Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Caffeic Acids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed2006

Antioxidant and antiradical activities in extracts of hazelnut kernel (Corylus avellana L.) and hazelnut green leafy cover.

Phenolic compounds in the aqueous systems were extracted, from hazelnut kernel (HK) and hazelnut green leafy cover (HGLC), with 80% (v/v) ethanol (HKe and HGLCe) or 80% (v/v) acetone (HKa and HGLCa). The extracts were examined for their phenolic and condensed tannin contents and phenolic acid profiles (free and esterified fractions) as well as antioxidant and antiradical activities by total antioxidant activity (TAA), antioxidant activity in a beta-carotene-linoleate model system, scavenging of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, and reducing power. Significant differences (p < 0.05) in the contents of total phenolics, condensed tannins, and TAA existed among the extracts that were examined. HGLCa extract had the highest content of total phenolics (201 mg of catechin equivalents/g of extract), condensed tannins (542 mg of catechin equivalents/g of extract), and TAA (1.29 mmol of Trolox equivalents/g of extract) followed by HGLCe, HKa, and HKe extracts, respectively. Five phenolic acids (gallic acid, caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid) were tentatively identified and quantified, among which gallic acid was the most abundant in both free and esterified forms. The order of antioxidant activity in a beta-carotene-linoleate model system, the scavenging effect on DPPH radical, and the reducing power in all extracts were in the following order: HGLCa > HGLCe > HKa > HKe. These results suggest that both 80% ethanol and acetone are capable of extracting phenolics, but 80% acetone was a more effective solvent for the extraction process. HGLC exhibited stronger antioxidant and antiradical activities than HK itself in both extracts and could potentially be considered as an inexpensive source of natural antioxidants.

Acetone↗
PubMed2006

Development of a stable isotope dilution analysis with liquid chromatography-tandem mass spectrometry detection for the quantitative analysis of di- and trihydroxybenzenes in foods and model systems.

A straightforward stable isotope dilution analysis (SIDA) for the quantitative determination of the di- and trihydroxybenzenes catechol (1), pyrogallol (2), 3-methylcatechol (3), 4-methylcatechol (4), and 4-ethylcatechol (5) in foods by means of liquid chromatography-tandem mass spectrometry was developed. With or without sample preparation involving phenylboronyl solid phase extraction, the method allowed the quantification of the target compounds in complex matrices such as coffee beverages with quantification limits of 9 nmol/L for 4-ethylcatechol, 24 nmol/L for catechol, 3-methyl-, and 4-methylcatechol, and 31 nmol/L for pyrogallol. Recovery rates for the analytes ranged from 97 to 103%. Application of the developed SIDA to various commercial food samples showed that quantitative analysis of the target compounds is possible within 30 min and gave first quantitative data on the amounts of di- and trihydroxybenzenes in coffee beverage, coffee powder, coffee surrogate, beer, malt, roasted cocoa powder, bread crust, potato crisps, fruits, and cigarette smoke and human urine. Model precursor studies revealed the carbohydrate/amino acid systems as well as the plant polyphenols catechin and epicatechin as precursors of catechol and 5-O-caffeoylquinic acid, caffeic acid as a precursor of catechol and 4-ethylcatechol, and gallocatechin, epigallocatechin, and gallic acid as precursors of pyrogallol.

Catechols↗
PubMed2006

Phenolic acids are absorbed from the rat stomach with different absorption rates.

The intestinal absorption characteristics of phenolic acids (PAs) have been elucidated in terms of their affinity for the monocarboxylic acid transporter (MCT). Recently, the involvement of the stomach has been implicated in the absorption of polyphenols. The present work demonstrates that the gastric absorption efficiency of each PA is apparently different between various PAs. Various PAs with different affinities for MCT were administered (2.25 mumol) to rat stomach, and then the plasma concentration of the PA was measured. The plasma concentration of ferulic acid (FA) peaked 5 min after administration in the stomach. At 5 min after administration, the plasma concentration of each PA increased in the order: gallic acid = chlorogenic acid < caffeic acid < p-coumaric acid = FA. This order matches their respective affinity for MCT in Caco-2 cells, which we have demonstrated in previous studies. These results indicated that MCT might be involved in the gastric absorption of PAs, similar to the intestinal absorption.

Absorption↗
PubMed1999

Antioxidant capacity of oat (Avena sativa L.) extracts. 2. In vitro antioxidant activity and contents of phenolic and tocol antioxidants.

Oat milling fractions were examined for concentrations of total phenolics, tocols, and phenolic acids and in vitro antioxidant activity to determine their potential as dietary antioxidants. Methanolic extracts of pearling fractions, flour and aspirations from flaking, and trichomes had high, intermediate, and low antioxidant activities, respectively, evaluated by the beta-carotene bleaching method. Pearling fractions were also highest in total phenolics and tocols. p-Hydroxybenzoic acid, vanillic acid, caffeic acid, vanillin, p-coumaric acid, and ferulic acid were identified and quantified by HPLC. Three avenanthramides and an unidentified ferulate derivative were also detected. Total phenolic content was significantly correlated with antioxidant activity, and regression equations that predicted antioxidant activity from phenolic and tocol concentrations were calculated. Antioxidant activity, evaluated by beta-carotene bleaching, was correlated with measures of oxygen radical absorbance capacity and low-density lipoprotein oxidation. These data indicate a potential for oat products, especially those enriched in outer layers of the groat, to contribute to dietary intakes of antioxidant phytonutrients.

Antioxidants↗
PubMed2000

Relationship among antioxidant activity, vasodilation capacity, and phenolic content of red wines.

The relationship among antioxidant activity, based on the electron-spin resonance determination of the reduction of Fremy's radical, vasodilation activity, and phenolic content was investigated in 16 red wines. The wines were selected to provide a range of origins, grape varieties, and vinification methods. Sensitive and selective HPLC methods were used for the analysis of the major phenolics in red wine: free and conjugated myricetin, quercetin, kaempferol, and isorhamnetin; (+)-catechin, (-)-epicatechin, gallic acid, p-coumaric acid, caffeic acid, caftaric acid, trans-resveratrol, cis-resveratrol, and trans-resveratrol glucoside. Total anthocyanins were measured using a colorimetric assay. The total phenolic content of the wines was determined according to the Folin-Ciocalteu colorimetric assay and also by the cumulative measurements obtained by HPLC. The 16 wines exhibited a wide range in the values of all parameters investigated. However, the total phenol contents, measured both by HPLC and colorimetrically, correlated very strongly with the antioxidant activity and vasodilation activity. In addition, the antioxidant activity was associated with gallic acid, total resveratrol, and total catechin. In contrast, only the total anthocyanins were correlated with vasodilation activity. The results demonstrate that the different phenolic profiles of wines can produce varying antioxidant and vasodilatant activities, which opens up the possibility that some red wines may provide enhanced health benefits for the consumer.

Antioxidants↗
PubMed2000

Phenolic compounds in virgin olive oil. 2. Reappraisal of the extraction, HPLC separation, and quantification procedures.

The extraction procedures (solid/liquid SPE and liquid/liquid LLE) and HPLC separation and quantification methods of polyphenolic compounds have been checked in virgin olive oils in order to explain the differences in content reported in the literature. The work has been carried out on oils prepared from one cultivar and produced under the same protocol. The extraction methods are practically equivalent, but the SPE technique is more favorable because it is faster and simpler. It has been proved that the chromatographic features and the method of chemical expression of the concentrations may greatly affect the final values. Thus, under the same analytical method, the total concentration values of polyphenols of the same oil show variations from 18% to 80%, according to the formality of expression as gallic acid, caffeic acid, or tyrosol equivalents. The role of the nature and spectrophotometric features of the phenols and of the internal standard is also discussed, and it was found to be an important source of reported variation. A gradient separation with an eluent mixture acetonitrile-sulfuric acid (0.1 mol/L), detection at 225 nm, and quantitative calculation of polyphenolic compounds in oils (expressed as tyrosol equivalents, THY(eq)) is proposed.

Chromatography, High Pressure Liquid↗
PubMed2004

Phelligridins C-F: cytotoxic pyrano[4,3-c][2]benzopyran-1,6-dione and furo[3,2-c]pyran-4-one derivatives from the fungus Phellinus igniarius.

Three unique pyrano[4,3-c][2]benzopyran-1,6-dione derivatives and a new furo[3,2-c]pyran-4-one, named phelligridins C-F (2-5), together with hispolon (8), (E)-4-(3,4-dihydroxyphenyl)but-3-en-2-one (9), 4-hydroxybenzaldehyde, protocatechualdehyde, syringic acid, protocatechuic acid, caffeic acid, isoergosterone, and octadecyl ferulate were isolated and identified from the ethanolic extract of Phellinus igniarius. Their structures were determined by spectroscopic methods including IR, MS, and 1D and 2D NMR experiments. The structures of the new compounds were characterized as 3-(4-hydroxystyryl)-8,9-dihydroxypyrano[4,3-c]isochromene-4-one (2), 3-(3,4-hydroxystyryl)-8,9-dihydroxypyrano[4,3-c]isochromene-4-one (3), 8,9-dihydroxy-3-[5',6'-dihydroxy-5' '-methyl-3' '-oxo-spiro[fural-2' '(3' 'H),1'-indene]-2'-yl]-1H,6H-pyrano[4,3-c][2]benzopyran-1,6-dione (4), and (3Z)-3-(3,4-dihydroxybenzylidene)-6-(3,4-dihydroxystyryl)-2,3-dihydro-2-methoxy-2-(2-oxo-propyl)furo[3,2-c]pyran-4-one (5), respectively. Some compounds including 2 and 3 showed in vitro selective cytotoxicity against a human lung cancer cell line (A549) and a liver cancer cell line (Bel7402). Possible biogenetic sequences to the formation of 1-9 are postulated.

Antineoplastic Agents↗
PubMedDate not supplied

Hepatoprotective activity of polyphenolic compounds from Cynara scolymus against CCl4 toxicity in isolated rat hepatocytes.

The hepatoprotective activity against CCl4 toxicity in isolated rat hepatocytes of some polyphenolic compounds, such as cynarin, isochlorogenic acid, chlorogenic acid, luteolin-7-glucoside, and two organic acids, caffeic and quinic, from Cynara scolymus, is tested. Only cynarine and, to a lesser extent, caffeic acid showed cytoprotective action. The possible relationship between the molecular structure and the protective effect found is discussed.

Alanine Transaminase↗
PubMed2003

In vitro formation of quinoid metabolites of the dietary supplement Cimicifuga racemosa (black cohosh).

Botanical dietary supplements containing Cimicifuga racemosa (Actaea racemosa; black cohosh) are used commonly by women to assuage menopausal symptoms including hot flashes and sleep disorders. Despite the popularity of such supplements, little is known about the metabolism or possible toxicity of many compounds that could be concentrated therein. The aim of this study was to selectively identify phase I metabolites resulting from metabolic bioactivation of constituents of black cohosh in vitro and to determine whether evidence of such metabolites could be found in the urine of perimenopausal women taking black cohosh oral supplements. A variation of an ultrafiltration mass spectrometric assay devised previously was used to screen an extract of black cohosh for the formation of electrophilic phase I metabolites that had been trapped as GSH conjugates. Mercapturates (N-acetylcysteine conjugates) corresponding to the GSH conjugates identified during screening were synthesized and characterized using LC-MS/MS with product-ion scanning. During a phase I clinical trial of black cohosh in perimenopausal women, urine was collected from seven subjects, each of whom took a single oral dose of either 32, 64, or 128 mg of the black cohosh extract. These urine samples were analyzed for the presence of mercapturate conjugates using positive-ion electrospray LC-MS and LC-MS/MS. On the basis of their propensity to form GSH adducts following metabolic activation by hepatic microsomes and NADPH in vitro, a total of eight electrophilic metabolites of black cohosh were detected, including quinoid metabolites of fukinolic acid, fukiic acid, caffeic acid, and cimiracemate B. Additional quinoid metabolites were formed from hydroxytyrosol and dihydroxyphenyl lactic acid, neither of which had been isolated previously from black cohosh. However, mercapturate conjugates of these black cohosh constituents were not detected in urine samples from women who consumed single oral doses of up to 256 mg of a standardized black cohosh extract. Therefore, for moderate doses of a dietary supplement containing black cohosh, this study found no cause for safety concerns over the formation of quinoid metabolites in women.

Acetaminophen↗
PubMed1968

Degradation of phenylalanine and tyrosine by Sporobolomyces roseus.

Ammonia-lyase activity for l-phenylalanine, m-hydroxyphenylalanine and l-tyrosine was demonstrated in cell-free extracts of Sporobolomyces roseus. Cultures of this organism converted dl-[ring-(14)C]phenylalanine and l-[U-(14)C]tyrosine into the corresponding cinnamic acid. Tracer studies showed that these compounds were further metabolized to [(14)C]protocatechuic acid. Benzoic acid and p-hydroxybenzoic acid were intermediates in this pathway. Washed cells of the organism readily utilized cinnamic acid, p-coumaric acid, caffeic acid, benzoic acid and p-hydroxybenzoic acid. Protocatechuic acid was the terminal aromatic compound formed during the metabolism of these compounds. The cells of S. roseus were able to convert m-coumaric acid into m-hydroxybenzoic acid, but the latter compound, which accumulated in the medium, was not further metabolized. 4-Hydroxycoumarin was identified as the product of o-coumaric acid metabolism by this organism.

Benzoates↗
PubMed2003

New Pyrrolizidine Alkaloids and Glycosides from Anchusa strigosa.

Six new pyrrolizidine alkaloids, a new carboxylic acid, a new phenolic and a new oleanane glycoside, together with the known compounds 7,7'-bis-(4-hydroxy-3,5-dimethoxyphenyl)-8,8'-dihydroxymethyltetrahydrofuran 4'-O-beta-D-glucopyranoside, rosmarinic acid, caffeic acid, tormentic acid 28-O-beta- D-glucopyranoside, euscaphic acid 28-O-beta-D-glucopyranoside, euscaphic acid, and allantoin were isolated from Anchusa strigosa roots. Their structures were established by high resolution NMR, MS, elemental analysis, and chemical reactions.

Boraginaceae↗
PubMed2005

Inhibition of thrombin activity by selected natural products in comparison to neutrophil elastase.

Enzymatic thrombin activity is significantly inhibited only by a few selected natural phenolic compounds (myricetin, rosmarinic acid, caffeic acid phenethyl ester) but more strongly by unsaturated fatty acids like erucic acid and oleic acids. Compared to the inhibitory potential against neutrophil elastase, thrombin activity is rather weakly inhibited by phenolic compounds and fatty acids. Because of the importance of thrombin as a ligand for protease-activated receptor 1 (PAR-1), which is involved in inflammation, the inhibition of thrombin activity by natural compounds might enhance the anti-inflammatory effects of neutrophil elastase inhibition.

Animals↗
PubMed1998

Food constituents attenuate monoamine oxidase activity and peroxide levels in C6 astrocyte cells.

Glial cell monoamine oxidase (MAO) activity has been implicated as a contributor to oxidative neuronal damage associated with various neurodegenerative diseases. The attenuation of MAO activity may provide protection against oxidative neurodegeneration. In this investigation, the presence of MAO-B in rat C6 astrocyte cells was substantiated by dose-dependent inhibition of enzyme activity in the presence of chlorgyline-HCl and L-deprenyl. The present study evaluated various dietary-derived food constituents for evidence of inhibition on oxidative deamination of monoamines or peroxide radical trapping capacity. Results of this investigation indicate that compounds which inhibit C6 glial cell MAO enzyme activity or scavenge peroxide product include chlorogenic acid, (+)-catechin, taxifolin, (-)-epigallocatechin gallate (EGCG), fisetin, coenzyme Q0, curcumin, sesamol, morin, sesame oil, silymarin, green tea, ferulic acid, caffeic acid, and rutin hydrate. The results of this study indicate that dietary compounds can attenuate peroxide production in glial cells by either inhibiting the deamination of monoamines or acting as a free radical scavenger.

Animals↗
PubMed2003

Determination of phenolic antioxidant compounds produced by calli and cell suspensions of sage (Salvia officinalis L.).

Sage (Salvia officinalis L.) calli were established by culturing internodal segments, excised from aseptic seedlings, on MS basal medium gellied with agar and supplemented with 0.05 mg/L dichlorophenoxyacetic acid (2,4-D) in presence of benzyladenine (BA) or zeatin (ZEA) or kinetin (KIN), at 1.5 mg/L. Suspended cells were established by transferring one callus to 50 mL of liquid MS basal medium devoid of agar and containing the same type of hormonal supplementation used in respective calli growth. The highest growth of calli and suspensions occurred with 1.5 mg/L ZEA. However, with this cytokinin supplementation, as well as with 1.5 mg/L KIN, both in presence of 0.05 mg/L 2,4-D, suspensions differentiated small root shaped structures. Well shaped, majority single cell suspensions were formed under the effect of 0.05 mg/L 2,4-D and 0.5 mg/L KIN. Calli grown with 0.05 mg/L 2,4-D and 1.5 mg/L BA and suspended cells grown with 0.05 mg/L 2,4-D and ZEA or KIN at 1.5 mg/L, or KIN at 0.5 mg/L, were searched for phenolics production. Twelve phenolic compounds were identified in calli: gallic acid, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, caffeic acid, rosmarinic acid, hesperetin, epirosmanol, hispidulin, genkwanin, carnosol, carnosic acid, and methyl carnosate. With the exception for genkwanin and epirosmanol all of these phenolic compounds were also produced by the sage suspension cultures grown in the presence of 1.5 or 0.5 mg/L KIN. Genkwanin was the only phenolic absent in the suspensions grown with 1.5 ZEA. Suspended cells, grown with 0.5 mg/L KIN, and calli cultures showed the highest specific accumulation of the total phenolics, with rosmarinic acid representing 94-97%.

Antioxidants↗
PubMed2000

Trypanosoma cruzi dihydrolipoamide dehydrogenase is inactivated by myeloperoxidase-generated "reactive species".

Dihydrolipoamide dehydrogenase (LADH) from Trypanosoma cruzi was inactivated by treatment with myeloperoxidase (MPO)-dependent systems. With MPO/H2O2/NaCl, LADH lipoamide reductase and diaphorase activities significantly decreased as a function of incubation time. Iodide, bromide, thiocyanide and chloride effectively supplemented the MPO/H2O2 system, KI and NaCl being the most and the least effective supplements, respectively. LADH inactivation by MPO/H2O2/NaCl and by NaOCl was similarly prevented by thiol compounds such as GSH, L-cysteine, N-acetylcysteine, penicillamine and N-(2-mercaptopropionyl-glycine) in agreement with the role of HOCI in LADH inactivation by MPO/H2O2/NaCl. LADH was also inactivated by MPO/NADH/halide, MPO/H2O2/NaNO2 and MPO/NADH/NaNO2 systems. Catalase prevented the action of the NADH-dependent systems, thus supporting H2O2 production by NADH-supplemented LADH. MPO inhibitors (4-aminobenzoic acid hydrazide, and isoniazid), GSH, L-cysteine, L-methionine and L-tryptophan prevented LADH inactivation by MPO/H2O2/NaNO2. Other MPO systems inactivating LADH were (a) MPO/H2O2/chlorpromazine; (b) MPO/H2O2/monophenolic systems, including L-tyrosine, serotonin and acetaminophen and (c) MPO/H2O2/di- and polyphenolic systems, including norepinephrine, catechol, nordihydroguaiaretic acid, caffeic acid, quercetin and catechin. Comparison of the above effects and those previously reported with pig myocardial LADH indicates that both enzymes were similarly affected by the MPO-dependent systems, allowance being made for T. cruzi LADH diaphorase inactivation and the greater sensitivity of its LADH lipoamide reductase activity towards the MPO/H2O2/NaCl system and NaOCl.

Animals↗
PubMed2006

Antioxidant profile of dihydroxy- and trihydroxyphenolic acids--a structure-activity relationship study.

Eight structurally similar dihydroxy and trihydroxyphenolic acids (protocatechuic acid, 3,4-dihydroxyphenylacetic acid, hydrocaffeic acid, caffeic acid, gallic acid, 3,4,5-trihydroxyphenylacetic acid, 3-(3,4,5-trihydroxyphenyl)propanoic acid and 3-(3,4,5-trihydroxyphenyl)propenoic acid) were examined for their total antioxidant capacity (TAC). Furthermore, their ability to scavenge peroxyl radicals, generated by AAPH in liposomes, was determined. The antioxidant/pro-oxidant activity of the compounds was screened using the 2'-deoxyguanosine assay. All compounds behave as radical scavengers, with 3,4,5-trihydroxyphenylacetic acid being the most potent. Nevertheless, in the lipid peroxidation assay an inverse ranking order was observed, 3,4-dihydroxyphenylacetic acid being the most effective compound. All the dihydroxylated compounds showed a pro-oxidant behaviour leading to an increase of 50% in 8-OH-dG induction. From the structure-antioxidant activity relationship studies performed it may be concluded that the number of phenolic groups and the type of the alkyl spacer between the carboxylic acid and the aromatic ring strongly influence the antioxidant activity.

Antioxidants↗
PubMed1999

Interaction of hydroxycinnamic acid derivatives with the Cl3COO radical: a pulse radiolysis study.

The electron transfer reactions between the trichloromethylperoxyl radical (Cl3COO*) and hydroxycinnamic acid derivatives, including chlorogenic acid, sinapic acid, caffeic acid, ferulic acid and 3,4-(methylenedioxy)cinnamic acid, have been studied by pulse radiolysis. The hydroxycinnamic acid derivatives, especially sinapic acid, are identified as good antioxidants for reduction of Cl3COO* via electron transfer reactions. From buildup kinetic analysis of phenoxyl radical, the rate constant for reaction of Cl3COO* with sinapic acid has been determined to be 8.2x10(7) dm3 mol(-1) s(-1), while the rate constants of electron transfer from other hydroxycinnamic acid derivatives to Cl3COO* were obtained to be about 2x10(7) dm3 mol(-1) s(-1). The reaction of 3,4-(methylenedioxy) cinnamic acid with Cl3COO* was investigated as an evidence for the electron transfer mechanism.

Antioxidants↗
PubMed2000

Effect of arachidonic acid metabolic inhibitors on hypoxia/reoxygenation-induced renal cell injury.

The present study was undertaken to examine the role of arachidonic acid (AA) metabolites in hypoxia/reoxygenation (H/R)-induced renal cell injury in rabbit renal cortical slices using AA metabolic inhibitors. Inhibitors of cyclooxygenase (indomethacin and diclofenac sodium) and lipoxygenase pathways (nordihydroguaiaretic acid, caffeic acid, and eicosapentaenoic acid) reduced H/R-induced LDH release in a dose-dependent manner, whereas an inhibitor of cytochrome P-450 monooxygenase pathway ethoxyresorufin was not effective. AA increased LDH release in control slices, and the effect was not altered by indomethacin and nordihydroguaiaretic acid. The protective effect of indomethacin was not affected by addition of PGE2, a main product of cyclooxygenase pathway in the kidney. H2O2-induced LDH release was prevented by inhibitors of lipoxygenase but not by inhibitors of cyclooxygenase and cytochrome P-450 monooxygenase H/R-induced LDH release was not altered by iron chelators, phenanthroline and deferoxamine, and a potent antioxidant, N,N'-diphenyl-p-phenylenediamine, suggesting that the H/R-induced cell injury is not attributed to a generation of reactive oxygen species. Morphological studies showed that H/R-induced structural changes including cell necrosis were significantly prevented by indomethacin. These results suggest that inhibitors of cyclooxygenase and lipoxygenase pathways exert a direct protective effect against the H/R-induced cell injury in renal tubules. Whether these effects are mediated by alterations of AA metabolic pathways is not certain.

Animals↗