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Epicatechin

Distribution by Scientific Domains
Chemistry60%
Life Sciences23%
Medical Sciences16%
Distribution within Chemistry
General & Introductory Food Science & Technology38%
Organic Chemistry6%

Terms modified by Epicatechin

  • epicatechin gallate
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  • epicatechin unit
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    Selected Abstracts

    Synthesis of (,)-Epicatechin 3-(3- O -Methylgallate) and (+)-Catechin 3-(3- O -Methylgallate), and Their Anti-Inflammatory Activity

    CHEMISTRY & BIODIVERSITY, Issue 4 2009
    Takashi Iijima
    Abstract A concise synthesis of (,)-epicatechin 3-(3- O -methylgallate) (1; ECG3,Me), which is a minor constituent of tea, and (+)-catechin 3-(3- O -methylgallate) (2; CG3,Me) via condensation of equimolar amount of catechin and gallate derivatives has been achieved. The anti-inflammatory effect of the synthetic compounds on 12- O -tetradecanoylphorbol-13-acetate (TPA)-induced inflammation of mouse ears was examined. Compounds 1 and 2 suppressed the TPA-induced inflammation of mouse ears by 50 and 43%, respectively, at a dose of 200,,g. Their activities are stronger than those of indomethacin and glycyrrhetinic acid, the normally used anti-inflammatory agents. [source]

    Nonaqueous capillary electrophoretic separation of polyphenolic compounds in wine using coated capillaries at high pH in methanol

    ELECTROPHORESIS, Issue 24 2003
    Zuzana Demianová
    Abstract Nonaqueous capillary electrophoretic separation of a group of flavonoids (quercetin, myricetin, catechin, epicatechin) and resveratrol in wine was investigated in methanol at high pH. Malonate background electrolyte (pH* 13.5, ionic strength I = 14.2 mmol/L) provided highly repeatable separations of the analytes. Tests of untreated and coated (poly(glycidylmethacrylate- co - N -vinylpyrrolidone)) capillaries showed the analysis to be faster (6.5 min vs. 25 min) and the repeatability better in the coated capillaries. The coating procedure was simple and highly repeatable and the coating was stable during 40,45 runs. Determination of the last migrating peaks (epicatechin, resveratrol and catechin) was achieved merely by evaporating the wine samples and reconstituting the residue in methanol. For determination of the first migrating peaks (quercetin and myricetin) the samples were submitted to solid-phase extraction in C8 cartridges. [source]

    An Improved Synthesis of Procyanidin Dimers: Regio- and Stereocontrol of the Interflavan Bond

    EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2006
    Isabelle Tarascou
    Abstract A direct and general synthesis of procyanidin dimers B1, B2, B3 and B4 (10a,d) is presented. The approach is based on the stoichiometric coupling of two protected monomeric units (the nucleophilic 2a,b and electrophilic 4a,b partners) and deals with the regio- and stereocontrol of the C4,C8 interflavan bond as well as the control of the degree of oligomerization. The synthesis involves a five-step pathway starting from the native catechin (1a) or epicatechin (1b) to the fully deprotected dimers 10a,d. Furthermore, the process appears to be iterative as the coupling intermediates 9a,d themselves can be readily used in further selective syntheses of trimers or higher oligomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    The effect of nitrogen fertilization on fungistatic phenolic compounds in roots of beech (Fagus sylvatica) and Norway spruce (Picea abies)

    FOREST PATHOLOGY, Issue 4 2005
    L. Tomova
    Summary The effect of nitrogen fertilization on fungistatic phenolic compounds in fine roots of beech and Norway spruce growing in afforestation plots was analysed. The plots were situated at two sites in Switzerland on acidic soil with low base saturation. For 9 years, the trees have been treated with dry ammonium nitrate to give 0, 10, 20, 40, 80, 160 kg N ha,1 year,1, respectively. The phenolic compounds responded differently to fertilization. Fine roots of beech showed a significant decrease of (,)-epicatechin and piceatannol with increasing nitrogen fertilization. The concentration of protocatechuic acid was increased with fertilization. Roots of fertilized Norway spruce showed significantly decreased concentrations of 4-hydroxyacetophenone and piceatannol. The mycelial growth of three isolates each of Heterobasidion annosum s.l. and Cylindrocarpon destructans was tested on agar media containing various phenolic compounds in concentrations found in fine roots of Norway spruce (Picea abies) and beech (Fagus sylvatica). All three H. annosum isolates were inhibited by p-coumaric acid and (,)-epicatechin. Two isolates were inhibited by another four phenolic compounds (p-hydroxybenzoic acid, 4-hydroxyacetophenone, piceatannol and protocatechuic acid), one by (+)-catechin. Two of three C. destructans isolates were inhibited by all phenolic compounds except for (+)-catechin which affected only one isolate, one isolate did not respond at all. Résumé L'effet d'une fertilisation azotée sur les composés phénoliques fongistatiques des racines fines de Hêtre (Fagus sylvatica) et d'Epicea (Picea abies) a été analysé dans des parcelles de reboisement. Ces parcelles sont situées dans deux localités de Suisse sur sol acide, avec un faible taux de saturation en bases. Pendant neuf ans, les arbres ont été traités par apports secs de nitrate d'ammonium à raison de 0, 10, 20, 40, 80, 160 kg N par hectare et par an, respectivement. La réponse des composés phénoliques à la fertilisation est variable. Les racines fines de hêtres ont montré une baisse significative d'épicatèchine (,) et de piceatannol avec l'augmentation de la fertilisation azotée. Les concentrations d'acide protocatéchique ont augmenté avec la fertilisation. Les racines d'épicèas fertilisés ont montré une baisse significative des concentrations de 4-hydroxyacétophénone et de piceatannol. La croissance mycélienne de trois isolats de chacune des espèces H .annosum s.l. et Cylindrocarpon destructans a été testée sur milieu agar contenant les différents composés phénoliques aux concentrations trouvées dans les racines fines d'épicèas (Picea abies) et de hêtres (Fagus sylvatica). Les trois isolats d'Heterobasidion annosum s.l. ont été inhibés par l'acide p-coumarique et l'épicatèchine (,). Deux isolats ont été inhibés par quatre autres composés phénoliques (acide p-hydroxybenzoïque, 4-hydroxyacétophénone, piceatannol et acide protocatéchique) et un par la catéchine (+). Deux des trois isolats de Cylindrocarpon destructans ont été inhibés par tous les composés phénoliques à l'exception de la catéchine (+) pour l'un des deux, le dernier isolat ne répondant à aucun composé. Zusammenfassung In einer Aufforstungs-Versuchsfläche wurde der Einfluss einer Stickstoffdüngung auf die fungistatischen phenolischen Verbindungen in Feinwurzeln von jungen Buchen und Fichten untersucht. Die Versuchsflächen befanden sich an zwei Standorten in der Schweiz mit sauren, basenarmen Bodenverhältnissen. Die Bäume wurden über neun Jahre mit 0, 10, 20, 40, 80 und 160 kg N ha,1 a,1 in Form von Ammoniumnitrat gedüngt. Die phenolischen Verbindungen reagierten unterschiedlich auf die Düngung. Die Feinwurzeln von Buchen zeigten mit zunehmender Stickstoffdüngung eine signifikante Abnahme von (,) Epicatechin und Piceatannol, während die Konzentration von Protocatechinsäure durch die Düngung erhöht wurde. Die Feinwurzeln gedüngter Fichten wiesen ebenfalls signifikant tiefere Konzentrationen von 4-Hydroyacetophenon und Piceatannol auf. In in-vitro-Tests wurde das Myzelwachstum von allen drei geprüften Isolaten von Heterobasidion annosum s. l. durch die in den Wurzeln gefundenen Konzentrationen von p-Coumarinsäure und (,)Epicatechin gehemmt. Zwei Pilzisolate zeigten zudem eine Hemmung durch vier weitere in den Wurzeln gefundene phenolische Verbindungen, nämlich p-Hydroxybenzoesäure, 4-Hydroxyacetophenon, Piceatannol und Protocatechinsäure, und eines wurde auch durch (+)-Catechin gehemmt. Bei zwei von drei geprüften Isolaten von Cylindrocarpon destructans wurde das Myzelwachstum durch alle untersuchten phenolischen Verbindungen gehemmt, mit Ausnahme von (+)-Catechin, welches sich nur auf ein Isolat negativ auswirkte. Ein Isolat von C. destructans reagierte auf keine der genannten Substanzen. [source]

    The chain-breaking antioxidant activity of phenolic compounds with different numbers of O-H groups as determined during the oxidation of styrene

    INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 2 2009
    Ivan Tikhonov
    The technique based on monitoring oxygen consumption was applied to test 18 polyphenols (PP) and model phenolics as a chain-breaking antioxidant during the oxidation of styrene initiated by 2,2,-azobis(2,4-dimethylvaleronitril) at 37°C. The chain-breaking capability of PP was characterized by two parameters: the rate constant k1 for the reaction of antioxidants with the peroxy radical produced from styrene and the stoichiometric coefficient of inhibition, f, which shows how many kinetic chains are terminated by one molecule of PP. Rate constants k1 × 105 (in M,1 s,1) were found to be 10 (catechol), 27 (pyrogallol), 34 (3,6-di-tert-Bu-catechol), 4.3 (protocatechic acid), 12 (gallic acid), 15 (caffeic acid), <0.01 (chrysin), 1.3 (kaempferol), 19 (quercetin), 5.3 (baicalein), 16 (epicatechin), 32 (epigallocatechin), 9.0 (dihydroquercetin), 3.3 (resveratrol), and 16 (nordihydroguaiaretic acid). The value of k1 increases when going from one to two and three adjacent O-H groups in a benzene ring (catechol and pyrogallol derivatives, respectively). At the same time, two O-H groups in metaposition in a A-ring of flavonoids actually do not participate in the inhibition. For the majority of PP, f is near to 2 independent of the number of OH groups. The correlation of k1 with the structure of PP and the OH bond dissociation enthalpy has been discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 92,100, 2009 [source]

    A simple and rapid turbidimetric method for determining catechins in beverages

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 10 2010
    Motokazu Nakayama
    Summary We have developed a simple and rapid turbidimetric method to determine catechins based on the fact that many polyphenols produce hydrogen peroxide in an alkaline environment and that hydrogen peroxide oxidises cerium to generate cerium oxide precipitates. Four catechins (epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate) aggregated with these precipitates to form massive precipitates with increased turbidity. The catechins solution (0.18 mL) was mixed with 0.02 mL of 1% CeCl3 solution, and absorbance (650 nm) was measured immediately after agitation for 3 min using a spectrophotometer. Absorbance was strongly correlated (0.99) with the concentration of each catechin compound. For commercially bottled green tea, the estimated catechin content determined using this turbidimetric method showed better correlation with the content determined by high-performance liquid chromatography than that determined using ferrous tartrate method, which is the official Japanese method for determining the tannin content of green tea. [source]

    Polyphenolic profile and antioxidant activity of five apple cultivars grown under organic and conventional agricultural practices

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2009
    Athanasios Valavanidis
    Summary The polyphenols and total antioxidant activities of five apple cultivars, grown by organic and conventional agricultural methods in neighbouring farms, were determined and compared. Total polyphenols in the whole fruit and in the peel were determined by the Folin-Ciocalteu method, and the total antioxidant activity was determined by three established methods, diphenyl picrylhydrazyl (DPPH), azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and ferric reducing/antioxidant power (FRAP). Polyphenolic content for the whole fruit was in the range of 80,196 and for the peel 165,400 (mg Gallic Acid Equivalent (GAE)/100 g fresh weight) for both types of agricultural practices. Antioxidant activities of fruit extracts were also relatively similar and well correlated to their polyphenolic content. High-performance liquid chromatography (HPLC) analysis of the most important polyphenolics (chlorogenic acid, catechin, epicatechin, procyanidin B1 and B2, cyaniding 3-galactoside, phloridzin, quercetin 3-galactoside and quercetin 3-arabinoside) also showed that concentrations do not differentiate significantly between the organic and conventional apples. Statistical significance of differences in antioxidant activities among the same cultivars was relatively small (flesh + peel or peel only) for both types of apples. These results indicate that organic apples do not present higher antioxidant or nutritional value compared with conventionally grown ones, as far as polyphenolic content and total antioxidant activities are concerned. [source]

    APPLICATION OF ULTRASONICATION OR HIGH-PRESSURE EXTRACTION OF FLAVONOIDS FROM LITCHI FRUIT PERICARP

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2009
    K. NAGENDRA PRASAD
    ABSTRACT Litchi (Litchi chinensis Sonn.) fruit pericarp (LFP) contains a high amount of flavonoids, which could be used as natural antioxidants. Some emerging novel technologies, such as ultrasonic extraction (UE) and high-pressure extraction (HPE), have exhibited great potential for flavonoid extraction. Experiments were conducted to comparatively investigate the effects of conventional extraction (CE), 40-KHz UE and 200- or 400-MPa HPE on the extraction efficiency of flavonoids from LFP. After 30 min of extraction, the extract yield, total phenolic content, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide anion scavenging ability were examined. The crude extract yields by the UE, 400 HPE and CE were 24, 30 and 1.83%, respectively. However, there were no significant differences (P > 0.05) in the total phenolic content and antioxidant activity tested among these three different extractions at the same concentration. In addition, two flavonoids, namely epicatechin and epicatechin gallate, were identified and quantified as the major compounds, while catechin and procyanidin B2 were identified as the minor compounds. The total flavonoid content detected was 0.65, 0.75, 0.29 and 0.07 mg/g dry weight by HPE at 200 and 400 MPs, UE, and CE, respectively. Thus, the HPE technique showed a higher efficiency in extracting flavonoids from LFP, and the HPE could reduce the extraction time and increase the amount of the extracted phenolics. PRACTICAL APPLICATIONS Litchi (Litchi chinensis Sonn.) is a subtropical fruit that originated in Southeast Asia. As litchi fruit is gradually accepted by consumers for its delicious taste and attractive red skin, litchi production has steadily increased in recent decades, with increasing exports to Europe and North America from both the southern and northern hemisphere production areas. Litchi fruit pericarp (LFP) accounts for approximately 16% by weight of the whole fresh fruit and is comprised of a significant amount of flavonoids. Therefore, LFP tissues may be considered an important source of dietary flavonoids. This work showed that HPE technique has a high efficiency in extracting flavonoids from LFP tissues, which may help the litchi industry develop new extraction methods to better utilize the flavonoids from LFP tissues. [source]

    Physicochemical, Nutritional, and Functional Characterization of Fruits Xoconostle (Opuntia matudae) Pears from Central-México Region

    JOURNAL OF FOOD SCIENCE, Issue 6 2010
    Salvador H. Guzmán-Maldonado
    Abstract:, Xoconostle cv. Cuaresmeño (Opuntia matudae) has attracted domestic and international industry attention; however, variations of composition from xoconostle structures have not been evaluated. Industries discard the pulp (endocarp) and peel (pericarp) as wastes and utilize the skin (mesocarp), which is the edible portion. The physicochemical, nutritional, and functional characterization of structures from xoconostle pear from 3 major sites of production in Mexico were assessed. Skin yield ranged from 58% to 64% and was higher to that of peel (22% to 24%) and pulp (12% to 18%) yields. pH, °Brix, and acidity were similar among xoconostle structures. Total fiber showed by peel (18.23% to 20.37%) was 2-fold higher than that of skin. Protein and ether extract were higher in xoconostle pulp compared to that showed by peel and skin. Iron content of xoconostle peel (6 to 9.6 mg/100 g, DWB) was higher to that of skin and pulp and prickly pear pulp. Soluble phenols of peel (840 to 863 mg GAE/100 g, DWB) were almost similar to that of skin (919 to 986 mg GAE/100 g, dry weigh basis); meanwhile, ascorbic acid concentration of skin was 2-fold higher compared to that of peel. The phenolic fraction of xoconostle structures consisted of gallic, vanillic, and 4-hydroxybenzoic acids; catechin, epicatechin, and vanillin were also identified by high-performance liquid chromatography,didoe array detection (HPLC-DAD). Xoconostle peel showed higher antioxidant activity (TEAC) compared to that of skin (2-fold) and pulp (6-fold) of commonly consumed fruits and vegetables. The potential of xoconostle peel and pulp for the production of feed or food is promissory. Practical Application:, Outstanding nutritional and functional properties of xoconostle cv. Cuaresmeño fruits are demonstrated. Increased consumption could contribute positively to improve the diet of rural and urban consumers. The high fiber, mineral, and antioxidant components of xoconostle peel and pulp suggest that these fruit structures, which are currently discarded as waste, have promissory use as feed or food by industry. [source]

    Inhibitory Effect of Morinda Citrifolia L. on Lipoprotein Lipase Activity

    JOURNAL OF FOOD SCIENCE, Issue 8 2008
    M.S. Pak-Dek
    ABSTRACT:, Efficacy of Morinda citrifolia L. leaf (MLE) and fruit extracts (MFE) in inhibiting lipoprotein lipase (LPL) was determined in vitro. The result of the study showed that the highest inhibition on the LPL activity was exhibited by MLE (66%± 2.1%), which is significantly higher than that demonstrated by MFE (54.5%± 2.5%), green tea extract (GTE) (54.5%± 2.6%), and catechin (43.6%± 6.1%). Percent of LPL inhibition increase with concentration of the extracts. Quantitative analysis of the extracts revealed the presence of high levels of (+),catechin at 63.5 ± 17 and 53.7 ± 5.7 mg/g in MLE and MFE, respectively, although not as high as that found in GTE (530.6 ± 42 mg/g). Appreciable amount of epicatechin was found in all extracts tested, while rutin was only found in MLE and MFE. The study suggested that both leaf and fruit of M. citrifolia may be used as antiobesity agents in body weight management. [source]

    Radical Scavenging Activity and Phenolic Compounds in Persimmon (Diospyros kaki L. cv. Mopan)

    JOURNAL OF FOOD SCIENCE, Issue 1 2008
    X.N. Chen
    ABSTRACT:, The Mopan persimmon (Diospyros kaki L. cv. Mopan) is the major cultivar of astringent persimmon in northern China. This study investigates the radical scavenging activity against ABTS and DPPH radical, and the content of total and individual phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) with apple, grape, and tomato as controls. The radical scavenging activities against ABTS and DPPH radicals of the Mopan persimmon are 23.575 and 22.597 ,m trolox eq/g f.w., respectively. These findings suggest that the Mopan persimmon's antioxidant activity is significantly (P < 0.05) stronger than that of reference materials. The Mopan persimmon showed the highest content of total phenolics among the 4 materials tested. Significant correlations (R2= 0.993, P < 0.05, ABTS radical; R2= 0.980, P < 0.05, DPPH radical) are found between the total phenolics and the radical scavenging activities. The total content of these 6 kinds of phenolics (catechin, epicatechin, epigallocatechin, chlorogenic acid, caffeic acid, and gallic acid) is significantly correlated (R2= 0.831, P < 0.05, ABTS radical; R2= 0.745, P < 0.05, DPPH radical) with the individual radical scavenging activity of the 4 materials, although the total content of the 6 phenolics accounts for no more than 20% of the total phenolics in the Mopan persimmon. Gallic acid exhibits the strongest antioxidant activity in all 6 kinds of phenolics and its content is the largest in the Mopan persimmon, presumably being responsible for its much higher antioxidant activity as compared to apple, grape, and tomato. [source]

    HPLC Analysis of Catechins, Theaflavins, and Alkaloids in Commercial Teas and Green Tea Dietary Supplements: Comparison of Water and 80% Ethanol/Water Extracts

    JOURNAL OF FOOD SCIENCE, Issue 6 2006
    Mendel Friedman
    ABSTRACT:, To help meet the needs of consumers, producers of dietary tea supplements, and researchers for information on health-promoting tea compounds, we compared the following conditions for the extraction of tea leaves and green tea-containing dietary supplements: 80% ethanol/water at 60 °C for 15 min and boiled water for 5 min. The following 7 catechins, 4 theaflavins, and 3 alkaloids were separated in a 70-min single HPLC analysis: (,)-epigallocatechin, (,)-catechin, (+)-epicatechin, (,)-epigallocatechin-3-gallate, (,),gallocatechin-3-gallate, (,)-epicatechin-3-gallate, (,)-catechin-3-gallate, theaflavin, theaflavin-3-gallate, theaflavin-3,-gallate, theaflavin-3,3,-digallate, caffeine, theobromine, and theophylline. The following ranges of concentrations of flavonoids (catechins plus theaflavins) in the tea leaves extracted with 80% ethanol were observed (in mg/g): in 32 black teas, 19.8 to 115.1; in 24 green teas, 12.3 to 136.3; in 14 specialty teas, 4.9 to 118.5; in 7 herbal teas, 0 to 46.0. Total alkaloids in all teas ranged from 0 to 32.6 mg/g. Significantly greater amounts of flavonoids were extracted from the tea leaves with aqueous ethanol than with boiled water. Levels of tea catechins in 10 capsules sold as dietary supplements were about 50 to 75% lower than the amounts listed on the labels. Catechin content of 4 commercial green tea extracts ranged from 96 to 696 mg/g. The results make it possible to maximize the extraction of tea compounds to better relate the flavonoid and alkaloid content of teas and dietary tea supplements to their health-promoting effects. [source]

    Polyphenol Oxidase from Apple (Malus domestica Borkh. cv Bramley's Seedling): Purification Strategies and Characterization

    JOURNAL OF FOOD SCIENCE, Issue 1 2006
    Deirdre M. Ni Eidhin
    ABSTRACT Polyphenol oxidase (PPO) was isolated from Bramley's Seedling apples with 75.7-fold purification and 26.5% recovery by ammonium sulfate precipitation, phenyl sepharose chromatography, ion exchange chromatography, and hydroxyapatite chromatography. Molecular weight was estimated to be about 45 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS PAGE). Optimum PPO activity was at pH 6.5 and greater than 50% activity was retained during storage for 72 h at pH 5.5 to 6.5. Optimum temperature for activity was 30 °C and the enzyme had residual activity of greater than 50% during storage for 72 h at 20 °C to 30 °C and for 24 h at 40 °C to 50 °C. Of the substrates tested, activity was greatest with 4-methylcatechol followed by catechol, pyrogallol, and (,)epicatechin. The most effective inhibitors tested were sodium metabisulfite and ascorbic acid. [source]

    A novel approach to enhancing cellular glutathione levels

    JOURNAL OF NEUROCHEMISTRY, Issue 3 2008
    Pamela Maher
    Abstract GSH and GSH-associated metabolism provide the major line of defense for the protection of cells from oxidative and other forms of toxic stress. Of the three amino acids that comprise GSH, cysteine is limiting for GSH synthesis. As extracellularly cysteine is readily oxidized to form cystine, cystine transport mechanisms are essential to provide cells with cysteine. Cystine uptake is mediated by system xc,, a Na+ -independent cystine/glutamate antiporter. Inhibition of system xc, by millimolar concentrations of glutamate, a pathway termed oxidative glutamate toxicity, results in GSH depletion and nerve cell death. Recently, we described a series of compounds derived from the conjugation of epicatechin (EC) with cysteine and cysteine derivatives that protected nerve cells in culture from oxidative glutamate toxicity by maintaining GSH levels. In this study, we characterize an additional EC conjugate, cysteamine-EC, that is 5- to 10-fold more potent than the earlier conjugates. In addition, we show that these EC conjugates maintain GSH levels by enhancing the uptake of cystine into cells through induction of a disulfide exchange reaction, thereby uncoupling the uptake from system xc,. Thus, these novel EC conjugates have the potential to enhance GSH synthesis under a wide variety of forms of toxic stress. [source]

    Potent anti-amyloidogenic and fibril-destabilizing effects of polyphenols in vitro: implications for the prevention and therapeutics of Alzheimer's disease

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2003
    Kenjiro Ono
    Abstract Cerebral deposition of amyloid ,-peptide (A,) in the brain is an invariant feature of Alzheimer's disease (AD). A consistent protective effect of wine consumption on AD has been documented by epidemiological studies. In the present study, we used fluorescence spectroscopy with thioflavin T and electron microscopy to examine the effects of wine-related polyphenols (myricetin, morin, quercetin, kaempferol (+)-catechin and (,)-epicatechin) on the formation, extension, and destabilization of ,-amyloid fibrils (fA,) at pH 7.5 at 37°C in vitro. All examined polyphenols dose-dependently inhibited formation of fA, from fresh A,(1,40) and A,(1,42), as well as their extension. Moreover, these polyphenols dose-dependently destabilized preformed fA,s. The overall activity of the molecules examined was in the order of: myricetin = morin = quercetin > kaempferol > (+)-catechin = (,)-epicatechin. The effective concentrations (EC50) of myricetin, morin and quercetin for the formation, extension and destabilization of fA,s were in the order of 0.1,1 µm. In cell culture experiments, myricetin-treated fA, were suggested to be less toxic than intact fA,, as demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Although the mechanisms by which these polyphenols inhibit fA, formation from A,, and destabilize pre-formed fA,in vitro are still unclear, polyphenols could be a key molecule for the development of preventives and therapeutics for AD. [source]

    Interaction between flavonoids and the blood,brain barrier: in vitro studies

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2003
    Kuresh A. Youdim
    Abstract There is considerable current interest in the neuroprotective effects of flavonoids. This study focuses on the potential for dietary flavonoids, and their known physiologically relevant metabolites, to enter the brain endothelium and cross the blood,brain barrier (BBB) using well-established in vitro models (brain endothelial cell lines and ECV304 monolayers co-cultured with C6 glioma cells). We report that the citrus flavonoids, hesperetin, naringenin and their relevant in vivo metabolites, as well as the dietary anthocyanins and in vivo forms, cyanidin-3-rutinoside and pelargonidin-3-glucoside, are taken up by two brain endothelial cell lines from mouse (b.END5) and rat (RBE4). In both cell types, uptake of hesperetin and naringenin was greatest, increasing significantly with time and as a function of concentration. In support of these observations we report for the first time high apparent permeability (Papp) of the citrus flavonoids, hesperetin and naringenin, across the in vitro BBB model (apical to basolateral) relative to their more polar glucuronidated conjugates, as well as those of epicatechin and its in vivo metabolites, the dietary anthocyanins and to specific phenolic acids derived from colonic biotransformation of flavonoids. The results demonstrate that flavonoids and some metabolites are able to traverse the BBB, and that the potential for permeation is consistent with compound lipophilicity. [source]

    Coumarins and phenolic fingerprints of oak and Brazilian woods extracted by sugarcane spirit

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 21 2009
    Alexandre Ataide da Silva
    Abstract A total of 25 sugarcane spirit extracts of six different Brazilian woods and oak, commonly used by cooperage industries for aging cachaça, were analyzed for the presence of 14 phenolic compounds (ellagic acid, gallic acid, vanillin, syringaldehyde, synapaldehyde, coniferaldehyde, vanillic acid, syringic acid, quercetin, trans -resveratrol, catechin, epicatechin, eugenol, and myricetin) and two coumarins (scopoletin and coumarin) by HPLC-DAD-fluorescence and HPLC-ESI-MSn. Furthermore, an HPLC-DAD chromatographic fingerprint was build-up using chemometric analysis based on the chromatographic elution profiles of the extracts monitored at 280,nm. Major components identified and quantified in Brazilian wood extracts were coumarin, ellagic acid, and catechin, whereas oak extracts shown a major contribution of catechin, vanillic acid, and syringaldehyde. The main difference observed among oak and Brazilian woods remains in the concentration of coumarin, catechin, syringaldehyde, and coniferaldehyde. The chemometric analysis of the quantitative profile of the 14 phenolic compounds and two coumarins in the wood extracts provides a differentiation between the Brazilian wood and oak extracts. The chromatographic fingerprint treated by multivariate analysis revealed significant differences among Brazilian woods themselves and oak, clearly defining six groups of wood extracts: (i) oak extracts, (ii) jatobá extracts, (iii) cabreúva-parda extracts, (iv) amendoim extracts, (v) canela-sassafrás extracts and (vi) pequi extracts. [source]

    Quantification of polyphenols with potential antioxidant properties in wines using reverse phase HPLC

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 12 2008
    Neuza Paixão
    Abstract A RP-HPLC method with photodiode array detection (DAD) was developed to separate, identify and quantify simultaneously the most representative phenolic compounds present in Madeira and Canary Islands wines. The optimized chromatographic method was carefully validated in terms of linearity, precision, accuracy and sensitivity. A high repeatability and a good stability of phenolics retention times (< 3%) were obtained, as well as relative peak area. Also high recoveries were achieved, over 80.3%. Polyphenols calibration curves showed a good linearity (r2 >0.994) within test ranges. Detection limits ranged between 0.03 and 11.5 ,g/mL for the different polyphenols. A good repeatability was obtained, with intra-day variations less than 7.9%. The described method was successfully applied to quantify several polyphenols in 26 samples of different kinds of wine (red, rosé and white wines) from Madeira and Canary Islands. Gallic acid was by far the most predominant acid. It represents more than 65% of all phenolics, followed by p -coumaric and caffeic acids. The major flavonoid found in Madeira wines was trans -resveratrol. In some wines, (,)-epicatechin was also found in highest amount. Canary wines were shown to be rich in gallic, caffeic and p -coumaric acids and quercetin. [source]

    Determination of some hydroxybenzoic acids and catechins in white wine samples by liquid chromatography with luminescence detection

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006
    Rafael Carlos Rodríguez-Díaz
    Abstract A liquid chromatographic method with luminescence detection for the determination of eight phenolic compounds is reported. The method involves postcolumn derivatization with terbium(III). This derivatization is based on the reaction between phenolics and terbium(III) to form luminescent chelates, which were determined at ,ex 295 and ,em 545 nm using the fluorescence mode. The long wavelength emission of lanthanide chelates can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Also, the chromatographic separation allows the individual determination of phenolics, which cannot be done using the direct measurement of the fluorescence of their corresponding terbium chelates. Dynamic ranges of the calibration graphs and detection limits, obtained with standard solutions of analytes were (,g/mL): gallic acid (0.9,40, 0.3), protocatechuic acid (0.05,7, 0.016), catechin (0.2,40, 0.07), vanillic acid (0.25,40, 0.08), p -hydroxybenzoic acid (0.8,40, 0.25), syringic acid (0.17,40, 0.05), epicatechin (0.3,40, 0.09) and salicylic acid (0.07,12, 0.02). The precision was established at two concentration levels of each analyte and expressed as the percentage of RSD with values ranging between 1.0 and 6.5%. The practical usefulness of the method was demonstrated by the analysis of white wine samples, which were diluted two-fold and directly injected into the chromatographic system. The recovery values obtained ranged between 93.3 and 108.0%. [source]

    Polyphenolics Increase t-PA and u-PA Gene Transcription in Cultured Human Endothelial Cells

    ALCOHOLISM, Issue 2 2001
    Laila H. Abou-Agag
    Background: Moderate red wine consumption has been associated with a reduced risk for coronary heart disease, and this cardioprotection may be mediated, in part, by promoting fibrinolysis. This protection may be attributed to the combined or perhaps synergistic effects of alcohol and other red wine components (i.e., polyphenolics). These studies were carried out to determine whether individual phenolics (i.e., catechin, epicatechin, quercetin, and resveratrol) affect fibrinolytic protein (tissue-type plasminogen activator [t-PA] and urokinase-type PA [u-PA]) e-pression and surface-localized fibrinolytic activity in cultured human umbilical vein endothelial cells (HUVECs). Methods: Cultured HUVECs were preincubated (1 hr, 37°C) in the absence or presence of varying concentrations of catechin, epicatechin, quercetin, and resveratrol (0.001,10 ,M) and then were washed and incubated for various times in the absence of phenolics. Secreted t-PA/u-PA antigen (24 hr, enzyme-linked immunoadsorbent assay) and mRNA [0,16 hr, reverse transcription-polymerase chain reaction(RT-PCR)] levels and fibrinolytic activity (direct activation of HUVEC-bound 125I-labeled glutamyl-plasminogen, quantitation of 125I-labeled M r 20 kDa plasmin light-chain) were measured. Transient transfections of cultured HUVECs were carried out with the pt-PA222/luc and pu-PA236/luc promoter constructs, by using lipofectamine. Results: Each of the phenolics similarly increased t-PA and u-PA antigen (2- to 3-fold) and mRNA (3- to 4-fold) levels, concomitant with an increase (2- to 3-fold) in sustained (24 hr), surface-localized fibrinolytic activity. Transcription inhibitor actinomycin D abolished the induction of t-PA and u-PA mRNA e-pression by these phenolics. Transfections with the pt-PA222/luc and pu-PA236/luc promoter constructs showed 2- to 3-fold and 2- to 4-fold increases in luciferase activity for t-PA and u-PA, respectively. Conclusions: These results demonstrate that each of these phenolics up-regulates both t-PA and u-PA gene transcription, which results in the sustained increased e-pression of surface-localized fibrinolytic activity in cultured HUVECs. Wine phenolics increase fibrinolytic activity, independent of ethanol, and it is likely that the overall cardioprotective benefits associated with moderate red wine consumption are attributable to the combined, additive, or perhaps synergistic effects of alcohol and other wine components. [source]

    Influence of branch bending on sugar, organic acid and phenolic content in fruits of ,Williams' pears (Pyrus communis L.)

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2006
    Mateja Colaric
    Abstract Selected sugars, organic acids and phenolic compounds were analysed in mature fruits of ,Williams' pears using high-performance liquid chromatography. Fruits were harvested from the branches of trees tested in three treatments: branches were bent in summer 2003 (1 September), in spring 2004 (15 May) and control (branches were not bent). Pears contained up to 73.54 g kg,1 fresh weight (FW) of fructose, 9.42 g kg,1 FW of glucose, 7.94 g kg,1 FW of sucrose and 24.59 g kg,1 FW of sorbitol. Major organic acids were (in order of descending quantity) citric, malic, shikimic and fumaric acid (up to 3.05 g kg,1 FW, 2.24 g kg,1 FW, 71.79 mg kg,1 FW and 0.49 mg kg,1 FW, respectively). Chlorogenic acid (280.86,357.34 mg kg,1 FW) was the predominant phenolic acid, followed in concentration (mg kg,1 FW) by syringic acid (95.46,131.32), epicatechin (46.55,83.09), catechin (25.67,44.81), vanillic acid (1.87,3.48), sinapic acid (0.83,1.72) and caffeic acid (0.72,1.04). Significant differences in content of fructose, sorbitol, total sugars, catechin, epicatechin, sinapic acid, syringic acid, and a sum of determined phenolic compounds were observed among the treatments. Fruits from summer bending branches had the lowest content of individual sugars, citric acid and phenolic compounds and the highest content of malic, shikimic and fumaric acid. The highest content of fructose, sorbitol, sucrose, total sugars, caffeic acid, catechin, epicatechin and syringic acid were determined in the fruits from the spring treatment. In the control treatment the highest content of glucose, citric acid, chlorogenic acid, sinapic acid, vanillic acid, as well a sum of determined phenolics, were observed. The lowest content of fumaric acid was in the spring treatment and of malic and shikimic acid in the control. Copyright © 2006 Society of Chemical Industry [source]

    Phenolic compounds in some apple (Malus domestica Borkh) cultivars of organic and integrated production

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2005
    Robert Veberic
    Abstract Eleven organically grown apple cultivars and 11 apple cultivars of integrated production from Austria and Slovenia were analyzed by HPLC for the content of phenolic compounds in peel and pulp. We identified chlorogenic acid, p -coumaric acid, procyanidin B3, protocatechuic acid, (,)-epicatechin, phloridzin, rutin and quercetin-3-rhamnoside in apple peel. In apple pulp, (+)-catechin was also identified in all the cultivars. Some other phenols (procyanidin B3, rutin and quercetin-3-rhamnoside) could not be identified or were not properly separated. With regard to the phenolic content in the apple peel, there were no differences between organically grown apple cultivars and apple cultivars of integrated production. Organically grown apples, however, exhibited a higher content of phenolic substances in the apple pulp compared with the apple cultivars of integrated production. This may be due either to the different genotype source or to the growing technology. Higher concentrations of phenolic compounds in organically grown cultivars could be a result of plant response to stress. The apple peel contained higher concentrations of identified phenols than the pulp. The apple peel represents up to 10% of the whole fruit; therefore the phenolsic compounds in the pulp are of greater importance to the consumer than the phenolic compounds in the peel. Copyright © 2005 Society of Chemical Industry [source]

    Anti- Helicobacter pylori activity of Chinese tea: in vitro study

    ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2000
    Yuk-Kei Yee
    Background: Chinese tea has an antibacterial activity against a wide range of bacteria. However, its activity against Helicobacter pylori has not been reported. Method: In this study the anti- Helicobacter pylori effects of a Chinese tea (Lung Chen tea), and two tea catechins, epigallocatechin gallate and epicatechin and their minimum inhibitory concentrations (MICs) were examined. The effect of Lung Chen on metronidazole resistance was also studied using the E -test. Results: Lung Chen, epigallocatechin gallate and epicatechin all inhibited the growth of H. pylori. The MIC90 for Lung Chen was 0.25,0.5% (w/w) and that of epigallocatechin gallate and epicatechin were 50,100 and 800,1600 ,g/mL, respectively. Epigallocatechin gallate is probably the active ingredient responsible for most of the anti- H. pylori activity of Chinese tea. Lung Chen did not reverse metronidazole resistance. Conclusions: Chinese tea has anti- H. pylori activity in a daily consumed concentration, and epigallocatechin gallate is probably the active ingredient responsible for the action. [source]

    Modulation of oxidative cell damage by reconstituted mixtures of phenolic apple juice extracts in human colon cell lines

    MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 4-5 2006
    Sandra Schaefer
    Abstract Diets rich in fruits and vegetables are associated with a lower risk of tumour induction in the intestine and other sites. Apple juice with high amounts of antioxidative phenolics might protect the intestine against reactive oxygen species-mediated cell damage. We investigated to which extent the preventive effectiveness of polyphenolic juice extracts is governed by the amounts of five major constituents (rutin, phloridzin, chlorogenic acid, caffeic acid and epicatechin). In human colon cell lines (Caco-2, HT29), reconstituted mixtures of these phenolics were investigated in comparison to the original juice extracts, originating from cider and table apples. Parameters studied were (oxidative) DNA damage (Comet assay), cellular redox status (dichlorofluorescein assay) and Trolox equivalent antioxidant capacity (TEAC). The TEAC of the reconstituted mixtures was higher compared to the respective original extracts (4.7,7.3 mM vs. 3.6,4.2 mM Trolox). After 24 h cell incubation, menadione-induced (oxidative) DNA damage was more effectively reduced by the reconstituted mixtures (1,100 ,g/mL, 24 h), as compared to the original extracts. In contrast, the cellular ROS level was reduced to a rather similar extent by original extracts and reconstituted mixtures. The results lead to the conclusion that the selected constituents in their authentic proportions substantially account for the antioxidative effectiveness of phenolic apple juice extracts. [source]

    Applied environmental stresses to enhance the levels of polyphenolics in leaves of hawthorn plants

    PHYSIOLOGIA PLANTARUM, Issue 2 2004
    Ara Kirakosyan
    In this investigation, two species of Crataegus (hawthorn) were chosen because their polyphenolic constituents have recently received greater attention for the treatment of patients with severe heart disease. One-year-old plants of hawthorn (Crataegus laevigata and C. monogyna) were subjected to water-deficit (continuous water deprivation), cold (4°C), flooding (immersion of roots of plants in water) or herbivory (leaf removal) stress treatments (each of 10 days duration) in order to assess their effects on levels of polyphenolics, namely (-)-epicatechin, catechin, chlorogenic acid, vitexin, vitexin-2,,- O -rhamnoside, acetylvitexin-2,,- O -rhamnoside, hyperoside, quercetin, and rutin in the leaves. The working hypothesis followed is that one or more of these stress treatment will elicit increases in the levels of these polyphenolics. Cold stress causes increases in levels of vitexin-2,,- O -rhamnoside, acetylvitexin-2,,- O -rhamnoside, hyperoside, and quercetin in both Crataegus species. Water-deficit stress increased the productivity of chlorogenic acid, catechin, and (-)-epicatechin in both hawthorn species. Flooding and herbivory caused no net increases, and in some cases, decreases in levels of polyphenolics. These studies indicate that either water-deficit stress or cold stress treatments, or a combination of the two, can be used to enhance the levels of desired polyphenolics in the leaves of these two hawthorn species in a photobioreactor system. These results may have significance for hawthorn in adapting to water-deficit or cold stress and are important considerations for the use of hawthorn in the treatment of heart disease in humans. [source]

    Isolation and Characterisation of Procyanidins from Rumex obtusifolius

    PHYTOCHEMICAL ANALYSIS, Issue 3 2007
    Paul Spencer
    Abstract An acetone:water (7:3) extract obtained from the leaves of Rumex obtusifolius was fractionated into procyanidin oligomer and polymer fractions using a linear gradient and a simple step method on Sephadex LH-20. The chemical characteristics of the procyanidin fractions were studied by 13C-NMR spectroscopy, acid-catalysed degradation in the presence of benzyl mercaptan, matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) MS and electrospray ionisation (ESI) MS. The 13C-NMR showed that the polymer fraction consisted predominantly of procyanidin polymers, some with galloyl groups attached. The thiolysis reaction products indicated a mean degree of polymerisation (DP) of 4.3 for the step method, and a range of 2.3,8.2 mean DP for the gradient fractionation, with epicatechin as the most abundant flavan-3-ol extension unit, while the terminal units consisted of equal proportions of catechin, epicatechin and epicatechin gallate. Singly charged ions observed in MALDI-TOF/MS showed a range of oligomeric procyanidins and their polygalloyl derivatives. These species (in the range DP 2,7) were also observed by ESI/MS but the spectra were more complex due to overlapping multiply charged ions. Isolation of oligomers from the Sephadex LH-20 fraction by chromatography on polyamide and C18 yielded B1, B2, B3 and B7 dimers, an A-type trimer and a B2 3,3,- O -digallate. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    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

    PHYTOCHEMICAL ANALYSIS, Issue 1 2005
    Ramila Guendez
    Abstract 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 ,avanol 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. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Concentration-dependent effect of (,) epicatechin in hypertensive patients

    PHYTOTHERAPY RESEARCH, Issue 10 2010
    Navneet Kumar
    Abstract Non-vitamin polyphenolic compounds are ubiquitous in food plants and therefore potentially present in human plasma in a diet-dependent concentration. The aim of this study was to evaluate the concentration-dependent effect of (,) epicatechin, a polyphenol present in green tea with antioxidant activity, on various biomarkers of oxidative stress. The current study examined the in vitro concentration-dependent (10,4,M to 10,7,M) effects of (,) epicatechin on biomarkers of oxidative stress viz. malondialdehyde (MDA), reduced glutathione (GSH), membrane sulfhydryl (-SH) group and protein carbonyl content in hypertensive patients and normal ones. This effect seems to be due to ability of (,) epicatechin to reduce MDA and protein carbonyl content while increase in GSH and membrane -SH group in hypertensive patients. It can be concluded that (-) epicatechin exerts an antioxidant action inside the cell, responsible for the observed modulation of cellular response to oxidative challenges. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Modification of gamma-radiation response in mice by green tea polyphenols

    PHYTOTHERAPY RESEARCH, Issue 10 2008
    Hae June Lee
    Abstract In this study we evaluated the effect of water extracts of green tea (GT) and mixtures of green tea polyphenols (GTPs), epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC) on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of mice irradiated with gamma-ray. The radioprotective effect of green tea was compared with the effect of diethyldithiocarbamate (DDC). Jejunal crypts were protected by pretreatment of GT and ECG. Administration of GT, GTPs and EC prior to irradiation resulted in an increase in the formation of endogenous spleen colonies. The frequency of apoptosis in crypt cells was also reduced by pretreatment of GT, GTPs, EGCG, ECG and EGC. In the experiment on the effect of catechins, the effects were partly contradicted in irradiated mice. The rank order of activity was ECG > EGC > EGCG > EC on intestinal crypt survival assay, EC > EGC > ECG > EGCG on the spleen colony formation assay, EGCG > EGC > EC > ECG on inhibiting the death of cells caused by apoptosis. The results indicate that GT and GTPs may have a major radioprotective effect. Each one of the catechins was a much less effective radioprotector, suggesting that total extract or a mixture of GTPs may be more effective than individual catechins. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Flavonoids from the leaves of Litsea japonica and their anti-complement activity

    PHYTOTHERAPY RESEARCH, Issue 4 2005
    Sun-Young Lee
    Abstract Four flavonoids, epicatechin (1), afzelin (2), quercitrin (3), and tiliroside (4), were isolated from the leaves of Litsea japonica (Thunb.) Jussieu (Lauraceae). The structures of compounds were identified by comparing their chemical and spectral data with those previously reported. The flavonoids (1,4) were tested for their anti-complement activity against classical pathway of complement system. Compounds 2,4 showed inhibitory activity against complement system with IC50 values of 258, 440, and 101 µm, respectively, whereas 1 was inactive. For the evaluation of the structure-activity relationship of 5,7-dihydroxyflavones, myricitrin (5) from Juglans mandshurica also tested for it's anti-complement activity and is inactive in this assay system. Furthermore, compounds 2, 3, and 5 were hydrolyzed with naringinase to give kaempferol (2a), quercetin (3a), and myricetin (5a), and these were also tested for their activity. Of the three aglycones, 2a exhibited anti-complement activity with an IC50 value of 730 µM, while 3a and 5a were inactive. The inhibitory potencies of 2, 2a, 3, 3a, 5, and 5a against complement activity increased in inverse proportion to number of free hydroxyls on B-ring of 5,7-dihydroxyflavone. Of the compounds tested, 4 showed the most potent inhibitory activity against the complement system. Copyright © 2005 John Wiley & Sons, Ltd. [source]