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PubMedDate not supplied

Effect of antioxidants on radical intensity and cytotoxic activity of eugenol.

The effect of antioxidants on the radical intensity of 2-methoxy-4-(2-propenyl)phenol (eugenol) was investigated, using ESR spectroscopy. Eugenol produced radicals in alkaline solutions, with an optimum pH of 9.5. The intensity of eugenol radical was a positive function of its concentration, reaching a plateau level at 100 mM. The eugenol radical was rapidly diminished under alkaline conditions. Water-soluble antioxidants, such as cysteine, N-acetyl-L-cysteine, glutathione and sodium ascorbate, completely scavenged the eugenol radical. Gallic acid at lower doses significantly, but not completely, scavenged the eugenol radical. Among water-insoluble antioxidants, terpenes (beta-carotene, retinol, lycopene) effectively scavenged the eugenol radical, whereas phenolic compounds (alpha-tocopherol, Trolox) were inactive. Millimolar concentrations of eugenol were cytotoxic against human salivary gland and oral squamous carcinoma cell lines. Addition of sodium ascorbate or beta-carotene reproducibly reduced the cytotoxic activity of eugenol. The applicability of the antioxidants in dentistry was discussed.

Acetylcysteine↗
PubMed1998

Antioxidant activity of gallates: an electrochemical study in aqueous media.

The electron-donating ability of gallates, which are food and pharmaceutical antioxidants, is quantitatively assessed on the basis of their electrochemical characteristics. Gallic acid and the propyl, i-propyl, butyl, i-butyl, pentyl and i-pentyl gallate derivatives were electrochemically oxidized on the glassy carbon electrode by using differential pulse voltammetry, cyclic voltammetry and hydrodynamic voltammetry on the rotating disk electrode. All the compounds under study were easily oxidized in acidic and neutral solutions. Electrochemical oxidation occurs via two electron-transfer steps; however good resolution for the second wave was obtained only by using hydrodynamic conditions. The oxidation process results to be irreversible, diffusion controlled and pH-dependent. The introduction of the alkyl groups seems to affect the intensities of the semiquinone gallate radicals as can be ascribed from the observed differences in i(II)d/i(I)d ratio obtained from hydrodynamic voltammetric experiments for the different derivatives. We have found that the intensity of the gallate radicals follows the sequence GA > or = i-PG > PG > i-BG > BG > i-PeG > PeG. From the pH-dependence of the peak current it is possible to affirm that pH 2 is the better condition for the oxidative activity showing that the antioxidant behaviour of these compounds are important in the stomach acid.

Antioxidants↗
PubMed2001

Cytogenetic effects of propyl gallate in CHO-K1 cells.

We investigated whether propyl gallate (PG) can induce sister-chromatid exchanges (SCEs) and chromosomal aberrations (CAs) in CHO-K1 cells. In the absence of an exogeneous metabolizing system, treatments with 0.25-1.5mM PG in plugged flasks for 3h resulted in increases in SCEs, CAs, and endoreduplications (ERDs), which were followed by an increase in the percentage of cells showing cell-cycle delay. At the end of the treatment, a decrease in PG concentration and production of PG dimer and ellagic acid (EA) in the medium were detected, indicating that PG had autoxidized. EA, an oxide of PG, was not genotoxic even at 0.3mM, the maximum concentration soluble in the medium. Several oxygen radical scavengers (superoxide dismutase (SOD), catalase, glutathione and o-phenanthroline (OP)) and an inhibitor of catalase activity (3-amino-1,2,4-triazole (AT)), did not significantly influence PG genotoxicity. When PG autoxidation was suppressed by low pH (6.8) or a 5% CO(2) atmosphere, cell-cycle delay intensified and induction of SCEs and CAs occurred even at the lowest PG dose (0.1mM). When PG (0.5mM) was assayed in the presence of S9 (1.5-9%), gallic acid (GA), a metabolite of PG, was generated in direct proportion to the S9 concentration, while cell-cycle delay and genotoxic effects varied inversely with S9 concentration at the levels over 3%. GA also autoxidized and at >or=0.5mM it induced SCEs. Both catalase and AT suppressed the induction of SCEs by GA or inhibited cell proliferation, indicating that H(2)O(2) participated in the effects. In conclusion, PG in the presence or absence of S9 can induce SCEs, CAs, and ERDs, and the oxides, metabolites and oxygen-free radicals generated during the treatment are partly responsible for these effects.

Amitrole↗
PubMedDate not supplied

Effect of cobalt ion on radical intensity and cytotoxic activity of antioxidants.

The effect of CoCl2 on the cytotoxic activity of various antioxidants against human oral tumor cell lines (HSC-2, HSG) and normal human gingival fibroblasts (HGF) was investigated. Noncytotoxic concentrations of CoCl2 significantly reduced the cytotoxic activity of sodium ascorbate, gallic acid, epigallocatechin gallate (EGCG), curcumin and dopamine, but not that of sodium 5,6-benzylidene-L-ascorbate (SBA) and benzaldehyde. Among these compounds, benzaldehyde showed the most prominent tumor-specific cytotoxic action. ESR spectroscopy showed that these antioxidants produced radicals under alkaline condition and that their radical intensity was transiently enhanced and finally disappeared by addition of CoCl2. Antioxidants which are sensitive to CoCl2 generally had higher cytotoxic activity and oxidation potential (measured by NO monitor) and addition of CoCl2 significantly reduced their oxidation potential. The present study suggests that cobalt ion stimulates the oxidation of antioxidants to their inactive products.

Antioxidants↗
PubMedDate not supplied

Chemical composition and analgesic activity of Calophyllum brasiliense leaves.

This paper describes a phytochemical and pharmacological study with Calophyllum brasiliense leaves, a medicinal plant employed in folk medicine for the treatment of several ailments. Based on spectroscopic evidence, five phenolic compounds were identified as hyperin (hyperoside), amentoflavone, quercetin, gallic acid, and protocatechuic acid. The fractions and some phenolic compounds exhibited significant analgesic activity against the writhing test and in relation to the second phase (inflammatory pain) of the formalin test in mice, suggesting that this plant can be useful for the treatment of dolorous processes.

Abdominal Pain↗
PubMed1997

Extraction and purification of effective antimicrobial constituents of Terminalia chebula RETS. against methicillin-resistant Staphylococcus aureus.

Examination of the EtOH extract of the fruiting bodies of Terminalia chebula RETZ. led to the isolation of two potent antimicrobial substances against even methicillin-resistant strains of Staphylococcus aureus. On the basis of spectroscopic evidence, the two isolates have been identified as gallic acid and its ethyl ester.

Anti-Bacterial Agents↗
PubMed2003

[Studies on the chemical constituents of Ampelopsis humulifolia var. heterophylla (Thunb.) K. Koch].

OBJECTIVE: To study the chemical constituents from Ampelopsis humulifolia var. heterophylla (Thunb.) K. Koch. METHODS: Chromatography and spectroscopic analysis were employed to isolate and elucidate the chemical constituents in the plant. RESULTS: Six compounds were isolated and elucidated as lupeol, beta-stiosterol, daucosterol, ethyl gallate, gallic acid and catechin. CONCLUSION: The six compounds were isolated from this plant for the first time.

Ampelopsis↗
PubMed1977

Fungitoxic properties of Rosa chinensis Jacq.

During a systematic survey of higher plants for their fungitoxicity, the flowers of Rosa chinensis Jacq. were found to exhibit strong antifungal properties. On chemical investigation the antifungal priniciple was isolated as a shining, needle-shaped cyrstalline substance. It was identified as gallic acid. It exhibited fungistatic action against as many as 17 fungi at 3% concentration.

Antifungal Agents↗
PubMed2003

Phenolic compounds and fatty acids from acorns (Quercus spp.), the main dietary constituent of free-ranged Iberian pigs.

The aim of the present work was to identify and quantify the phenolic compounds and fatty acids in acorns from Quercus ilex, Quercus rotundifolia, and Quercus suber. The concentration of oleic acid was >63% of total fatty acids in all cases, followed by palmitic and linoleic acids at similar concentrations (12-20%). The concentrations of alpha-tocopherol in Q. rotundifolia, Q. ilex, and Q. suber were 19, 31, and 38 mg/kg of dry matter (DM), respectively, whereas the concentrations of gamma-tocopherol were 113, 66, and 74 mg/kg of DM, respectively. Thirty-two different phenolic compounds were distinguished. All of them were gallic acid derivatives, in the form of either galloyl esters of glucose, combinations of galloyl and hexahydroxydiphenoyl esters of glucose, tergallic O- or C-glucosides, or ellagic acid derivatives. Several tergallic acid C-glucosides were also present in the extracts obtained from Q. suber. Acorns from Q. ilex and Q. rotundifolia showed similar polyphenol patterns mainly with gallic acid-like spectra. Chromatograms of Q. suber showed mainly polyphenols with ellagic acid-like spectra. Valoneic acid dilactone was especially abundant in Q. suber skin. The contribution of skin to the total phenolics of the acorn was relatively small in Q. rotundifolia and Q. ilex but relatively high in Q. suber. Skin extracts from Q. suber, Q. rotundifolia, and Q. ilex showed 1.3, 1.4, and 1.0 antioxidant efficiencies, respectively (compared to that of butylhydroxyanisole). Endosperm extracts showed lower capacity to prevent lipid peroxidation than skin extracts.

Animals↗
PubMed2003

Method for analysis of tannic acid and its metabolites in biological samples: application to tannic acid metabolism in the rat.

A new analytical method for measuring tannic acid (TA) using tannase was developed and applied to the investigation of TA metabolism in the rat following oral administration at a dose of 1.0 g/kg. The proposed method for TA determination was based on the enzymatic hydrolysis of TA to gallic acid (GA) and subsequent determination by HPLC. TA metabolites were determined by HPLC. 4-O-Methylgallic acid (4-OMGA), pyrogallol (PY), and resorcinol (RE) were detected in serum. TA was excreted into urine as GA (0.01%), 4-OMGA (0.10%), PY (0.24%), and RE (2.06%) and into feces as TA (62.74%), GA (0.19%), PY (0.02%), and RE (0.76%) within 54 h after oral administration. It was suggested that >60% of TA remained unchanged but that some was hydrolyzed to GA by tannase in the intestine and further metabolized to 4-OMGA, PY, and RE.

Animals↗
PubMed2006

Xanthine oxidase inhibitory activity of alkyl gallates.

A series (C1-C12) of alkyl gallates was examined for their effects on the activity of xanthine oxidase. Octyl (C8), decyl (C10), and dodecyl (C12) gallates competitively inhibited uric acid formation generated by xanthine oxidase, and the inhibition increased upon increasing the alkyl chain length. Interestingly, neither menthyl nor bornyl gallates inhibited uric acid formation. These data indicate that the hydrophobic alkyl portion is associated with the xanthine-binding site in the Mo-binding domain. It is likely that the linear alkyl portion interacts with the hydrophobic domain close to the binding site, and the hydrophobic interaction is crucial to inhibit the xanthine oxidase reaction. On the other hand, all of gallic acid and its esters equally suppress superoxide anion generation catalyzed by xanthine oxidase at low concentration. The suppression is not due to scavenging activity of these gallates but due to reduction of xanthine oxidase by these gallates. The reduced enzyme catalyzes the reaction to generate hydrogen peroxide and uric acid.

Alkylation↗
PubMed2000

[A new fatty ketone of Radix Polygoni Multiflori Preparata].

OBJECTIVE: Investigating the chemical constituents of Radix Polygoni Multiflori Preparata. METHODS: Compounds were isolated from the CHCl3 extract with column chromatography on silica gel, and identified on the basis of spectral analysis(IR, EI-MS, 1H-NMR, 13C-NMR) and phytochemical properties. RESULTS: Two compounds were isolated and identified as 1,2-dihydroxynonadecone-3(I) and gallic acid(II). CONCLUSION: Compound I is a new compound.

Drugs, Chinese Herbal↗
PubMed1992

[Chemical components of the leaves of Pistacia Chinensis Bge].

Six compounds have been isolated from the leaves of Pistacia chinensis, a species of Anacardiaceae family. Their structures were identified on the basis of UV, IR, NMR, and MS as gallic acid, m-digallic acid, quercetin, 6-0-galloyl arbutin-quercitrin and quercetin-3-0(6''-galloyl)-beta-D-glucosides.

Arbutin↗
PubMedDate not supplied

Chemical composition and biological activity of propolis from Brazilian meliponinae.

Twenty-one propolis samples produced by 12 different Meliponinae species were analyzed by GC-MS. Several chemical types of stingless bees' propolis could be grouped, according to the prevailing type of compounds like: 'gallic acid", "diterpenic" and "triterpenic" types. The results confirm that neither the bee species nor the geographical location determine the chemical composition of Meliponinae propolis and the choice of its plant source, respectively. This could be explained by the fact that Meliponinae forage over short distances (maximum 500 m) and thus use as propolis source the first plant exudate they encounter during their flights. The antibacterial, antifungal and cytotoxic activities of the samples were also investigated. Most samples had weak or no activity against E. coli, weak action against Candida albicans. Some of them showed significant activity against St. aureus., presumably connected to the high concentration of diterpenic acids. Samples rich in diterpenic acids possessed also high cytotoxic activity (Artemia salina test).

Animals↗
PubMed2002

Studies on exudate-depleted sclerotial development in Sclerotium rolfsii and the effect of oxalic acid, sclerotial exudate, and culture filtrate on phenolic acid induction in chickpea (Cicer arietinum).

Exudate depletion from developing sclerotia of Sclerotium rolfsii Sacc. in culture caused reduced size and weight of sclerotia. Germination of exudate-depleted sclerotia was delayed on Cyperus rotundus rhizome meal agar medium when compared with that of control sclerotia. The exudate-depleted sclerotia caused infection in chickpea (Cicer arietinum) plants in a glasshouse. Different temperatures and incubation periods had no effect on the germination ability of the exudate-depleted sclerotia. Oxalic acid, sclerotial exudate, and culture filtrate of S. rolfsii induced the synthesis of phenolic acids, including gallic, ferulic, chlorogenic, and cinnamic acids, as well as salicylic acid, in treated chickpea leaves. Gallic acid content was increased in treated leaves compared with the untreated controls. Maximum induction of gallic acid was seen in both leaves treated with oxalic acid followed by exudate and leaves treated with culture filtrate. Cinnamic and salicylic acids were not induced in exudate-treated leaves. Ethyl acetate fractionation indicated that the sclerotial exudates consisted of gallic, oxalic, ferulic, chlorogenic, and cinnamic acids, whereas the culture filtrate consisted of gallic, oxalic, and cinnamic acids along with many other unidentified compounds.

Basidiomycota↗
PubMed2005

Molecular characterization of the gallate dioxygenase from Pseudomonas putida KT2440. The prototype of a new subgroup of extradiol dioxygenases.

In this work we have characterized the galA gene product from Pseudomonas putida KT2440, a ring-cleavage dioxygenase that acts specifically on gallate to produce 4-oxalomesaconate. The protein is a trimer composed by three identical subunits of 47.6 kDa (419 amino acids) that uses Fe2+ as the main cofactor. The gallate dioxygenase showed maximum activity at pH 7.0, and the Km and Vmax values for gallate were 144 microM and 53.2 micromol/min/mg of protein, respectively. A phylogenetic study suggests that the gallate dioxygenase from P. putida KT2440 is the prototype of a new subgroup of type II extradiol dioxygenases that share a common ancestor with protocatechuate 4,5-dioxygenases and whose two-domain architecture might have evolved from the fusion of the large and small subunits of the latter. A three-dimensional model for the N-terminal domain (residues 1-281) and C-terminal domain (residues 294-420) of the gallate dioxygenase from P. putida KT2440 was generated by comparison with the crystal structures of the large (LigB) and small (LigA) subunits of the protocatechuate 4,5-dioxygenase from Sphingomonas paucimobilis SYK-6. The expression of the galA gene was specifically induced when P. putida KT2440 cells grew in the presence of gallate. A P. putida KT2440 galA mutant strain was unable to use gallate as the sole carbon source and it did not show gallate dioxygenase activity, suggesting that the GalA protein is the only dioxygenase involved in gallate cleavage in this bacterium. This work points to the existence of a new pathway that is devoted to the catabolism of gallic acid and that remained unknown in the paradigmatic P. putida KT2440 strain.

Amino Acid Sequence↗
PubMed1987

Effect of four synthetic antioxidants on the formation of ethylene from methional in rat liver microsomes.

Four commonly used food antioxidants, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate and octyl gallate, were tested for their ability to inhibit the formation of ethylene from methional in NADPH-oxidizing rat liver microsomes. It is assumed that the action of the antioxidants on ethylene formation reflects their free radical scavenging activity. Only propyl gallate and octyl gallate are efficient inhibitors of ethylene formation. BHT is inhibitory only at very high concentrations, and BHA tends to increase ethylene formation. It is concluded that gallic acid ester antioxidants may possess a protective potential during chemical-induced microsomal oxidations.

Aldehydes↗