SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Values of ID50 for a collection of structurally-related gallic acid derivatives have been employed to create a predictive quantitative structure-activity relationship (QSAR) which links structure to values of analgesic activity. The QSAR model developed has substantial predictive power for the design of novel gallic acid derivatives having improved analgesic potency.
Terminalia belerica Roxb. is one of the oldest medicinal herb of India, is an ingredient of Indian Ayurvedic drug 'triphala' used for the treatment of digestion and liver disorders. Present study is aimed to evaluate the protective effect of Terminalia belerica fruit extract and its active principle, gallic acid (3,4,5-trihydroxybenzoic acid) at different doses against carbon tetrachloride intoxication. Toxicant caused significant increase in the activities of serum transaminases and serum alkaline phosphatase. Hepatic lipid peroxidation level increased significantly whereas significant depletion was observed in reduced glutathione level after carbon tetrachloride administration. A minimum elevation was found in protein content on the contrary a significant fall was observed in glycogen content of liver and kidney after toxicant exposure. Activities of adenosine triphosphatase and succinic dehydrogenase inhibited significantly in both the organs after toxicity. Treatment with TB extract (200, 400 and 800mg/kg, p.o.) and gallic acid (50, 100 and 200mg/kg, p.o.) showed dose-dependent recovery in all these biochemical parameters but the effect was more pronounced with gallic acid. Thus it may be concluded that 200mg/kg dose of gallic acid was found to be most effective against carbon tetrachloride induced liver and kidney damage.
Oxidative stress, produced as a consequence of normal metabolism or induced by extraneous stimuli, has been proved to be a mediator of cell death. The inherent antioxidant defense system and exogenous antioxidants can help the body to combat this oxidative stress-induced cell death. In this study, we explored the antiapoptotic potential of gallic acid, a dietary phenolic having antioxidative and anticarcinogenic properties, in normal human peripheral blood lymphocytes (PBLs). Incubation of PBLs with 100 microM H2O2 for 1.5-2.0 h induced phosphatidyl serine externalisation, lipid peroxidation and high molecular weight DNA fragmentation. Pretreatment of lymphocytes with gallic acid for 18 h could effectively inhibit lipid peroxidation and apoptosis induced by oxidative stress. Treatment of PBLs with gallic acid failed to induce any change in the expression of Bcl-2, an antiapoptotic protein. It seems that the protection provided by gallic acid was due to its direct action in the scavenging of free radicals as it was found to be a stronger antiradical than trolox, a water- soluble analogue of vitamin E.
Whole plant of Phyllanthus amarus Linn. is a reputed drug of the Indian systems of medicine that is used as hepatoprotective agent. A simple high-performance thin-layer chromatography (HPTLC) densitometric method has been developed for the simultaneous quantitation of phyllanthin, hypophyllanthin, gallic acid, and ellagic acid in the whole plant of P. amarus. They were found at levels of 0.37, 1.16, 0.36, and 0.17% (w/w), respectively. The method was validated for precision, repeatability, and accuracy. Instrumental precision was found to be 0.54, 0.93, 0.08, and 0.78% (coefficient of variation, CV); repeatability of the method was 1.01, 0.79, 0.98, and 1.06% (CV) for phyllanthin, hypophyllanthin, gallic acid, and ellagic acid, respectively. Accuracy of the method was determined by a recovery study conducted at 3 different levels, and the average recovery was found to be 99.09% for phyllanthin, 99.27% for hypophyllanthin, 98.69% for gallic acid, and 100.49% for ellagic acid. The proposed HPTLC method was found to be simple, precise, specific, sensitive, and accurate and can be used for routine quality control of raw material of P. amarus and formulations containing P. amarus. It also has the applicability in quantitating any of these marker compounds in other drugs.
Methodologies based on FT-Raman spectroscopy and HPLC were developed for monitoring the stability of lovastatin in the solid state in the presence of gallic acid, a natural antioxidant. A Raman calibration curve was constructed using the area of the strong but overlapping vibration mode of lovastatin at 1645 cm(-1) and of the gallic acid at 1595 cm(-1). Mixtures of the active ingredient with the antioxidant were heated in the presence of atmospheric air up to 120 degrees C. The molar ratios of lovastatin and gallic acid in the artificially oxidized mixtures were determined from their Raman spectra using the calibration curve. The results were compared to those obtained from the application of the HPLC methodology and found to match satisfactorily. The HPLC analysis was based on a reserved-phase Zorbax C(g), 10 microm (4.6mm x 25 cm i.d.) column, using a gradient elution program by varying the proportion of solvent A acetonitrile 100% to solvent B 0.1% v/v phosphoric acid, and a programmable diode array detection at 225 nm. The Raman methodology was simpler and non-destructive for the sample but yielded only molar ratios as opposed to the HPLC technique where the moles of the both ingredients were determined.
The adsorption isotherms of catechol (1,2-dihydroxybenzene) and gallic acid (3,4,5-trihydroxybenzoic acid) onto titanium dioxide (Degussa P-25) were measured at various pH values and room temperature using attenuated total reflection Fourier transform infrared (FTIR-ATR) data, processed by singular value decomposition. The affinity is largely pH independent, although the deprotonatation of the carboxylic group in gallic acid might produce a slight increase in the affinity. Catechol was shown to form two complexes, with Langmuir stability constants log K of 4.66 (strong mode) and 3.65 (weak mode). Both complexes have the same spectral signature, and mononuclear and binuclear chelate structures are proposed for them. Gallic acid chemisorbs by complexation through two -OH groups and forms one complex only, log K = 4.70. The third -OH and the pendant carboxylate do not influence much the stability of the surface complex. Comparison with literature data demonstrates that the affinity of 4-chlorocatechol is also similar, whereas 2,3-dihidroxynaphthalene and 4-nitrocatechol form more stable complexes, probably because of the solvation contribution to the overall Gibbs adsorption energy. All quoted constants refer to the surface complexation equilibria written as follows: ([triple bond]Ti-OH)2 + H2L = ([triple bond]Ti)2-L + 2H2O, i.e., as electroneutral processes. The FTIR-ATR spectra of the surface complexes are also discussed.
The antimutagenic properties of various tea extracts (green tea, pauchong tea, oolong tea and black tea) and their components including (-)-epigallocatechin-3-gallate (EGCG), gallic acid and caffeine were examined by the Ames test. The antimutagenic activity of the green tea extract against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), folpet and monocrotophos was greater than those of pouchong, oolong and black tea extracts. The antimutagenic effects of tea extracts against 2-acetylaminofluorene (AAF) decreased as follows: oolong tea > pauchong tea > black tea > green tea. Furthermore, black tea showed a greater antimutagenic activity against benzo[a]pyrene (BP). The pauchong tea showed a stronger inhibitory effect against 9-aminoacridine (9AA) and aflatoxin B1 (AFB1) than other tea extracts. EGCG markedly suppressed the direct-acting mutagenicity of MNNG, N-nitroso-N-methylurea (MNU), captan, and folpet which were alkylating agents and fungicides. Similarly, gallic acid, the major component of black tea strongly inhibited the mutagenicity of 9AA, and moderately inhibited the mutagenicity of MNNG and folpet. The caffeine was less active. EGCG and gallic acid perhaps could act as nucleophiles to scavenge the electrophilic mutagens. Taken together, these results suggest that formation of different metabolites during various stages of tea fermentation may affect antimutagenic potencies against different types of chemical mutagens.
It was demonstrated that the rat liver cell line BRL-3A converted exogenous C19 odd chain-polyunsaturated fatty acids (PUFAs) into the corresponding C21- and C23-PUFAs as follows: 21:3n-8, 21:4n-8, 23:3n-8, and 23:4n-8 (from 19:3n-8); 21:4n-5, 21:5n-5, 23:4n-5, and 23:5n-5 (from 19:4n-5); 21:5n-2, 21:6n-2, 23:5n-2, and 23:6n-2 (from 19:5n-2). It presumed that these C19 PUFAs were converted through the mimic route to docosahexaenoic acid (22:6n-3) from eicosapentaenoic acid (20:5n-3). In addition, the characterization of the change of fatty acid composition of cellular lipids in rat liver cells were examined, using 19:4n-5 and several fatty acid desaturation inhibitors. Curcumin related compounds, curcumin, capsaicin, isoeugenol, 4-(4-hydroxy-3-methoxyphenyl)-3-buten-2-one, and gallic acid esters with near five carbon numbered alcohol had great changes of fatty acid composition of cellular lipids based on inhibition of the A6 desaturation of C24-PUFAs in rat liver cells.
The gallic acid and several n-alkyl gallates, with the same number of hydroxyl substituents, varying only in the side carbonic chain length, with respective lipophilicity defined through the C log P, were studied. It evidenced the structure-activity relationship of the myeloperoxidase activity inhibition and the hypochlorous acid scavenger property, as well as its low toxicity in rat hepatic tissue. The gallates with C log P below 3.0 (compounds 2-7) were more active against the enzyme activity, what means that the addition of 1-6 carbons (C log P between 0.92 and 2.92) at the side chain increased approximately 50% the gallic acid effect. However, a relationship between the HOCl scavenging capability and the lipophilicity was not observed. With these results it is possible to suggest that the gallates protect the HOCl targets through two mechanisms: inhibiting its production by the enzyme and scavenging the reactive specie.
OBJECTIVE: To establish a HPLC method for the determination of gallic acid in garden burnet. METHOD: The sample was extracted with methanol under ultrasonic management for 25 min. Chromatographic conditions: Shimadzu LC-6A with SPD-6AV detector at 270 nm and auto injector SIL-6A, methanol-0.025 mol/L phosphoric acid(15:85) as the mobile phase. Shin-pack CLC-ODS column(6.0 mm x 15 mm). RESULT: Gallic acid in garden burnet was baseline separated and determined. The average content was 0.22%, recovery rate 97.4% and relative standard deviation 1.3%. CONCLUSION: Simple, rapid and accurate, the method provides new indexes for quality control of Garden Burnet.
Gallic acid was separated from a n-butanol extract of the fruit of Cornus officinalis Sieb. et Zucc by high-speed countercurrent chromatography in two steps using two solvent systems composed of ethyl-acetate-ethanol n-butanol-water (5:1.8:6, v/v/v) and ethyl acetate-ethanol-water (5:0.5:6, v/v/v) successively. From 1 g of n-butanol extract the method produced 60 mg of gallic acid at a purity of 97%.
An HPLC method for the determination of hamamelitannin, catechins and gallic acid in witch hazel bark, twig and leaf has been developed. The separation system consisted of a C18 reversed-phase column, a gradient elution system of methanol/water and orthophosphoric acid, and a photodiode array detector. The concentrations of hamamelitannin, gallic acid, (+)-gallocatechin and (+)-catechin were 4.77, 0.59, 0.22 and 0.39% (w/w), respectively, in the bark. Hamamelitannin and catechins were also detected in the leaves at concentration less than 0.04% (w/w). This method is simple, sensitive and reproducible, ideally suited for rapid, routine analysis.
Gallic acid and its alkylesters, polyphenolic compounds with antioxidative activity, acted as a prooxidant causing a copper-dependent DNA damage. Treatment of DNA from plasmid pBR322 and calf thymus with gallic acid plus copper ion caused strand scission and the formation of 8-hydroxy-2'-deoxyguanosine in DNA. Addition of catalase protected DNA from the gallic acid/copper-dependent strand breaks and the formation of 8-hydroxy-2'-deoxyguanosine, indicating that hydroxyl radical may participate in the DNA damage. Ethyl-, propyl- and butylgallates showed only a little DNA damage. Octyl- and laurylgallates caused negligible damage of DNA. DNA strand breaks and formation of 8-hydroxy-2'-deoxyguanosine were closely related to the reduction of copper by gallate compounds. These results imply that cuprous ion reduced by gallate derivatives may play a key role in the oxidative cleavage of DNA and the formation of base adduct. The cytotoxic effect of gallate compounds can be explained by their prooxidant action dependent on the reducing activity.
The present study is an effort to identify a potent chemopreventive agent against various diseases (including cancer) in which oxidative stress and cell proliferation plays an important causative role. This study was designed to investigate the effect of gallic acid against ferric nitrilotriacetic acid (Fe-NTA)-induced carcinogen/ drug metabolizing phase I and phase II enzymes, antioxidative parameters, kidney markers, tumour promotion markers and lipid peroxidation (LPO) in kidney of male Wistar rats. Fe-NTA (9 mg Fe/kg body weight, intraperitoneally) caused significant depletion in the detoxification and antioxidant enzyme armoury with concomitant elevation in renal LPO, serum creatinine, blood urea nitrogen, hydrogen peroxide generation, ornithine decarboxylase activity and [3H]thymidine incorporation into renal DNA. However, pretreatment of animals with gallic acid (10 and 20 mg/kg body weight) resulted in a significant decrease in the levels of the parameters measured (P <0.001). Renal glutathione content (P <0.001), glutathione metabolizing enzyme (P <0.001) and antioxidant enzyme levels were also recovered to a significant level (P <0.001). The enhanced reduced glutathione level and enzyme activities involved in xenobiotic metabolism and maintaining antioxidant status of cells are suggestive of a chemopreventive efficacy of gallic acid against Fe-NTA-mediated oxidative stress, toxicity and cell proliferative response in Wistar rats.
Lung adenomas were induced in strain A mice by chronic treatment with N-nitroso compounds (given in drinking water) and with amines or ureas in food plus NaNO2 in drinking water. We studied the effects of varying the concentrations of three N-nitroso compounds and NaNO2 concentration in the morpholine plus NaNO2 and methylurea plus NaNO2 systems. Sodium ascorbate (NaASC) at the highest level tested (11.5 or 23 g/kg food) gave 89-98% inhibition of adenoma induction by the NaNO2 plus piperazine, morpholine, and methylurea systems. In 7 groups, NaASC produced increases of 15-59% in adenoma induction by nitrosomorpholine (NM) and mononitrosopiperazine (MNP), possibly because the mice consumed more of the nitrosamine solution. Adenoma induction by morpholine plus NaNO2 was strongly inhibited by gallic acid, moderately inhibited by caffeine, and unaffected by thiocyanate (all added to the food). Gallic acid inhibited or had no effect on the action of NM and MNP. We discussed the proposal that NaASC (or perhaps gallic acid) be administered with readily nitrosatable drugs.
The growth inhibitory and bactericidal activities of eight alkyl esters of gallic acid towards Escherichia coli NCTC 5933 have been determined. A previously suggested role for gallic acid and its esters as shikimate antimetabolites could not be substantiated. No induction of gross changes in cell morphology was observed. Bactericidal activity was accompanied only be very slight leakage of general ionic materials from the bacteria. Propyl gallate did not appear to uncouple oxidative phosphorylation from respiration as indicated by its failure to stimulate proton translocation across the cytoplasmic membrane.
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 fibrin-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 significant 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 significantly 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 identification of other responsible compounds.
Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA, BOA and gallic acid, were isolated and quantified from Calceolaria thyrsiflora Graham, a native medicinal plant of Chile belonging to the Scrophulariaceae family. The highest DIBOA contents were determined in leaves (145 mmol kg(-1) dry wt) and flowers (161 mmol kg(-1) dry wt). Antibacterial activities of DIBOA, HBOA, BOA, gallic acid and infusions of flowers and leaves were determined. The phytomedicinal properties attributed to C. thyrsiflora Graham could be understood on the basis of its antibacterial activity.