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PubMed2002

In-line pressurized-fluid extraction-solid-phase extraction for determining phenolic compounds in grapes.

A new method of pressurized-fluid extraction coupled in-line with solid-phase extraction has been used for the extraction of phenolic compounds from grapes. The full extraction method is performed under an inert atmosphere. Five different solvents have been assayed using different extraction pressures and temperatures. Using two extraction stages with two different solvents, water and methanol, quantitative recovery for most of the assayed compounds has been found in the second extract. Only the most polar phenolic compound, gallic acid, was found distributed in both extracts. The application to real samples allows for a clean-up of the extracts. Cinnamic esters like caftaric acid, cis and trans-coutaric acids were found only in the methanolic extract. The reproducibility for the new method was measured using both an inert solid spiked with standards and grapes. Using between 202 and 424 microg of spiked standards, the resulting relative standard deviations were less than 5%, with the exception of gallic acid (RSD=13%). For grapes, the resulting RSD were 11% for trans-coutaric acid, 10% for caftaric acid and 6% for cis-coutaric acid.

Phenols↗
PubMed2000

Determination of neutral lipid hydroperoxides by size exclusion HPLC with fluorometric detection. Application to fish oil enriched mayonnaises during storage.

A fast (12 min) high-performance size exclusion chromatography (HPSEC) method for the separation of neutral lipid class hydroperoxides in the oil phases from fish oil enriched mayonnaises was developed. Detection and quantification were performed using the postcolumn fluorometric (FL) diphenyl-1-pyrenylphosphine oxidation principle. The reproducibilities judged by intra- and inter-assay variations were 0.64 and 7.2%, respectively. The HPSEC-FL method was applied to assess the effect of supplementations with emulsifier, gallic acid, and EDTA on the oxidative processes in the mayonnaises during storage. Substantial amounts of hydroperoxy triacylglycerols (TAGOOH) and cholesterol esters (CEOOH), together with traces of TAGOOH-dimers, were detected. All supplementations significantly decreased the levels of TAGOOH and to a lesser degree CEOOH. Supplementations with EDTA and gallic acid resulted in constant and slightly increasing levels of TAGOOH, respectively, thus affecting the oxidation mechanisms seen in reference mayonnaise. The emulsifier Panodan TR DATEM reduced the levels of TAGOOH as compared to the appropriate controls.

Chromatography, High Pressure Liquid↗
PubMed1987

Detection of oxygen activation and determination of the activity of antioxidants towards reactive oxygen species by use of the chemiluminigenic probes luminol and lucigenin.

Reactive oxygen metabolites can transfer, via oxygenation, the chemiluminigenic probes luminol and lucigenin to an excited state and thus induce light emission from these probes. This technique has been applied to a study of the effect of common food antioxidants on the availability of reactive oxygen species in aqueous model systems and in microsomal preparations. In all systems tested, propyl gallate and its congener octyl gallate proved to be the most active scavengers of the oxygenating species involved in the chemiluminescence reaction. In aqueous model systems, butylated hydroxyanisole was 10 times less efficient than the gallic acid ester antioxidants. In biological material, the lower scavenger activity of butylated hydroxyanisole is further compromised by its ability to induce a marked increase in production of hydrogen peroxide in the endoplasmic reticulum. Butylated hydroxytoluene is only marginally active in aqueous media and in biological material. It is concluded that gallic acid ester antioxidants may possess a significant protective potential towards toxic and carcinogenic agents due to their ability to remove toxic oxygen metabolites.

Acridines↗
PubMed1989

The effects of repeated parenteral administration of chelating agents on the distribution and excretion of uranium.

The effects of repeated ip administration of gallic acid, 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) on the distribution and excretion of uranium were assessed in male Swiss mice. Only Tiron significantly increased the amount of uranium excreted into urine and feces. A significant decrease in the concentration of uranium in liver, spleen and bone was observed after administration of Tiron, whereas injection of gallic acid or DTPA resulted in a significant decrease in the concentration of the metal in the liver. The results show that Tiron was consistently the most effective chelator of those tested in the treatment of uranium poisoning after repeated daily administration of the metal.

Animals↗
PubMed2000

Activities of antioxidants are affected by colloidal properties of oil-in-water and water-in-oil emulsions and bulk oils.

The activity of alpha-tocopherol, Trolox, propyl gallate, gallic acid, methyl carnosoate, and carnosic acid was studied in two oil-in-water (o/w) emulsions, in two water-in-oil (w/o) emulsions, and in bulk oil with and without added emulsifiers. All antioxidants had either moderate or higher activity in bulk oil than in the emulsions. In most emulsions, the most polar antioxidants, propyl gallate and gallic acid, exhibited either prooxidant activity or no antioxidant activity. Methyl carnosoate was the most active antioxidant in w/o emulsions but was less active than Trolox in o/w emulsions. alpha-Tocopherol was less active in bulk oil than in emulsions, but its activity in bulk oil was markedly enhanced by the addition of o/w emulsifiers. Partitioning of antioxidants, hydrogen bonding, interphase transport, surface accessibility, and interaction of emulsifier with antioxidants are considered to be important parameters that determine antioxidant activity in lipid-containing systems.

Antioxidants↗
PubMed2000

Galloylglucosides from berries of Pimenta dioica.

Three new galloylglucosides, (4S)-alpha-terpineol 8-O-beta-D-(6-O-galloyl)glucopyranoside (1); (4R)-alpha-terpineol 8-O-beta-D-(6-O-galloyl)glucopyranoside (2), and 3-(4-hydroxy-3-methoxyphenyl)propane-1,2-diol 2-O-beta-D-(6-O-galloyl)glucopyranoside (3), were isolated from the berries of Pimenta dioica together with three known compounds, gallic acid (4), pimentol (5), and eugenol 4-O-beta-D-(6-O-galloyl)glucopyranoside (6). The structures of 1-3 were elucidated on the basis of MS and NMR spectral data and enzymatic hydrolysis. These galloylglucosides (1-3, 5, and 6) showed radical-scavenging activity nearly equivalent to that of gallic acid (4) against 1,1-diphenyl-2-picrylhydrazyl radical.

Cyclohexane Monoterpenes↗
PubMed2006

4-O-methylgallic acid down-regulates endothelial adhesion molecule expression by inhibiting NF-kappaB-DNA-binding activity.

We here investigated the functional effect of 4-O-methylgallic acid (4-OMGA), a major metabolite of gallic acid abundant in red wine, on vascular inflammation and its action mechanism. 4-OMGA inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in human umbilical vein endothelial cells (HUVECs) stimulated with tumor necrosis factor-alpha (TNF-alpha), resulting in the suppression of leukocyte adhesion to HUVECs. In addition, 4-OMGA inhibited the promoter activities of ICAM-1 and VCAM-1 and the activity of nuclear factor-kappaB (NF-kappaB) without affecting cytosolic IkappaB kinase (IKK) activation, inhibitor of kappaB (IkappaB) phosphorylation and degradation, and nuclear translocation of NF-kappaB. This compound did not alter nitric oxide (NO) generation, but inhibited reactive oxygen species (ROS) production in TNF-alpha-stimulated HUVECs, suggesting that NO and ROS are not involved in 4-OMGA-mediated inhibition of NF-kappaB activity. Moreover, 4-OMGA directly blocked the binding activity of NF-kappaB to its consensus DNA oligonucleotide, when pre-incubated with the nuclear extract from TNF-alpha-stimulated HUVECs, but not with the oligonucleotide alone. This inhibition was completely abolished by the addition of dithiothreitol. 4-OMGA exhibits an anti-inflammatory property by interfering with the formation of the NF-kappaB-DNA complex in the nuclei through direct and redox-sensitive interactions and may play an important role in the prevention of inflammatory responses such as the atherosclerotic process.

Anti-Inflammatory Agents↗
PubMed2000

Cytotoxic activity of hydrolyzable tannins against human oral tumor cell lines--a possible mechanism.

Hydrolyzable tannins showed higher cytotoxic activity against human oral squamous cell carcinoma and salivary gland tumor cell lines than against normal human gingival fibroblasts, whereas gallic acid, a component unit of tannins, showed much weaker selective cytotoxicity. The cytotoxic activity of dimeric compounds was generally higher than that of monomeric compounds. Macrocyclic ellagitannin oligomers, such as oenothein B, woodfordin C and woodfordin D showed the greatest cytotoxic activity, and their activity (per given number of molecules) was one order higher than those of gallic acid and epigallocatechin gallate, a major component of green tea. These compounds induced apoptotic cell death characterized by DNA fragmentation (as demonstrated by the TUNEL method) and cleavage of cytokeratin 18 by activated caspase(s) (as demonstrated by M30 monoclonal antibody). ESR spectroscopy revealed that these macrocyclic compounds at higher concentrations produced their own radicals and significantly enhanced the radical intensity of sodium ascorbate, possibly by their prooxidant actions. Catalase failed to eliminate their apoptosis-inducing activity, reducing the possibility of the involvement of hydrogen peroxide production in the extracellular fraction. These observations suggested that the antitumor activity of macrocyclic ellagitannin oligomers reported previously might be explained by their apoptosis-inducing activity.

Antineoplastic Agents↗
PubMedDate not supplied

Effect of antioxidants, oxidants, metals and saliva on cytotoxicity induction by sodium fluoride.

We have recently found that millimolar concentrations of sodium fluoride (NaF) induced apoptotic cell death, characterized by caspase activation and DNA fragmentation, in tumor cell lines. This finding paved the way to investigating the interaction between NaF and the oral environment. As an initial step, we investigated redox compounds, metals and saliva, which may modify the cytotoxic activity of NaF against a human oral squamous cell carcinoma cell line (HSC-2). The minimum exposure time to NaF required for cytotoxicity induction was 8 hours. Noncytotoxic concentrations of antioxidants (sodium ascorbate, gallic acid, epigallocatechin gallate, chlorogenic acid, curcumin, superoxide dismutase, catalase), oxidants (hydrogen peroxide, sodium hypochlorite), metals (CuCl, CuCl2, FeCl2, FeCl3, CoCl2) or saliva neither protected against, nor enhanced the cytotoxic activity of NaF. Cytotoxic concentrations of these compounds produced somewhat additive, but not synergistic, effects on the cytotoxicity of NaF. ESR analysis demonstrated that NaF did not apparently change the radical intensity of sodium ascorbate and gallic acid, measured under alkaline conditions. During the cell death induction in human promyelocytic leukemia HL-60 cells by NaF, the consumption of glucose rapidly declined, followed by a decline in the consumption of major amino acids. The present study suggests that the cytotoxic activity of NaF is not regulated by the redox mechanism, but rather linked to the rapid decline in glucose consumption at early stage.

Amino Acids↗
PubMedDate not supplied

Use of pruned computational neural networks for processing the response of oscillating chemical reactions with a view to analyzing nonlinear multicomponent mixtures.

The suitability of pruned computational neural networks (CNNs) for resolving nonlinear multicomponent systems involving synergistic effects by use of oscillating chemical reaction-based methods implemented using the analyte pulse perturbation technique is demonstrated. The CNN input data used for this purpose are estimates provided by the Levenberg-Marquardt method in the form of a three-parameter Gaussian curve associated with the singular profile obtained when the oscillating system is perturbed by an analyte mixture. The performance of the proposed method was assessed by applying it to the resolution of mixtures of pyrogallol and gallic acid based on their perturbating effect on a classical oscillating chemical system, viz. the Belousov-Zhabotinskyi reaction. A straightforward network topology (3:3:2, with 18 connections after pruning) allowed the resolution of mixtures of the two analytes in concentration ratios from 1:7 to 6:2 with a standard error of prediction for the testing set of 4.01 and 8.98% for pyrogallol and gallic acid, respectively. The reduced dimensions of the selected CNN architecture allowed a mathematical transformation of the input vector into the output one that can be easily implemented via software. Finally, the suitability of response surface analysis as an alternative to CNNs was also tested. The results were poor (relative errors were high), which confirms that properly selected pruned CNNs are effective tools for solving the analytical problem addressed in this work.

Journal Article↗
PubMed2001

Oxygen radical absorbance capacity (ORAC) and phenolic and anthocyanin concentrations in fruit and leaf tissues of highbush blueberry.

Antioxidant capacity, as measured by oxygen radical absorbance capacity (ORAC), and total phenolic and total anthocyanin contents were evaluated in fruit tissues of 87 highbush blueberry (Vacciniumcorymbosum L.) and species-introgressed highbush blueberry cultivars. ORAC and phenolic levels were evaluated in leaf tissues of the same materials. Average values for ORAC, phenolics, and anthocyanins in fruit were 15.9 ORAC units, 1.79 mg/g (gallic acid equivalents), and 0.95 mg/g (cyanidin-3-glucoside equivalents), respectively. Cv. Rubel had the highest ORAC per gram of fresh weight values, at 31.1 units, and cv. Elliott had the highest values on the basis of ORAC per square centimeter of surface area. In leaf tissue, values for both ORAC and phenolics were significantly higher than in fruit tissue, with mean values of 490 ORAC units and 44.80 mg/g (gallic acid equivalents), respectively. Leaf ORAC had a low, but significant, correlation with fruit phenolics and anthocyanins, but not with fruit ORAC. An analysis of ORAC values versus calculated midparent values in 11 plants from the 87-cultivar group in which all parents were tested suggested that, across cultivars, ORAC inheritance is additive. An investigation of ORAC values in a family of 44 cv. Rubel x Duke seedlings showed negative epistasis for ORAC values, suggesting Rubel may have gene combinations contributing to ORAC that are broken up during hybridization.

Anthocyanins↗
PubMed2004

Tea polyphenols inhibit acetyl-CoA:1-alkyl-sn-glycero-3-phosphocholine acetyltransferase (a key enzyme in platelet-activating factor biosynthesis) and platelet-activating factor-induced platelet aggregation.

BACKGROUND: Tea extracts have antiallergic and anti-inflammatory actions in rats and mice. However the mechanism through which tea polyphenols act in vivo are still incompletely understood. We found inhibitory effects of black tea extracts on an fMLP-induced aggregating response in a rabbit platelet-polymorphonuclear leukocyte (PMN) system. METHOD: To elucidate whether 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) production in PMNs and/or PAF-stimulated platelet activation were inhibited, the effects of tea polyphenols were investigated on the enzyme activity of acetyl-CoA:1-alkyl-sn-glycero-3-phosphocholine acetyltransferase (EC 2.3.1.67), PAF biosynthesis in A23187-activated rabbit PMNs, and rabbit platelet aggregation. By comparing the inhibitory effects of 31 galloyl esters and gallic acid, the structure-inhibitory activity relationship was characterized. RESULTS: Theaflavin and its galloyl esters and pentagalloyl glucose were found to be potent inhibitors of the acetyltransferase (IC(50) = 28-58 microM) and the PAF biosynthesis as well as (-)-epicatechin-3-O-gallate (IC(50) = 72 +/- 13 microM) and (-)-epigallocatechin-3-O-gallate (IC(50) = 46 +/- 6 microM). On the other hand, flavan-3-ols without galloyl group at C-3 and gallic acid did not show significant enzyme inhibition. In addition, theaflavin and its galloyl esters (IC(50) = 32-77 microM) and geranyl gallate, farnesyl gallate and geranylgeranyl gallate (IC(50) = 6.4-7.6 microM) were found to be potent inhibitors of PAF- and TPA-induced rabbit platelet aggregation but not A23187-induced aggregation. CONCLUSIONS: Theaflavin and its galloyl esters in black tea extract, and isoprenyl gallates were potent inhibitors of PAF synthesis and platelet aggregation and these activities may be relevant to the claimed therapeutic effects of tea extracts.

Acetyltransferases↗
PubMedDate not supplied

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

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

Flavonoids↗
PubMed2000

Relationship among antioxidant activity, vasodilation capacity, and phenolic content of red wines.

The relationship among antioxidant activity, based on the electron-spin resonance determination of the reduction of Fremy's radical, vasodilation activity, and phenolic content was investigated in 16 red wines. The wines were selected to provide a range of origins, grape varieties, and vinification methods. Sensitive and selective HPLC methods were used for the analysis of the major phenolics in red wine: free and conjugated myricetin, quercetin, kaempferol, and isorhamnetin; (+)-catechin, (-)-epicatechin, gallic acid, p-coumaric acid, caffeic acid, caftaric acid, trans-resveratrol, cis-resveratrol, and trans-resveratrol glucoside. Total anthocyanins were measured using a colorimetric assay. The total phenolic content of the wines was determined according to the Folin-Ciocalteu colorimetric assay and also by the cumulative measurements obtained by HPLC. The 16 wines exhibited a wide range in the values of all parameters investigated. However, the total phenol contents, measured both by HPLC and colorimetrically, correlated very strongly with the antioxidant activity and vasodilation activity. In addition, the antioxidant activity was associated with gallic acid, total resveratrol, and total catechin. In contrast, only the total anthocyanins were correlated with vasodilation activity. The results demonstrate that the different phenolic profiles of wines can produce varying antioxidant and vasodilatant activities, which opens up the possibility that some red wines may provide enhanced health benefits for the consumer.

Antioxidants↗
PubMed2004

Solar UV-B radiation affects leaf quality and insect herbivory in the southern beech tree Nothofagus antarctica.

We examined the effects of solar ultraviolet-B (UV-B) radiation on plant-insect interactions in Tierra del Fuego (55 degrees S), Argentina, an area strongly affected by ozone depletion because of its proximity to Antarctica. Solar UV-B under Nothofagus antarctica branches was manipulated using a polyester plastic film to attenuate UV-B (uvb-) and an Aclar film to provide near-ambient UV-B (uvb+). The plastic films were placed on both north-facing (i.e., high solar radiation in the Southern Hemisphere) and south-facing branches. Insects consumed 40% less leaf area from north- than from south-facing branches, and at least 30% less area from uvb+ branches than from uvb- branches. The reduced herbivory on leaves from uvb+ branches occurred for both branch orientations. Leaf mass per area increased and relative water content decreased on north- versus south-facing branches, while no differences were apparent between the UV-B treatments. Solar UV-B did lead to lower gallic acid concentration and higher flavonoid aglycone concentration in uvb+ leaves relative to uvb- leaves. Both the flavonoid aglycone and quercetin-3-arabinopyranoside were higher on north-facing branches. In laboratory preference experiments, larvae of the dominant insect in the natural community, Geometridae "Brown" (Lepidoptera), consumed less area from field-grown uvb+ leaves than from uvb- leaves in 1996-97, but not in 1997-98. Correlation analyses suggested that the reduction in insect herbivory in the field under solar UV-B may be mediated in part by the UV-B effects on gallic acid and flavonoid aglycone.

Animals↗
PubMed2001

Immunomodulatory principles of Pelargonium sidoides.

Extracts and isolated constituents (coumarins and phenols) of Pelargonium sidoides DC, a plant species used in folk medicine by the Southern African native population, were evaluated for their effects on nonspecific immune functions. Although this herbal medicine is also successfully employed in modern phytotherapy in Europe to cure infectious diseases of the respiratory tract, the scientific basis of its remedial effects is still unclear. Thus, functional bioassays including an in vitro model for intracellular infection with Leishmania parasites, an extracellular Leishmania growth assay, a fibroblast-virus protection assay (IFN activity), a fibroblast-lysis assay (TNF activity) and a biochemical assay for inorganic nitric oxides (iNO) were employed. None of the test samples revealed significant activity against extracellular, promastigote Leishmania donovani, the causative agent of human visceral leishmaniasis. In contrast, apart from the coumarin samples, all the Pelargonium extracts (EC(50) <0.1-3.3 microg/mL), gallic acid (EC(50) 4.4 microg/mL) and its methyl ester (EC(50) 12.5 microg/mL) significantly reduced the intracellular survival of L. donovani amastigotes within murine macrophages. These data indicate that the samples acted indirectly on Leishmania parasites, possibly by activating leishmanicidal macrophage functions. Macrophage activation was confirmed by detection of tumour necrosis factor (TNF-alpha) and inorganic nitric oxides (iNO) in supernatants of sample-treated macrophage cultures. Synthesis of iNO is a well-known effector mechanism of macrophages against microorganisms such as Leishmania. Interestingly, blocking iNO-synthase with L-NMMA had no substantial effect on sample-induced intracellular Leishmania kill. From bioassay-guided fractionation, gallic acid and its methyl ester present in large amounts in P. sidoides and in its active extracts, were identified as the prominent immunomodulatory principle for this herbal medicine. The results, when taken together with recent reported antibacterial activity, provide a rational basis for both the traditional and the present utilization of P. sidoides in the claimed conditions.

Animals↗
PubMedDate not supplied

[Changes in the antioxidant properties of substituted phenol polydisulfides during interaction with human serum albumin].

Gallic acid polydisulfide and poly(2-aminodisulfide-4-nitrophenol) in aqueous solutions were shown to form polycomplexes with human serum albumin. This process was accompanied by considerable changes in the spectrum of protein circular dichroism recorded in distilled water in the far UV range at 20 degrees C. Complex formation between human serum albumin and polydisulfides was followed by a marked decrease in the content of alpha-helices and increase in the count of antiparallel beta-structures in the protein. Stable complexes containing 1.5, 2.8, and 7.7 poly(2-aminodisulfide-4-nitrophenol) molecules per human serum albumin molecule were formed in bicarbonate buffer (pH 9.0). In these complexes, the secondary protein structure underwent changes similar to those in polycomplexes of human serum albumin and polydisulfides. Gallic acid polydisulfide and poly(2-aminodisulfide-4-nitrophenol) inhibited the catalase-induced degradation of 50 mM H2O2. Complexes of human serum albumin and poly(2-aminodisulfide-4-nitrophenol) increased the catalytic activity and operational stability of catalase 1.5 and 4-7-fold, respectively. This was characterized by the effective reaction rate constant (kin, s-1). Our results indicate that complexes of human serum albumin and substituted phenol polydisulfides act as potent protectors and activators of catalase during enzymatic degradation of H2O2 at high concentrations.

Animals↗
PubMed1984

In vitro interaction of neuroleptics and tricylic antidepressants with coffee, tea, and gallotannic acid.

The in vitro interaction of selected drugs with coffee, tea, gallic acid, and gallotannic acid was examined by mixing solutions of drug with each of these four preparations. Results of these experiments indicate that significant precipitation occurs for a variety of agents, including several phenothiazines, amitriptyline, haloperidol, imipramine, and loxapine. The strong complex which is formed between these drugs and tannins is probably the basis of the interaction of these drugs with coffee and tea. Although precipitates did occur with a number of neuroleptics, two members of this drug class, thiothixene and molindone, failed to interact with the solutions used.

Antidepressive Agents, Tricyclic↗