Catechol Content Research Articles

Electrochemical determination of catechol in tea samples using anthraquinone modified carbon paste electrode

Electrochemical investigation of catechol using square wave voltammetry with anthraquinone modified carbon paste electrode was found to be very sensitive. Compared with the unmodified carbon paste electrode, the anthraquinone modified electrode remarkably increases the peak currents of catechol, and greatly lowers the peak potential separation. Two varieties of tea, namely green, and black variety: Wush Wush tea, from Ethiopia, known by its brand name were investigated. Responses for the extracts using ethanol: water (1:4) % v/v showed green tea to be superior in catechol content. Optimization of different variables such as pH of working solution, modifier composition and square wave parameters such as frequency, amplitude and step potential were made to improve the method efficiency during the experiment. The reproducibility for the nine repeated analysis of 80 μmol·L－1 of catechol gave a relative standard deviation of 3.65% and linear calibration plots were obtained in the range 6 to 80 μmol·L－1 with (R = 0.998) and the detection limit with (S/N = 3) was as low as 2.155 x 10－7 mol·L－1.

Contribution of flavonoids and catechol to the reduction of ICAM-1 expression in endothelial cells by a standardised Willow bark extract

IntroductionA quantified aqueous Willow bark extract (STW 33-I) was tested concerning its inhibitory activity on TNF-α induced ICAM-1 expression in human microvascular endothelial cells (HMEC-1) and further fractionated to isolate the active compounds. ResultsAt 50μg/ml the extract, which had been prepared from Salix purpurea L., decreased ICAM-1 expression to 40% compared to control cells without showing cytotoxic effects. Further liquid–liquid partition revealed an ethyl acetate phase with potent reduction of ICAM-1 expression to 40% at 8μg/ml. This fraction was comprehensively characterised by the isolation of flavanone aglyca and their corresponding glycosides, chalcone glycosides, salicin derivatives, cyclohexane-1,2-diol glycosides, catechol and trans-p-coumaric acid. All compounds were investigated for their activity on TNF-α induced ICAM-1 expression. The flavonoid and chalcone glycosides were not active up to 50μM, whereas catechol and eriodictyol at the same concentration showed a significant reduction of ICAM-1 expression to 50% of control. Interestingly, other isolated flavanone aglyca like taxifolin, dihydrokaempferol and naringenin showed only weak or moderate inhibitory activity. Eriodictyol was a minor compound in the extract, whereas the catechol content in the extract (without excipients) reached 2.3%, determined by HPLC. One of the isolated cyclohexan-1,2-diol glucosides, 6′-O-4-hydroxybenzoyl-grandidentin, is a new natural compound. ConclusionAs catechol is quantitatively important in Willow bark extracts it can be concluded from the in vitro data that not only flavonoids and salicin derivatives, but also catechol can probably contribute to the anti-inflammatory activity of Willow bark extracts.

Synthesis of a poly(vinylcatechol-co-divinylbenzene) resin and accessibility to catechol units

Poly(vinylcatechol-co-divinylbenzene) resins have been prepared by suspension copolymerization of 3,4-dimethoxystyrene (DMS) with divinylbenzene (DVB) using toluene as the porogen and followed by deprotection of the catechol functions. The ratio of DMS versus DVB was modified and led to a maximum catechol content (determined by elemental analysis) varying from 0.82 to 3.16mmolg−1. Large surface areas were found for copolymers prepared with a divinylbenzene content larger than 35% v/v: from 464 to 658m2g−1. Accessibility (determined by back titration of the hydroxyl groups) was improved by prior contact with ethanol but remained inferior to 20%. This can be the result of the morphology of the resin beads and of the bottle-shape form of the pores, or/and of the embedding of the catechol units inside the polymer network. The sorption capacities were determined for Cu(II) and Cd(II) and reached 101.5 and 81.0μmolg−1 for copper and cadmium, respectively. Moreover, a significant variation of coloration has been observed upon complexation of copper by the resins.

Molecular and Functional Analyses of Amino Acid Decarboxylases Involved in Cuticle Tanning in Tribolium castaneum

Aspartate 1-decarboxylase (ADC) and 3,4-dihydroxyphenylalanine decarboxylase (DDC) provide beta-alanine and dopamine used in insect cuticle tanning. beta-Alanine is conjugated with dopamine to yield N-beta-alanyldopamine (NBAD), a substrate for the phenol oxidase laccase that catalyzes the synthesis of cuticle protein cross-linking agents and pigment precursors. We identified ADC and DDC genes in the red flour beetle, Tribolium castaneum (Tc), and investigated their functions. TcADC mRNA was most abundant prior to the pupal-adult molt. Injection of TcADC double-stranded (ds) RNA (dsTcADC) into mature larvae resulted in depletion of NBAD in pharate adults, accumulation of dopamine, and abnormally dark pigmentation of the adult cuticle. Injection of beta-alanine, the expected product of ADC, into dsTcADC-treated pupae rescued the pigmentation phenotype, resulting in normal rust-red color. A similar pattern of catechol content consisting of elevated dopamine and depressed NBAD was observed in the genetic black mutants of Tribolium, in which levels of TcADC mRNA were drastically reduced. Furthermore, from the Tribolium black mutant and dsTcADC-injected insects both exhibited similar changes in material properties. Dynamic mechanical analysis of elytral cuticle from beetles with depleted TcADC transcripts revealed diminished cross-linking of cuticular components, further confirming the important role of oxidation products of NBAD as cross-linking agents during cuticle tanning. Injection of dsTcDDC into larvae produced a lethal pupal phenotype, and the resulting grayish pupal cuticle exhibited many small patches of black pigmentation. When dsTcDDC was injected into young pupae, the resulting adults had abnormally dark brown body color, but there was little mortality. Injection of dsTcDDC resulted in more than a 5-fold increase in levels of DOPA, indicating that lack of TcDDC led to accumulation of its substrate, DOPA.

Substrate‐Independent Layer‐by‐Layer Assembly by Using Mussel‐Adhesive‐Inspired Polymers

A new method for creating layer-by-layer (LbL) assembled films on any substrate using polymers inspired by the high catechol content of mussel adhesive proteinsis presented. Catechol-derivatized polymers permit LbL assembly on challenging substrates without prior surface preparation. Catechol groups incorporated into the LbL film induce the reduction of silver ions to metallic silver when immersedin an aqueous metal salt solution, providing antibacterial properties.

Productivity and biochemical properties of green tea in response to full-length and functional fragments of HpaGXooc, a harpin protein from the bacterial rice leaf streak pathogen Xanthomonas oryzae pv. oryzicola

Harpin proteins from plant pathogenic bacteria can stimulate hypersensitive cell death (HCD), drought tolerance, defence responses against pathogens and insects in plants, as well as enhance plant growth. Recently, we identified nine functional fragments of HpaG;Xooc, a harpin protein from Xanthomonas oryzae pv.oryzicola, the pathogen that causes bacterial leaf streak in rice. Fragments HpaG;1-94'HpaG;10-42, and HpaG;62-138, which contain the HpaG;Xooc regions of the amino acid sequence as indicated by the number spans, exceed the parent protein in promoting growth, pathogen defence and HCD in plants. Here we report improved productivity and biochemical properties of green tea (Camellia sinensis) in response to the fragments tested in comparison with HpaG;Xooc and an inactive protein control. Field tests suggested that the four proteins markedly increased the growth and yield of green tea, and increased the leaf content of tea catechols, a group of compounds that have relevance in the prevention and treatment of human diseases. In particular, HpaG;1-94 was more active than HpaG;Xooc in expediting the growth of juvenile buds and leaves used as green tea material and increased the catechol content of processed teas. When tea shrubs were treated with HpaH;Xooc and HpaG;1-94 compared with a control, green tea yields were over 55% and 39% greater, and leaf catechols were increased by more than 64% and 72%, respectively. The expression of three homologues of the expansin genes, which regulate plant cell growth, and the CsCHS gene encoding a tea chalcone synthase, which critically regulates the biosynthesis of catechols, were induced in germinal leaves of tea plants following treatment with HpaG;1-94 or HpaG;Xooc. Higher levels of gene expression were induced by the application of HpaG;1-94 than HpaG;Xooc. Our results suggest that the harpin protein, especially the functional fragment HpaG;1-94, can be used to effectively increase the yield and improve the biochemical properties of green tea, a drink with medicinal properties.

Dopamine Contamination of Infused Tyramine

Clinical assessments of autonomic function often include tyramine (TYR) infusion. After uptake of TYR by sympathetic nerves via the cell membrane norepinephrine (NE) transporter and translocation of axoplasmic TYR into vesicles, NE exits the vesicles. Some of the NE enters the extracellular fluid and occupies adrenoceptors on cardiovascular smooth muscle cells, increasing blood pressure. A small proportion reaches the circulation, so that plasma NE concentrations increase (1)(2)(3). Jacob et al. (4) reported an ∼50-fold mean increase in plasma dopamine (DA) concentrations during intravenous TYR infusion, associated with “paradoxical” forearm vasodilation. We also noted high plasma DA concentrations in healthy volunteers during TYR infusion (5). When we assayed the catechol contents of the TYR infusate dispensed by our pharmacy [1 g/L (6.5 mmol/L)], we found that the infusate contained ∼50 μmol/L DA, corresponding to 0.7% contamination (6). Whether during TYR infusion such contamination could actually raise plasma DA concentrations was unclear, as was whether, while stored as is customary in solution at 4 °C, TYR could be converted to DA. The present study examined these possibilities. Solutions of TYR for infusion were prepared by the NIH Pharmaceutical Development Service, using TYR hydrochloride (Sigma) dissolved in sterile water, with pH ∼9. The solutions were stored either in a refrigerator at 4 °C or in an ultra-low temperature freezer at −70 °C for up to 9 months and then were assayed for catechol content, including DA. Infusate and arterial plasma concentrations of catechols were assayed (7), and hemodynamics were assessed before and during intravenous TYR infusion [6.5 μmol (1 mg)/min] in a total of 34 adults who underwent TYR infusion as part of autonomic function testing. Of the 34 participants, 6 were healthy volunteers, 13 were patients with chronic orthostatic intolerance, 9 had neurogenic orthostatic hypotension, 5 had …

Antibacterial and antioxidant activities of ethanol extract from Paullinia cupana Mart.

The antibacterial and antioxidant activity of the ethanol extract from Paullinia cupana var. sorbilis Mart. (Sapindaceae) seeds, commonly called guarana, was assessed towards selected bacteria as well as in different antioxidant models. The extract, at a concentration between 16 and 128 μg/ml, showed a significant antibacterial effect expressed as minimum inhibitory concentration (MIC) against both Gram-negative and Gram-positive bacteria. In particular, Pseudomonas aeruginosa (MIC = 16 μg/ml), Proteus mirabilis (MIC = 32 μg/ml), Proteus vulgaris (MIC = 32 μg/ml) and Escherichia coli (MIC = 32 μg/ml) were the most inhibited. The antioxidant activity was determined by the malonyldialdehyde (MDA) test, measuring the MDA concentration in 3T3-L1 cells after induced cellular damage using ferric ammonium citrate (FAC). The reduction of lipid peroxidation was 62.5% using a guarana extract with a concentration of 2 μg/ml. This effect was dose/dependent. The ethanol extract from Paullinia cupana seeds was analysed by spectrophotometry to determine the concentration of catechol substances after treatment of the extract with p-aminophenol. The total phenolics content in the ethanol extract was also determined spectrophotometrically according to the Folin–Ciocalteu procedure and calculated as gallic acid equivalents (GAE). The concentration of catechol equivalent was 6.06 ± 0.13 mg/g (mean ± S.D.), while the total phenolic content was 8.43 ± 0.21 mg/g (mean ± S.D.). The correlation index between antioxidant activity and catechol content was 0.96.

Molecular basis of the activity of the dopamine synapse in the mechanisms of learning and amnesia.

The neurochemical correlates of dopamine synapse activity were studied during the retrieval of memory traces and in the absence of retrieval ("psychogenic" amnesia). The physiochemical parameters of D2 receptor function, the synaptic membrane, and the catechol content were assessed in various regions of the brain (striatum, neostriatum, hypothalamus, amygdala, frontal cortex, hippocampus, nucleus accumbens, and nuclei A9 and A10) in intact, trained, and amnesiac rats. It was demonstrated that disturbances in memory trace retrieval were associated with decreased activation of synaptic dopamine receptors and alterations in the dopamine transformation pathway in the rat brain.

The influence of inorganic matter on the pyrolysis of Canadian lignite in a fluidized bed

In low rank coals much of the inorganic matter is present as cations associated with organic carboxyl groups in the coal rather than as discrete mineral phases. By treating the coal with acid the inorganic content is reduced by cation exchange, as well as by acid leaching of discrete minerals. Whole and acid treated samples of pulverized lignite were pyrolyzed in pilot scale (1 to 3 kg coal/h) and bench scale (60 to 100 g coal/h) fluidized bed reactors at atmospheric pressure, 0.45 second vapour-residence time, and temperatures ranging from 500 to 730°C. Yields of char, tar, water and light gases were determined. Removal of inorganic matter from a Saskatchewan lignite resulted in increased yields of tar and total volatile matter, with little effect on the yields of light gases. Increased yields of tar are largely a result of an increased asphaltene fraction in general and specifically of an increased catechol content. Char from acid-washed coal is less reactive to carbon dioxide than is char obtained from raw lignite.

Introduction and oxidation of catechols during the formation of the skate (Raja erinacea) egg capsule

Tanning of theRaja erinaceaegg capsule occurs after secretion of capsule precursors from the nidamental gland and involves the introduction of catechols and their subsequent oxidation to quinones by catechol oxidase. At the time of secretion and assembly of capsular precursors in the nidamental gland, the capsule is white, contains no catechols and lacks chemical and mechanical stability. Following formation in the nidamental gland, catechols accumulatein uteroin parallel with colour development. An inactive form of catechol oxidase is incorporated in the capsular matrix at the time of secretion. Catechol oxidase activity increases concomitantly with increasing catechol content and colour development.

Pharmacokinetics, Bioavailability, Metabolism, Tissue Distribution and Urinary Excretion of γ-L-Glutamyl-L-dopa in the Rat

gamma-L-Glutamyl-L-dopa (gludopa) is believed to be a dopamine prodrug specific for the kidney. Its pharmacokinetics have been studied in the rat given 50 mg kg-1 intravenously (i.v.) and 60 mg kg-1 intraperitoneally (i.p.). By the i.v. route, elimination followed apparent first order kinetics and was biphasic with a t 1/2 alpha of 7 min and terminal half-life of 67 min. After i.p. administration absorption was rapid (t 1/2 ab 6 min), elimination was monophasic with a terminal half-life almost identical following i.v. dosing (65 min), and bioavailability was 40%. In tissues (liver and kidney) gludopa was biotransformed to four intact catecholic products (L-dopa, dopamine, DOPAC and gamma-L-glutamyl-dopamine) which appeared quickly (peaks at 15 min) and which were almost completely cleared by 4 h. Dopamine was the major kidney metabolite accounting for 69% of total catechol content with an AUC 31 times greater than in liver where it accounted for only 34% of total catechols. In rat urine eight major metabolites (5.7% of the dose) and at least 12 minor metabolites were detected of all of which 85% was dopamine. A higher percentage of the dose was excreted as intact catechols in man (15.7%) but fewer metabolites were detected (L-dopa, dopamine, DOPAC). It is confirmed that gludopa is kidney specific in rat but that the pharmacological effects of dopamine are likely to be short lived due to rapid clearance. Gludopa appears to be less dopamine specific in man.

A method for very rapid determinations of catechols using ion-pairing reverse phase HPLC with electrochemical detection: effects of L-dopa treatment on the catechol content in various rat brain structures.

A simple and rapid method for determination of 12 catechols (9 endogenous and 3 internal standards, i.s.) using ion-pairing reverse phase HPLC with electrochemical detection is presented. This study basically concentrates on the importance of optimizing the mobile phase composition in isocratic systems where ordinary 25 cm X 4.6 mm i.d. columns are used. Mobile phase compositions for three different purposes are reported: 1) separation of 9 endogenous catechols, possibly occurring in the samples, and 3 i.s. in a moderately short retention time (tR) (L-DOPA, DOPEG, alpha-Methyldopa (alpha-MeDOPA, i.s.), Noradrenaline (NA), DOPAC, Adrenaline (A), Dihydroxybensylamine (DHBA, i.s.), Norsalsolinol (NS), Dopamine (DA), Epinine (EPI), Salsolinol (S) and Isoprenaline (ISO, i.s.) within 11 min), 2) ultra rapid separation of detectable endogenous catechols except L-DOPA (NA, DOPAC, A, DHBA (i.s.), NS and DA within 5.2 min and with S within 5.7 min) and 3) moderately fast separation of detectable endogenous catechols (L-DOPA, NA, A, DHBA (i.s.), NS, DOPAC and DA within 7.6 min and with S within 10 min). By balancing the pH, concentration of organic modifier (2-propanol) and pairing ion (1-heptanesulphonic acid) as well as preconditioning new columns with more packing material (Nucleosil 5 micron C18) and to high pressures (5000 psi) for 7 days, very fast separations with good baseline resolution between the peaks are possible. The method was applied on L-DOPA treated rats (100 mg/kg), where the catechol content was analysed in 7 different brain structures during the time course of synthesis and degradation (4 hours) of catechols from L-DOPA.

Catechols in primary and metastatic human malignant melanoma cells in monolayer culture

Dopa and 5-S-cysteinyldopa were determined in permanent cell lines obtained from two primary and two metastatic human malignant melanoma and also in one clone of one of the primary melanoma cell lines. The cell lines differed considerably with regard to catechol content and secretion into the media. The clone also differed from the original cell line. Results in the exponential growth phase differed from those in the plateau phase and change of medium affected catechol content. Determination of catechols in cultured melanoma cells can be used for characterization of cell lines that cannot be separated by optical or ultrastructural morphological methods.

Hydrogenation of kraft lignin

AbstractA series of high temperature hydrogenolyses‐hydrogenations of kraft lignin in water, organic solvents and aqueous alkali using a variety of catalysts were run. The liquefaction and distillation yields for the resulting products were measured. The products from these reactions were characterized by titration for acidic materials, elemental analyses, catechol content, ultraviolet absorption, and NMR.

Effect of a catechol amine blocking agent (dibenzyline) on organ content and urine excretion of noradrenaline and adrenaline.

Summary.1. The urinary excretion of noradrenaline and adrenaline was determined in normal rats and rats receiving dibenzyline. The effect of this blocking agent on the catechol content of the adrenals, heart and spleen was also observed.2. Dibenzyline caused an increased excretion of noradrenaline, and a decreased organ content of catechols. Urinary adrenaline remained unchanged.3. The significance of these findings is discussed in the light of the effector catechol receptor theory. It is suggested that dibenzyline may interfere with the metabolism of catechols in areas not contiguous to their site of production.

The relation between sweating and the catechol content of the blood in the horse.

The Journal of PhysiologyVolume 132, Issue 3 p. 542-552 ArticleFree Access The relation between sweating and the catechol content of the blood in the horse C. Lovatt Evans, C. Lovatt EvansSearch for more papers by this authorD. F. G. Smith, D. F. G. SmithSearch for more papers by this authorH. Weil-Malherbe, H. Weil-MalherbeSearch for more papers by this author C. Lovatt Evans, C. Lovatt EvansSearch for more papers by this authorD. F. G. Smith, D. F. G. SmithSearch for more papers by this authorH. Weil-Malherbe, H. Weil-MalherbeSearch for more papers by this author First published: 28 June 1956 https://doi.org/10.1113/jphysiol.1956.sp005547Citations: 27AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume132, Issue3June 28, 1956Pages 542-552 RelatedInformation

Chromaffin tissue in the lizard adrenal gland.

BOTH adrenaline and its possible precursor nor-adrenaline can be obtained from the adrenals of many animals in the different classes of vertebrates1. In the dogfish, where adrenocortical and chromaffin tissue are entirely separate, the latter contains wholly noradrenaline2. In the Amphibia, where the two tissues are intermingled, noradrenaline forms 50–69 per cent of the total catechol content in the frog2 and 35–58 per cent in the toad3. In the eutherian mammal, chromaffin tissue, formed as a medulla surrounded by cortical tissue, produces mostly adrenaline1,2,4.

The functional relationship between the hypothalamus and the anterior pituitary-adrenal system.

1) Stimulation of the posterior part of the hypothalamus caused increase of Ch. C. content in the adrenal vein blood and decrease of sudanophile substance in the adrenal cortex. In hypophysectomized cat, these changes were not obtained.2) Catechol content in the adrenal vein blood was remarkably increased by stimulation of the middle part of the hypothalamus in most cases.3) On the influence of the hypothalamic stimulation upon the potassium content in the blood serum, from the anterior and middle parts of the hypothalamus, remarkable increase was obtained, and from the posterior part the tendency to decrease was generally observed. In hypophysectomized or adrenalectomized rabbits, the response from the posterior part reversed, namely potassium content markedly increased.4) Direct electrical stimulation of the anterior pituitary gland did not cause increase of Ch. C. content in the adrenal vein blood. Local application of minimal doses of acetylcholine (0.15mg.) into the anterior pituitary gland caused the increase of Ch. C. content and decrease of potassium content, but the application of adrenaline (10γ) did not cause the change.From the above results it may be considered that acetylcholine-like substance liberated at nerve ending by excitation of nerve cells in the posterior part of the hypothalamus reaches the anterior pituitary cells as a neuro-chemical transmitter via the portal vessels and causes increase of secretion of ACTH, and consequentely increace of Ch. C. content in the adrenal vein blood and decrease of serum potassium content occurs.