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PubMed2006

Determination of active constituents in Lonicera confusa DC. by capillary electrophoresis with amperometric detection.

A method based on capillary electrophoresis with amperometric detection has been developed for the determination of luteolin, chlorogenic acid, 3,5-dicaffeoylquinic acid and caffeic acid in the dried flower buds, leaves and stems (three medicinal parts) of Lonicera confusa DC., respectively. The effects of several important factors such as detection potential, the concentration of the running buffer, separation voltage and injection time were investigated to acquire the optimum conditions. The detection electrode was a 300 microm diameter carbon disc electrode at a working potential of + 0.90 V (vs saturated calomel electrode). The four analytes can be well separated within 10 min in a 40 cm-long fused silica capillary at a separation voltage of 12 kV in a 50 mM borate-25 mM phosphate buffer (pH 8.0). The relationship between peak current and analyte concentration was linear over about 3 orders of magnitude with detection limits (S/N = 3) ranging from 0.35 to 0.52 microM for all analytes. The proposed method has been successfully applied to the monitoring of bioactive constituents in the real plant samples with satisfactory assay results.

Buffers↗

PubMed1999

Plant polyphenols inhibit benzoyl peroxide-induced superoxide anion radical production and diacylglyceride formation in murine peritoneal macrophages.

Naturally occurring plant polyphenols, which include ellagic acid (EA), tannic acid (TA), caffeic acid (CA), and ferulic acid (FA), were tested for their superoxide anion radical (SOR)-scavenging activities. SOR were produced by interaction of the tumor promoter benzoyl peroxide (BPO) with murine peritoneal macrophages in vitro. The levels of SOR were assessed microscopically by counting the number of formazan-positive cells per 250 cells produced by the reduction of nitro blue tetrazolium. BPO at a concentration of 15 micrograms/1.85 x 10(6) cells/0.5 ml induced maximum formation of SOR in resident and thioglycollate-elicited cells. All the tested polyphenols were able to inhibit the formation of SOR induced by the tumor promoter to a variable degree. Inhibition of BPO-induced SOR formation by polyphenols was in the following order: FA > TA > CA > EA. BPO stimulated the accumulation of diacylglycerol (DAG) in resident and elicited macrophages with concurrent release of choline equivalents from macrophages. Polyphenols inhibited DAG accumulation, which paralleled the inhibition of choline equivalent release. FA was observed to be the most effective and EA the least effective inhibitor of SOR formation, DAG accumulation, and release of choline equivalents. It is likely that inhibition of SOR formation might be due to some interference in the cellular lipid metabolism and phospholipid equivalent deacylation and choline release.

Animals↗

PubMed2000

Functional expression of an Arabidopsis cDNA clone encoding a flavonol 3'-O-methyltransferase and characterization of the gene product.

We report that the cDNA clone (Accession No. U70424), previously isolated from Arabidopsis thaliana as encoding a caffeic acid/5-hydroxyferulic acid O-methyltransferase (OMT) (1), has now been overexpressed in Escherichia coli BL21 and its recombinant protein identified as a novel flavonol 3'-OMT. It is, therefore, renamed AtOMT1. This cDNA clone has previously been identified on the basis of its 88% amino acid sequence similarity and 80% identity to the aspen bispecific lignin OMT (2), the type member of the group involved in lignin biosynthesis. Our data indicate that this novel OMT uses the flavonol quercetin as the preferred substrate, but neither of the hydroxycinnamic acids, caffeic or 5-hydroxyferulic, to any significant extent. This indicates that the high sequence similarity/identity of AtOMT1 to that of the aspen lignin OMT (2) is not sufficient to assign the function of this gene product.

Arabidopsis↗

PubMed2003

Ability of antioxidants to prevent oxidative mutations in Salmonella typhimurium TA102.

An assay for the ability of antioxidants to prevent mutations induced by various oxidants in Salmonella typhimurium TA102 cells was developed. Protection against hydrogen-peroxide-induced mutagenicity was observed for quercetin, caffeic acid, ascorbic acid and dimethyl sulfoxide (used as a solvent for water-insoluble antioxidants). No protective effect was observed for green tea extract (weakly pro-oxidative), catechin, rutin, sinigrin, ferulic acid and alpha-tocopherol. Mutagenicity caused by tert-butyl hydroperoxide (tBOOH) was prevented most effectively by quercetin and ascorbic acid, whereas weaker effects were observed for green tea extract and for rutin, and no effect being observed for the other antioxidants tested. The results for hydrogen peroxide indicate iron chelation to be the most important protective mechanism. Radical scavenging appeared to be effective only with dimethyl sulfoxide and ascorbic acid, which are effective scavengers of hydroxyl radicals and were used here in high concentrations. It is proposed that the hydrogen-peroxide-induced mutations in the Salmonella cells are caused by hydroxyl radicals generated by iron ions closely associated with DNA. Protection against mutagenicity caused by tert-butyl hydroperoxide appears to occur mainly through the scavenging of alkoxyl and possibly of alkyl radicals.

Antimutagenic Agents↗

PubMed2006

Chlorogenic acid is absorbed in its intact form in the stomach of rats.

The bioavailability of chlorogenic acid, a major polyphenol of the human diet that is particularly abundant in coffee and various fruits, was explored in rats. To identify the form under which it is absorbed through the gut mucosa and the site of absorption along the gastrointestinal tract, rats were fed a diet supplemented with chlorogenic acid (0.25%, wt:wt). Chlorogenic acid and its metabolites were estimated in the stomach, small intestine and cecal contents as well as in bladder urine and plasma by HPLC with coulometric detection at several time points (1.5, 3, 4.5, and 7 h) after the beginning of the meal. Minor hydrolysis of chlorogenic acid (<1%) occurred in the stomach and small intestine contents, whereas 15-32% of ingested chlorogenic acid was hydrolyzed into caffeic acid in the cecum. Chlorogenic acid and caffeic acid appeared early (at 1.5 h) in plasma and urine, suggesting an absorption of chlorogenic acid into the upper part of the gastrointestinal tract. Gastric absorption of chlorogenic acid was further examined by infusing chlorogenic acid in the ligated stomach of food-deprived rats. After 30 min of infusion, intact chlorogenic acid was found in the gastric vein and aorta. No other metabolites could be detected by HPLC-electrospray ionization-MS-MS. These results show for the first time that chlorogenic acid is quickly absorbed in the rat stomach in its intact form.

Absorption↗

PubMed1989

[The action of inhibitors of the amine nitrosation reaction in human gastric juice and in the body of animals].

The effect of ascorbic, ferulic and caffeic acids on dimethylamine and amidopyrine nitrosation in a medium containing 3 samples of total gastric juice taken from 10 humans (pH = 6.1; 3.2 and 1.7) was studied versus the amount of inhibitor added to the medium. The resultant relationship proved bizarre, the inhibitor at low concentrations stimulating nitrosation in some situations. When gastric juice concentration in the medium was further lowered by dilution with a buffer at relevant value of pH, the paradoxical effect of inhibition gradually disappeared.

Aminopyrine↗

PubMed1996

[Anti-inflammatory effect of Urtica dioica folia extract in comparison to caffeic malic acid].

Urtica dioica extract is a traditionary used adjuvant therapeutic in rheumatoid arthritis. The antiphlogistic effects of the urtica dioica folia extract IDS 23 (Extractum Urticae dioicae foliorum) and the main phenolic ingredient caffeic malic acid were tested concerning the inhibitory potential on biosynthesis of arachidonic acid metabolites in vitro. The caffeic malic acid was isolated from Urtica folia extract using gel exclusion- and high performance liquid chromatography and identified by mass spectroscopy and nuclear magnetic resonance. Concerning the 5-lipoxygenase products IDS 23 showed a partial inhibitory effect. The isolated phenolic acid inhibited the synthesis of the leukotriene B4 in a concentration dependent manner. The concentration for halfmaximal inhibition (IC50) was 83 microns/ml in the used assay. IDS 23 showed a strong concentration dependent inhibition of the synthesis of cyclooxygenase derived reactions. The IC50 were 92 micrograms/ml for IDS 23 and 38 micrograms/ml for the caffeic malic acid. Calculating the content in IDS 23 the caffeic malic acid is a possible but not the only active ingredient of the plant extract in the tested assay systems. It is demonstrated that the phenolic component showed a different enzymatic target compared with IDS 23. The antiphlogistic effects observed in vitro may give an explanation for the pharmacological and clinical effects of IDS 23 in therapie of rheumatoid diseases.

Animals↗

PubMed1999

The phenolic vir gene inducer ferulic acid is O-demethylated by the VirH2 protein of an Agrobacterium tumefaciens Ti plasmid.

Some or possibly all Ti plasmids of Agrobacterium tumefaciens encode a bicistronic operon designated virH, which encodes two proteins, VirH1 and VirH2, that resemble a family of cytochrome P450-type monooxygenases. Expression of this operon is induced by a family of phenolic compounds that induce all other operons within the vir regulon. We hypothesized that either or both of these proteins might metabolize some or all of these phenolic compounds. We therefore tested induction of a vir promoter by a variety of phenolic compounds in isogenic strains that express or lack virH1 and virH2. Although some compounds were equally effective inducers regardless of the virH status, other compounds induced vir expression far more effectively in the virH mutant than in the virH-proficient host. For all tested compounds, VirH2 appeared to be solely responsible for this effect. One such compound, ferulic acid, was chosen for biochemical analysis. Ferulic acid was degraded by a VirH-proficient host but not by a VirH mutant. The wild-type strain released large amounts of a more hydrophilic compound into the cell supernatant. This compound was tested by mass spectroscopy, nuclear magnetic resonance and UV spectroscopy and found to consist of caffeic acid. This indicates that wild-type strains convert virtually all added ferulic acid to caffeic acid, and that VirH2 is essential for this O-demethylation reaction. Ferulic acid was far more toxic than caffeic acid to the wild-type strain, although the wild-type strain was more resistant to ferulic acid than was the virH mutant. Caffeic acid was slowly removed from the broth, suggesting further metabolic reactions.

Agrobacterium tumefaciens↗

PubMed2001

Purification and characterization of a O-methyltransferase capable of methylating 2-hydroxy-3-alkylpyrazine from Vitis vinifera L. (cv. Cabernet Sauvignon).

An S-adenosyl-L-methionine-dependent O-methyltransferase capable of methylating 2-hydroxy-3-alkylpyrazine (HP) was purified 7,300-fold to apparent homogeneity with an 8.2% overall recovery from Vitis vinifera L. (cv. Cabernet Sauvignon) through a purification procedure including column chromatography on DEAE-Sepharose FF, Ether-5PW, hydroxyapatite, G2000SW(XL), and DEAE-5PW. The relative molecular mass of the native enzyme estimated on gel permeation chromatography was 85 kDa, and the subunit molecular mass was estimated to be 41 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme also methylates caffeic acid. The Vmax for IBHP and caffeic acid were 0.73 and 175 pkatals/mg, respectively, and the respective Km for IBHP and caffeic acid were 0.30 and 0.032 mm. The optimum pH for IBHP (8.5) was different from that for caffeic acid (7.5).

Amino Acid Sequence↗

PubMed2004

Phenolic composition and radical scavenging activity of sweetpotato-derived shochu distillery by-products treated with koji.

Phenolic composition and radical scavenging activity in the shochu distillery by-products of sweetpotato (Ipomoea batatas L.) treated with koji (Aspergillus awamori mut.) and cellulase (Cellulosin T2) were investigated to develop new uses. Koji and Cellulosin T2 treatment of shochu distillery by-products from sweetpotatoes, rice, and barley increased phenolic content. Caffeic acid was identified as a dominant phenolic component in the shochu distillery by-products of the sweetpotato. Adding koji and/or Cellulosin T2 to the shochu distillery by-product indicated that koji was involved in caffeic acid production. Caffeic acid was not detected in raw or steamed roots of "Koganesengan", the material of sweetpotato for shochu production, suggesting that it is produced during shochu fermentation. The phenolic content and radical scavenging activity the shochu distillery by-product treated with koji and Cellulosin T2 were superior to those of commercial vinegar. These results suggest that koji treatment of sweetpotato-derived shochu distillery by-products has potential for food materials with physiological functions. Further koji treatment of sweetpotato shochu-distillery by-products may be applicable to mass production of caffeic acid.

Acetic Acid↗

PubMed2001

[Determination of polyphenols in tobacco by solid phase extraction and high performance liquid chromatography].

A high performance liquid chromatographic (HPLC) method for the determination of polyphenols in tobacco was studied. Polyphenols can be extracted from tobacco sample by refluxing with 80% (volume fraction) methanol, then subjected to degrease by solid phase extraction with Sep-Pak-C18 column. Chlorogenic acid, rutin, scopoletin, caffeic acid, scopolin and other polyphenols can be separated on a Nova-Pak-C18 column (3.9 mm i.d. x 150 mm) gradiently eluted with methanol and 0.05 mol.L-1 potassium dihydrogen phosphate buffer solution as mobile phase at a flow-rate of 0.5 mL.min-1. Polyphenols were determined at the maximum wavelength of each polyphenol, for chlorogenic acid 326.1 nm, rutin 354.8 nm, scopoletin 344.0 nm, caffeic acid 323.7 nm and scopolin 365.2 nm by photodiode array detector. The main polyphenols in tobacco can be identified with UV spectroscopy. The recoveries of tobacco polyphenols were 94%-105%, and the relative standard deviations were 1.28%-1.49%. This method can be applied to the determination of polyphenols in tobacco with satisfactory results.

Chromatography, High Pressure Liquid↗

PubMed2006

Acteoside and its aglycones protect primary cultures of rat cortical cells from glutamate-induced excitotoxicity.

We have previously reported that acteoside isolated from the leaves of Callicarpa dichotoma has significant neuroprotective activity against glutamate-induced neurotoxicity in primary cultured rat cortical cells. To determine the essential structural moiety within this phenylethanoid glycoside needed to exert neuroprotective activity, acteoside was hydrolyzed with acid into its aglycones, caffeic acid and 3',4'-dihydroxylphenylethanol. Caffeic acid and 3',4'-dihydroxylphenylethanol also showed significant neuroprotective activities. Acteoside and its aglycones inhibited glutamate-induced intracellular Ca2+ influx resulting in overproduction of nitric oxide and reduced the formation of reactive oxygen species. These compounds preserved the mitochondrial membrane potential and the activities of antioxidative enzymes, such as superoxide dismutase, glutathione reductase and glutathione peroxidase reduced by glutamate. It was followed by the preservation of the level of glutathione and finally the inhibition of membrane lipid peroxidation.

Animals↗

PubMed2005

Comparison of the 2,2'-azinobis-3-ethylbenzotiazo-line-6-sulfonic acid (ABTS) and ferric reducing anti-oxidant power (FRAP) methods to asses the total antioxidant capacity in extracts of fruit and vegetables.

A comparison was made on the use of two spectrophotometric methods, the ferric reducing antioxidant power (FRAP) method and the 2,2'-azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) method, for the measurement of the total antioxidant capacity (TAC) of plant foods. The correlations of TAC measured by the two methods were highly significant in both water-soluble (r2= 0.90) and water-insoluble extracts (r2= 0.98) from 13 strawberry samples. Also a corresponding comparison of TAC in extracts from 14 plant species showed high correlation coefficients, r2= 0.98 for water-soluble extracts and r2= 0.88 for water-insoluble extracts. The ratio of TAC values obtained with the two methods (ABTS/FRAP) varied between 0.7 and 3.3 for different plant extracts indicating that they contained antioxidants with varying reactivity in the two methods. TACs in six pure antioxidant substances were ranked in the following order by both methods: quercetin > ferulic acid > catechin > rutin > caffeic acid > Trolox = chlorogenic acid. The two methods showed similar TAC values for quercetin, rutin, caffeic acid and chlorogenic acid while ferulic acid and catechin gave higher results with the ABTS method than with the FRAP method, and such differences probably explain the varying ratios of ABTS/FRAP obtained in foods. Regarding storage TAC in water-soluble strawberry extracts stored at -20 or -80 degrees C was stable for at least five months while storage at 4 degrees C decreased the TAC value with 40% during five weeks of storage. The study showed that both the ABTS and FRAP methods can be used for convenient monitoring of the antioxidant capacities in fruit and vegetables, and that different antioxidants had varying reactivity in the two methods.

Antioxidants↗

PubMedDate not supplied

Interaction of reactive and inert chemicals in the presence of oxidoreductases: reaction of the herbicide bentazon and its metabolites with humic monomers.

The herbicide bentazon (3-isopropyl-1H-2,1,3-benzothiadiazine-4(3H)-one-2,2-dioxide), a relatively inert chemical, and some of its metabolites were incubated with a laccase or a peroxidase in the presence or absence of humic monomers to evaluate the incorporation of the herbicide and its metabolites into humic material by oxidative enzymes. Guaiacol and ferulic acid were used as representative electron donor co-substrates in most of the oxidative coupling reactions. Bentazon and its metabolites, with the exception of hydroxy metabolites, underwent little or no transformation by the two enzymes in the absence of guaiacol and ferulic acid, but in the presence of these co-substrates transformation occurred. The reaction of bentazon with guaiacol in the presence of the laccase or a peroxidase was almost complete in 30 min. 6-Hydroxy- and 8-hydroxy-bentazon were completely transformed by each enzyme both with and without co-substrates. At pH 3.0 and in the presence of laccase and guaiacol, the concentrations of bentazon and its metabolites 2-amino-N-isopropyl-benzamide (AIBA), des-isopropyl-bentazon and 8-chloro-bentazon decreased by 27, 57, 20 and 4%, respectively. The corresponding levels of transformation with peroxidase at pH 3.0 were 9, 70, 30 and 5%, respectively. The extent of transformation decreased with increasing pH. At low pH, the hydroxy-bentazons were completely transformed, followed by (in order of percentage transformation) AIBA, des-isopropyl-bentazon, bentazon and 8-chloro-bentazon. Transformation of bentazon by the laccase increased with increasing guaiacol concentration. In the presence of the peroxidase, the most effective co-substrates for transformation of bentazon were (in decreasing order) catechol, vanillic acid, protocatechuic acid, syringaldehyde and caffeic acid, while in the presence of the laccase, catechol was most effective, followed by caffeic acid, protocatechuic acid and syringaldehyde.

Benzothiadiazines↗

PubMed2000

Potential nitrite scavengers as inhibitors of the formation of N-nitrosamines in solution and tobacco matrix systems.

The ability of 20 compounds, all but one tobacco constituents, to inhibit the formation of tobacco-specific N-nitrosamines (TSNA) was investigated in buffer and detergent solution and in tobacco midrib and lamina systems. In solution at pH 5.5, ascorbic acid and the phenolic acids caffeic and ferulic acid were the most potent inhibitors of the reaction between nornicotine and nitrite, with nearly complete inhibition at molar ratios test compound/nitrite > 1:1. Also, cysteine > dihydrocaffeic acid > protocatechuic acid approximately catechin acted as strong inhibitors with >90% inhibition at a ratio of 3:1. Lower inhibitions were observed with chlorogenic acid > p-coumaric acid > sclareol > serine. Rutin showed an inhibition of 34% at a ratio of 0.1:1. Sclareol, alanine, proline, and serine did not significantly affect the N-nitrosonornicotine (NNN) formation. alpha-Tocopherol and glutathione enhanced NNN formation at pH 5.5 but were inhibitors at pH 3. Cinnamic acid, vanillic acid, eugenol, and esculin enhanced NNN formation. Increased NNN formation was also observed for dihydrocaffeic acid, chlorogenic acid, protocatechuic acid, and catechin at a less-than-equimolar ratio of test compound to nitrite. The tobacco matrix experiments were performed with air-cured, ground tobacco midrib and lamina. Caffeic acid, ferulic acid, dihydrocaffeic acid and catechin were potent inhibitors of the formation of TSNA in the midrib as well as in the lamina. Also protocatechuic acid, glutathione, ascorbic acid, p-coumaric acid, chlorogenic acid and cysteine were inhibitors, while alpha-tocopherol and rutin inhibited the reaction in the midrib but not in the lamina. Cinnamic acid, vanillic acid, eugenol, alanine, proline and serine showed small effects only. The molar ratio of secondary alkaloid(s)/nitrite in the test systems were 0.1:1 (solution), approximately 0.25:1 (midrib), and approximately 1:1 (lamina) and is most likely the major contributor to the observed order of inhibition potency (solution > midrib > lamina) of the test compounds. The vicinal phenolic hydroxyl groups of polyphenols and the simultaneous presence of a phenol group and an olefinic bond in hydroxycinnamic acids were the most characteristic structural elements of the potent inhibitors.

Free Radical Scavengers↗

PubMed1984

Caffeic and ferulic acid as blockers of nitrosamine formation.

Caffeic acid and ferulic acid, which are naturally occurring phenols present in a wide variety of plants, were examined for their ability to react with nitrite in vitro and to inhibit nitrosamine formation in vivo. Their activities were compared with other phenols (butylated hydroxyanisole and Trolox) and with a non-phenolic polyhydroxylated compound, glycerol guaiacolate. In simulated gastric fluid, caffeic acid and ferulic acid reacted rapidly and completely with an equimolar quantity of sodium nitrite. In rats receiving aminopyrine and nitrite, caffeic acid and ferulic acid blocked the elevation of serum N-nitrosodimethylamine (NDMA) levels and the serum glutamic pyruvic transaminase levels associated with hepatotoxicity. Neither phenol had any effect on serum levels of NDMA in rats treated with NDMA. In both the in vitro (reaction with nitrite) and in vivo (inhibition of hepatotoxicity) systems, caffeic acid was more effective than ferulic acid. Butylated hydroxyanisole and Trolox were partially effective, and glycerol guaiacolate was inactive. The results of this study suggest that dietary caffeic acid and ferulic acid may play a role in the body's defense against carcinogenesis by inhibiting the formation of N-nitroso compounds.

Alanine Transaminase↗

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

Substrate preferences of O-methyltransferases in alfalfa suggest new pathways for 3-O-methylation of monolignols.

Measurement of relative O-methyltransferase activities against all potential substrates in the monolignol pathway in developing alfalfa stem extracts revealed activities in the order: caffeoyl CoA > caffeoyl alcohol > 5-hydroxyferulic acid > caffeoyl aldehyde > 5-hydroxyconiferyl alcohol > 5-hydroxyferuloyl CoA > 5-hydroxyconiferaldehyde > caffeic acid. Maxima for all activities occurred in the seventh internode. In stem extracts from transgenic alfalfa with antisense downregulated caffeoyl CoA O-methyltransferase (CCoAOMT), activities with all substrates except for the two coenzyme A esters were unaffected. In contrast, downregulation of caffeic acid O-methyltransferase (COMT) reduced activities against the non-esterifed substrates in the order: 5-hydroxyconiferyl alcohol > 5-hydroxyferulic acid and caffeoyl alcohol > caffeoyl aldehyde > caffeic acid > 5-hydroxyconiferaldehyde. Recombinant COMT expressed in Escherichia coli exhibited the highest V(max)/K(m) values with 5-hydroxyconiferaldehyde and caffeoyl aldehyde, and the lowest with caffeic acid. These results indicate that COMT is unlikely to methylate caffeic acid during lignin biosynthesis in vivo, and provide enzymatic evidence for an alternative pathway to monolignols involving methylation of caffeoyl aldehyde and/or caffeoyl alcohol by COMT. The concept of independent pathways to guaiacyl and syringyl monolignols is discussed.

Catechol O-Methyltransferase↗