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PubMed2004

Potential anti-atherogenic cell action of the naturally occurring 4-O-methyl derivative of gallic acid on Ang II-treated macrophages.

We have recently established that the blood concentrations of gallic acid (GA), a polyphenolic component naturally found in food, and its O-methyl derivatives are very low (practically < or = 1 microM) in physiological (postprandial) condition. Using acellular oxidant systems and macrophage-differentiated promonocytes (MDPs) THP-1, we show here that the direct and indirect (through depressing effect on the superoxide cell production) antioxidant properties of these components were not effective at these concentrations. In contrast, 4-O-methyl GA was the most efficient component to depress AT1R and CD36 mRNA expression in Ang II-treated MDPs, suggesting a strong inhibition of Ang II-triggered pro-atherogenic mechanisms of foam cell formation.

Angiotensin II↗
PubMedDate not supplied

Application of semiempirical method to estimate the cytotoxic activity of gallic acid and its related compounds.

The semiempirical method was applied to estimate the cytotoxic activity of 9 gallic acid derivatives against human promyelocytic leukemic HL-60 cells. Positive correlation was found between their 50% cytotoxic concentration (CC50) value and the heat of formation or total energy, but not between the CC50 value and size of the molecule (determined either by the length of the side chains, the largest distance of the molecule, the distance from R2 to carbonyl C or benzene ring C, or by Van der waals area). When CC50 value was plotted vs octanol/water partition coefficient (log P), parabolic curve, with a bottom at log P = 3-4, was produced, in a similar fashion to vitamin K, prenylflavanone and eugenol-related compounds. The present study suggests the usefulness of the semiempirical method to estimate the cytotoxicity of structurally related compounds.

Drug Screening Assays, Antitumor↗
PubMed2000

Gallic acid induces vascular smooth muscle cell death via hydroxyl radical production.

In the present study, we investigated whether gallic acid (GA) can induce death in cultured vascular smooth muscle cells (VSMCs), and whether production of the hydroxyl radical (.OH) is involved in the process of GA action. GA killed cultured VSMCs from rat aorta, in a dosc- and time-dependent manner. Cytoplasmic shrinkage and nuclear condensation were observed light microscopically in GA-treated VSMCs, which appeared apoptotic. However, the ultrastructure of the VSMC was not typical of apoptosis: nuclear condensation was not glossy, and the plasma membrane and subccellular organelles were disrupted. Although the VSMC were positive for in situ nick end-labeling (TUNEL). they did not show a DNA ladder pattern on gel electrophoresis and were negative for T aq polymerase-based in situ ligation, which is more specific for apoptosis than TUNEL. Moreover. GA-induced cell death was not prevented by Boc-Asp-fmk (a pan-caspase inhibitor). Production of OH was detected in GA-treated VSMCs using high-performance liquid chromatography with salicylic acid as a trapping agent. Lipid peroxidation was also observed. The production of .OH was inhibited by catalase (CAT) and deferoxamine (DFX), and these treatments completely rescued VSMCs from cell death. In a cell-free system, GA produced .OH in the presence of Fe2+-EDTA, which was quenched by CAT and DFX, suggesting involvement of the Haber-Weiss reaction. Oxidative stress by reactive oxygen species, .OH in particular, is one of the mechanisms of GA-induced death of VSMCs, the mode of which was different from typical apoptosis.

Animals↗
PubMed2000

Simultaneous analysis of tea catechins, caffeine, gallic acid, theanine and ascorbic acid by micellar electrokinetic capillary chromatography.

A micellar electrokinetic capillary chromatography (MEKC) method for the simultaneous analysis of five tea catechins, theanine, caffeine, gallic acid and ascorbic acid has been developed. The catechins are (-)-epicatechin, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate and (-)-epigallocatechin gallate. p-Nitrophenol serves as both reference and internal standard. All the components are separated within 13 min with a 57 cm uncoated fused-silica column. On-column detection was carried out at 200 nm. This method has been used to measure these compounds in fresh tea leaves and tea liquor. The limit of detection for all analytes ranged from 1 to 20 microg/ml.

Ascorbic Acid↗
PubMed1990

[Synthesis of gallic acid derivatives with L-thiazolidin-4-carboxylic acid and study on their antiradical and antitoxic activity].

The authors report the synthesis of three new derivatives of gallic acid with L-thiazolidine-4-carboxylic acid. The new compounds were tested for radical scavenger activity against doxorubicin toxicity in mice and for antitoxic activity against acetaldehyde and formaldehyde toxicities in rats. Unlike the utilized standards, the new compounds show no activity.

Acetaldehyde↗
PubMed2000

Effect of gallic acid polydisulfide on activity and stability of catalase in various media.

The effect of the active bioantioxidant polydisulfide of gallic acid (PDSG) on the catalytic activity and operational and thermal stability of catalase was studied in three media: distilled water (pH approximately 5.6), phosphate buffer, pH 7.4, and reversed micelles of Aerosol OT (AOT) in heptane of varied hydration degree w0. PDSG inhibited the catalase-induced decomposition of H2O2 by the mixed or noncompetitive mechanism: in various media the inactivation constant Ki varied in the range of (0.63-2.32).10-5 M. PDSG nearly twofold decreased the rate constant of interaction of the complex I of catalase with H2O2 (k2, M-1.sec-1) in water and reversed micelles of AOT and 3-5 times increased the effective rate constant of catalase thermal inactivation, k*in, sec-1, depending on the reaction medium. PDSG significantly decreased the rate constant of catalase inactivation during the enzymatic reaction, kin, sec-1, and thus increased the enzyme operational stability in water and reversed AOT micelles in heptane. The interaction of PDSG with catalase in water and in phosphate buffer was accompanied by significant changes in CD spectra in the far UV-region that indicated disturbances in the secondary structure of catalase subunits induced by the bioantioxidant; the latter was suggested to initiate the reaction of thiol--disulfide exchange with the enzyme. The problem of the compatibility of catalase with disulfide bioantioxidants is discussed.

Animals↗
PubMed2004

A gallic acid derivative and polysaccharides with antioxidative activity from rose (Rosa rugosa) flowers.

In this study, the major antioxidant components of rose flower were identified. An aqueous extract of rose flowers was chromatographed on CM-cellulose in ammonium acetate buffer (10 mM, pH 4.5) to yield three un-adsorbed peaks F1, F2 and F3. Each of these peaks was subjected to gel filtration on Sephadex G75. F1 yielded two peaks, whereas both F2 and F3 gave rise to only a single peak. Spectroscopic studies using NMR and FTIR revealed that F3 is a gallic acid derivative. It exhibited the highest antioxidative potency. F1-a derived from F1 by gel filtration is mainly a polysaccharide-peptide complex with less potent antioxidative activity. F2 is a polysaccharide also with reduced antioxidant activity. This study demonstrates, for the first time, the presence of both gallic acid derivatives and polysaccharides as major antioxidant principles of the aqueous extract of rose flowers.

Animals↗
PubMed1999

The involvement of K+ channels and Gi/o protein in the antinociceptive action of the gallic acid ethyl ester.

The anti-hyperalgesic action, antinociception, and also the possible mechanisms involved in the action of gallic acid ethyl ester (GAEE) isolated from the aerial part of Phyllanthus urinaria, have been investigated in different models of chemical, mechanical and thermal nociception in mice and rats. GAEE given by intraperitoneal (i.p.), oral (p.o.), intrathecal (i.t.) or by intracerebroventricular (i.c.v.) routes produced dose-related antinociception when assessed against chemical nociception in mice. GAEE significantly inhibited the hyperalgesia induced by bradykinin or substance P in rat paw, but did not affect the hyperalgesia caused by carrageenan or prostaglandin E2. Furthermore, GAEE, in contrast to morphine, was completely ineffective in the hot-plate test in mice. The antinociception produced by GAEE (i.p.) in the formalin test was significantly reversed by i.c.v. treatment of animals with pertussis toxin and by i.t. administration of K+ channel blockers such as apamin, charybdotoxin or glibenclamide, but not by tetraethylammonium. In contrast, GAEE (i.p.) antinociception was unaffected by i.p. treatment of animals with naloxone or by nitric oxide precursor, L-arginine, and this action was not secondary to its anti-inflammatory effect, nor was it associated with non-specific effects such as muscle relaxation or sedation. Thus, GAEE produces dose-dependent and pronounced systemic, spinal and supraspinal antinociception in mice, probably via activation of K + channels and by a Gi/o pertussis toxin-sensitive mechanism.

Analgesics↗
PubMed2005

Environmental effects on the spectroscopic properties of gallic acid: a combined classical and quantum mechanical study.

The solvation of gallic acid (in water and acetonitrile) is studied by means of its spectroscopic properties. IR, UV, and NMR spectra are predicted by using various solvation models obtained in terms of both purely classical and density functional approaches. Comparison with experiments is used to validate solvation models. Hydrogen-bond and long-range (or bulk) effects are evaluated by comparing different solvation models. A continuum-only approach, a purely discrete, and a mixed continuum/discrete approach based on quantum-mechanical and classical molecular-dynamics solute-solvent clusters are tested.

Journal Article↗
PubMed1996

Time- and dose-dependent antigonadotropic activity of oxidation products of gallic acid and pyrogallol on Leydig cells in vitro.

Auto-oxidation products of plant phenolics in alkaline medium, such as gallic acid and pyrogallol were used to show antigonadotropic activity. The complex mixture of oxidation products was extracted from aqueous medium successively by ethyl ether and ethyl acetate. The fractions obtained were tested on a model of mouse Leydig cells in vitro. All compounds used inhibited luteinizing hormone-stimulated testosterone secretion during 6 and 24 h culture whereas basal secretion was stimulated by pyrogallol oxidation products. Not only low molecular weight substances extracted by organic solvents but also the remaining water soluble, dark brown, high molecular weight products were found to be antigonadotropically active.

Animals↗
PubMed2001

Different generation of inhibitors against gallic acid-induced apoptosis produces different sensitivity to gallic acid.

Gallic acid (3,4,5-trihydroxybenzoic acid), a naturally occurring plant phenol, showed selective cytotoxicity against tumor cells with higher sensitivity than normal cells such as hepatocytes and keratinocytes. To elucidate the difference in sensitivity between normal and tumor cells to gallic acid, we studied whether the inhibitor of gallic acid-induced apoptosis existed or not. A serum-free conditioned medium, prepared from high density rat primary cultured hepatocytes and cytoplasm of hepatocytes, prevented gallic acid-induced apoptosis. In contrast, hepatomas and hepatic cell lines such as dRLh-84, PLC/PRF/5, HLE, and HUH and two other kinds of tumor cell, HeLa and KB, scarcely generated such an inhibitor in either their conditioned medium or their cells. Biochemical characterization of the inhibitors revealed that the inhibitor in the hepatocyte conditioned medium was completely inactivated by heating at 65 degrees C for 10 min. Its molecular weight was estimated at 150-250 kDa by gel filtration column chromatography, indicating that the inhibitor may be a protein-like substance. These results suggest that the generation of a large amount of the inhibitor may endow hepatocytes with insensitivity to gallic acid. In conclusion, the difference in the amount of the inhibitors generated by hepatocytes and tumor cells should contribute to the underlying mechanism in the difference in sensitivity of cells to gallic acid.

Animals↗
PubMed1998

Mechanism of the protective effects of sumac gall extract and gallic acid on the progression of CCl4-induced acute liver injury in rats.

To examine the mechanism of the preventive effect of tannins on the progression of carbon tetrachloride (CCl4)-induced acute liver injury in rats, sumac gall (SG) extract and gallic acid (GA) were used as substitutes for crude tannins, because SG is a kind of Chinese traditional medicinal herb containing large amounts of various tannins, and GA is one of the major constituents of SG. The protective effect of oral (p.o.) and intraperitoneal (i.p.) administration of each substance on progression of CCl4-induced hepatitis was investigated in rats. Speculating that the superoxide dismutase (SOD)-like activities (O2 radical-scavenging activities) and/or protective effects of these substances on cell membranes might play a key role in the mechanism opposing the progression of CCl4-induced hepatitis, the O2 radical-scavenging activities in liver cells and serum in rats were monitored. Both substances significantly prevented the progression of acute liver injury with both p.o. and i.p. administration. These findings suggest that the mechanism for this prevention might be due mainly to the protective effect of these substances on cell membranes rather than O2 radical-scavenging activities.

Acute Disease↗
PubMed2005

Gallic acid antagonizes P-selectin-mediated platelet-leukocyte interactions: implications for the French paradox.

BACKGROUND: Current paradigm attributes the low incidence of cardiovascular disorders in Mediterranean countries despite a high saturated fat intake, the "French paradox," to the antioxidant capacity of red wine polyphenols. Conceivably, other antiinflammatory pathways may contribute to at least a similar extent to the atheroprotective activity of these polyphenols. We have investigated whether gallic acid (GA), an abundant red wine polyphenol, modulates the activity of P-selectin, an adhesion molecule that is critically involved in the recruitment of inflammatory cells to the vessel wall and thus in atherosclerosis. METHODS AND RESULTS: GA potently inhibited the binding of a peptide antagonist (IC50, 7.2 micromol/L) and biotin-PAA-Le(a)-SO3H, an established high-affinity ligand, to P-selectin (IC50, 85 micromol/L). Under dynamic flow conditions, GA markedly and dose dependently attenuated the rolling of monocytic HL60 cells over P-selectin-transfected Chinese hamster ovary cells (EC50, 14.5 micromol/L) while increasing the velocity of P-selectin-dependent rolling of human blood leukocytes over a platelet monolayer. In vivo tests established that GA administration to normolipidemic C57/Bl6 and aged atherosclerotic apolipoprotein E-deficient mice impaired the baseline rolling of conjugates between activated platelets and circulating monocytes over femoral vein endothelium, as judged by online video microscopy (ED50, 1.7+/-0.3 and 1.5+/-0.4 mg x kg(-1) x h(-1), respectively). CONCLUSIONS: Our findings provide a solid mechanistic foundation through which GA intervenes in major inflammatory pathobiologies by binding and antagonizing P-selectin.

Acrylamides↗
PubMed1997

Inhibition of solubilized superoxide dismutase co-immobilized with catalase by the polydisulfide of gallic acid.

The catalytic activity of superoxide dismutase (SOD) and its conjugates with catalase and polymer peroxidase (p-peroxidase) obtained during covalent binding of enzymes with aldehyde dextrans was indirectly characterized by inhibition of adrenaline autoxidation in 0.1 M bicarbonate buffer, pH 10.2, and in microemulsion of 0.1 M aerosol OT (AOT) and Triton X-45 in octane containing 15% aqueous phase. The polydisulfide of gallic acid (PDGA) effectively inhibited SOD and its conjugates by a mixed mechanism. The inhibition constants Ki for SOD and its conjugate (SOD-catalase)mic in 0.1 M bicarbonate buffer, pH 10.2, were 0.1 and 0.25 microM, respectively. Autoxidation of PDGA by molecular oxygen in alkaline media (pH 10.2) influenced its inhibitory properties in buffer solution and microemulsion of AOT and Triton X-45 in octane. The radical chain mechanism of co-oxidation of adrenaline and PDGA apparently includes the anion radical O2-. as a coupling agent which propagated the chain.

Animals↗
PubMed2006

Phenolics of Arbutus unedo L. (Ericaceae) fruits: identification of anthocyanins and gallic acid derivatives.

Arbutus unedo L., the strawberry tree (Ericaceae family), is an evergreen shrub or small tree, typical of the Mediterranean fringe and climate. The aim of the present study was to evaluate the profile of the phenolic constituents of A. unedo fruits. Seven compounds were purified by Sephadex LH-20 column chromatography of the MeOH extract followed by HPLC and were characterized as arbutin, beta-D-glucogalline, gallic acid 4-O-beta-D-glucopyranoside, 3-O-galloylquinic acid, 5-O-galloylquinic acid, 3-O-galloylshikimic acid, and 5-O-galloylshikimic acid, by means of NMR and ESI-MS analyses. Moreover, LC-PDA-MS analysis of the red pigment of A. unedo fruits revealed the presence of three anthocyanins recognized as cyanidin 3-O-beta-D-galactopyranoside, delphinidin 3-O-beta-D-glucopyranoside, and cyanidin 3-O-beta-D-arabinopyranoside. These pigments were also quantified.

Anthocyanins↗
PubMed2006

Fractionation of grape seed extract and identification of gallic acid as one of the major active constituents causing growth inhibition and apoptotic death of DU145 human prostate carcinoma cells.

The anti-cancer efficacy of grape seed extract (GSE) against prostate cancer (PCA) via its anti-proliferative, pro-apoptotic and anti-angiogenic activities in both cell culture and animal models have recently been described by us. GSE is a complex mixture containing gallic acid (GA), catechin (C), epicatechin (EC) and several oligomers (procyanidins) of C and/or EC, some of which are esterified to GA. To determine which components are most active against PCA, an ethyl acetate extract of GSE was separated by reverse-phase high-performance liquid chromatography (HPLC) into three fractions. Fraction 1 was far more effective than others in causing growth inhibition and apoptotic death of human PCA DU145 cells. Of the components in this fraction, GA showed a very strong dose- and time-dependent growth inhibition and apoptotic death of DU145 cells, but C and procyanidins B1 (EC-C dimer), B2 (EC-EC dimer) and B3 (C-C dimer) were nearly ineffective. Mechanistic studies demonstrated a strong caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavages by GA in DU145 cells. Procyanidin oligomers eluting in HPLC Fractions 2 and 3 were obtained in larger quantities by separating GSE into eight fractions (I-VIII) on a gel filtration column. All fractions were analyzed by HPLC-UV and negative-ion electrospray mass spectrometry. Fractions I-III contained the active compound GA and inactive components C, EC, B1 and B2. Fraction IV contained other dimers and a dimer-GA ester and was also less active than GSE in DU145 cells. Fractions V-VIII, however, caused significant growth inhibition and apoptosis with the highest activity present in the later fractions that contained procyanidin trimers and GA esters of dimers and trimers. Together, these observations identify GA as one of the major active constituents in GSE. Several procyanidins, however, and especially the gallate esters of dimers and trimers also may be efficacious against PCA and merit further investigation.

Adenocarcinoma↗