[Characterization of the chlorogenic acid in certain yeasts by paper chromatography].
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A complex antioxidant system is present in human saliva, with uric acid being the most concentrated component. Ascorbic acid, present at low concentrations in saliva, is actively secreted into the gastric lumen. We report that ascorbic acid added to human saliva at pH 2 was consumed within a few minutes, regenerating HNO(2), whereas uric acid was consumed relatively slowly in a nitrite-dependent manner. The consumption of uric acid was (i) rapid under normoxic conditions and slower at low oxygen tensions, (ii) coupled to *NO release, (iii) linked to the decrease in nitrite consumption and in nitrate formation, and (iv) unaffected by the nitrosation catalyst thiocyanate. Both chlorogenic acid and bovine serum albumin, representative of a phenol- and a protein-rich meal, respectively, were able to spare uric acid, although chlorogenic acid increased, whereas bovine serum albumin inhibited, *NO release. We hypothesize that the major role of uric acid in saliva at pH 2 could be to preserve the stomach from the formation of toxic nitrogen species and that low levels of uric acid, together with ascorbic acid consumption, may contribute to the high occurrence of tumors at the gastroesophageal junction and cardia. The sparing effects of dietary compounds may therefore be an important not fully appreciated effect.
An ultrasonic method for the extraction of chlorogenic acid from fresh leaves of Eucommia ulmodies Oliv. was investigated and optimized. The influence of four extraction variables on extraction efficiency of chlorogenic acid was investigated. The optimum extraction conditions found were: 70% aqueous methanol; solvent: sample ratio=20:1 (v/w); extraction time 3 x 30 min. The recovery of chlorogenic acid was studied (HPLC) and the reproducibility of the extraction method was determined. The optimized ultrasonic extraction conditions were applied to extract chlorogenic acid from fresh leaves, fresh bark and dried bark of E. ulmodies and four traditional Chinese medicines. The application of sonication method was shown to be highly efficient in the extraction of chlorogenic acid from E. ulmodies and other Chinese medicines compared with classical methods.
Chlorogenic acid is the major polyphenol in foods derived from plants and is a good substrate for polyphenol oxidase. Chlorogenic acid quinone (CQA-Q), which is an oxidative product of chlorogenic acid by polyphenol oxidase, is an important intermediate compound in enzymatic browning. CQA-Q was prepared, and its properties and the relationship with browning were examined. The quinone solution was yellow or orange, and its molecular absorption coefficient was estimated to be 1.7 x 10(3) for 325 nm and 9.7 x 10(2) for 400 nm in an acidic aqueous solution. Chlorogenic acid and H2O2 were spontaneously generated in the CQA-Q solution as the yellowish color of the solution gradually faded. A pale colored polymer was the major product in the reaction solution. Amino acids such as lysine and arginine added to CQA-Q solution did not repress the fading of the yellowish color of the solution. We concluded from these results that CQA-Q itself and a mixture of CQA-Q and amino acids did not form intensive brown pigments in the acidic aqueous solution. H2O2 spontaneously formed in the CQA-Q solution, and other polyphenols might have played an important role in the formation of the brown color by enzymatic browning.
Phenolic non-flavonoid compounds in diets, such as chlorogenic acid and caffeic acid are widely recognized to be antioxidants. However, it is not known how these phenolics scavenge reactive species of oxygen and nitrogen. We determined the rate constants of the reactions between the phenolics with superoxide and hydroxyl radical with a pulse radiolysis. The second-order rate constants of the reactions of chlorogenic acid with superoxide and hydroxyl radical were 1.67 +/- 0.14 x 10(6) M(-1) s(-1) and 3.34 +/- 0.19 x 10(9) M(-1) s(-1), respectively, while those of caffeic acid with superoxide and hydroxyl radical were 0.96 +/- 0.01 x 10(6) M(-1) s(-1) and 3.24 +/- 0.12 x 10(9) M(-1) s(-1), respectively. By scavenging peroxy radical chlorogenic acid inhibited the initiation of chain lipid peroxidations by organic free radical. The second-order rate constant of the reaction of chlorogenic acid with peroxy radical was estimated to be 1.28 +/- 0.11 x 10(5) M(-1) s(-1). Chlorogenic acid was rapidly oxidized by peroxynitrite in concentration- and pH-dependent manners and its rate constant was determined to be 1.6 +/- 0.7 x 10(5) M(-1) s(-1), using competitive inhibitions by glutathione and methionine.
OBJECTIVE: To determine the contents of chlorogenic acid in flower of Chrysanthemum morifolium. METHOD: Column: Nova-Pak C18, 4 microns, 4.6 mm x 250 mm, mobile phase: MeOH-0.1 mol.L-1 NaH2PO4(pH 2.65)30:70, detection wavelength: 328 nm. RESULTS: Flowers of 20 batches bought from the market were analysed. Contents of chlorogenic acid were 0.060%-0.467%. CONCLUSION: Chlorogenic acid is a suitable component for the quality control of C. morifolium.
The isolation and characterization of a specific chlorogenic acid esterase is described. The enzyme activity is measured by determination of the hydrolysis product caffeic acid. The enzyme had been concentrated by means of ultrafiltration and column-chromatography. The pH- and temperature optimum were 6.5 and 45 degrees C respectively. Divalent cations were not required for the enzyme activity. As other esterases, this enzyme is inhibited by di-isopropyl-phosphorofluoridate. The Km-value is 0.70 mM chlorogenic acid, the molecule weight 240 000. The described enzyme is specific for chlorogenic acid. On the other hand a typical unspecific esterase like the pig liver esterases does not split chlorogenic acid. The isoelectric focusing reveals several isoenzymes of chlorogenase within a pI-range of 4.0-4.5.
BACKGROUND: In population studies, high intakes of coffee are associated with raised concentrations of plasma homocysteine, a predictor of risk of cardiovascular disease. Chlorogenic acid is a major polyphenol in coffee; coffee drinkers consume up to 1 g chlorogenic acid/d. OBJECTIVE: We studied whether chlorogenic acid affects plasma total homocysteine concentrations in humans. For comparison we also studied the effects of black tea rich in polyphenols and of quercetin-3-rutinoside, a major flavonol in tea and apples. DESIGN: In this crossover study, 20 healthy men and women ingested 2 g (5.5 mmol) chlorogenic acid, 4 g black tea solids containing approximately 4.3 mmol polyphenols and comparable to approximately 2 L strong black tea, 440 mg (0.7 mmol) quercetin-3-rutinoside, or a placebo daily. Each subject received each of the 4 treatments for 7 d, in random order. RESULTS: Total homocysteine in plasma collected 4-5 h after supplement intake was 12% (1.2 micromol/L; 95% CI: 0.6, 1.7) higher after chlorogenic acid and 11% (1.1 micromol/L; 95% CI: 0.6, 1.5) higher after black tea than after placebo. Total homocysteine in fasting plasma collected 20 h after supplement intake was 4% (0.4 micromol/L; 95% CI: 0.0, 0.8) higher after chlorogenic acid and 5% (0.5 micromol/L; 95% CI: 0.0, 0.9) higher after black tea than after placebo. Quercetin-3-rutinoside did not significantly affect homocysteine concentrations. CONCLUSIONS: Chlorogenic acid, a compound in coffee, and black tea raise total homocysteine concentrations in plasma. Chlorogenic acid could be partly responsible for the higher homocysteine concentrations observed in coffee drinkers. Whether these effects on homocysteine influence cardiovascular disease risk remains to be established.
OBJECTIVE: To study the influence of drug compatibility on the extractive rates of chlorogenic acid and isochlorogenic acid in Simiaoyonglan Tang (SMYAT) decoction. METHOD: The contents of chlorogenic acid and isochlorogenic acid in SMYAT decoction, Flos Lonicerae and Flos Lonicerae in combination with other single drugs were determined by TLC-UV spectrophotometry respectively. The data from this experiment were treated statistically. RESULTS: The contents of chlorogenic acid in other five prescriptions of different compatibilities decreased markedly in comparison with those in Flos Loniceraés decoction (P < 0.01). The content of isochlorogenic acid in SMYAT decoction as a whole was about the same as thar in Flos Loniceraés decoction, but decreased significantly in other prescriptions of different compatibilities (P < 0.01). CONCLUSION: Drug compatibility is one of the main causes for changes of chlorogenic acid and isochlorogenic acid contents in SMYAT decoction.
Synchrotron radiation and the time-correlated single-photon counting technique were used to investigate the spectral and time-resolved characteristics of blue-green fluorescence (BGF) of artichoke leaves. Leaves emitted BGF under ultraviolet (UV) excitation; the abaxial side was much more fluorescent than the adaxial side, and in both cases, the youngest leaves were much more fluorescent than the oldest ones. The BGF of artichoke leaves was dominated by the presence of hydroxycinnamic acids. A decrease in the percentage of BGF attributable to the very short kinetic component (from 42 to 20%), in the shape of the BGF excitation spectra, and chlorogenic acid concentrations indicate that there is a loss of hydroxycinnamic acid with leaf age. Studies on excitation, emission, and synchronized fluorescence spectra of leaves and trichomes and chlorogenic acid contents indicate that chlorogenic acid is one of the main blue-green fluorophores in artichoke leaves. Results of the present study indicate that 20-42% (i.e., the very short kinetic component) of the overall BGF is emitted by chlorogenic acid. Time-resolved BGF measurements could be a means to extract information on chlorogenic acid fluorescence from the overall leaf BGF.
Previous research on plants used in folk medicine as antidotes against snake-bite revealed some constituents responsible for such protection. Chlorogenic acid (3-0-caffeoyl quinic acid) was one of these substances, studied with more attention. It has been shown that this substance binds to proteins through hydrophobic interactions and hydrogen bonds. This paper shows the preliminary results about the anti-complementary action of chlorogenic acid. Human and guinea pig sera, treated with chlorogenic acid, were added to the hemolytic system (sheep erythrocyte sensitized with hemolysin) to study its effect on the activation of the classical complement pathway. The action on the alternative pathway was studied with human serum treated with chlorogenic acid and zymosan. Our results show that chlorogenic acid presents anti-complementary action at the classical pathway, since the sera are not able to lysis the indicator system. The presence of C3b fragments on the surface of the yeast cells demonstrates that the alternative pathway was not affected.
A phenylpropanoid compound has been characterized in a Nicotiana plumbaginifolia cell suspension. This compound has been isolated and purified by semi-preparative reverse phase-high performance liquid chromatography. Its structure has been identified by NMR spectroscopy as 5-O-caffeoylquinic acid, which is chlorogenic acid (CA). The influence of culture conditions on the accumulation of this metabolite by N. plumbaginifolia cell suspensions has been studied. Darkness strongly inhibits the CA accumulation. Moreover, it has been shown that feeding experiments with caffeic acid had a deleterious effect upon the CA content. This one was not influenced by a supplementation with quinic acid.
A novel HPLC-UV method was developed for the simultaneous determination of two major active components in Yinhuang injection, chlorogenic acid and baicalin, in rat plasma. Extracted from the plasma samples with methanol-acetonitrile (3:1, v/v), the two compounds were successfully separated using a C18 column with a gradient elution composed of 15 and 54% methanol-acetonitrile (1:1, v/v) in 0.2% (v/v) phosphoric acid water solution (pH 2.0). The flow-rate was set at 1 ml min(-1) and the eluent was detected at 327 nm for chlorogenic acid, 278 nm for baicalin. Puerarin and rutin were used as the internal standards for chlorogenic acid and baicalin, respectively. The method was linear over the range of 0.388-12.4 microg ml(-1), 0.485-124 microg ml(-1) for chlorogenic acid and baicalin, respectively. The correlation coefficient for each analyte was above 0.998. The intra-day and inter-day precisions were better than 7 and 9%, with the relative error ranging from -9.5 to 7.3% and from -4.2 to 1.8%. The limit of detection (LOD) and the limit of quantification (LOQ) for chlorogenic acid and baicalin in plasma were 0.194, 0.122, 0.388 and 0.485 microg ml(-1), respectively. This assay has been successfully applied in the pharmacokinetic study of chlorogenic acid and baicalin in vivo through intravenous administration of Yinhuang injection to rats.
Chlorogenic acid, the ester of caffeic acid with quinic acid, is one of the most abundant polyphenols in the human diet with coffee, fruits and vegetables as its major sources. Its antioxidant and anticarcinogenic properties have been well established in animal studies. However, little is known about its gut absorption and metabolism. In the present work, four groups of rats (n = 8) were fed a diet supplemented with chlorogenic, caffeic or quinic acids (250 micromol/d) or an unsupplemented diet for 8 d. Parent compounds and their metabolites were estimated in urine (24-h collection) and plasma by HPLC-electrospray ionization-tandem mass spectrometry. Significant differences in their levels were observed among the groups. The recovery of chlorogenic acid in urine was low (0.8%, mol/mol), and the total urinary excretion of caffeic acid liberated by hydrolysis of chlorogenic acid and its tissular methylated metabolites (ferulic and isoferulic acids) did not account for >0.5% (mol/mol) of the dose ingested. On the other hand, the metabolites of microbial origin, namely, m-coumaric acid and derivatives of phenylpropionic, benzoic and hippuric acids, represented the major compounds in both urine and plasma. Hippuric acid largely originated from the transformation of the quinic acid moiety, and all other metabolites from the caffeic acid moiety. These microbial metabolites accounted for 57.4% (mol/mol) of the chlorogenic acid intake. Such a high abundance of microbial metabolites shows that the bioavailability of chlorogenic acid depends largely on its metabolism by the gut microflora. Their potential importance in explaining the biological effects of dietary polyphenols is emphasized.
A simple, rapid and reproducible capillary electrophoretic method was developed for the determination of chlorogenic acid, glycyrrhizin and glycyrrhetinic acid in Yinqiaojiedupian. The buffer solution used in this method was a mixture of 20 mmol/L NaH2PO4 and 5 mmol/L Na2B4O7(pH 7.0). The other conditions were as follows: applied voltage, 20 kV (positive to negative polarity); L = 60 cm; Leff = 55 cm; i.d. = 75 microns; lambda = 254 nm; temperature, 25 degrees C; injection time, 5 s hydrostatic. The linear calibration range was 1.568-100.4 mg/L for glycyrrhetinic acid, 8.000-128.0 mg/L for glycyrrhizin and 8.080-129.3 mg/L for chlorogenic acid, and recoveries were 98.0%-103% for glycyrrhetinic acid, 97.3%-102% for glycyrrhizin and 97.3%-100% for chlorogenic acid. The relative standard deviations (n = 3) were 0.2%-1.3% (intra-day) and 1.9%-3.0% (inter-day) for glycyrrhetinic acid, 0.5%-1.2%(intra-day) and 1.9%-2.1%(inter-day) for glycyrrhizin and 0.7%-1.3%(intra-day) and 1.6%-2.1%(inter-day) for chlorogenic acid. The contents of these three acids in Yinqiaojiedupian were successfully determined within 10 min.
1. Partially purified preparations of tobacco-leaf o-diphenol oxidase (o-quinol-oxygen oxidoreductase; EC 1.10.3.1) oxidize chlorogenic acid to brown products, absorbing, on average, 1.6atoms of oxygen/mol. oxidized, and evolving a little carbon dioxide. 2. The effect of benzenesulphinic acid on the oxidation suggests that the first stage is the formation of a quinone; the solution does not go brown, oxygen uptake is restricted to 1 atom/mol. oxidized, and a compound is produced whose composition corresponds to that of a sulphone of the quinone derived from chlorogenic acid. 3. Several other compounds that react with quinones affect the oxidation of chlorogenic acid. The colour of the products formed and the oxygen absorbed in their formation suggest that the quinone formed in the oxidation reacts with these compounds in the same way as do simpler quinones. 4. Some compounds that are often used to prevent the oxidation of polyphenols were tested to see if they act by inhibiting o-diphenol oxidase, by reacting with quinone intermediates, or both. 5. Ascorbate inhibits the enzyme and also reduces the quinone. 6. Potassium ethyl xanthate, diethyldithiocarbamate and cysteine inhibit the enzyme to different extents, and also react with the quinone. The nature of the reaction depends on the relative concentrations of inhibitor and chlorogenic acid. Excess of inhibitor prevents the solution from turning brown and restricts oxygen uptake to 1 atom/mol. of chlorogenic acid oxidized; smaller amounts do not prevent browning and slightly increase oxygen uptake. 7. 2-Mercaptobenzothiazole inhibits the enzyme, and also probably reacts with the quinone; inhibited enzyme is reactivated as if the inhibitor is removed as traces of quinone are produced. 8. Thioglycollate and polyvinylpyrrolidone inhibit the enzyme. Thioglycollate probably reduces the quinone to a small extent.
OBJECTIVE: To develop the identification and assay for chlorogenic acid in commercial Herba Artemisiae Scopariae. METHOD: TLC method was used for identification with silica gel G plate and butyl acetate-formic acid-water (7:2.5:2.5) upper layer as a developing solvent. Chlorogenic acid in 85% methanolic extract was separated on the ODS column with methonal-3% acetic acid solution (15:85) as mobile phase. The detection wavelength was 327 nm. RESULT: The qualitative method is repeatable. Chlorogenic acid in extracts is well separated, relationship of injection amount and peak area is linear (r = 0.9998) within the range of 0.075-0.6 microgram. The average recovery is 100.9% and repeatability is 1.4%. Ten samples purchased from different areas in the country were identified and quantified with the methods. CONCLUSION: The methods and data could be used for quality control.