Gallic Acid (gallic + acid)

Distribution by Scientific Domains
Distribution within Chemistry

Terms modified by Gallic Acid

  • gallic acid equivalent

  • Selected Abstracts


    Micellar Effects on the Reaction between an Arenediazonium Ion and the Antioxidants Gallic Acid and Octyl Gallate

    HELVETICA CHIMICA ACTA, Issue 1 2008
    Losada Barreiro, Sonia
    Abstract The effect of sodium dodecyl sulfate (SDS) micelles on the reaction between the 3-methylbenzenediazonium (3MBD) ion and either the hydrophilic antioxidant gallic acid (GA) or the hydrophobic analogue octyl gallate (OG) have been investigated as a function of pH. Titration of GA in the absence and presence of SDS micelles showed that the micelles do not alter the first ionization equilibrium of GA. Analysis of the dependence of the observed rate constant (kobs) with pH shows that the reactive species are GA2, and OG,. Kinetics results in the absence and presence of SDS micelles suggest that SDS aggregates do not alter the expected reaction pathway. SDS Micelles inhibit the spontaneous decomposition of 3MBD as well as the reaction between 3MBD and either GA or OG, and upon increasing the SDS concentration, with kobs approaching the value for the thermal decomposition of 3MBD in the presence of SDS. Our results are consistent with the prediction of the pseudophase model and show that the origin of the inhibition for the reaction with GA is different to that for the reaction with OG; in the former case, the observed inhibition can be rationalized in terms of the micelle-induced electrostatic separation of reactants in the micellar Stern layer, whereas the observed inhibition in the reaction with OG is a consequence of the dilution effect caused by increasing SDS concentration, decreasing the local OG, concentration in the Stern layer. [source]


    Inhibition of butter oxidation by some phenolics

    EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2007
    Kalliopi Soulti
    Abstract The ability of some phenolic compounds to inhibit butter oxidation was evaluated. Peroxide values and thiobarbituric acid reactive substances were monitored during storage of butter at 50,°C and at 110,°C. Gallic acid, caffeic acid and catechin, each at 80,mg/L, inhibited butter oxidation at 50,°C to a degree equal to that of butylated hydroxyanisole (BHA) at 200,mg/L. Gallic acid, at 80,mg/L, was more effective than BHA, at 200,mg/L, in inhibiting butter oxidation at 110,°C. Present results indicate that some phenolics, and especially gallic acid, may be taken into account as antioxidants in butter. [source]


    Hepatoprotective and antioxidant effects of gallic acid in paracetamol-induced liver damage in mice

    JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2010
    Mahaboob Khan Rasool
    Abstract Objectives The aim of this research paper was to investigate the hepatoprotective and antioxidant effects of gallic acid in paracetamol-induced liver damage in mice. Methods In the present study, the hepatoprotective and antioxidant effects of gallic acid were evaluated against paracetamol-induced hepatotoxicity in mice and compared with the silymarin, a standard hepatoprotective drug. The mice received a single dose of paracetamol (900 mg/kg body weight i.p.). Gallic acid (100 mg/kg body weight i.p.) and silymarin (25 mg/kg body weight i.p.) were administered 30 min after the injection of paracetamol. After 4 h, liver marker enzymes (aspartate transaminase, alanine transaminase and alkaline phosphatase) and inflammatory mediator tumour necrosis factor-alpha (TNF-,) were estimated in serum, while the lipid peroxidation and antioxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione- S -transferase and glutathione) were determined in liver homogenate of the control and experimental mice. Key findings Increased activities of liver marker enzymes and elevated TNF-, and lipid peroxidation levels were observed in mice exposed to paracetamol (P < 0.05), whereas the antioxidant status was found to be depleted (P < 0.05) when compared with the control group. However gallic acid treatment (100 mg/kg body weight i.p.) significantly reverses (P < 0.05) the above changes by its antioxidant action compared to the control group as observed in the paracetamol-challenged mice. Conclusions The results clearly demonstrate that gallic acid possesses promising hepatoprotective effects. [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]


    A rapid densitometric method for simultaneous quantification of gallic acid and ellagic acid in herbal raw materials using HPTLC

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005
    Milind Bagul
    Abstract Gallic acid and ellagic acid are two widely occurring phenolic compounds of plant origin, to which many biological activities including anticancer and antiviral activity have been attributed. A simple HPTLC method has been developed for the simultaneous quantification of gallic acid and ellagic acid. The method was validated for precision, repeatability, and accuracy. Instrumental precision was found to be 0.083 and 0.78, and the repeatability of the method was found to be 1.07 and 1.50 (% CV) for gallic acid and ellagic acid, respectively. The accuracy of the method was checked by a recovery study conducted at two different levels and the average percentage recovery was found to be 101.02% for gallic acid and 102.42% for ellagic acid. The above method was used for the quantification of gallic acid and ellagic acid content in seeds of Abrus precatorius Linn., whole plant of Phyllanthus maderaspatensis Linn., and flowers of Nymphaea alba Linn. The proposed HPTLC method for the simultaneous quantification of gallic acid and ellagic acid was found to be simple, precise, specific, sensitive, and accurate and can be used for routine quality control of herbal raw materials and for the quantification of these compounds in plant materials. [source]


    Gallic acid is partially responsible for the antiangiogenic activities of Rubus leaf extract

    PHYTOTHERAPY RESEARCH, Issue 9 2006
    Zhijun Liu
    Abstract An aqueous extract of leaves from Rubus suavissimus S. Lee (Rosaceae) or sweet leaf tea was tested for antiangiogenic activity in a human tissue-based ,brin,thrombin clot angiogenesis assay. Further fractionation of this crude extract was performed and the antiangiogenic effect of individual fractions was assessed. The extract was also tested for its oral bioavailability by using the serum of normal rats gavaged with the extract in the assay. At a 0.1% w/v concentration, the extract inhibited initiation of the angiogenic response and subsequent neovessel growth from samples that had already initiated an angiogenic response. Two subfractions of the extract showed signi,cant inhibition of angiogenesis at 0.1% w/w. Gallic acid was elucidated as one of the active angiogenesis inhibitors in one fraction. A 1 mm concentration of gallic acid totally inhibited angiogenesis. In the form of leaf extract, a one-tenth concentration produced the same total inhibition as pure gallic acid. The 10-fold difference in potency suggests the presence of other active compounds contributing to the overall antiangiogenic effect of the extract. The oral absorption of this extract was tested by using serum from rats given the extract orally (gavage) in the angiogenesis assay system. The serum of rats orally administered the sweet leaf tea extract at doses of 0.1% w/w and 0.3% w/w did not signi,cantly inhibit angiogenesis. However, the serum of rats injected intraperitoneally at a dose of 0.1% w/w caused a 41% inhibition of angiogenesis compared with saline injected controls. These preliminary results warrant further bioassay directed identi,cation of other responsible compounds. Copyright © 2006 John Wiley & Sons, Ltd. [source]


    A simple light-emitted diode-induced fluorescence detector using optical fibers and a charged coupled device for direct and indirect capillary electrophoresis methods

    ELECTROPHORESIS, Issue 9 2006
    David Arráez-Román
    Abstract We constructed a simple fluorescence detector for both direct and indirect CE methods using a blue light-emitted diode (470,nm) as excitation source, a bifurcated optical fiber as a waveguide, and a CCD camera as a detector. The connection of all the components is fairly easy even for nonexperts and the use of a CCD camera improves the applicability of this detector compared to the others using PMTs because it permits the recording of 2-D electropherograms or phosphorescence measurements. This detector provides a compact, low cost, and rapid system for the determination of native fluorescence compounds which have high quantum yields by CE with direct fluorescence detection, showing an LOD of 2.6×10,6,M for fluorescein; the determination of fluorescence derivative compounds by CE with direct fluorescence detection, showing an LOD of 1.6×10,7,M for FITC-labeled 1,6-diaminohexane; and nonfluorescence compounds by CE with indirect fluorescence detection with an LOD of 2.7×10,6,M for gallic acid. [source]


    Inhibition of butter oxidation by some phenolics

    EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2007
    Kalliopi Soulti
    Abstract The ability of some phenolic compounds to inhibit butter oxidation was evaluated. Peroxide values and thiobarbituric acid reactive substances were monitored during storage of butter at 50,°C and at 110,°C. Gallic acid, caffeic acid and catechin, each at 80,mg/L, inhibited butter oxidation at 50,°C to a degree equal to that of butylated hydroxyanisole (BHA) at 200,mg/L. Gallic acid, at 80,mg/L, was more effective than BHA, at 200,mg/L, in inhibiting butter oxidation at 110,°C. Present results indicate that some phenolics, and especially gallic acid, may be taken into account as antioxidants in butter. [source]


    Inhibition of lipid peroxidation by anthocyanins, anthocyanidins and their phenolic degradation products

    EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 1 2007
    Jonathan E. Brown
    Abstract Food components that delay or prevent biomolecule oxidation may be relevant in shelf life extension as well as disease prevention. Anthocyanins are a potentially important group of compounds, but they are prone to degradation both in vitro and in vivo, producing simple phenols. In this study, eight structurally related (poly)phenols [anthocyan(id)ins and phenolic acids] were examined for their ability to inhibit lipid oxidation at physiologically relevant concentrations (100,1000,nM) using the Cu2+ -mediated low-density lipoprotein oxidation model. Interaction between each (poly)phenol and Cu2+ ions was also investigated. (Poly)phenols with an ortho -dihydroxy group arrangement, i.e. cyanidin-3-glucoside, cyanidin and protocatechuic acid, were the most effective within their class, extending the lag phase to oxidation by 137, 255 and 402%, respectively (at 1000,nM). At the same concentration, trihydroxy-substituted compounds (delphinidin and gallic acid) were of intermediate efficacy, extending the lag phase by 175 and 38%, respectively. Compounds with the 4'-hydroxy-3',5'-methoxy arrangement (i.e. malvidin-3-glucoside and malvidin) were the least effective (3 and 58% extension, respectively), while syringic acid (4-hydroxy-3,5-dihydroxy benzoic acid) was pro-oxidant (lag phase shortened by 31%). (Poly)phenols with the ortho -dihydroxy arrangement chelated Cu2+ ions, which in part explains their greater efficacy over the other (poly)phenols in this model oxidation system. However, differences in their hydrogen-donating properties and their partitioning between lipid and hydrophilic phases are also relevant in explaining these structure-activity relationships. [source]


    Micellar Effects on the Reaction between an Arenediazonium Ion and the Antioxidants Gallic Acid and Octyl Gallate

    HELVETICA CHIMICA ACTA, Issue 1 2008
    Losada Barreiro, Sonia
    Abstract The effect of sodium dodecyl sulfate (SDS) micelles on the reaction between the 3-methylbenzenediazonium (3MBD) ion and either the hydrophilic antioxidant gallic acid (GA) or the hydrophobic analogue octyl gallate (OG) have been investigated as a function of pH. Titration of GA in the absence and presence of SDS micelles showed that the micelles do not alter the first ionization equilibrium of GA. Analysis of the dependence of the observed rate constant (kobs) with pH shows that the reactive species are GA2, and OG,. Kinetics results in the absence and presence of SDS micelles suggest that SDS aggregates do not alter the expected reaction pathway. SDS Micelles inhibit the spontaneous decomposition of 3MBD as well as the reaction between 3MBD and either GA or OG, and upon increasing the SDS concentration, with kobs approaching the value for the thermal decomposition of 3MBD in the presence of SDS. Our results are consistent with the prediction of the pseudophase model and show that the origin of the inhibition for the reaction with GA is different to that for the reaction with OG; in the former case, the observed inhibition can be rationalized in terms of the micelle-induced electrostatic separation of reactants in the micellar Stern layer, whereas the observed inhibition in the reaction with OG is a consequence of the dilution effect caused by increasing SDS concentration, decreasing the local OG, concentration in the Stern layer. [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]


    Antioxidant properties of methanolic extracts from different parts of Sclerocarya birrea

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2008
    Abdalbasit A. Mariod
    Summary The methanolic extracts from Sclerocarya birrea leaves (SCL), roots (SCR), barks (SCB), and kernel oil cake (SCK) were examined for radical scavenging capacities and antioxidant activities. The total phenolics of the extracts was determined spectrophotometrically according to the Folin-Ciocalteau method using gallic acid as standard solution. The total phenolic compounds were found as 304.5, 367.5, 593, 148.0 and 258.0 mg g -1 of dry product, respectively. The extracts of SCL, SCR, SCB and SCK were markedly effective in inhibiting the oxidation of linoleic acid and subsequent bleaching of ,-carotene in comparison with the control. Based on oxidation of ,-carotene/linoleic acid, the SCK extract is the most effective followed by SCR, SCL and SCB extract. The antioxidant activity determined by the DPPH (1,1-diphenyl-,-picrylhydrazyl) method revealed that the SCK extract had the highest antioxidant activity on DPPH free radicals followed by SCB, SCR and SCL extracts. The effect of different extracts on the oxidative stability of sunflower oil at 70 °C was tested in the dark and compared with BHA. The oil peroxide values (PVs) were generally lower with the addition of extract in comparison to a control. [source]


    Some properties of polyphenol oxidase from lily

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2008
    Ying Yang
    Summary A study of crude polyphenol oxidase (PPO) from lily bulbs was carried out to provide information useful for guiding food processing operations. Optimum pH for the enzyme activity in the presence of catechol, were 4.0 and 7.0 at room temperature(approximately 20 °C) and the enzyme was stable in the pH range from 5.0 to 6.5 at 4 °C for 10 h. Its optimum temperature was 40 °C and the heat inactivation of the enzyme followed first-order kinetics. Lily PPO possessed a diphenolase activity toward catechol, catechin and gallic acid; catechin was the best substrate for the enzyme considering the Vmax/Km ratio. The most effective enzyme inhibitor was sodium sulphite, although ascorbic acid, l -cysteine and thiourea were also effective inhibitors at high concentration. But NaCl and citric acid were poor inhibitors of the enzyme. Data generated by this study might help to better prevent lily bulbs browning. [source]


    Enhancement in mineralization of some natural refractory organic compounds by ozonation,aerobic biodegradation

    JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006
    Devendra P Saroj
    Abstract Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry [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]


    Hepatoprotective and antioxidant effects of gallic acid in paracetamol-induced liver damage in mice

    JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2010
    Mahaboob Khan Rasool
    Abstract Objectives The aim of this research paper was to investigate the hepatoprotective and antioxidant effects of gallic acid in paracetamol-induced liver damage in mice. Methods In the present study, the hepatoprotective and antioxidant effects of gallic acid were evaluated against paracetamol-induced hepatotoxicity in mice and compared with the silymarin, a standard hepatoprotective drug. The mice received a single dose of paracetamol (900 mg/kg body weight i.p.). Gallic acid (100 mg/kg body weight i.p.) and silymarin (25 mg/kg body weight i.p.) were administered 30 min after the injection of paracetamol. After 4 h, liver marker enzymes (aspartate transaminase, alanine transaminase and alkaline phosphatase) and inflammatory mediator tumour necrosis factor-alpha (TNF-,) were estimated in serum, while the lipid peroxidation and antioxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione- S -transferase and glutathione) were determined in liver homogenate of the control and experimental mice. Key findings Increased activities of liver marker enzymes and elevated TNF-, and lipid peroxidation levels were observed in mice exposed to paracetamol (P < 0.05), whereas the antioxidant status was found to be depleted (P < 0.05) when compared with the control group. However gallic acid treatment (100 mg/kg body weight i.p.) significantly reverses (P < 0.05) the above changes by its antioxidant action compared to the control group as observed in the paracetamol-challenged mice. Conclusions The results clearly demonstrate that gallic acid possesses promising hepatoprotective effects. [source]


    An extract of Lannea microcarpa: composition, activity and evaluation of cutaneous irritation in cell cultures and reconstituted human epidermis

    JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2006
    P. Picerno
    Lannea microcarpa (Anacardiaceae) is a tropical tree used in African folk medicine and commercial dermopharmaceutical formulations. Fractionation and analysis of its polar extract allowed the identification of 4,-methoxy-myricetin 3- O -,- l -rhamnopyranoside, myricetin 3- O -,- l -rhamnopyranoside, myricetin 3- O -,- d -glucopyranoside, vitexin, isovitexin, gallic acid and epi-catechin, as the major constituents. In-vivo assay (the croton oil ear test in mice) showed that the extract had significant anti-inflammatory effect (ID50 = 900 ,g cm2) but ten times lower than that of indometacin (ID50 = 93 ,g cm2), the non-steroidal anti-inflammatory drug used as reference. Cytotoxicity and cutaneous irritation of the extract and its constituents were investigated. The crude extract and its major components did not affect cell viability in-vitro either in three different cultures (J774.A1, WEHI-164 and HEK-293) of cells grown in monolayers or in the reconstituted human epidermis (RHE, 3D model), nor did they cause release of pro-inflammatory mediators (IL-1,) or histomorphological modification of RHE. [source]


    Inhibition of CYP3A-mediated oxidation in human hepatic microsomes by the dietary derived complex phenol, gallic acid

    JOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 2 2002
    Ieva Stupans
    Plant polyphenols, such as gallic acid, have been reported to have a range of biological activities including antimutagenic effects. Previously, we reported that gallic acid (3,4,5-trihydroxy-benzoic acid), an agent found in wine and tea, inhibits androstenedione 6,-hydroxylase activity (Ki 70 ,M), a cytochrome P450 (CYP3A) marker in human liver microsomes. The preincubation of gallic acid (100 ,M) with human liver microsomes in the absence of NADPH, as compared with the presence of NADPH, before assay of androstenedione 6,-hydroxylase activity significantly increased the inhibitory effects of the gallic acid (0.03 ± 0.03 nmol (mg microsomal protein),1 min,1 compared with 0.20 ± 0.06 nmol (mg microsomal protein),1 min,1 (P< 0.05)). The antioxidant ascorbic acid and the radical scavenger glutathione prevented this observed increase in inhibition. Removal of gallic acid-derived products from the incubation completely restored CYP3A activity. In contrast, the activities of CYP1A and CYP2E, and non-CYP mediated reductive microsomal 17,-hydroxysteroid dehydrogenase activity were refractory to inhibition by gallic acid. [source]


    Induction of Phenolic Compounds in Pea (Pisum sativum L.) Inoculated by Rhizobium leguminosarum and Infected with Orobanche crenata

    JOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2007
    Y. Mabrouk
    Abstract Parasitic plants are among the most important problematic weeds, they are responsible of major losses of many crops. Early growth stages, such as seed germination stimulated by host root exudates and tubercle development, are key phases for these parasites development. Inhibition of these early phases could be a general strategic option for parasitic plants management. In our previous study, we have demonstrated that some Rhizobium leguminosarum strains decrease pea infection by Orobanche crenata and germinated seeds enhanced browning symptoms. These observations suggested the probability of toxic compounds accumulation such as gallic acid and naringenin used as a defence strategy by inoculated pea plants. In this study, we demonstrate that these two phenolic compounds cause severe physiological disorder of germination broomrape seeds. They inhibited germination of O. crenata seeds induced by strigol analogue GR24, and caused a browning reaction in germinated seeds. [source]


    Screening of antioxidant phenolic compounds in Chinese Rhubarb combining fast counter-current chromatography fractionation and liquid chromatography/mass spectrometry analysis

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 11 2010
    Ruilin Hu
    Abstract In this paper, an effective method combing fast elution-extrusion counter-current chromatography (CCC) and LC/MS for rapid screening of antioxidative phenolic compounds in Chinese Rhubarb is presented. An integrated three-coil CCC column (40,mL each coil) was used to accomplish the optimization of biphasic liquid system. In a single run (approximately 40,min), the solvent system composed of n -hexane/ethyl acetate/methanol/water (1:1:1:1, v/v) was selected as optimum CCC liquid system for fast fractionation of the crude ethanol extract. With a 140,mL-capacity CCC instrument, 100,mg Chinese Rhubarb extract was separated under the optimized conditions, producing six fractions in only 100,min. The quantities of each fraction were ,15,mg. In addition, each fraction was subjected to antioxidant activity assay and characterized by LC/MS analysis. Fifty compounds, including phenolic acids, phenolic glucosides and hydroxyanthraquinones, were detected by LC/MS/MS analysis. As a result, gallic acid together with Fr I showed excellent antioxidant activity, which was well consistent with previous studies and exhibited great potential for natural drug discovery program of the present method. [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]


    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]


    A rapid densitometric method for simultaneous quantification of gallic acid and ellagic acid in herbal raw materials using HPTLC

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6 2005
    Milind Bagul
    Abstract Gallic acid and ellagic acid are two widely occurring phenolic compounds of plant origin, to which many biological activities including anticancer and antiviral activity have been attributed. A simple HPTLC method has been developed for the simultaneous quantification of gallic acid and ellagic acid. The method was validated for precision, repeatability, and accuracy. Instrumental precision was found to be 0.083 and 0.78, and the repeatability of the method was found to be 1.07 and 1.50 (% CV) for gallic acid and ellagic acid, respectively. The accuracy of the method was checked by a recovery study conducted at two different levels and the average percentage recovery was found to be 101.02% for gallic acid and 102.42% for ellagic acid. The above method was used for the quantification of gallic acid and ellagic acid content in seeds of Abrus precatorius Linn., whole plant of Phyllanthus maderaspatensis Linn., and flowers of Nymphaea alba Linn. The proposed HPTLC method for the simultaneous quantification of gallic acid and ellagic acid was found to be simple, precise, specific, sensitive, and accurate and can be used for routine quality control of herbal raw materials and for the quantification of these compounds in plant materials. [source]


    Antioxidant activity of the ethanolic extract from the bark of Chamaecyparis obtusa var. formosana

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2008
    Palanisamy Marimuthu
    Abstract BACKGROUND:Chamaecyparis obtusa var. formosana (Taiwan hinoki) is an endemic conifer in Taiwan and the purpose of this study is to evaluate the antioxidant activity of various fractions obtained from the bark of this plant material. The ethanolic extract of the bark was sequentially separated into three fractions, including n -hexane, ethyl acetate and ethanol soluble fractions, by liquid,liquid partition. Then the antioxidant activities of crude extract and three fractions along with 13 subfractions obtained from the ethyl acetate (EA) soluble fraction were tested for several antioxidant assays. RESULTS: The total phenolic content of the samples varied from 27.71 to 102.86 mg GAE g,1 dry weight for fractions, and from 49.94 to 206.46 mg GAE g,1 for subfractions (where GAE is milligrams of gallic acid per gram of extract). The Trolox equivalent antioxidant capacity (TEAC) ranged from 0.15 to 0.26 mmol L,1 Trolox equivalents. The EA soluble fraction was found to be the best antioxidant-rich fraction in terms of DPPH and reducing power assays. With further data analysis it was found that there was a positive correlation between the total phenolic content of extracts and TEAC is R2 = 0.61. CONCLUSION: Results from various antioxidant assays showed that the EA fraction possessed strong antioxidant activity. This would provide additional information about the antioxidant activity of bark extract of this plant species. Copyright © 2008 Society of Chemical Industry [source]


    Binding of olive oil phenolics to food proteins

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2005
    Are Hugo Pripp
    Abstract In this paper we investigate the interaction of phenolics extracted from olive oil with different food proteins (sodium caseinate, bovine serum albumin, ,-lactoglobulin and gelatin). Binding parameters are estimated using different experimental techniques: gel filtration, HPLC, isothermal titration calorimetry and NMR diffusion measurements. For comparison, the binding properties of gallic acid and tannic acid are also studied. The affinity of olive oil phenolics for the different food proteins is found to be relatively weak (compared with tannic acid). Binding constants are measured for the different phenolics in the extract: tyrosol and hydroxytyrosol do not (or very weakly) bind to the proteins, whereas other phenolics in the extract had binding constants of the order 102,104M,1. The binding parameters determined have been discussed in relation to the possible effect of proteins on sensory properties (bitterness) of food emulsions containing olive oil. Copyright © 2004 Society of Chemical Industry [source]


    Soil moisture stress-induced alterations in bioconstituents determining tea quality

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2003
    PR Jeyaramraja
    Abstract The impact of water stress on the biochemical constituents that determine black tea quality was investigated. Phenylalanine ammonia lyase (PAL) activity was highest in the drought tolerant ,Assam' cultivar UPASI-2, followed by UPASI-8 and UPASI-9, under non-stress conditions. Under soil moisture stress a reduction in PAL activity was found in all three clones investigated. A strong positive correlation was observed between an increase in soil moisture deficit and a decrease in PAL activity. Lower PAL activity correlated well with lower synthesis of flavanols such as epigallocatechin gallate (EGCG) and epicatechin gallate (ECG), which are important precursors of theaflavin-3,3,-digallate that determines final tea quality. Altered synthesis of EGCG and ECG could be due to their molecular rearrangement at elevated leaf temperature during drought. Synthesis of quality constituents such as gallic acid and caffeine declined significantly owing to both drought and waterlogging stress. The reduction in gallic acid due to water stress could lead to lower synthesis of theaflavin fractions such as epitheaflavic acid, epitheaflavic acid-3,-gallate and theaflavic acid and, thereby, quality deterioration. Similarly to drought, flooding stress was also found to alter the biochemical constituents necessary for tea quality. Copyright © 2003 Society of Chemical Industry [source]


    Screening of chemiluminescence constituents of cereals and DPPH radical scavenging activity of ,-oryzanol

    LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 3 2001
    Yoshinobu Akiyama
    Abstract The chemiluminescence (CL) constituents of cereals were detected by CL using the H2O2,acetaldehyde system. The cereals tested, such as rice, millet and sorghum, exhibited various levels of CL activity. The ,-oryzanol fraction was extracted from brown rice and separated into four constituents by HPLC. The four constituents were identified as cycloartenyl ferulate, 24-methylenecycroartanyl ferulate, campesteryl ferulate and ,-sitosteryl ferulate. Free radical scavenging activities with 1,1-diphenyl-2-picrylhydrazyl (DPPH) and CL intensities of four constituents (,-oryzanol components) were measured and compared with that of gallic acid, which is a typical free radical scavenger. Four constituents scavenged DPPH radicals and scavenging activities were proportional to CL intensities. Concentrations of four CL constituents required to quench 50% (IC50) of the free radicals ranged from 0.9 to 1.1,mmol/L. We demonstrated that measurement of CL intensities was a rapid and convenient method for screening DPPH radical scavenging activities of rice. Copyright © 2001 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]


    Identification and quantification of galloyl derivatives, flavonoid glycosides and anthocyanins in leaves of Pistacia lentiscus L.

    PHYTOCHEMICAL ANALYSIS, Issue 2 2002
    A. Romani
    Abstract Separation, identification and quantification of polyphenols was carried out on leaves of Pistacia lentiscus L., an evergreen member of the family Anacardiaceae, using semi-preparative HPLC, HPLC-photodiode array detection and HPLC-MS analysis, together with 1H- and 13C NMR. Three major classes of secondary metabolites were detected: (i) gallic acid and galloyl derivatives of both glucose and quinic acid; (ii) flavonol glycosides, i.e. myricetin and quercetin glycosides; and (iii) anthocyanins, namely delphinidin 3- O -glucoside and cyanidin 3- O -glucoside. Low amounts of catechin were also detected. The concentration of galloyl derivatives was extremely high, representing 5.3% of the leaf dry weight, and appreciable amounts of myricetin derivatives were also detected (1.5% on a dry weight basis). These findings may be useful in establishing a relationship between the chemical composition of the leaf extract and the previously reported biological activity of P. lentiscus, and may also assign a new potential role of P. lentiscus tissue extracts in human health care. Copyright © 2002 John Wiley & Sons, Ltd. [source]


    Gallic acid is partially responsible for the antiangiogenic activities of Rubus leaf extract

    PHYTOTHERAPY RESEARCH, Issue 9 2006
    Zhijun Liu
    Abstract An aqueous extract of leaves from Rubus suavissimus S. Lee (Rosaceae) or sweet leaf tea was tested for antiangiogenic activity in a human tissue-based ,brin,thrombin clot angiogenesis assay. Further fractionation of this crude extract was performed and the antiangiogenic effect of individual fractions was assessed. The extract was also tested for its oral bioavailability by using the serum of normal rats gavaged with the extract in the assay. At a 0.1% w/v concentration, the extract inhibited initiation of the angiogenic response and subsequent neovessel growth from samples that had already initiated an angiogenic response. Two subfractions of the extract showed signi,cant inhibition of angiogenesis at 0.1% w/w. Gallic acid was elucidated as one of the active angiogenesis inhibitors in one fraction. A 1 mm concentration of gallic acid totally inhibited angiogenesis. In the form of leaf extract, a one-tenth concentration produced the same total inhibition as pure gallic acid. The 10-fold difference in potency suggests the presence of other active compounds contributing to the overall antiangiogenic effect of the extract. The oral absorption of this extract was tested by using serum from rats given the extract orally (gavage) in the angiogenesis assay system. The serum of rats orally administered the sweet leaf tea extract at doses of 0.1% w/w and 0.3% w/w did not signi,cantly inhibit angiogenesis. However, the serum of rats injected intraperitoneally at a dose of 0.1% w/w caused a 41% inhibition of angiogenesis compared with saline injected controls. These preliminary results warrant further bioassay directed identi,cation of other responsible compounds. Copyright © 2006 John Wiley & Sons, Ltd. [source]