreased significantly, but only at the highest grape juice dose. Thus, these studies indicate that specific constituents or combinations of phytochemicals in purple grape juice can block the initiation stage of DMBA-induced rat mammary tumorigenesis. This tumor inhibitory effect was associated with a suppression of mammary DMBA-DNA adduct formation, which in part may be explained by increased liver activity of the phase II metabolizing enzyme, glutathione S-transferase. Mammary and liver 8-oxo-dG levels were not significantly altered by grape juice consumption. Thus, grape juice constituents appear to have benefit in decreasing susceptibility of the rat mammary gland to the tumor-initiating action of DMBA.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2005

Anticancer activity of grape and grape skin extracts alone and combined with green tea infusions.

Grapes and grape extracts were compared for inhibition of a growth-related and cancer-specific form of cell surface NADH oxidase with protein disulfide-thiol interchange activity designated tNOX from human cervical carcinoma (HeLa) cells and growth of HeLa and mouse mammary 4T1 cells in culture and transplanted tumors in mice. Grapes and grape extracts of several varieties had activity. With an extracted grape preparation provided by the California Table Grape Commission, an active fraction was eluted with methanol from a Diaion HP-20 column after removal of inactive water-soluble materials. Grape skins were a much more potent source than either grape pulp, juice or seeds. Ethanol extracts of the ground freeze-dried pomace was an excellent source. The grape extracts interacted, often synergistically, with decaffeinated green tea extracts both in the inhibition of tNOX activity and in the inhibition of cancer cell growth. Intratumoral injections of a 25:1 mixture of a green tea extract plus ground freeze-dried pomace was nearly as effective as standard synergistic green tea-Capsicum mixtures in inhibiting growth of 4T1 mammary tumors in situ in mice.

Animals↗
PubMed2006

Grape juice causes endothelium-dependent relaxation via a redox-sensitive Src- and Akt-dependent activation of eNOS.

OBJECTIVES: An enhanced endothelial formation of nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF), is thought to contribute to the protective effect of moderate consumption of red wine on coronary diseases. The present study has characterized endothelium-dependent relaxations to Concord grape juice (CGJ), a non-alcoholic rich source of grape-derived polyphenols, in the coronary artery. METHODS: Porcine coronary artery rings were suspended in organ chambers for the measurement of changes in isometric tension in the presence of indomethacin. NO formation was assessed by electron spin resonance spectroscopy, and the phosphorylation of Src, Akt and endothelial NO synthase (eNOS) by Western blot analysis in cultured endothelial cells. RESULTS: Endothelium-dependent relaxations to CGJ were slightly but significantly reduced by L-NA, not affected by charybdotoxin (CTX) plus apamin (APA, two inhibitors of EDHF-mediated responses) whereas the combination of L-NA, CTX plus APA reduced maximal relaxation to about 50%. In the presence of CTX plus APA, relaxations to CGJ were markedly reduced by the membrane permeant mimetic of superoxide dismutase (SOD), MnTMPyP, the membrane permeant analogue of catalase polyethyleneglycol-catalase (PEG-catalase), PP2, an inhibitor of Src kinase, and by wortmannin, an inhibitor of the PI3-kinase. CGJ stimulated the formation of reactive oxygen species and the N(omega)-nitro-L-arginine-, PP2- and wortmannin-sensitive formation of NO in endothelial cells. The formation of NO was associated with a redox-sensitive and time-dependent phosphorylation of Src, Akt and eNOS. CONCLUSIONS: CGJ induces endothelium-dependent relaxations of coronary arteries, which involve a NO-mediated component and also, to a minor extent, an EDHF-mediated component. In addition, CGJ-induced NO formation is due to the redox-sensitive activation of Src kinase with the subsequent PI3-kinase/Akt-dependent phosphorylation of eNOS.

Animals↗
PubMed2006

Measurement of plasma antioxidant reserve after supplementation with various antioxidants in healthy subjects.

BACKGROUND: Current methods to estimate antioxidant status of plasma have many associated difficulties including questionable sensitivity, unreliability, non-reproducible results and procedural difficulties. In addition, there is no significant elevation in the measured value of biomarkers of oxidative stress until pathological disease is already evident. We have developed a new method that eliminates many of these problems. METHODS: This new method includes 3 steps: (1) enzymatic removal of uric acid; (2) ex vivo free radical oxidation of plasma by the addition of a free-radical generator such as SIN-1 or AAPH; and (3) measurement of a marker of lipid peroxidation, 8-isoprostanes. RESULTS: It has been shown in an in vitro experiment that the addition of various antioxidants to plasma significantly reduced the amount of free-radical induced 8-isoprostanes. In a human single dose supplementation clinical study with vitamin C, vitamin E, and grape seed and green tea extracts (on separate days) 8-isoprostane formation was also significantly reduced compared to no supplementation (74.2 to 53.8+/-5.1 pg/ml for vitamin C). CONCLUSIONS: The reduction in 8-isoprostane formation demonstrates that the total amount of antioxidant protection in the plasma can be increased with supplementation of antioxidants and this new method can effectively measure the plasma antioxidant reserve (PAR) in healthy subjects.

Antioxidants↗
PubMed2004

Sonochemical decomposition of natural polyphenolic compound (condensed tannin).

Sonochemical treatment of grape condensed tannin was studied with the aim to destroy phenolic constituents, using ultrasonic frequency of 20 kHz in the presence and in the absence of hydrogen peroxide (H2O2), as an oxidative agent. Various pH, H2O2 concentration and temperature combinations were used in order to investigate the role of these parameters in the studied process. In order to estimate the effect of ultrasound, similar experiments were conducted in terms of pH, H2O2 concentration and temperature conditions, but without sonication. In all cases the presence of H2O2 was resulted in considerably higher removal of total phenolics (TP). It was observed that pH and temperature present also a significant effect on TP removal in the presence of H2O2, both with and without sonication. Under similar experimental conditions higher reaction rates, concerning TP removal, were obtained in the presence of ultrasonic irradiation, than in its absence.

Hydrogen Peroxide↗
PubMed2005

Leaching of oryzalin and diuron through undisturbed vineyard soil columns under outdoor conditions.

Field studies monitoring herbicide pollution in the vineyards of Burgundy (France) have revealed that drinking water reservoirs are contaminated with several pre-emergence herbicides. An assessment of the leaching of two such herbicides, diuron and oryzalin, was therefore performed using lysimeters, under outdoor conditions, from May 2001 to May 2002. Four vineyard soils from Vosne-Romanée (Burgundy) were chosen along a topolithosequence: a rendosol and three calcosols. After 673 mm of rainfall, greater amounts of diuron than oryzalin were measured in percolates: respectively 0.10-0.84% and 0.02-0.43% of applied herbicide, depending on soils. Measurements for diuron metabolites detected greater amounts of DCPMU than DCPU in the percolates: respectively 0.05-0.13% and 0-0.04% of the applied diuron. At the end of the monitoring period, more residues of diuron than oryzalin were recovered in the soil profiles: respectively 4.6-9% and 1.4-4.4%. The oryzalin residues were found mainly in the upper 10 cm of soil columns, whereas diuron residues were present in the whole core. The mobility of both oryzalin and diuron seems fairly well-related to soil organic carbon content; the mobility of diuron is also related to soil texture (sand and coarse material contents). Under such experimental conditions, this study confirms that diuron leaching, and therefore potential groundwater contamination, is greater than that of oryzalin.

Agriculture↗
PubMed2003

Supercritical fluid extraction of grape seed oil and subsequent separation of free fatty acids by high-speed counter-current chromatography.

Supercritical fluid extraction (SFE) of grape seed oil was performed to study the effect of various parameters such as pressure, temperature and the particle size of the sample on the yield and composition of oil using an analytical-scale SFE system. Then the extraction was scaled up by 125 times using a preparative SFE system under the optimized conditions of high pressure (30-40 MPa) and low temperature (35-40 degrees C) with medium particle size (20-40 mesh). The maximum yield of the oil can reach 6.2% with pure supercritical CO2 and 4.0% more oil can be obtained by adding 10% of ethanol as modifier. The unsaturated fatty acids (UFSs) make up about 70% in the oil on the basis of free fatty acids. The grape seed oil was then subjected to separation and purification for free fatty acids after saponification by high-speed counter-current chromatography coupled with evaporative light scattering detection (ELSD). The separation of 1.0 g of oil can yield about 430 mg pure linoleic acid at 99% purity. The fatty acids were analyzed by HPLC-ELSD.

Chromatography, High Pressure Liquid↗
PubMed2004

Determination of catechins by means of extraction with pressurized liquids.

The technique of extraction with pressurized liquids is applied for extraction of catechin and epicatechin in tea leaves and in grape seeds. The extracts obtained are then analyzed by HPLC. A comparison has been made of the recoveries obtained employing extraction by magnetic stirring, ultrasound-assisted extraction, and extraction with pressurized liquids. In the three extraction systems, four different pure solvents were utilized, namely water, methanol, ethanol, and ethyl acetate. Methanol produced the best results. For this comparison, an initial step was to check the stability of catechins during the process of extraction using pressurized liquids at high temperature (100-200 degrees C). It has been confirmed that recoveries of these two compounds begin to fall, to below 95%, at 130 degrees C and above. Pressurized liquid extraction using methanol as solvent, produces results, in terms of recovery of catechin and of epicatechin, notably higher than any of the other conditions of extraction tested. The duration of the extraction cycle was also evaluated and re-extractions were performed to ensure the full recovery from the samples. It was found that, forcatechin, the R.S.D. of the method is 3.21%, and for epicatechin the R.S.D. was 2.96% (n = 5). The final optimized pressurized liquid extraction method allows for the determination of catechin and epicatechin in diverse types of samples with a rapid (10 min) and reproducible method.

Catechin↗
PubMed2004

New materials for solid-phase extraction and multiclass high-performance liquid chromatographic analysis of pesticides in grapes.

Sample preparation procedures which included the use of new aminopropyl (NH2) and octadecyl (C18) solid-phase extraction (SPE) sorbents are proposed for the simultaneous multiclass determination of the fungicide benomyl and of the herbicides tebuthiuron, diuron, simazine, atrazine, and ametryn in grapes, using single wavelength high-performance liquid chromatography. Sorbent preparation uses a fast, easy, and effective procedure to obtain silica-based materials, made by depositing polysiloxanes on a silica support followed by thermal immobilization. Recovery results of the compounds, after elution from the SPE cartridges, indicate that the most efficient system employed silica loaded with 40% of an aminofunctional polydimethylsiloxane as sorbent, using dichloromethane:methanol (95:5, v/v) as eluent. Method validation, carried out in agreement with International Conference on Harmonization directives, was performed at three fortification levels (100, 200, and 1000 microg kg(-1)). Limits of detection and quantification show that the method developed can be used to detect the pesticides at concentrations below the maximum residue levels established by Codex Alimentarius, the US Environmental Protection Agency, the European Union, and Brazilian legislation.

Chromatography, High Pressure Liquid↗
PubMed2004

Evaluation of solid-phase extraction and stir-bar sorptive extraction for the determination of fungicide residues at low-microg kg(-1) levels in grapes by liquid chromatography-mass spectrometry.

A liquid chromatography-mass spectrometry method has been developed for determining bitertanol, carboxin, flutriafol, pyrimethanil, tebuconazole and triadimefon. The evaluation of both atmospheric pressure interfaces (API), atmospheric pressure chemical ionization (APCI) and electrospray (ESI) using positive and negative ionization modes, clearly shows that the studied pesticides are more sensitive using APCI in positive mode. Two procedures based on solid-phase extraction (SPE) and stir-bar sorptive extraction (SBSE) have been assessed for extracting these compounds in grape. The recoveries obtained by SPE in samples spiked at the limit of quantification (LOQ) level ranged from 60 to 100% with relative standard deviation (R.S.D.s) from 7 to 17%. With the SBSE the recoveries obtained from samples spiked at LOQ level were between 15 and 100% and the R.S.D.s between 10 and 19%. The LOQs of most compounds are better by SPE (0.003-0.01 mg kg(-1)) than by SBSE (0.01 mg kg(-1) for all fungicides). Although SPE provided higher recoveries, lower R.S.D.s, best LOQs and is more rapid to carry out compared with SBSE, this last one has some advantages such as lower organic solvent consumption, and cleaner extracts. Results obtained applying both techniques to real samples are analogous.

Adsorption↗
PubMed2005

Analysis of trans-resveratrol by laser ionization mass spectrometry and HPLC with fluorescence detection. Comparison between both techniques.

A comparison between two analytical techniques is presented using trans-resveratrol as analyte and vine leaf as sample. The employed methods were: (a) laser desorption followed by resonance enhanced multiphoton ionization coupled with time-of-flight mass spectrometry (LD-REMPI-TOFMS), and (b) reversed-phase high performance liquid chromatography (RP-HPLC) with fluorescence detection. While both techniques show a similar range of linearity and reproducibility, marked differences were found in their sensitivity and required time for a single analysis. For example: (i) the chromatographic method required considerable less time (30min) than the REMPI method to implement the analysis, (ii) the detection and quantification limits of the REMPI technique were 2.1 and 6.7 microg L(-1), respectively, while for the chromatographic method they were ten times minor, i.e. 20 and 67 microg L(-1), respectively. A critical assessment including advantages and drawbacks of each technique is presented.

Chromatography, High Pressure Liquid↗
PubMed2005

Autoanalyzer for continuous fractionation and quantitation of the polyphenols content in wines.

A simple continuous flow autoanalyzer for the on-line fractionation of the polyphenols content in wines is proposed. The target compounds are isolated from the matrix by solid-phase extraction on an RP-C18 sorbent column, using selective solvents for the sequential elution of each polyphenol family. Moreover, evaporative light scattering detection (ELSD) is used for the first time for the on-line monitorization of the three polyphenol fractions present in the wine samples. Thus, a single sample injection is required to determine the global concentration of the three selected polyphenol fractions and the whole analysis is completed within a few minutes. Three calibration graphs were constructed for quantitative analysis of the global compounds concentration in every fraction and covered the range 5-300 mg l(-1) (expressed as gallic acid). Average repeatability, expressed as relative standard deviation, was 4%. The proposed autonalyzer was applied to the analysis of a variety of commercial wine samples. The results obtained were compared with those provided by the Folin-Ciocalteau method, being similar in all instances.

Anthocyanins↗
PubMed2005

Development of direct size-exclusion chromatography separation for the determination of molar mass of native procyanidins in the phenolate form.

A size-exclusion chromatographic method using an aqueous solvent as eluent was developed for the determination of the molecular mass of procyanidins has been developed. Size-exclusion chromatography is a chromatographic technique used to determine molecular weight distribution of polymers. During the development work, PL aquagel-OH columns and several different eluent compositions were investigated. The best separation of procyanidins was obtained with an eluent consisting of water-methanol (50:50, v/v), NaNO3: 0.18 M, pH < pKa + 2. The results from this aqueous SEC method were compared with results obtained using SEC with organic solvents.

Calibration↗
PubMed2005

Varietal differences among the anthocyanin profiles of 50 red table grape cultivars studied by high performance liquid chromatography.

In order to develop a method that allows to distinguish between grape cultivars, the anthocyanin profiles of 50 accessions from the "Misión Biológica de Galicia" germplasm collection were studied by high performance liquid chromatography (HPLC). Nineteen anthocyanins were totally or partly identified and significant quantitative differences between the studied anthocyanin markers were found. With this method all 50 cultivars examinated could be easily distinguished from each other. In addition, the HPLC fingerprints and the relative-area anthocyanins plot for every cultivar has been elaborated and stored in a database. To test the validity of this method, several unknown samples have been analysed comparing their anthocyanin profile with the fingerprint database, and we may conclude that this has been proved to be of great value for grape cultivar recognition.

Anthocyanins↗