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To investigate the stabilizing effect of chlorogenic acid against beta-cyclodextrin, beta-cyclodextrin inclusion compound of chlorogenic acid was prepared by liquid phase method, and affirmed by UV and different thermal analysis. Stability in solution was contrasted between chlorogenic acid and its inclusion complex with beta-cyclodextrin, and the stability of the latter was increased.
The effect of chlorogenic acid on the sleep-wakefulness cycle in rats was investigated in comparison with those of caffeic acid (the metabolite of chlorogenic acid) and dihydrocaffeic acid (the metabolite of caffeic acid). A significant prolongation of sleep latency was observed with chlorogenic acid and caffeic acid at a dose of 500 and 200 mg/kg, respectively. On the other hand, no remarkable effects were observed with dihydrocaffeic acid even at a dose of 500 mg/kg. Caffeine caused a significant increase in sleep latency and waking time and decrease in non-rapid eye movement sleep time at a dose of 10 mg/kg. In contrast, chlorogenic acid and its metabolites had no significant effects on each sleep state. From these results, it may be concluded that chrologenic acid caused a mild arousal effect compared with that of caffeine, and the effect of chlorogenic acid may have occurred through its metabolite caffeic acid.
OBJECTIVE: To investigate the stability of chlorogenic acid in extract of flos lonicerae in different conditions. METHOD: The stability of chlorogenic acid in extract of flos lonicerae in phosptat buffe with different pH values, methanol, ethanol and different base solutions(Ca(OH)2 and NaOH) was investigated by the classical isothermal method. RESULT: The experiments showed the chlorogenic acid in extract of flos lonicerae was more stable in acidic water than in basic water. It was stable in these organic solutions and base solution[Ca(OH)2]. CONCLUSION: In different conditions, the stability of chlorogenic acid in extract of flos lonicerae was different. It provided a reference to the extraction and analysis of chlorogenic acid and production of chlorogenic acid preparation.
The interaction between chlorogenic acid (CGA) and antioxidants was investigated by two different parameters: radical intensity and cytotoxicity induction. ESR spectroscopy shows that CGA produced radicals under alkaline condition. The CGA radical was scavenged by 100-300-fold lower concentrations of sodium ascorbate or N-acetyl-l-cysteine (NAC), whereas the ascorbate radical was not completely scavenged by CGA. The cytotoxic activity of CGA against human oral tumor cells (HSC-2, HSG) was completely eliminated by lower concentrations of sodium ascorbate or NAC, whereas that of sodium ascorbate or NAC was only slightly reduced by CGA. The present study demonstrated that CGA induces cytotoxicity by its radical-mediated oxidation mechanism and suggests the applicability of ESR spectroscopy for the screening of drug to drug interaction.
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.
The effect of chlorogenic acid (CGA) on the killing of Escherichia coli by hypochlorous acid (HOCI) was examined. CGA prevented E. coli from bactericidal action of HOCI in a concentration-dependent manner. HOCI reacted rapidly with CGA. By comparison with the one- and two-electron oxidation products produced by peroxidase and phenolase reactions, respectively, the main product was identified as o-quinone of CGA via the formation of o-semiquinone of CGA as an intermediate The quinone form of CGA reacted further with HOCI to yield unstable product(s).
Chlorogenic acid (CGA) is considered to act as an antioxidant. However, the inhibitory effects of CGA on specific radical species are not well understood. Electron spin resonance (ESR) in combination with spin trapping techniques was utilized to detect free radicals. 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) was used as a spin trapping reagent while the Fenton reaction was used as a source of hydroxyl radical (*OH). We found that CGA scavenges *OH in a dose-dependent manner. The kinetic parameters, IC50 and Vmax, for CGA scavenging of *OH were 110 and 1.27 microM/sec, respectively. The rate constant for the scavenging of *OH by CGA was 7.73 x 10(9) M(-1) sec(-1). Our studies suggest that the antioxidant properties of CGA may involve a direct scavenging effect of CGA on *OH.
The analytical method of chlorogenic acid in sunflower cake by thin-layer chromatography(TLC) was developed. With 36% acetic acid as mobile phase and on the polyamide film plate, the Rf value of chlorogenic acid was 0.61. The calibration curve was linear in the range of 0.05 microgram-0.6 microgram of chlorogenic acid with the detection limit of 0.025 microgram and the average recovery of 97.53%. The inter-plate accuracy of chlorogenic acid was 2.57%. With 70% ethyl alcohol as extracting solvent and 30 min of extraction time, the amount of chlorogenic acid in the extract, the residue amount of chlorogenic acid in the sunflower cake and the extraction rate were determined and calculated by applying this method. The optimal time of extraction was found.
Absorption of orally administered chlorogenic acid (5-caffeoylquinic acid) and caffeic acid in rats was studied to obtain plasma pharmacokinetic profiles of their metabolites. Rats were administered 700 micromol/kg body weight of chlorogenic or caffeic acid, and blood was collected from the tail for 6 h after administration. Ingested caffeic acid was absorbed from the alimentary tract and was present in the rat blood circulation in the form of various metabolites. On the other hand, only traces of metabolites, supposedly caffeic and ferulic acids conjugates, were detected in rat plasma for 6 h after chlorogenic acid administration. Chlorogenic acid and small amounts of caffeic acid were found in the small intestine for 6 h after chlorogenic acid administration. These results suggest that chlorogenic acid is not well absorbed from the digestive tract, unlike caffeic acid, and subject to almost no structural changes to the easily absorbed forms.
The protective effects of chlorogenic acid on paraquat-induced oxidative stress were examined in rats. The activities of erythrocytes and liver glutathione peroxidase, and of both liver catalase and glutathione reductase, which were increased by feeding paraquat, declined to the levels in the control rats by supplementing chlorogenic acid to the paraquat diet. The activity of superoxide dismutase was not changed by dietary paraquat or by supplementing chlorogenic acid to the paraquat diet. Paraquat in the diet markedly decreased the liver triacylglycerol and phospholipid concentrations, as well as the food intake and body weight gain, while chlorogenic acid protected against these decreases. These in vivo results and the in vitro superoxide anion scavenging activity of chlorogenic acid suggest that chlorogenic acid acted preventively against paraquat-induced oxidative stress.
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.
AIMS: Conjugated hydroxycinnamates, such as chlorogenic acid (caffeoyl-quinic acid), are widely consumed in a Western diet, coffee being one of the richest sources. Ingested hydroxycinnamate esters can reach the large intestine essentially unaltered, and may then be hydrolysed by esterases produced by the indigenous microflora. This study is aimed at identifying bacterial species responsible for the release of natural antioxidants, such as hydroxycinnamic acids, in the human large intestine. METHODS AND RESULTS: Thirty-five isolates recovered after anaerobic batch culture incubation of human faecal bacteria in a chlorogenic acid-based medium were screened for cinnamoyl esterase activity. Six isolates released the hydroxycinnamate, ferulic acid, from its ethyl ester in a plate-screening assay, and these were identified through genotypic characterization (16S rRNA sequencing) as Escherichia coli (three isolates), Bifidobacterium lactis and Lactobacillus gasseri (two strains). Chlorogenic acid hydrolysing activities were essentially intracellular. These cinnamoyl esterase-producing organisms were devoid of other phenolic-degrading activities. CONCLUSION: The results show that certain gut bacteria, including some already recognized as potentially health-promoting (i.e. species belonging to the genera Bifidobacterium and Lactobacillus), are involved in the release of bioactive hydroxycinnamic acids in the human colon. SIGNIFICANCE AND IMPACT OF THE STUDY: Free hydroxycinnamates, including caffeic, ferulic and p-coumaric acids, exhibit antioxidant and anticarcinogenic properties both in vitro and in animal models. Given that the gut flora has a major role in human nutrition and health, some of the beneficial effects of phenolic acids may be ascribed to the microflora involved in metabolism.
Chlorogenic acid prevented a stepwise conversion of plasmid pUC18 DNA, from I-->form II-->form III, induced by 3 mM monochloramine with a half inhibition of 67.4 microM. Chlorogenic acid reacted with monochloramine in a time-dependent manner, and the reaction rate increased with decreasing pH. These results suggest that chlorogenic acid prevents genotoxicity of monochloramine in gastric mucosa.
To investigate the pharmacokinetics of unbound chlorogenic acid, a sensitive microbore liquid chromatographic method for the determination of chlorogenic acid in rat blood by microdialysis has been developed. A microdialysis probe was inserted into the jugular vein of male Sprague-Dawley rats, to which chlorogenic acid (20, 40, 60 or 80 mg/kg, i.v.) had been administered. On-line microdialysate was directly injected into a microbore column using a methanol-100 mM sodium dihydrogenphosphate (30:70, v/v, pH 2.5 adjusted with orthophosphoric acid) as the mobile phase and ultraviolet detection at 325 nm. The method is rapid, easily reproduced, selective and sensitive. The limit of detection for chlorogenic acid was 0.01 microg/ml and the limit of quantification was 0.05 microg/ml. The in vivo recovery of the chlorogenic acid of the microdialysis probe, based on a 5 microg/ml standard, was approximately 49-65% (n=6). The disposition of chlorogenic acid at each dose was best fitted to a two-compartment pharmacokinetic model. The area under the concentration curve increased greater than in direct proportion with the dose and terminal disposition become much slower as the dose was increased. The results indicated that the pharmacokinetics of unbound chlorogenic acid in rat blood is non-linear.
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