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PubMed1998

Structural features of tannic acid important for DNA degradation in the presence of Cu(II).

Tannic acid has numerous food and pharmacological applications. It is an additive in medicinal products and is used as a flavouring agent and as an antioxidant in various foods and beverages. However, there are reports of its mutagenicity and carcinogenicity in bacterial and animal test systems. Tannic acid and its structural monomer gallic acid are also capable of inducing apoptosis in animal cells. We have earlier shown that tannic acid in the presence of Cu(II) causes DNA degradation through generation of reactive oxygen species such as hydroxyl radicals. In order to understand the chemical basis of the various biological properties of tannic acid we have studied the structure-activity relationship between tannic acid and gallic acid using the DNA cleavage assay. Results in the present paper indicate that gallic acid is considerably more active than tannic acid. However, if two of the three hydroxyl groups of gallic acid are methylated (syringic acid) the DNA degrading capacity declines sharply. Further, decarboxylation of gallic acid (pyrogallol) leads to enhancement of its activity. In conclusion, the results indicate that the DNA cleavage activity of tannic acid is due to its digalloyl moeity and that free hydroxyl groups are essential for cleavage.

Animals↗
PubMed2003

Two derivative spectrophotometric methods for the simultaneous determination of lovastatin combined with three antioxidants.

A zero crossing and an algorithm bivariate calibration derivative method for the simultaneous determination of lovastatin combined separately with three antioxidants (ascorbic acid, quercetin and gallic acid) in synthetic mixtures are described. The aqueous or methanolic solutions obeyed Beer's law in the concentration ranges of 3.20-17.36 microg/ml for lovastatin, 1.76-8.80 microg/ml for ascorbic acid, 1.41-7.04 microg/ml for gallic acid and 1.84-9.20 microg/ml for quercetin, for both methods, respectively. In the second derivative (2D) zero crossing method measurements were carried out at 238.4 nm for lovastatin and 265.6 nm for ascorbic acid, 247.7 nm for lovastatin and 281.1 nm for quercetin, 251.8 nm for lovastatin and 267.6 nm for gallic acid. In the first derivative (1D) bivariate spectrophotometric method an optimum pair of wavelengths was chosen for the determination of different binary mixtures. The proposed procedures were successfully applied to the simultaneous determination of lovastatin and different antioxidants in mixtures with high percentage of recovery, 98.3-100.4% for lovastatin, 98.3-98.6% for ascorbic acid, 99.0-99.8% for quercetin and 100.5-101.1% for gallic acid and good precision. In addition, the results from the above procedures were verified by using partial least-squares (PLS) multivariate calibration method.

Algorithms↗
PubMed1982

Inhibition of Clostridium botulinum by antioxidants, phenols, and related compounds.

A total of 75 compounds, including antioxidants, preservatives, gallic acid and p-hydroxybenzoic acid esters, hydroquinones, hydroxyquinolines, phenol derivatives, and related compounds, were screened for their antibotulinal activity in prereduced Thiotone-yeast extract-glucose broth. The most effective inhibitors of Clostridium botulinum growth and toxin production were long-chain esters of p-hydroxybenzoic acid and gallic acid, antioxidants, and butylphenol derivatives. The antioxidant nordihydroguaiaretic acid at 100 microgram/ml delayed the growth and toxin production for the entire incubation period (7 days). Other antioxidants, such as butylated hydroxytoluene, butylated hydroxyanisole, and tert-butylhydroquinone were also very effective (at 200 to 400 microgram/ml) for the inhibition of C. botulinum growth and toxin production. Toxin was detected, although no detectable growth was found by daily absorbance measurements, in the prereduced medium containing 50 to 400 microgram of 8-hydroxyquinoline, pentylphenol, tert-pentylphenol, 3,5-ditert-butylphenol, 3,5-ditert-butylcatechol, (2-hydroxydiphenyl)methane, or (4-hydroxydiphenyl)methane per ml.

Antioxidants↗
PubMed2001

Oxidation of lovastatin in the solid state and its stabilization with natural antioxidants.

Oxidative instability of the hydroxy methylglutaryl Co-A reductase inhibitor lovastatin in the solid state and stabilization with natural antioxidants (ascorbic acid, rutin, gallic acid, quercetin and caffeic acid) was investigated. Lovastatin in the solid state and binary mixtures with 10% (w/w), 25% (n/n), 12.5% (n/n) and 6.3% (n/n) of each of the antioxidants were prepared. Oxidation experiments were performed on the scanning calorimeter using dynamic oxygen atmosphere. The amount of non-oxidized lovastatin was determined using HPLC. The results of the experiments have shown that lovastatin is unstable to oxidation under higher temperatures and in the presence of oxygen, and that some antioxidants markedly stabilize the drug. The most significant antioxidative effect was seen with caffeic acid and rutin, followed by gallic acid and quercetin. Ascorbic acid was only moderately effective. The results prove that flavonoids do have significant antioxidative potential. This phenomenon can be used to improve oxidative stability of drugs such as lovastatin which are sensitive to the presence of oxygen.

Anticholesteremic Agents↗
PubMed2001

Antiproliferative constituents in the plant 8. Seeds of Rhynchosia volubilis.

The MeOH extract of the seeds of Rhynchosia volubilis (Leguminosae) showed antiproliferative activity against human gastric adenocarcinoma [MK-1, 50% growth inhibition (GI50): 25 microg/ml], human uterus carcinoma (HeLa, GI50: 30 microg/ml), and murine melanoma (B16F10, GI50: 8 microg/ml) cells. Bioactivity-guided fractionation resulted in the isolation of gallic acid methylester (1), gallic acid (2), 7-O-galloylcatechin (3), 1,6-di-O-galloylglucose (4), 1-O-galloylglucose (5), and trigalloylgallic acid (6), and their antiproliferative activity was estimated. All showed much stronger inhibition against B16F10 cell growth than against HeLa and MK-1 cell growth. Compound 2 and its tetramer (6) with a free carboxyl group showed higher activity than those which did not have a free carboxyl group. In relation to the gallic acid tetramer (6), two gallic acid dimers (ellagic acid and dehydrodigallic acid) and trimers (tergallic acid dilactone and flavogallonic acid dilactone) were tested for their activity, and compared with those of the isolates.

Animals↗
PubMed1985

Inhibition of the mutagenicity of bay-region diol-epoxides of polycyclic aromatic hydrocarbons by tannic acid, hydroxylated anthraquinones and hydroxylated cinnamic acid derivatives.

Tannic acid and several hydroxylated anthraquinone and cinnamic acid derivatives inhibited the mutagenic activity of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [a]pyrene (B[a]P 7,8-diol-9,10-epoxide-2), an ultimate mutagenic and carcinogenic metabolite of benzo [a]pyrene. The mutagenic activity of 0.05 nmol of B[a]P 7,8-diol-9,10-epoxide-2 towards strain TA 100 of Salmonella typhimurium was inhibited 50% by incubation of the bacteria and the diol-epoxide with tannic acid (0.5 nmol), anthraflavic acid (7 nmol), rufigallol (7 nmol), quinalizarin (10 nmol), alizarin (30 nmol), purpurin (60 nmol), and danthron (88 nmol). Dose-dependent, but weaker antimutagenic activity was observed for quinizarin, and a number of hydroxylated cinamic acid derivatives. Gallic acid and m-digallic acid, major components of tannic acid, possessed less than 1% of the anti-mutagenic activity of tannic acid, although m-digallic acid was over 3 times more active than gallic acid. The anti-mutagenic activity of tannic acid was a result of its interaction with B[a]P 7,8-diol-9,10-epoxide-2 since the rate of disappearance of the diol-epoxide from cell-free solutions in 1:9dioxane:water was markedly stimulated by the polyphenol. Tannic acid was a highly potent inhibitor of the mutagenic activity of the bay-region diol-epoxides of benzo[a]pyrene, dibenzo[a,h]pyrene and dibenzo[a,i]pyrene, but higher concentrations of tannic acid were needed to inhibit the mutagenicity of the chemically less reactive benzo[a]-pyrene 4,5-oxide and the bay-region diol-epoxides of benz[a]-anthracene, chrysene and benz[c]phenanthrene.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1999

Active-oxygen scavenging activity of traditional nourishing-tonic herbal medicines and active constituents of Rhodiola sacra.

The active-oxygen scavenging activity of 70 traditional herbal medicines used in China and Japan as nourishing tonics were evaluated by electron spin resonance (ESR) technique, in order to evaluate their effectiveness for anti-aging and to search for new active-oxygen scavengers from natural resources. Most of the 70 herbal medicines showed scavenging activity with various intensities. Areca catechu (methanol extract), Dendrobium plicatile (methanol extract), Juglans regia (water extract), Paeonia lactiflora (methanol extract), Psychotria serpens (water and methanol extracts), Rhodiola sacra (water and methanol extracts) and Uncaria rhynchophylla (water extract) especially showed strong scavenging activity against superoxide anion radical (*O2-), while J. regia (water and methanol extracts), Morus alba (water extract) and Schisandra chinensis (water extract) revealed strong scavenging activity against hydroxyl radical (HO*). In addition, the active-oxygen scavenging activities of 19 compounds isolated from R. sacra were also examined, and hydroquinone (1), caffeic acid (3), protocatechuic acid (6), gallic acid (7), (-)-epigallocatechin 3-O-gallate (8), 3-O-galloylepigallocatechin-(4beta-->8)-epigallocatechin+ ++ 3-O-gallate (10), heterodendrin (17) and gallic acid 4-O-beta-D-glucopyranoside (19) were found to show mild or strong inhibitory activity against superoxide anion radical (*O2-), while 4-hydroxybenzoic acid (2), 3, 4-hydroxycinnamic acid (4), 6-8 and 19 inhibited hydroxyl radical (OH*). These active-oxygen scavengers may contribute, to different extents, to their anti-aging action.

Antioxidants↗
PubMed2005

Cellular and in vivo hepatotoxicity caused by green tea phenolic acids and catechins.

Tea phenolic acids and catechins containing gallic acid moieties are most abundant in green tea, and various medical benefits have been proposed from their consumption. In the following, the cytotoxicities of these major tea phenolics toward isolated rat hepatocytes have been ranked and the mechanisms of cytotoxicity evaluated. The order of cytotoxic effectiveness found was epigallocatechin-3-gallate>propyl gallate>epicatechin-3-gallate>gallic acid, epigallocatechin>epicatechin. Using gallic acid as a model tea phenolic and comparing it with the tea catechins and gallic acid-derivative food supplements, the major cytotoxic mechanism found with hepatocytes was mitochondrial membrane potential collapse and ROS formation. Epigallocatechin-3-gallate was also the most effective at collapsing the mitochondrial membrane potential and inducing ROS formation. Liver injury was also observed in vivo when these tea phenolics were administered ip to mice, as plasma alanine aminotransferase levels were significantly increased. In contrast, GSH conjugation, methylation, metabolism by NAD(P)H:quinone oxidoreductase 1, and formation of an iron complex were important in detoxifying the gallic acid. In addition, for the first time, the GSH conjugates of gallic acid and epigallocatechin-3-gallate have been identified using mass spectrometry. These results add insight into the cytotoxic and cytoprotective mechanisms of the simple tea phenolic acids and the more complex tea catechins.

Alanine Transaminase↗
PubMed2006

Electrochemical estimation of the polyphenol index in wines using a laccase biosensor.

The use of a laccase biosensor, under both batch and flow injection (FI) conditions, for a rapid and reliable amperometric estimation of the total content of polyphenolic compounds in wines is reported. The enzyme was immobilized by cross-linking with glutaraldehyde onto a glassy carbon electrode. Caffeic acid and gallic acid were selected as standard compounds to carry out such estimation. Experimental variables such as the enzyme loading, the applied potential, and the pH value were optimized, and different aspects regarding the operational stability of the laccase biosensor were evaluated. Using batch amperometry at -200 mV, the detection limits obtained were 2.6 x 10(-3) and 7.2 x 10(-4) mg L(-1) gallic acid and caffeic acid, respectively, which compares advantageously with previous biosensor designs. An extremely simple sample treatment consisting only of an appropriate dilution of wine sample with the supporting electrolyte solution (0.1 mol L(-1) citrate buffer of pH 5.0) was needed for the amperometric analysis of red, rosé, and white wines. Good correlations were found when the polyphenol indices obtained with the biosensor (in both the batch and FI modes) for different wine samples were plotted versus the results achieved with the classic Folin-Ciocalteu method. Application of the calibration transfer chemometric model (multiplicative fitting) allowed that the confidence intervals (for a significance level of 0.05) for the slope and intercept values of the amperometric index versus Folin-Ciocalteu index plots (r = 0.997) included the unit and zero values, respectively. This indicates that the laccase biosensor can be successfully used for the estimation of the polyphenol index in wines when compared with the Folin-Ciocalteu reference method.

Biosensing Techniques↗
PubMed1999

Prolyl endopeptidase inhibitors from the underground part of Rhodiola sacra S. H. Fu.

Prolyl endopeptidase (PEP, EC 3.4.21.26) is an enzyme which plays a role in the metabolism of proline-containing neuropeptides, e.g., vasopressin, substance P and thyrotropin-releasing hormone (TRH), which have been suggested to be involved in learning and memory processes. In our systematic screening for PEP inhibitors from traditional Chinese medicines, we found that MeOH extract from the underground part of Rhodiola sacra S. H. Fu shows significant inhibitory activity against PEP from Flavobacterium meningosepticum. Examination of the constituents of the extract resulted in the isolation of nineteen known compounds, identified as hydroquinone (1), 4-hydroxybenzoic acid (2), caffeic acid (3), 4-hydroxycinnamic acid (4), suberic acid (5), protocatechuic acid (6), gallic acid (7), (-)-epigallocatechin 3-O-gallate (8), 2-phenylethyl beta-D-glucopyranoside (9), 3-O-galloylepigallocatechin-(4beta-->8)-epigallocatechin+ ++ 3-O-gallate (10), 2-phenylethyl alpha-L-arabinopyranosyl-(1-->6)-beta-D-glucopyranoside (11), sacranoside A (12), beta-D-glucopyranosyl 4-hydroxybenzoate (13), rhodiocyanoside A (14), rhodiooctanoside (15), sarmentosin (16), heterodendrin (17), arbutin (18) and 4-O-(beta-D-glucopyranosyl)-gallic acid (19). Among these, 1, 2, 5, 8-10, 13, 16, 18 and 19 have been isolated for the first time from R. sacra, among which 5, 9, 10, 13, 16, 18 and 19 have been isolated from Rhodiola plants for the first time. On the PEP inhibition, seven compounds (6-8, 10, 12, 18, 19) showed inhibition with an 1C50 of 27.8, 487, 1.47, 0.437, 348, 391 and 215 microM, respectively. The kinetic study of these inhibitors indicated that they are noncompetitive inhibitors, except for 6 which is a competitive inhibitor.

Drugs, Chinese Herbal↗
PubMed2000

Prolyl endopeptidase inhibitory activity of fourteen Kampo formulas and inhibitory constituents of Tokaku-joki-to.

Prolyl endopeptidase (PEP, EC 3.4.21.26) is an enzyme playing a role in the metabolism of proline-containing neuropeptides which have been suggested to be involved in learning and memory processes. In screening for PEP inhibitors from fourteen traditional Kampo formulas, we found that Tokaku-joki-to shows a significant inhibitory activity. Examination of the constituents of the Kampo formula resulted in the isolation of two new compounds, cis-3,5,4'-trihydroxystilbene 4'-O-beta-D-(6-O-galloyl)glucopyranoside (10) and 4-(4-hydroxyphenyl)-2-butanone 4'-O-beta-D-(6-O-galloyl-2-O-cinnamoyl)glucopyranoside (16), along with twenty-five known compounds, cinnamic acid (1), protocatechuic acid (2), gallic acid (3), torachrysone 8-O-beta-D-glucoside (4), emodin (5), emodin 8-O-beta-D-glucoside (6), 3,5,4'-trihydroxystilbene 4'-O-beta-D-glucopyranoside (7), 3,5,4'-trihydroxystilbene 4'-O-beta-D-(2-O-galloyl)glucopyranoside (8), 3,5,4'-trihydroxystilbene 4'-O-beta-D-(6-O-galloyl)glucopyranoside (9), 4-(4-hydroxyphenyl)-2-butanone 4'-O-beta-D-glucopyranoside (11), isolindleyin (12), lindleyin (13), 4(4-hydroxyphenyl)-2-butanone 4'-O-beta-D-(2,6-di-O-galloyl)glucopyranoside (14), 4-(4-hydroxyphenyl)-2-butanone 4'-O-beta-D-(2-O-galloyl-6-O-cinnamoyl)glucopyranoside (15), 1-O-galloylglucose (17), 1,2,6-tri-O-galloylglucose (18), gallic acid 4-O-beta-D-(6-O-galloyl)glucopyranoside (19), liquiritigenin (20), liquiritigenin 4'-O-beta-D-glucoside (21), liquiritigenin 7,4'-diglucoside (22), liquiritigenin 4'-O-beta-D-apiofuranosyl-(1-->2)-beta-D-glucopyranoside (23), licuroside (24), (-)-epicatechin (25), (-)-epicatechin 3-O-gallate (26) and (+)-catechin (27). Among these compounds, twelve (7-10, 14-16, 18, 19, 24-26) showed noncompetitive inhibition with an IC50 of 22.9, 3.0, 14.9, 2.8, 10.5, 0.69, 8.2, 0.44, 9.39, 26.5, 28.1 and 0.052 microM, respectively.

Drugs, Chinese Herbal↗
PubMed2006

Evaluation of the antioxidant properties and bioavailability of free and bound phenolic acids from Trichilia emetica Vahl.

Trichilia emetica Vahl. is commonly used in folk medicine of Mali for the treatment of various diseases. In this study, the content and the antioxidant activity of phenolic acids from Trichilia emetica root were evaluated. Free phenolic acids were extracted with a mixture of methanol and 10% acetic acid. Bound phenolic acids were released using first alkaline and then acid hydrolysis. All fractions were quantified separately by HPLC. After alkaline hydrolysis, a remarkable increase in caffeic acid, ferulic acid, p-coumaric acid, syringic acid, vanillic acid, protocathecuic acid and gallic acid content was observed, showing that most of phenolic acids in the drug are present as bound forms. Moreover, the extracts submitted to alkaline hydrolysis showed high antioxidant properties in two in vitro assays: autooxidation of methyl linoleate (MeLo) and ascorbate/Fe(2+)-mediated lipid peroxidation in rat microsomes. An in vivo study was also performed to investigate the intestinal absorption of phenolic acids after oral administration of Trichilia emetica extracts. Results showed high levels of phenolic acids, free or conjugated to glucuronide, in the plasma of rats treated with the hydrolyzed extract. Due to the absence of chlorogenic acid in plasma samples, the presence of caffeic acid seems to be derived from hydrolysis of chlorogenic acid in the gastrointestinal tract.

Animals↗
PubMed2003

Antioxidant and pro-oxidant effects of tannins in digestive cells of the freshwater mussel Unio tumidus.

Bivalve molluscs, particularly mussels, are sensitive biomarkers of aquatic ecosystem pollution. The tannins, water-soluble plant polyphenols, may play an important role in this environment and, mainly as a consequence of interaction with pollutants, their toxicity may change. We studied three naturally occurring compounds, tannic acid, ellagic acid and gallic acid, for their ability to modulate DNA damage produced by these tannins alone and in the presence of the oxidative stress inducer H(2)O(2), in cells of the digestive gland of mussels (Unio tumidus). After the treatment of the cells with polyphenols at different concentrations (1, 5, 15, 30, 60, 80, 100, 120, 180, 240 microM) and with hydrogen peroxide in the range of 0.04 and 0.1mM, single-strand breaks (ssb) in DNA were investigated, using the comet assay. The ability of phenolic acids to decrease DNA damage through their antioxidant properties was also assessed. The results show that the phenols, which are known as antioxidative agents, could also act as pro-oxidants. They induced ssb in DNA of the digestive gland at concentrations higher that 10 microM, but lower doses (1 and 5 microM) did not contribute to the DNA damage. This study was also designed to evaluate the protective effect of these tannins against H(2)O(2)-mediated DNA damage in the cells. In this treatment, the two concentrations (1 and 5 microM) significantly decreased the amount of lesions induced by H(2)O(2) (0.04 and 0.1mM). In conclusion, our results demonstrate that antioxidative properties of tannins may change to pro-oxidative activities at the higher concentrations. This suggests that the biologic actions of these compounds may be rather complicated.

Animals↗
PubMed2006

Induction of hepatic antioxidant enzymes by phenolic acids in rats is accompanied by increased levels of multidrug resistance-associated protein 3 mRNA expression.

Phenolic acids are widespread in plant foods; they contain important biological and pharmacological properties, some of which were shown to be effective in preventing cancer. We investigated the modulatory effects of phenolic acids on an antioxidant system in male Sprague-Dawley rats. Rats were orally administrated gentisic acid (GEA), gallic acid (GA), ferulic acid (FA), and p-coumaric acid (p-CA) at a dosage of 100 mg/kg body weight for 14 consecutive days. At this dose, the activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase were greater after administration of all 4 phenolic acids compared with the control group (P < 0.05). The activities of these enzymes in the small intestine of rats were also significantly greater after GA and p-CA treatment compared with controls. The changes in hepatic CuZnSOD, GPx, and catalase mRNA levels induced by phenolic acids were similar to those noted in the enzyme activities. Oxidized glutathione levels were lower (P < 0.05) in the liver of all phenolic acid-supplemented rats, whereas reduced glutathione was markedly higher than in control rats, especially after administration of GA and p-CA. The liver homogenates obtained from rats that had been administered phenolic acids had higher oxygen radical absorbance capacity than those obtained from control rats. Immunoblot analysis revealed an increased total level of Nrf2, a transcription factor governing the antioxidant response element in phenolic acid-supplemented rats. Phenolic acid-mediated antioxidant enzyme expression was accompanied by upregulation of multidrug resistance-associated protein Mrp3. These experiments show that modulation of phase II antioxidant enzymes and oxidative status in the liver by phenolic acids may play an important role in the protection against adverse effects related to mutagenesis and oxidative damage.

ATP Binding Cassette Transporter, Subfamily B↗
PubMedDate not supplied

Effect of lignins and their precursors on nitric oxide, citrulline and asparagine production by mouse macrophage-like Raw 264.7 cells.

Lignins, tannins and flavonoids are commonly found polyphenols. Among these polyphenols, lignins, polymers of phenylpropenoids complexed with polysaccharides, were the least cytotoxic and most potently stimulated the production of nitric oxide (NO), citrulline and asparagine by mouse macrophage-like Raw 264.7 cells. The maximum production of these substances reached the level attained by lipopolysaccharide (LPS). However, epigallocatechin gallate, phenylpropenoid monomers (ferulic acid, caffeic acid) and gallic acid (component unit of tannin) were inactive. These data suggest that the macrophage-stimulation activity of polyphenols depends, at least in part, on their molecular weight or structural configuration. There was a positive relationship between the extent of asparagine production and that of NO or citrulline. Western blot analysis demonstrated that both lignins and LPS elevated the cellular level of asparagine synthetase. The present study suggests the possible link between the stimulated asparagine production and macrophage activation.

Animals↗
PubMed1975

Characterization and growth-depressing activity for chickens of several natural phenolic materials.

Several natural phenolic materials were analyzed for gallic acid and were further characterized for dialyzability and flavonoid content. These materials were added to a diet and fed to broiler strain chicks for 4 weeks. The depression in growth caused by these phenolic materials was compared with that of tannic acid on a gallic acid equivalency basis. The activities relative to tannic acid (congruent to 100) were as follows: methyl gallate, 195; valonia, 117; wattle, 114; allepo tannic acid, 107; eucalyptus, 105, myrobalan, 98; tara crystals, 76; mangrove, 72; quebracho, 39; gallic acid, and ellagic acid, O. It was impossible to clearly relate the growth depressing activity of the materials to hydrolyzability or relative content of smaller phenols.

Animals↗
PubMed1999

Partitioning of selected antioxidants in mayonnaise.

This study examined partitioning of alpha-, beta-, and gamma-tocopherol and six polar antioxidants (Trolox, ferulic acid, caffeic acid, propyl gallate, gallic acid, and catechin) in mayonnaise. Partitioning of antioxidants between different phases was determined after separation of mayonnaise by either (a) centrifugation + ultracentrifugation or (b) centrifugation + dialysis. Antioxidants partitioned in accordance with their chemical structure and polarity: Tocopherols were concentrated in the oil phase (93-96%), while the proportion of polar antioxidants in the oil phase ranged from 0% (gallic acid and catechin) to 83% (Trolox). Accordingly, proportions of 6% (Trolox) to 80% (gallic acid and catechin) were found in the aqueous phase. Similar trends were observed after dialysis. After ultracentrifugation, large proportions of polar antioxidants were found in the "emulsion phase" and the "precipitate" (7-34% and 2-7%, respectively). This indicated entrapment of antioxidants at the oil-water interface in mayonnaise. The results signify that antioxidants partitioning into different phases of real food emulsions may vary widely.

Acetic Acid↗
PubMed2005

Pharmacokinetic study of caffeic and rosmarinic acids in rats after oral administration.

p-Coumaric and ferulic acid are actively taken up by monocarboxylic acid transporter (MCT), whereas gallic acid, caffeic acid (CA), and rosmarinic acid (RA) are absorbed by paracellular diffusion in human intestinal Caco-2 cells, although CA has low affinity for MCT. We previously demonstrated that p-coumaric acid has a much higher absorption efficiency than gallic acid in rats, owing to the MCT-mediated absorption of p-coumaric acid in vivo (J. Agric. Food Chem. 2004, 52, 2527-2532). Here, absorption of orally administered CA and RA in rats has been studied to investigate their intestinal absorption characteristics and pharmacokinetics in vivo and to compare the results with those of p-coumaric and gallic acids obtained under identical conditions. Rats were given 100 micromol/kg body weight of CA and RA, and blood was collected from the portal vein and abdominal artery after administration. CA, RA, and their metabolites were quantified by a coulometric detection method using HPLC-ECD. The serum concentration of intact CA and RA in the portal vein peaked at 10 min after administration, with a C(max) of 11.24 micromol/L for CA and 1.36 micromol/L for RA. The area under the curve (AUC) for intact CA and RA in the portal vein was calculated from the serum concentration-time profile to be 585.0 and 60.4 micromol min L-1, respectively. The absorption efficiency of CA was about 9.7-fold higher than that of RA. Overall, the absorption efficiency of these compounds in vivo increases in the order: gallic acid = RA < CA < p-coumaric acid, which is in good agreement with results obtained in Caco-2 cells in vitro.

Animals↗