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Hydroxybenzoic Acid (hydroxybenzoic + acid)
Selected AbstractsBacterioplankton assemblages transforming dissolved organic compounds in coastal seawaterENVIRONMENTAL MICROBIOLOGY, Issue 8 2007Xiaozhen Mou Summary To characterize bacterioplankton functional assemblages that transform specific components of the coastal seawater dissolved organic carbon (DOC) pool, bromodeoxyuridine (BrdU) was used to label the bacterioplankton cells that were active following addition of single-DOC model compounds: two organic osmolytes [dimethylsulfoniopropionate (DMSP) and glycine betaine (GlyB)] and two aromatic monomers [para -hydroxybenzoic acid (pHBA) and vanillic acid (VanA)]. Bacterial populations were analysed based on in situ fluorescent immunodetection of BrdU incorporation followed by fluorescence-activated cell sorting (FACS). Sorted cells were then characterized by 16S rDNA-based analysis. Populations with high BrdU incorporation level (HI) developed within 8 h of introduction of 100 nM model compound. Terminal restriction fragment length polymorphisms (T-RFLP) analysis indicated that the HI populations in all four amendments were composed of bacteria from the same major taxa (phylum and subphylum levels), but the relative abundance of each differed. High-resolution clone libraries (each containing ,200 clones) showed that the HI populations in the GlyB and VanA amendments consisted of both metabolic generalists and specialists within the , -Proteobacteria (mainly members of the Roseobacter clade), , -Proteobacteria and , -Proteobacteria (mainly members of Altermonadaceae, Chromatiaceae, Oceanospirillaceae and Pseudomonadaceae). The presence of members of OM60/241, OM185, SAR11, SAR86 and SAR116 in the HI populations indicated that members of these groups can assimilate the model DOC compounds, providing some of the first glimpses into heterotrophy by members of these poorly understood environmental clusters. [source] Influence of the monomer feeding sequence on the structure and properties of thermotropic liquid-crystalline poly(ester imide)sJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Zhenguo Chi Abstract A series of poly(ester imide)s mainly derived from N,N,-hexane-1,6-diylbistrimellitimides, 4,4,-dihydroxybenzophenone, and p -hydroxybenzoic acid were synthesized by a direct polycondensation method in benzenesulfonyl chloride, N,N,-dimethylformamide, and pyridine with different monomer feeding sequences. The molecular structures and properties of the resultant poly(ester imide)s were characterized with NMR, IR spectrometry, polarized light microscopy, wide-angle X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results showed that the monomer feeding sequences had a great effect on the sequential structure of the molecular chains of the copolymers and consequently on their liquid-crystalline (LC) properties, fiber-forming capability, and other properties. Thus, it is probable that one could obtain an LC poly(ester imide) with given properties by controlling the monomer feeding sequence during the polycondensation process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Parabens, oestrogenicity, underarm cosmetics and breast cancer: a perspective on a hypothesisJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2003Philip W. Harvey Abstract A recent review by Darbre (2003) published in this journal (J. Appi. Toxicol. 23: 89,95) has attracted public and scienti,c interest that requires perspective, particularly on the use of esters of p -hydroxybenzoic acid (parabens) as preservatives in underarm cosmetics. Although parabens are generally regarded as safe, recent reports suggest that they are oestrogenic in a variety of in vitro (including MCF7 and ZR-75-1 human breast cancer cell lines) and in vivo tests for oestrogenicity (uterotrophic assays in both rat and mouse). There are also recent reports of adverse reproductive and developmental outcomes in rodent toxicity studies. Of interest is the lack of activity by the oral route but clear activity by the subcutaneous and topical routes, which is of some relevance to the use of underarm cosmetics. There would seem to be a case now to supplement these emerging toxicity data with longer term regulatory standard tests examining other oestrogenic endpoints and at least to consider these ,ndings in more up-to-date risk assessments speci,c for cosmetic use. Further, there are few data on the use of underarm cosmetics and the risk of breast cancer, and although one recent retrospective interview-based study found no association there is a need for more thorough investigation taking into account the type of chemicals used. Darbre has forwarded a hypothesis and called for further work to establish whether or not the use of underarm cosmetics (particularly containing oestrogenic formulants) contributes to the rising incidence of breast cancer. It would seem prudent to conduct this work because the current database is sparse and the effects of long-term low-level exposures to weakly oestrogenic chemicals on human health, particularly their application to the underarm and the risks of breast cancer, are unknown. The role of oestrogens in breast cancer, however, is undisputed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Oestrogenic activity of isobutylparaben in vitro and in vivoJOURNAL OF APPLIED TOXICOLOGY, Issue 4 2002P. D. Darbre Abstract The alkyl esters of p -hydroxybenzoic acid (parabens) are used widely as preservatives in foods, pharmaceuticals and cosmetics to which the human population is exposed. Recent studies have reported that methylparaben, ethylparaben, n -propylparaben and n -butylparaben all possess oestrogenic activity in several in vitro assays and in animal models in vivo. This study reports on the oestrogenic activity of isobutylparaben in a panel of assays in vitro and in vivo. Isobutylparaben was able to displace [3H]oestradiol from cytosolic oestrogen receptor , of MCF7 human breast cancer cells by 81% at 100 000-fold molar excess. Using a clonal line of MCF7 cells containing a stably transfected oestrogen-responsive ERE-CAT reporter gene, CAT gene expression could be increased by isobutylparaben such that the magnitude of the response was the same at 10,5 M isobutylparaben as with 10,8 M 17,-oestradiol. Isobutylparaben could also increase expression of the endogenous oestrogen-responsive pS2 gene in MCF7 cells and maximal expression at 10,5 M isobutylparaben could be inhibited with the anti-oestrogen ICI 182 780. The proliferation of two oestrogen-dependent human breast cancer cell lines MCF7 and ZR-75-1 could be increased with isobutylparaben such that at concentrations of 10,5 M the proliferation response was of the same magnitude as with 10,8 M 17,-oestradiol. Evidence for oestrogen receptor mediation of proliferation effects was provided by the inability of isobutylparaben to influence the growth of oestrogen-unresponsive MDA-MB-231 human breast cancer cells and by the ability of the anti-oestrogen ICI 182 780 to inhibit the isobutylparaben effects on MCF7 cell growth. The proliferation response to 10,10 M 17,-oestradiol was not antagonized with isobutylparaben at any concentration from 10,9 M to 10,4 M in either MCF7 or ZR-75-1 cells. Finally, subcutaneous administration of isobutylparaben was able to increase the uterine weight in the immature mouse after three daily doses of 1.2 or 12.0 mg per mouse. Previous work using linear-alkyl-chain parabens has shown that oestrogenic activity increases with alkyl chain length from methylparaben to n -butylparaben. The results here show that branching of the alkyl chain to isobutylparaben increases oestrogenic activity beyond that of the equivalent length linear alkyl chain in n -butylparaben. Copyright © 2002 John Wiley & Sons, Ltd. [source] Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinisJOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2000C. El Modafar The roots of date palm contain four cell wall-bound phenolic acids identified as p -hydroxybenzoic, p -coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2,55.8% of cell wall-bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre-infection contents of p -coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p -hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre-infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall-bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post-infection contents of cell wall-bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p -hydroxybenzoic acid (1.54 ,mol/g), p -coumaric acid (2.77 ,mol/g) and ferulic acid (2.64 ,mol/g) and on the fifteenth day for sinapic acid (1.85 ,mol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p -hydroxybenzoic acid, 2.6 times for p -coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p -coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre-infection contents of the resistant cultivar. The contents of p -hydroxybenzoic acid in the susceptible cultivar roots did not present post-infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall-bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection. Zusammenfassung Die Wurzeln der Dattelpalme enthalten vier zellwandgebundene Phenolsäuren, die als p -Hydroxybenzoesäure, p- Cumarsäure, Ferulasäure und Sinapinsäure identifiziert wurden. Ferulasäure ist die wichtigste phenolische Verbindung, denn sie stellt 48,2 bi 55,8% der zellwandgebundenen Phenolsäuren. Alle vier Phenolsäuren waren in der resistenten Sorte BSTN und in der anfälligen Sorte JHL vorhanden. Die Gehalte an p -Cumarsäure, Ferulasäure und Sinapinsäure waren vor der Infektion bei der resistenten Sorte jedoch höher als bei der anfälligen Sorte. Hinsichtlich des Gehalts an p -Hydroxybenzoesäure unterschieden sich die resistente und die anfällige Sorte nicht signifikant voneinander. Auch die Ligningehalte vor der Infektion waren bei beiden Sorten ungefähr gleich. Die Inokulation von Dattelpalmenwurzeln mit Fusarium oxysporum f. sp. albedinis induziert wichtige Änderungen der Gehalte an zellwandgebundenen phenolischen Verbindungen und Lignin, was eine Unterscheidung resistenter von anfälligen Sorten ermöglicht. Nach der Infektion nehmen die Gehalte an zellwandgebundenen phenolischen Verbindungen rasch und erheblich zu, mit maximaler Akkumulation am 10. Tag bei p -Hydroxybenzoesäure (1,54 ,mol/g), p -Cumarsäure (2,77 ,mol/g) und Ferulasäure (2,64 ,mol/g) sowie am 15. Tag bei Sinapinsäure (1,85 ,mol/g). Die in der resistenten Sorte akkumulierten maximalen Gehalte waren höher als die maximalen Gehalte der anfälligen Sorte , um das Elffache bei p -Hydroxybenzoesäure, das 2,6-fache bei p -Cumarsäure, das 1,8-fache bei Ferulasäure und das 2,3-fache bei Sinapinsäure. Bei der anfälligen Sorte steigen die Gehalte an p -Cumarsäure und Ferulasäure nach der Inokulation ebenfalls an, bleiben aber niedriger als die Werte der resistenten Sorte vor der Infektion. Der p -Hydroxybenzoesäuregehalt in den Wurzeln der anfälligen Sorte ist nach der Infektion nicht verändert, und der Sinapinsäuregehalt nimmt ab. Der Ligningehalt steigt bei beiden Sorten, mit maximaler Akkumulation am 15. Tag. Der maximale Gehalt in den Wurzeln der resistenten Sorte war jedoch 1,5-mal höher als bei der anfälligen Sorte. Diese Ergebnisse zeigen deutliche Unterschiede zwischen der resistenten Sorte (BSTN) und der anfälligen Sorte (JHL). Die Bedeutung der zellwandgebundenen phenolischen Verbindungen und des Lignins für die Resistenz der Dattelpalme gegen F. oxysporum f. sp. albedinis scheint von der Geschwindigkeit und der Intensität der Akkumulation abzuhängen, wobei die Gehalte im ersten Stadium der Infektion höher sind. [source] Preparation of single-walled carbon nanotubes-induced poly(p -oxybenzoyl) crystalsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2008Kazufumi Kobashi Abstract Crystallization of oligomers was applied for the preparation of single-walled carbon nanotubes (SWNTs)/poly(p -oxybenzoyl) (POB) crystals using SWNTs as a nucleating agent. Polymerization conditions were investigated to induce the crystallization of POB oligomers through SWNTs. SWNTs/POB plate-like or lozenge-shaped crystals were successfully prepared by direct polymerization of p -hydroxybenzoic acid (HBA) in a mixed solvent of DMF/Py with TsCl in the presence of functionalized SWNTs. The size of the plate-like crystals were ,200 nm to 3 ,m. The crystals consisted of some layers, ,3 nm thick plates. Model reactions showed that esterification reactions proceed between functionalized SWNTs and HBA monomers in the polymerization system. The obtained crystals exhibited unique morphology and high crystallinity, producing a novel SWNT/POB hybrid. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1265,1277, 2008 [source] Determination of some hydroxybenzoic acids and catechins in white wine samples by liquid chromatography with luminescence detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006Rafael Carlos Rodríguez-Díaz Abstract A liquid chromatographic method with luminescence detection for the determination of eight phenolic compounds is reported. The method involves postcolumn derivatization with terbium(III). This derivatization is based on the reaction between phenolics and terbium(III) to form luminescent chelates, which were determined at ,ex 295 and ,em 545 nm using the fluorescence mode. The long wavelength emission of lanthanide chelates can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Also, the chromatographic separation allows the individual determination of phenolics, which cannot be done using the direct measurement of the fluorescence of their corresponding terbium chelates. Dynamic ranges of the calibration graphs and detection limits, obtained with standard solutions of analytes were (,g/mL): gallic acid (0.9,40, 0.3), protocatechuic acid (0.05,7, 0.016), catechin (0.2,40, 0.07), vanillic acid (0.25,40, 0.08), p -hydroxybenzoic acid (0.8,40, 0.25), syringic acid (0.17,40, 0.05), epicatechin (0.3,40, 0.09) and salicylic acid (0.07,12, 0.02). The precision was established at two concentration levels of each analyte and expressed as the percentage of RSD with values ranging between 1.0 and 6.5%. The practical usefulness of the method was demonstrated by the analysis of white wine samples, which were diluted two-fold and directly injected into the chromatographic system. The recovery values obtained ranged between 93.3 and 108.0%. [source] Antibacterial substances of low molecular weight isolated from the blowfly, Lucilia sericataMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2007L. HUBERMAN Abstract Low molecular weight compounds were isolated by high-performance liquid chromatography from the maggot or haemolymph extracts of Lucilia sericata (Meigen) (Diptera: Calliphoridae). Using gas chromatography-mass spectrometry analysis, three compounds were obtained: p -hydroxybenzoic acid (molecular weight 138 Da), p -hydroxyphenylacetic acid (molecular weight 152 Da) and octahydro-dipyrrolo[1,2-a;1,,2,-d] pyrazine-5,10-dione (molecular weight 194 Da), also known as the cyclic dimer of proline (or proline diketopiperazine or cyclo[Pro,Pro]). All three molecules revealed antibacterial activity when tested against Micrococcus luteus and/or Pseudomonas aeruginosa, and the effect was even more pronounced when these molecules were tested in combination and caused lysis of these bacteria. [source] Selective bio-availability of phenolic acids from Scottish strawberriesMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue S1 2009Wendy R. Russell Abstract Scottish strawberries were found to be a rich source of phenolic acids, namely benzoic (1287.95 ± 279.98 mg/kg) and cinnamic (1159.40 ± 233.96 mg/kg) acids, both free and attached to other plant components. Studies suggest a chemopreventative role for such compounds in several major clinical conditions, but the anticipated benefits are likely to be affected by their bio-availability and metabolic fate. In this pilot study, strawberries (750 g) was consumed by four healthy human volunteers (32 ± 6 years). Only the benzoic acids were detected in the plasma. Of these, the major free (gentisic, protocatechuic and p -hydroxybenzoic acid) and conjugated (syringic acid) benzoic acids were 26,27% recovered in the urine within 5 h. Cinnamic acids were completely undetected in plasma and only trace amounts were found in the urine. Since, the cinnamic acids escaped absorption early in the gastrointestinal tract, their release and/or metabolism is dependant on the host colonic microbiota. Results indicate that there is a high degree of selective absorption of strawberry phenolic acids into the systemic circulation. If selective absorption of phenolic acids is observed with consumption of other plant-based foods, this is likely to have implications for the bioactive role of these compounds in chronic disease prevention. [source] Ferutinin stability in human plasma and interaction with human serum albuminBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2008H. Greige-Gerges Abstract Ferutinin is a potent phytoestrogen extracted from plants of the genus Ferula. The biological activity of this sesquiterpene is associated with the esterification of p -hydroxybenzoic acid with the daucane alcohol, jaeschkeanadiol. A HPLC method was developed to investigate the stability of ferutinin in acidic and basic solutions (pH 1.5 and 9.0, respectively), in buffer (pH 7.4) as well as in serial dilutions of albumin and in human plasma. The degradation of ferutinin was relatively slow at physiological pH 7.4 compared with low or high pH. Ferutinin was fully stable in human plasma as well as in albumin solution and the stability increased with albumin concentration. The binding of ferutinin to albumin was investigated by fluorescence spectroscopy. Ferutinin decreased the fluorescence of HSA and that of the only tryptophan residue located in domain IIA. As a result of the interaction between ferutinin and albumin, the binding of bilirubin decreased. The stability of ferutinin in plasma is attributable to ferutinin,albumin binding. Copyright © 2007 John Wiley & Sons, Ltd. [source] Carbonic Anhydrase Inhibitors: Inhibition of Human Erythrocyte Isozymes I and II with a Series of Phenolic AcidsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 5 2010S. Beyza Öztürk Sar, kaya The inhibitory effects of some phenolic acids on the cytosolic human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes hCA I and hCA II were investigated. Ellagic acid, gallic acid, ferulic acid, caffeic acid, quercetin, p -coumaric acid, p -hydroxybenzoic acid, and syringic acid showed KI values in the range of 99,1061 ,m for hCA I and of 105,758 ,m against hCA II, respectively. Quercetin (for hCA I), p -coumaric acid (for hCA II), and gallic acid (for hCA II) exhibited competitive inhibitory effects with 4-nitrophenyl acetate as substrate. All of the other phenolic acids were found as non-competitive inhibitors with 4-nitrophenylacetate as substrate for hCA I and hCA II. The phenolic acids investigated here showed thus interesting hCA I and hCA II inhibitory effects and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents. [source] BACE1 (Beta-Secretase) Inhibitory Phenolic Acids and a Novel Sesquiterpenoid from Homalomena occultaCHEMISTRY & BIODIVERSITY, Issue 4 2010Xiao-Yan Tian Abstract Four phenolic acids, namely 2-[(Z)-heptadec-11-enyl]-6-hydroxybenzoic acid (1), 2-[(6Z,9Z,12Z)-heptadeca-6,9,12-trienyl]-6-hydroxybenzoic acid (2), 2-[(9Z,12Z)-heptadeca-9,12-dienyl] - 6 - hydroxybenzoic acid (3), and 2-hydroxy-6-(12-phenyldodecyl)benzoic acid (4), and one sesquiterpene, asperpenoid (5), were isolated from the 95% EtOH extract of the roots of Homalomena occulta, among which 1, 2, and 5 represent new compounds. Further, the phenolic acids 1,4 exhibited BACE1 (, -secretase) inhibitory activity with IC50 values of 6.23±0.94, 6.28±0.63, 7.93±0.38, and 7.65±0.62,,M, respectively. [source] Study of electromigration effects on a pH boundary during the on-line electrokinetic preconcentration by capillary electrophoresisELECTROPHORESIS, Issue 16 2010ina Vítková Abstract A contribution to the description of electrokinetic effects on the pH boundary formed by sodium borate pH 9.5 and sodium phosphate pH 2.5 electrolytes for on-line preconcentration of weak acids is presented in this article. Simulations of electrokinetic injections together with experimental studies using contactless conductivity detection verified that the preconcentration is induced mainly by dissociation changes of analytes on the pH boundary and transient ITP state. Moreover, a study of the addition of organic solvent to the injection electrolyte was performed with impressive results. Subnanomolar LODs of hydroxybenzoic acids were achieved with 80% of methanol in the injection electrolyte which represents more than 70,000-fold preconcentration in comparison with classical CZE method. [source] A computational study of the carboxylic acid of phloroglucinol in vacuo and in water solutionINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2010Liliana Mammino Abstract 2,4,6-Trihydroxybenzoic acid (FA) is the carboxylic acid of phloroglucinol and, in turn, the parent compound of many biologically active compounds. The biological activities of FA are "extreme" among trihydroxybenzoic acids (e.g., lowest antioxidant activity, highest toxicity toward crustaceans). A complete MP2/6-31++G(d,p) conformational study in vacuo shows that the lowest energy conformers contain two intramolecular hydrogen bonds between the COOH function and the two ortho phenolic OH, with the Z form of COOH preferred over the E form. Comparisons with conformers in which the H-bonds are removed enable fairly reliable evaluations of their energy, because of an off-plane shift of COOH on H-bond removal, decreasing the effects of lone pair repulsion. Comparisons with the other hydroxybenzoic acids (extensively calculated in vacuo at the same level of theory) suggest that FA has the strongest intramolecular H-bonds. PCM calculations of FA in water solution show the same sequence of relative stabilities as in vacuo, with narrower differences because of the greater solvent stabilization of higher energy conformers. Calculations of adducts with water molecules H-bonded to different donor,acceptor centers of FA show the preferred arrangements of water molecules around the different regions of FA and confirm that the stronger intramolecular H-bonds are not broken on competition with the possibility of formation of intermolecular H-bonds. HF/6-31++G(d,p) calculations of adducts, in which the FA molecule is completely surrounded by water molecules, show that 14,16 water molecules (depending on the FA conformer geometry) realize arrangements corresponding to a presumable first solvation layer, with all the water molecules directly H-bonded to donor,acceptor centers of FA or bridging water molecules directly H-bonded to them. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardiiJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2003F.M. Campos Abstract Aims: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. Methods and Results: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p -hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p -coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanol-containing phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p- Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. Conclusions: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p- coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. Significance and Impact of the Study: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures. [source] HPLC-MS of anthraquinoids, flavonoids, and their degradation products in analysis of natural dyes in archeological objectsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2007Izabella Surowiec Abstract LC with MS detection was optimized for sensitive and selective analysis of main classes of natural dyes used in ancient times for dyeing textiles , red anthraquinoids, yellow flavonoids, and known degradation products of flavonols , hydroxybenzoic acids. Fragmentation patterns of both negative and positive molecular ions for the above mentioned compounds were investigated. Three acquisition modes of MS analysis: scanning, SIM, and multiple reaction monitoring (MRM) in both positive and negative ion modes were optimized and compared with each other and with the UV-Vis diode-array detection. Even though in the applied chromatographic system formic acid was used in the mobile phase, SIM in the negative ion mode was the most selective and sensitive detection for all the investigated compounds when both mixtures of standards and analysis of extracts from archeological samples were concerned, with one exception , alizarin, for which MS detection in positive ion mode was more sensitive. Detection limits obtained with MS detection for all investigated compounds except quinizarin were lower than the ones obtained with the diode-array UV-Vis detection, making MS detection the most suitable tool for the analysis of natural dyes and their degradation products in extracts from archeological samples. [source] Determination of some hydroxybenzoic acids and catechins in white wine samples by liquid chromatography with luminescence detectionJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006Rafael Carlos Rodríguez-Díaz Abstract A liquid chromatographic method with luminescence detection for the determination of eight phenolic compounds is reported. The method involves postcolumn derivatization with terbium(III). This derivatization is based on the reaction between phenolics and terbium(III) to form luminescent chelates, which were determined at ,ex 295 and ,em 545 nm using the fluorescence mode. The long wavelength emission of lanthanide chelates can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Also, the chromatographic separation allows the individual determination of phenolics, which cannot be done using the direct measurement of the fluorescence of their corresponding terbium chelates. Dynamic ranges of the calibration graphs and detection limits, obtained with standard solutions of analytes were (,g/mL): gallic acid (0.9,40, 0.3), protocatechuic acid (0.05,7, 0.016), catechin (0.2,40, 0.07), vanillic acid (0.25,40, 0.08), p -hydroxybenzoic acid (0.8,40, 0.25), syringic acid (0.17,40, 0.05), epicatechin (0.3,40, 0.09) and salicylic acid (0.07,12, 0.02). The precision was established at two concentration levels of each analyte and expressed as the percentage of RSD with values ranging between 1.0 and 6.5%. The practical usefulness of the method was demonstrated by the analysis of white wine samples, which were diluted two-fold and directly injected into the chromatographic system. The recovery values obtained ranged between 93.3 and 108.0%. [source] | ||||||||||||||||