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At least 127 records · Page 7Linked to original sources
PubMed2005

[Determination of gallic acid in Melastoma dodecandrum by RP-HPLC].

OBJECTIVE: To establish a RP-HPLC method for the determination of gallic acid in Chinese herb Melastoma dodecandrum, and to evaluate the quality of the herb. METHOD: The RP-HPLC analysis was achieved by using a Polaris C18 column and tetrahydrofuran-methanol-0.2% phosphoric acid (0.5:0.5:99) as the mobile phase, with a flow rate of 1.0 mL x min(-1), and detected by UV at 274 nm. RESULT: The content of gallic acid was from 0.020% to 0.081%, in ten groups of M. dodecandrum collected from different locations. CONCLUSION: The method is a simple, convenient and rapid. It can be used for quality evaluation of M. dodecandrum.

China↗
PubMed2006

Gallic acid and tannase accumulation during fungal solid state culture of a tannin-rich desert plant (Larrea tridentata Cov.).

Larrea tridentata (Sesse & Mocino ex DC.) Coville, also known as Larrea, gobernadora, chaparral, or creosote bush, is a shrubby plant which dominates some areas of the desert southwest in the United States and Northern Mexico and its use has not been exploited and standardized. In this study, gobernadora was studied to evaluate its potential use for support of solid state culture. Influence of two minimal media added with gobernadora powder as the sole carbon source and inducer of tannin-degrading enzymes was evaluated. Cultures were initially 70% moisture, had a pH of 5.5 and were inoculated with Aspergillus niger Aa-20 at 2 x 10(7) spores per gram of media. Analysis of pH, moisture, tannin uptake, gallic acid accumulation and tannase production were evaluated. Results indicated a high content of condensed (39.4%dm) and hydrolysable (22.8%dm) tannins. Invasion capacity of fungal growth was of 0.15 mmh(-1). Tannase production reached values of 1040 Ul(-1) at 43 h of culture. During the first 48 h of culture, the concentration of gallic acid accumulation was 0.33 gl(-1). Gobernadora is a potential source of gallic acid and tannase production by solid state culture; however, further optimization of the process is needed.

Aspergillus niger↗
PubMed2004

A comparative study of quantitative structure-activity relationship methods based on gallic acid derivatives.

By using hologram quantitative structure-activity relationship (HQSAR) and comparative molecular field analysis (CoMFA) methods, the relationships between the structures of 49 gallic acid derivatives and their analgesic activity have been investigated to yield statistically reliable models with considerable predictive power. The best HQSAR model was generated using atoms, bond and connectivity as fragment distinction parameters and fragment size 5-7 from a hologram length of 307 with 3 components. High conventional r2 (r2 = 0.825) and cross-validation r2 (r2(cv) = 0.726) values were obtained. CoMFA analyses varying lattice size and location, grid spacing, probe charges and using, Tripos standard and Indicator force field were performed. The best model was developed with 4 components using sp3-hybridized carbon atom with +1.0 charge as probe, grid spacing (2 A), lattice offset (1.0, 3.0, -2.5). The CoMFA model showed a conventional correlation coefficient r2 of 0.889 and across-validation r2(cv) equals to 0.633. The robustness and predictive ability of the HQSAR and CoMFA models have been validated by means of an external test set. The results indicate that both models possess high statistical quality in the prediction of analgesic potency of novel gallic acid analogs.

Forecasting↗
PubMed2001

Pharmacokinetics of gallic acid and its relative bioavailability from tea in healthy humans.

Gallic acid (GA), a food component that is especially abundant in tea, is an antimutagenic, anticarcinogenic and anti-inflammatory agent. We conducted a study using acidum gallicum tablets that contained 10% GA and 90% glucose and a black tea brew that contained 93% of its GA in free form to determine the pharmacokinetics and relative bioavailability of GA in healthy humans. After the administration of a single oral dose of acidum gallicum tablets or tea (each containing 0.3 mmol GA) to 10 volunteers, plasma and urine samples were collected over various time intervals. Concentrations of GA and its metabolite, 4-O-methylgallic acid (4OMGA), were determined, and the pharmacokinetic parameters were calculated. GA from both the tablets and tea was rapidly absorbed and eliminated with mean half-lives of 1.19 +/- 0.07 and 1.06 +/- 0.06 h and mean maximum concentrations of 1.83 +/- 0.16 and 2.09 +/- 0.22 micromol/L (plasma), respectively. After oral administration of the tablets and black tea, 36.4 +/- 4.5 and 39.6 +/- 5.1% of the GA dose were extracted in urine as GA and 4OMGA, respectively. The relative bioavailability of GA from tea compared with that from the tablets was 1.06 +/- 0.26, showing that GA is as available from drinking tea as it is from swallowing tablets of GA.

Adult↗
PubMed2004

Phenolic acid derivatives with potential anticancer properties--a structure-activity relationship study. Part 1: methyl, propyl and octyl esters of caffeic and gallic acids.

The antiproliferative and cytotoxic properties of polyphenolic acid derivatives, structurally related with the natural models caffeic and gallic acids, have been tested in human cervix adenocarcinoma cells (HeLa). Simultaneous structural information was obtained for these compounds through theoretical ab initio methods. This study was conducted for the following esters: methyl caffeate (MC, 1), propyl caffeate (PC, 2), octyl caffeate (OC, 3), methyl gallate (MG, 4), propyl gallate (PG, 5) and octyl gallate (OG, 6). A significant growth-inhibition effect was assessed for some of these compounds, clearly dependent on their structural characteristics. Marked structure-activity relationships (SARs)--namely the number of hydroxyl ring substituents--were found to rule the biological effect of such systems.

Antineoplastic Agents↗
PubMed1998

Formation of reactive oxygen intermediates might be involved in the trypanocidal activity of gallic acid.

We investigated the mechanism of the trypanocidal activity of gallic acid (GA). GA-induced trypanocidal activity was significantly reduced by pretreatment with superoxide dismutase (SOD) and/or catalase. The ESR technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent revealed that a DMPO-OH adduct was detected in culture medium containing GA. The intensity of ESR signals of the DMPO-OH adduct was increased in a time dependent manner. SOD also inhibited the formation of GA-induced DMPO-OH adducts. Furthermore, GA enhanced DNA single-strand breaks induced by Fenton reagent. These results suggest the possibility that GA acts as pro-oxidant for trypanocidal activity.

Animals↗
PubMed2001

Subchronic toxicity study of gallic acid by oral administration in F344 rats.

Subchronic toxicity of gallic acid (GA) was investigated in F344 rats by feeding diet containing 0, 0.2, 0.6, 1.7 and 5% GA for 13 weeks. Each group consisted of 10 rats of each sex. Toxicological parameters included clinical signs, body weight, food consumption, hematology, blood biochemistry, organ weights and histopathological assessment. Body weight gain in the 5% GA-treated animals of both sexes from week 1 to the end of the experiment was significantly lower than that of the untreated controls. Toxic effects following administration of 0.6% or more in males and 5% in females included reduction of hemoglobin concentration, hematocrit and red blood cell counts and increase in reticulocytes. Histopathologically, extramedullary hematopoiesis, hemosiderin deposition and congestion appeared in the spleens of 5% GA-treated animals, suggesting development of hemolytic anemia. In addition, centrilobular liver cell hypertrophy, reflected in increase in liver weight, was observed in animals of both sexes from 1.7%. In the kidney, Berlin blue-negative brown pigment deposition in the proximal tubular epithelium was observed at 5% GA. However, the severity of these pathological changes was weak. Based on the present toxicology data, 0.2% was determined to be a no-observed-adverse-effect level (NOAEL) in rats. This level was translated into 119 and 128 mg/kg/day, respectively for male and female rats.

Animals↗
PubMed2003

Red-wine beneficial long-term effect on lipids but not on antioxidant characteristics in plasma in a study comparing three types of wine--description of two O-methylated derivatives of gallic acid in humans.

The purpose of this double clinical study was (1) to evaluate the effect of one single intake (300 ml) of red wine (RW) on the plasma antioxidant capacity (pAOC) and plasma phenolics over the 24-h time period following the intake, and (2) to compare the long-term effects of daily intakes (250 ml/d) of RW, white wine (WW) and Champagne (CH) on the plasma and LDL characteristics of healthy subjects. In the first part, blood samples were collected just before and after wine consumption. In the second part, subjects received the 3 types of wine successively, only at the mealtime, over 3-week periods separated by a 3-week wash out. Blood samples were drawn in fasting condition before and after each 3-week wine consumption period. The peak of pAOC was at 3-4 h following the single intake of RW, that of catechin was at 4 h (0.13 micromol/l) and that of gallic acid and caffeic acid was earlier (< or = 1.5 and 0.3 micromol/l, respectively). In plasma, the major form of gallic acid was 4-O-methylated, but a minor form (the 3-O-methyl derivative) appeared. In the long term study, no wine was able to change LDL oxidizability, but some other parameters were modified specifically: RW decreased pAOC (without changing TBARS and uric acid plasma levels), LDL lipids and total cholesterol (TC), and increased plasma apoA1, whereas CH increased plasma vitamin A. The beneficial effect of RW seems to mainly be explained by its action on lipid and lipoprotein constants, and not by its antioxidant one.

Adult↗
PubMed1992

Antiasthmatic effects of Galphimia glauca, gallic acid, and related compounds prevent allergen- and platelet-activating factor-induced bronchial obstruction as well as bronchial hyperreactivity in guinea pigs.

A methanolic extract from Galphimia glauca (320 mg/kg, orally) inhibited acute bronchial reactions to allergen (ovalbumin, 10 mg/ml) and platelet-activating factor (PAF, 1 microgram/ml) inhalation challenges, but not to histamine or acetylcholine in spontaneously breathing guinea pigs. Furthermore, the PAF-induced bronchial hyperreactivity was markedly reduced. Gallic acid and related compounds as well as the flavonoid, quercetin, were identified as active compounds. Gallic acid, methyl gallate and quercetin showed significant effects after a single oral dose of 45 mg/kg, tetragalloyl quinic acid after 5 mg/kg. Continuous treatment of the animals with one certain fraction (GG II, 3 days, 3 x 2 mg/kg) containing all active compounds reduced allergen- and PAF-induced bronchial reactions by more than 70%.

Animals↗
PubMedDate not supplied

[Gallic acid: a potent inhibitor of tetramethylbenzidine peroxidation in aqueous and micellar media].

Gallic acid competitively inhibited 3,3',5,5'-tetramethylbenzidine peroxidation both in 0.01 M phosphate buffer (pH 6.4) (KI 13.3 microM) and in reversed aerosol OT micelles of different hydration degrees dispersed in heptane (KI 21.3 to 29.3 microM). The average number of free radical particles terminated by one inhibitor molecule (f) was estimated to be 1.3 to 1.6 in aqueous buffer solutions and 1.08 to 2.72 in reversed micelles, depending on their hydration.

Benzidines↗
PubMed2004

Synergistic effect of antioxidant phenolic acids on human phenolsulfotransferase activity.

Sulfate conjugation by phenolsulfotransferases (PSTs) is an important process in the detoxification of xenobiotics and endogenous compounds. There are two forms of PSTs for the sulfation of small phenols (PST-P) and monoamines (PST-M). Phenolic acids are known to increase the activities of PST-P and PST-M. The purpose of this study is to investigate the synergistic effect of the combinations of phenolic acids on human PSTs activities. The combinations of p-hydroxybenzoic acid, gentisic acid, ferulic acid, gallic acid, and coumaric acid in a random order for their effects on PSTs activities were evaluated at concentrations of 2.5, 5.0, and 7.5 microM. The PST-M activity was significantly increased when gentisic acid was combined with each of the other phenolic acids. When p-hydroxybenzoic acid was combined with each of the other phenolic acids, a synergistic effect with respect to the promotion of PST-P activity was obtained. A potential synergistic effect for the PST-P activity was also found in the following combination: p-hydroxybenzoic acid + gallic acid + gentisic acid, p-hydroxybenzoic acid + gallic acid + m-coumaric acid, p-hydroxybenzoic acid + o-coumaric acid + p-coumaric acid, p-hydroxybenzoic acid + o-coumaric acid + m-coumaric acid, gallic acid + gentisic acid + p-coumaric acid, and gallic acid + o-coumaric acid + m-coumaric acid. Therefore, the activities of both forms of PSTs can be promoted by all of these combinations of phenolic acids. These results provide a better understanding regarding the effect of phenolic acids on human PSTs activities, as well as more information on the intake of antioxidant phenolic acids for human health.

Antioxidants↗
PubMed2005

[Study on the qualitative and quantitative methods of gallic acid in pomegranate rind].

OBJECTIVE: To establish the qualitative and quantitative methods of gallic acid in pomegranate rind. METHOD: The thin layer chromatographic method was used for identitication, and the high performance liquid chromatographic method was used for assay. Extracts were separated on a Diamonsil C18 column eluted with the mobile phase of a mixture of acetonitrile containing 0.2% methanol and water containing 0.1% phosphoric acid and 0.1% TEA (3:97). The detection wavelength was set at 216 nm, and colum temperature was 40 degrees C. RESULT: The calibration curve was linear in the range of 0.085-0.768 microg (r = 0.9996). The average recovery was 96.7% (RSD 0.8%, n = 5). 20 batches of the crude drug were identified and assayed, with the methods. CONCLUSION: The methods were sensitive and reliable, and can be used for quality control of the pomegranate rind.

Chromatography, High Pressure Liquid↗
PubMed1999

Influence of hydration degree of aerosol OT reversed micelles in heptane on inhibitory effect of gallic acid polydisulfide in peroxidase-dependent oxidation of 3,3;,5,5;-tetramethylbenzidine.

Gallic acid polydisulfide (GAPD) inhibits with high efficiency tetramethylbenzidine (TMB) peroxidation at 20 degreesC in reversed aerosol OT (AOT) micelles in heptane with various hydration degrees w0 ranging from 8.3 to 47.2. Like in aqueous medium, the inhibition constant Ki for GAPD is approximately 10(-6) M and decreases with increasing w0 from 15.3 to 25. In AOT micelles with various hydration degree, the initial rates of TMB oxidation catalyzed by peroxidase were determined in the absence of GAPD (v0). Using the dependencies of the induction time of TMB peroxidation on the initial GAPD concentration, the values of the stoichiometric coefficient for inhibition by GAPD (f) were calculated at various hydration degrees of AOT micelles. Increase of hydration degree of AOT micelles is accompanied by a decrease of coefficient f from 30-31 (at low hydration degree) to 11.5-12.5 (at w0 > 30), and this significantly exceeds the f values (2) typical for most known inhibitors.

Benzidines↗
PubMed2006

Gallic acid inhibits ribonucleotide reductase and cyclooxygenases in human HL-60 promyelocytic leukemia cells.

Gallic acid (GA) is a naturally occurring polyhydroxyphenolic compound and an excellent free radical scavenger. In this study, we examined its cytotoxic and biochemical effects on the human HL-60 promyelocytic leukemia cell line. GA caused a significant imbalance of deoxynucleosidetriphosphate (dNTP) pool sizes, indicating ribonucleotide reductase inhibition. Moreover, GA induced dose-dependent apoptosis in HL-60 cells (80microM GA led to the induction of apoptosis in 39% of cells) and attenuated progression from G0/G1 to the S phase of the cell cycle (60microM GA doubled the number of cells in G0/G1 phase from 22 to 44% when compared to untreated controls). We further determined IC(50) values of 3.5 and 4.4nM for the inhibition of cyclooxygenases I and II, respectively. When cells were simultaneously treated with GA and trimidox, another inhibitor of RR, highly synergistic growth inhibitory effects could be observed. Taken together, we identified novel biochemical effects of GA which could be the basis for further preclinical and in vivo studies.

Adenosine Triphosphate↗
PubMed2002

Synthesis of novel polyphenols consisted of ferulic and gallic acids, and their inhibitory effects on phorbol ester-induced Epstein-Barr virus activation and superoxide generation.

We prepared novel polyphenols which were esters composed of two naturally occurring products, ferulic and gallic acids, and investigated their inhibitory effects on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus (EBV) activation and superoxide (O2-) generation. Most of these compounds exhibited significant EBV activation suppression at a concentration of 20 microM and in particular, the ester 5f having 2-methyl-1-butyl group showed high activity. The suppressive effects on O2- generation were also observed in most of the esters.

Coumaric Acids↗
PubMed1998

Derivatives of gallic acid induce apoptosis in tumoral cell lines and inhibit lymphocyte proliferation.

The effect of gallic acid (3,4,5-trihydroxybenzoic acid) and its alkyl esters (methyl, propyl, octyl, and lauryl) has been studied on several tumoral and nontumoral cells. Three types of behavior have been observed; the first type is represented by the mouse B cell lymphoma Wehi 231 cell line in which death occurs according to the biochemical characteristics of classical apoptosis showing the DNA ladder fragmentation pattern. The second type is represented by the mouse fibroblast L929 cell line in which morphological characteristics such as cell shrinkage, chromatin condensation, and appearance of apoptotic bodies can be evidenced by microscopical observation. However, the typical DNA fragmentation is absent. Peripheral blood lymphocytes are representative of a third type of behavior. In a resting state they can withstand higher concentrations of these compounds. If the drug is washed, they proliferate normally upon the addition of the mitogen phytohemagglutinin (PHA). However, if the drug is added in the presence of PHA, a clear antiproliferative effect can be demonstrated. A special interest for these compounds stems from the fact that some of them are currently used as antioxidant food additives with the European Community codes E-310 (propylgallate), E-311 (octylgallate), and E-312 (laurylgallate).

Animals↗
PubMed1976

Effects of gallic acid and of ethanol on formation of nitrosodiethylamine.

In vitro experiments demonstrate that the polyphenol, gallic acid, can both catalyse and inhibit NDEA formation. The products of reaction depend considerably on pH conditions and relative concentrations of the reactants. Therefore, interpretation of in vitro experiments in terms of possible in vivo effects in a given population must take into consideration detailed information on eating and drinking habits which might affect pH conditions and relative concentrations of the reactants in the digestive tract. In this respect, it is interesting to note that epidemiological studies conducted by the agency (Day 1) indicate that tea, which contains gallotannins, is consumed more frequently but in a more diluted brew in the area of high oesophageal cancer incidence of the Caspian littoral than in the low incidence area. Our preliminary study on ethanol suggests that its effects will be found to lack the complications present with the tannins and would thus be more easily extrapolated to in vivo situations.

Catalysis↗