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PubMed2001

Baicalein protects cortical neurons from beta-amyloid (25-35) induced toxicity.

Accumulation of amyloid beta peptide (Abeta) has been suggested to contribute to neurodegeneration in Alzheimer's disease (AD). Since chronic inflammation occurs in AD pathogenesis and lipoxygenases are important mediators of inflammatory processes, we evaluated the effect of lipoxygenase inhibitors on apoptosis induced by Abeta on rat cortical cells. The 12-lipoxygenase inhibitor baicalein attenuated both neuronal apoptosis and c-jun protein over-expression induced by Abeta(25- 35), whereas no protection was found with the broad spectrum lipoxygenase inhibitor nordihydroguaiaretic acid or the 5-lipoxygenase inhibitor caffeic acid. These results suggest that 12-lipoxygenase participates in a c-jun-dependent apoptosis pathway triggered by Abeta(25-35), and that specific 12-lipoxygenase inhibitors might be of interest in AD.

Amyloid beta-Peptides↗
PubMed2000

Phenolic acids protect low density lipoproteins from peroxynitrite-mediated modification in vitro.

The role of reactive nitrogen species, such as peroxynitrite, in atherogenesis and the protective effect of dietary phenolic compounds are not yet understood. In this study, we sought firstly to determine whether phenolic acids become nitrated by peroxynitrite and then whether phenolic acid nitration can prevent consumption of gamma-tocopherol and thus enhance the resistance of LDL to oxidation by peroxynitrite. Coumaric acid was found to be readily nitrated by peroxynitrite and it also demonstrated a protective effect on y-tocopherol. Of greater significance was its potent inhibition of lipid peroxidation which was equal to that of caffeic acid.

Caffeic Acids↗
PubMed2002

Antimutagenicity of mono-, di-, and tricaffeoylquinic acid derivatives isolated from sweetpotato (Ipomoea batatas L.) leaf.

The caffeoylquinic acid derivatives, 3-mono-O-caffeoylquinic acid (chlorogenic acid, ChA), 3,4-di-O-caffeoylquinic acid (3,4-diCQA), 3,5-di-O-caffeoylquinic acid (3,5-diCQA), 4,5-di-O-caffeoylquinic acid (4,5-diCQA) and 3,4,5-tri-O-caffeoylquinic acid (3,4,5-triCQA), and caffeic acid (CA) were isolated from the sweetpotato (Ipomoea batatas L.) leaf. We examined the antimutagenicity of these caffeoylquinic acid compounds to promote new uses of the sweetpotato leaf. These caffeoylquinic acid derivatives effectively inhibited the reverse mutation induced by Trp-P-1 on Salmonella typhimurium TA 98. The antimutagenicity of these derivatives was 3,4,5-triCQA > 3,4-diCQA = 3,5-diCQA = 4,5-diCQA > ChA in this order. There was no difference in the antimutagenicity of all dicaffeoylquinic acid derivatives. A comparison of the activities and structures of these compounds suggested that the number of caffeoyl groups bound to quinic acid played a role in the antimutagenicity of the caffeoylquinic acid derivatives. The sweetpotato leaves contained distinctive polyphenolic components with a high content of mono-, di-, and tricaffeoylquinic acid derivatives and could be a source of physiological functions.

Antimutagenic Agents↗
PubMed1996

Ex-vivo in-vitro inhibition of lipopolysaccharide stimulated tumor necrosis factor-alpha and interleukin-1 beta secretion in human whole blood by extractum urticae dioicae foliorum.

An extract of Urtica dioica folium (IDS 23, Rheuma-Hek), monographed positively for adjuvant therapy of rheumatic diseases and with known effects in partial inhibition of prostaglandin and leukotriene synthesis in vitro, was investigated with respect to effects of the extract on the lipopolysaccharide (LPS) stimulated secretion of proinflammatory cytokines in human whole blood of healthy volunteers. In the assay system used, LPS stimulated human whole blood showed a straight increase of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion reaching maximum concentrations within 24 h following a plateau and slight decrease up to 65 h, respectively. The concentrations of these cytokines was strongly positively correlated with the number of monocytes/macrophages of each volunteer. TNF-alpha and IL-1 beta concentration after LPS stimulation was significantly reduced by simultaneously given IDS 23 in a strictly dose dependent manner. At time 24 h these cytokine concentrations were reduced by 50.8% and 99.7%, respectively, using the highest test IDS 23 assay concentration of 5 mg/ml (p < 0.001). After 65 h the corresponding inhibition was 38.9% and 99.9%, respectively (p < 0.001). On the other hand IDS 23 showed no inhibition but stimulated IL-6 secretion in absence of LPS alone. Simultaneously given LPS and IDS 23 resulted in no further increase. In contrast to described effects on arachidonic acid cascade in vitro, tested Urtica dioica phenol carbon acid derivates and flavonoides such as caffeic malic acid, caffeic acid, chlorogenic acid, quercetin and rutin did not influence LPS stimulated TNF-alpha, IL-1 beta and IL-6 secretion in tested concentrations up to 5 x 10(-5) mol/l. These further findings on the pharmacological mechanism of action of Urticae dioica folia may explain the positive effects of this extract in the treatment of rheumatic diseases.

Adult↗
PubMed1998

Inhibition of cholesterol biosynthesis in primary cultured rat hepatocytes by artichoke (Cynara scolymus L.) extracts.

High-dose aqueous extracts from artichoke leaves were found to inhibit cholesterol biosynthesis from 14C-acetate in primary cultured rat hepatocytes in a concentration-dependent biphasic manner with moderate inhibition (approximately 20%) between 0.007 and 0.1 mg/ml and more strong inhibition at 1 mg/ml. Cytotoxic effects detected by lactate dehydrogenase leakage and the 3-[4, 5-dimethylthiazol-2-yl]-2,5-dephenyl tetrazolium bromide-assay were restricted to higher concentrations. Replacement of 14C-acetate by 14C-mevalonate largely omitted the inhibiting effect of artichoke extracts indicating an inhibition at the level of hydroxymethylglutaryl-CoA-reductase. However, no direct inhibition of this enzyme could be detected and no other enzymic steps later in the biosynthetic pathway for cholesterol seemed to be affected. Instead, inhibition was found to occur in a time-dependent manner, to last for several hours even after washing out the extracts by fresh medium and to be fully reversible within 20 hr after removal of the extracts. In addition, the stimulation of HMGCoA-reductase activity by insulin was efficiently blocked by the extracts, although other insulin-dependent phenomena, such as increased lactate production, were not influenced. These results suggest an indirect modulation of hydroxymethylglutaryl-CoA-reductase activity as the most likely inhibitory mechanism of the artichoke extracts. Screening of several known constituents of artichoke extracts revealed that cynaroside and particularly its aglycone luteolin were mainly responsible for inhibition, whereas chlorogenic acid was much less effective and caffeic acid, cynarin and other dicaffeoylquinic acids were without significant influence. Indeed, luteolin also efficiently blocked the insulin effect on cholesterol biosynthesis. In conclusion, these results demonstrate that artichoke extracts may inhibit hepatic cholesterol biosynthesis in an indirect but efficient manner and, thus, may contribute via this action to the recently confirmed hypolipidemic influence of this phytopharmacon in man.

Acetates↗
PubMed2005

Chlorogenate hydrolase-catalyzed synthesis of hydroxycinnamic acid ester derivatives by transesterification, substitution of bromine, and condensation reactions.

A chlorogenate hydrolase (EC 3.1.1.42) synthesized 2-phenylethyl caffeate (2-CAPE) from 5-chlorogenic acid (5-CQA) and 2-phenylethyl alcohol (2-PA) (by transesterification), from 5-CQA and 2-phenylethyl bromide (2-PBr) (by substitution of bromine), and from caffeic acid (CA) and 2-PA or 2-PBr (by condensation) as well as hydrolysis of 5-CQA. Some reaction conditions including pH, temperature, substrate and solvent concentrates, and reaction time were optimized for the production of 2-CAPE. A maximal molar yield of 50% was achieved by transesterification, 4.7% by substitution of bromine, and 13% by condensation. Among the parameters studied for optimization, the pH of the buffer solution and concentration of 2-PA or 2-PBr affected the production of 2-CAPE. The optimum pH for the hydrolysis reaction was within the neutral range (pH 6.5), whereas the residual three reactions were only catalyzed within the acidic range (pH 3.0-4.0). The optimum concentrations of 2-PA and 2-PBr for three reactions were 5-70 vol% and no 2-CAPE was produced in the 2-PA or 2-PBr solutions containing powdered enzyme. The enzyme may bind to the caffeoyl moiety of 5-CQA or CA to form an enzyme-substrate complex. It then catalyzes four different reactions corresponding to the reaction conditions.

Aspergillus↗
PubMed2006

Phenolic constituents from Perovskia atriplicifolia.

Perovskoate, an isorinic acid derivative (1) and perovskoside, the catechol derivative (2) have been isolated from the ethyl acetate soluble fraction of the whole plant of Perovskia atriplicifolia and assigned the structure 3(7-hydroxyphenyl)-2-hydroxy propanoic acid; (R)-form, 2-O-(6',7'-dihydroxy-E-cinnamoyl) (1) and 2-methoxy-4-(undecyl-4'-O-beta-D-glucopyranosyl) phenol (2). In addition, caffeic acid (3) and ferulic acid (4) have been reported for the first time from this species. The structures of these compounds were assigned on the basis of 1D and 2D NMR techniques. The compound 1 showed significant inhibitory activity against lipoxygenase and weak to moderate activity against cholinesterases.

Caffeic Acids↗
PubMed2005

Phenolic acids from beer are absorbed and extensively metabolized in humans.

In spite of the wide literature describing the biological effects of phenolic compounds, scarce data are available on their absorption from diet. In the present work, we studied the absorption in humans of phenolic acids from beer, a common beverage rich in different phenolic acids with related chemical structures. Beer was analyzed for free and total (free+bound) phenolic acids. Ferulic, caffeic and sinapic acids were present in beer mainly as bound forms, while 4-hydroxyphenylacetic acid and p-coumaric acid were present mainly as free forms. Vanillic acid was present equally in the free and bound forms. Plasma samples were collected before and 30 and 60 min after beer administration and analyzed for free and conjugated phenolic acid content. A significant two- to fourfold increase in plasma levels of phenolic acids was detected with peak concentrations at 30 min after beer ingestion. 4-Hydroxyphenylacetic acid was present in plasma mainly as nonconjugated forms while p-coumaric acid was present equally as nonconjugated and conjugated forms. Ferulic, vanillic and caffeic acids were present in plasma predominantly as conjugated forms, with a slight prevalence of sulfates with respect to glucuronates. Our results indicate that phenolic acids from beer are absorbed from the gastrointestinal tract and are present in blood after being largely metabolized to the form of glucuronide and sulfate conjugates. The extent of conjugation is related to the chemical structure of phenolic acids: the monohydroxy derivatives showing the lowest conjugation degree and the dihydroxy derivatives showing the highest one.

Absorption↗
PubMed1995

[Chemical constituents of Clematis intricata Bunge].

Five compounds were isolated from the aerial part of Clematis intricata for the first time. On the basis of spectral data (UV, IR, MS, 1HNMR and 13CNMR), they were identified as scopoletin, caffeic acid, inositol, 1-tria-contanol and beta-sitosterol.

Caffeic Acids↗
PubMed2004

A new test method for the evaluation of total antioxidant activity of herbal products.

A new test method for measuring the antioxidant power of herbal products, based on solid-phase spectrophotometry using tetrabenzo-[b,f,j,n][1,5,9,13]-tetraazacyclohexadecine-Cu(II) complex immobilized on silica gel, is proposed. The absorbance of the modified sorbent (lambda(max) = 712 nm) increases proportionally to the total antioxidant activity of the sample solution. The method represents an attractive alternative to the mostly used radical scavenging capacity assays, because they generally require complex long-lasting stages to be carried out. The proposed test method is simple ("drop and measure" procedure is applied), rapid (10 min/sample), requires only the monitoring of time and absorbance, and provides good statistical parameters (s(r)<or= 0.2). The method was approved in the analysis of the most popular herbal beverages (black and green teas) and drugs (Echinacea products). The results obtained were compared with the content of total flavonoids and tannins of teas and total caffeic acid derivatives of Echinacea, determined spectrophotometrically.

Antioxidants↗
PubMed1992

[Chemical constituents of Drynaria propinqua (Wall) J. Sm].

Four compounds isolated from the rhizomes of Drynaria propinqua collected in Sichuan have been identified. One of them was a new natural product, namely propinqualin, whose structure was established as (-)-epiafzelechin-3-O-beta-D-allopyranoside. The other three were 4-O-beta-D-glucopyranosyl caffeic acid, beta-sitosterol-3-O-beta-D-glucopyranoside and sucrose.

Caffeic Acids↗
PubMed2002

Antioxidant properties of ferulic acid and its related compounds.

Antioxidant activity of 24 ferulic acid related compounds together with 6 gallic acid related compounds was evaluated using several different physical systems as well as their radical scavenging activity. The radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) decreased in the order caffeic acid > sinapic acid > ferulic acid > ferulic acid esters > p-coumaric acid. In bulk methyl linoleate, test hydroxycinnamic acids and ferulic acid esters showed antioxidant activity in parallel with their radical scavenging activity. In an ethanol-buffer solution of linoleic acid, the activity of test compounds was not always associated with their radical scavenging activity. Ferulic acid was most effective among the tested phenolic acids. Esterification of ferulic acid resulted in increasing activity. The activity of alkyl ferulates was somewhat influenced by the chain length of alcohol moiety. When the inhibitory effects of alkyl ferulates against oxidation of liposome induced by AAPH were tested, hexyl, octyl, and 2-ethyl-1-hexyl ferulates were more active than the other alkyl ferulates. Furthermore, lauryl gallate is most effective among the tested alkyl gallates. These results indicated that not only the radical scavenging activity of antioxidants, but also their affinity with lipid substrates, might be important factors in their activity.

Antioxidants↗
PubMed2002

Green coffee bean extract and its metabolites have a hypotensive effect in spontaneously hypertensive rats.

The effects of a water-soluble green coffee bean extract (GCE) on blood pressure were investigated using spontaneously hypertensive rats (SHR). There was a dose-dependent reduction in blood pressure after a single ingestion (180 to 720 mg/kg, p.o.) or long-term ingestion (0.25 to 1% diet for 6 weeks) of GCE. A single oral ingestion (50 to 200 mg/kg) of 5-caffeoylquinic acid (5-CQA), the major component of GCE, dose-dependently decreased blood pressure, suggesting that 5-CQA is involved in the hypotensive effect of GCE in SHR. Because significant increases in caffeic acid (CA) or ferulic acid (FA) were detected in plasma after oral ingestion of 5-CQA in SHR, these acids (2.5, 5,10 micromol/kg) were intravenously injected into SHR under anesthesia and the carotid arterial pressure was measured. Of the two components, FA had a stronger depressor effect than CA. The depressor effect of FA (50 mg/kg, p.o.) was attenuated by the concurrent injection of atropine sulfate (5 mg/kg, s.c.), suggesting that the hypotensive effect of FA in SHR might be mediated via the muscarinic acetylcholine receptors. These findings indicate that oral ingestion of GCE or 5-CQA decreases blood pressure in SHR, and that FA, which is a metabolite of 5-CQA, is a candidate hypotensive component.

Administration, Oral↗
PubMed1981

Evidence against the reported antithiamine effect of caffeic and chlorogenic acids.

Contrary to earlier literature reports, chlorogenic acid (I) is shown to have little or no deleterious effect on thiamine (II) when the 2 compounds are codissolved in aqueous solution. Evidence from nmr spectroscopy and from t. l. c. determination demonstrate that when II is heated at 60 degrees C and at pH 7.8 for 24h, about 10% is destroyed. This result is the same whether I is present or not. Incubating II with I or with caffeic acid (III) in a phosphate buffer at pH 7 or in thiamine assay medium at pH 6 for up to 24h at 37 degrees C did not reduce the growth activity of II or Lactobacillus viridescens. We conclude that I and III are not antithiamine agents.

Caffeic Acids↗
PubMed2005

Separation and purification of chlorogenic acid by molecularly imprinted polymer monolithic stationary phase.

Separation and purification of chlorogenic acid by removal of the impurities compounds co-existed in the product using molecular imprinting technique was firstly reported. In this work, an in situ synthesis method was utilized for the preparation of molecularly imprinted polymer monolithic stationary phase using the impurity molecule (caffeic acid) as template, the mixture of tetrahydrofuran and isooctane as solvent, and methacrylic acid and ethyl glycol dimethacrylate as functional monomer and cross-linker, respectively. The retention behavior of the monolithic polymer to chlorogenic acid molecule, the template and several main impurities compounds in the product was studied and the adsorption capacity of compounds on the stationary phase determined by frontal chromatographic technique. A relatively weak retention of the target product molecule (chlorogenic acid) on the polymer and a strong adsorption capability of the monolith to the template and several main impurities were observed. This might mainly result from the 'shape' difference of chlorogenic acid molecule with the impurities compounds molecules. This approach was shown to be successful for the separation and purification of chlorogenic acid from the extract of Eucommia ulmodies leaves.

Adsorption↗
PubMed2005

Neoflavonoids and related constituents from Nepalese propolis and their nitric oxide production inhibitory activity.

A methanolic extract of Nepalese propolis yielded 10 new open-chain neoflavonoids (1-10), a new chalcone (11), and eight previously reported compounds (12-19). Their structures were determined on the basis of spectroscopic data and chemical conversion. The isolated compounds other than 5, 8, and 16 showed dose-dependent inhibitory activities on nitric oxide production in lipopolysaccharide-activated macrophage-like J774.1 cells and were more active than a positive control, N(G)-monomethyl-L-arginine (IC(50), 27.1 microM). The most potent activities, of 6 and 7 (IC(50), 0.5 microM), were greater than another positive control, caffeic acid phenethyl ester (IC(50), 4.8 microM).

Caffeic Acids↗
PubMed1998

[Chemical constituents of Taraxacum sinicum Kitag].

Five compounds were separated from Taraxacum sinicum by means of solvent extraction and rechromatography on silical gel. Their structures were established as caffeic acid, ferulic acid, chlorogenic acid, luteolin and diosmetin by spectral analysis and chemical evidence. All the compounds were isolated from this plant for the first time. Chlorogenic acid and diosmetin have not been discovered from Taraxacum genus previously.

Asteraceae↗
PubMed1995

Chemoprevention of colon carcinogenesis by phenylethyl-3-methylcaffeate.

Previous studies from this laboratory have established that caffeic acid esters present in propolis, a natural resin produced by honey bees, are potent inhibitors of human colon adenocarcinoma cell growth, carcinogen-induced biochemical changes, and preneoplastic lesions in the rat colon. The present study was designed to investigate the chemopreventive action of dietary phenylethyl-3-methylcaffeate (PEMC) on azoxymethane-induced colon carcinogenesis and to examine the modulating effect of PEMC on phosphatidylinositol-specific phospholipase C (PI-PLC), phospholipase A2, lipoxygenase (LOX), and cyclooxygenase activities in the colonic mucosa and tumor tissues in male F344 rats. At 5 weeks of age, groups of rats were fed the control (modified AIN-76A) diet, or a diet containing 750 ppm of PEMC. At 7 weeks of age, all animals except those in the vehicle (normal saline)-treated groups were given 2 weekly s.c. injections of azoxymethane at a dose rate of 15 mg/kg body weight/week. All groups were maintained on their respective dietary regimen until the termination of the experiment 52 weeks after the carcinogen treatment. Colonic tumors were evaluated histopathologically. Both colonic mucosa and tumors were analyzed for PI-PLC, phospholipase A2, cyclooxygenase, and LOX activities. The results indicate that dietary administration of PEMC significantly inhibited the incidence and multiplicity of invasive, noninvasive, and total (invasive plus noninvasive) adenocarcinomas of the colon (P < 0.05-0.004). Dietary PEMC also suppressed the colon tumor volume by 43% compared to the control diet. Animals fed the PEMC diet showed significantly decreased activities of colonic mucosal and tumor PI-PLC (about 50%), but PEMC diet had no effect on phospholipase A2. The production of 5(S)-, 8(S)-, 12(S)-, and 15(S)-hydroxyeicosatetraenoic acids via the LOX pathway from arachidonic acid was reduced in colonic mucosa and tumors (30-60%) of animals fed the PEMC diet as compared to control diet. PEMC had no effect on the formation of colonic mucosal cyclooxygenase metabolites but inhibited the formation in colonic tumors by 15-30%. The precise mechanism by which PEMC inhibits colon tumorigenesis remains to be elucidated. It is likely that the chemopreventive action may be related, at least in part, to the modulation of PI-PLC-dependent signal transduction and LOX-mediated arachidonic acid metabolism.

Animals↗