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PubMed1996

Antibacterial activity of the phenolic acids fractions of Scrophularia frutescens and Scrophularia sambucifolia.

The phenolic fractions of aerial part of Scrophularia frutescens and S. sambucifolia (Scrophulariaceae) showed a potent antibacterial activity. Ferulic, isovanillic, p-hydroxycinnamic, p-hydroxybenzoic, syringic, caffeic, gentisic and protocatechuic acids were isolated from S. frutescens and ferulic, p-coumaric, vanillic, p-hydroxibenzoic and syringic acids were isolated from S. sambucifolia. Since phenolic acids have been shown in the literature to exert an antibacterial effect, the presence of these compounds in the two plants explains their antibacterial activity.

Anti-Bacterial Agents↗

PubMed1991

Chromatographic and spectroscopic analysis of bound and unbound phenolic acids in Lagenaria breviflora fruit.

The fruit pulp of Lagenaria breviflora Robert (Cucurbitaceae), used in Nigeria as an anti-bacterial and anti-fertility drug, was found to contain phenolic acids. Isolation and characterization of these compounds was based on column chromatography, TLC, PC, UV, IR and GC-MS. While p-hydroxybenzoic and vanillic acids were found to occur as free and bound acids in the pulp, ferulic acid was found to occur only as an ester. An optimized HPLC procedure for the quantitative analysis of these acids was developed, featuring short retention, times, high sensitivity and excellent resolution. The concentration of these phenols in the fruit mesocarp was established.

Chromatography, High Pressure Liquid↗

PubMed1990

The hydroxylation of the salicylate anion by a Fenton reaction and T-radiolysis: a consideration of the respective mechanisms.

The yield of 2,3- and 2,5-dihydroxybenzoates (dHB's) from the reaction of .OH radicals with salicylate (SA) ions has been measured as a function of pH and in the presence of oxidants. Under steady-state radiolysis conditions, the production of these products occurs via the reactions .OH + SA----HO-SA. (radical adduct) HO-SA. H+.OH+----2-carboxyphenoxyl radical (SA.) + H2O HO-SA. + SA.----2,3-/2,5-dHB + SA The addition of the oxidants O2, Fe3+ edta, or Fe(CN)63- increases the relative yield of 2,5-dHB/2,3-dHB from about 0.2 to 1. A model to account for this effect is presented. Steady-state radiolyses of 3- and 4-hydroxybenzoate give dihydroxybenzoate products consistent with the phenol group being an ortho-para director in the electrophilic attack of the hydroxyl radical on the aromatic ring. A comparison of product distributions from the reaction of ferrous edta with hydrogen peroxide using salicylate as a scavenger strongly suggests that the same hydroxyl radical adducts are formed as in the radiation experiments.

Azides↗

PubMed1995

Effects of N-acetylcysteine in the rat heart reperfused after low-flow ischemia: evidence for a direct scavenging of hydroxyl radicals and a nitric oxide-dependent increase in coronary flow.

The capacity of N-acetylcysteine to directly scavenge hydroxyl radical produced by rat hearts reperfused after 90 min of low-flow ischemia was assessed by the hydroxylation of 4-hydroxybenzoate into 3,4-dihydroxybenzoate using a gas chromatography-mass spectrometric assay. Reperfused hearts showed a massive release of 3,4-dihydroxybenzoate, lactate dehydrogenase, and total glutathione, contained less reduced and oxidized glutathione, but maintained spontaneous beating and coronary flow rates close to preischemic values. Compared to untreated hearts: reperfused hearts treated with N-acetylcysteine from the start of ischemia (i) released four times less 3,4-dihydroxybenzoate, but similar amounts of lactate dehydrogenase or glutathione, (ii) showed a nitric oxide-dependent increase in coronary flow rate, and (iii) contained less oxidized glutathione, but similar amounts of reduced glutathione. Reperfused hearts receiving N-acetylcysteine since the last 5 min of ischemia had also a four-times lower 3,4-dihydroxybenzoate release, but their coronary flow rate response was similar to that of untreated hearts. These results indicate that N-acetylcysteine can directly scavenge hydroxyl radicals produced by reperfused ischemic hearts, although this effect is not associated with any protective effects as indicated by the lactate dehydrogenase and glutathione release and cannot explain the nitric oxide-dependent reperfusion hyperemia.

Acetylcysteine↗

PubMed2005

Dynamics involved in catalysis by single-component and two-component flavin-dependent aromatic hydroxylases.

Flavoprotein monooxygenases are involved in a wide variety of biological processes including drug detoxification, biodegradation of aromatic compounds in the environment, biosynthesis of antibiotics and siderophores, and many others. The reactions use NAD(P)H and O2 as co-substrates and insert one atom of oxygen into the substrate. The flavin-dependent monooxygenases utilize a general cycle in which NAD(P)H reduces the flavin, and the reduced flavin reacts with O2 to form a C4a-(hydro)peroxyflavin intermediate, which is the oxygenating agent. This complicated catalytic process has diverse requirements that are difficult to be satisfied by a single site. Two general strategies have evolved to satisfy these requirements. para-Hydroxybenzoate hydroxylase, the paradigm for the single-component flavoprotein monooxygenases, is one of the most thoroughly studied of all enzymes. This enzyme undergoes significant protein and flavin dynamics during catalysis. There is an open conformation that gives access of substrate and product to solvent, and a closed or in conformation for the reaction with oxygen and the hydroxylation to occur. This closed form prevents solvent from destabilizing the hydroperoxyflavin intermediate. Finally, there is an out conformation achieved by movement of the isoalloxazine toward the solvent, which exposes its N5 for hydride delivery from NAD(P)H. The protein coordinates these dynamic events during catalysis. The second strategy uses a reductase to catalyze the reduction of the flavin and an oxygenase that uses the reduced flavin as a substrate to react with oxygen and hydroxylate the organic substrate. These two-component systems must be able to transfer reduced flavin from the reductase to the oxygenase and stabilize a C4a-peroxyflavin until a substrate binds to be hydroxylated, all before flavin oxidation and release of H2O2. Again, protein dynamics are important for catalytic success.

4-Hydroxybenzoate-3-Monooxygenase↗

PubMed2006

Aspirin protects striatal dopaminergic neurons from neurotoxin-induced degeneration: an in vivo microdialysis study.

The effect of aspirin on dopaminergic neuronal damage induced by in vivo infusion of 1-methyl-4-phenylpiridinium iodide (MPP(+)) and 6-hydroxydopamine (6-OHDA) was studied in rats, using microdialysis. Rat striata were perfused with 1 mM MPP(+) or 6-OHDA for 10 min, causing peak levels of dopamine (DA) in the dialytic fluid, after 40 min. After 24 h, 1 mM MPP(+) was perfused again for 10 min and DA levels measured in the dialytic fluid, as an index of neuronal cell integrity. Pretreatment with Aspidol (lysine acetylsalicylate), 180 mg/kg i.p., 1 h before MPP(+) or 6-OHDA perfusion, did not modify DA extracellular output, on day 1, but restored MPP(+)-induced DA release on day 2, indicating a neuroprotective effect of Aspidol. Conversion of 0.5 mM 4-hydroxybenzoic acid (4-HBA) to 3,4-dihydroxybenzoic acid (3,4-DHBA) was measured as an index of reactive oxygen species (ROS). 6-OHDA, but not MPP(+), significantly enhanced 3,4-DHBA levels in the perfusion fluid. Aspidol (180 mg/kg, i.p.) reduced 6-OHDA-dependent increase of 3,4-DHBA levels. Meloxicam (50 mg/kg, i.p.), a specific cyclooxygenase-2 (COX-2) inhibitor, was ineffective against both neurotoxins. These data suggest that the protective effect of aspirin is due to different mechanisms of action according to the neurotoxin used, and it is independent from COX-2 inhibition.

Analysis of Variance↗

PubMed2006

Chemical and biological characterization of dissolved organic matter from silver fir and beech forest soils.

Despite a growing attention to the dissolved organic matter (DOM) in terrestrial ecosystems and evidence of the fact that vegetation affects the quality of both undissolved and dissolved organic matter in soil, the role of DOM as a biological indicator is still poorly understood. In this work, the fertility of 59 sites, divided into eight key alliances of the order Fagetalia sylvaticae Pawl., was studied considering chemical and biological parameters such as soil DOM, hormone-like activity, low-molecular-weight (LMW) aliphatic and phenolic acids, and floristic data. Both non-parametric tests and principal component analysis (PCA) revealed differences between silver fir and beech forests and within each type of forest. There were also differences between neutrophilous and acidophilous types. What's more, PCA reveals the dominance of the auxin (IAA)-like activity, and of some phenolic acids in distinguishing the acidophilous beeches (ACI) form the other types, whereas the gibberellin (GA)-like activity is more relevant in neutrophilous conditions such as thermophilous (THE) and mesophilous (MESO) beeches and montane (MO), high montane (HMA), high montane (HMC) silver fir forests. The GA-like activity is also related to the succinic, fumaric, malonic, and l-malic acids in the MO, HMA and HMC silver fir forests. Moreover, the role of LMW aliphatic acids in mobilizing the hormone-like activity, which improves forest growth, is stressed. The growth of seedlings of Picea abies was influenced by the phenolic acid content. At concentrations between 1 and 100 microM, phenylacetic and protocatechuic acids inhibited root growth to the same extent as indoleacetic acid, while p-hydroxybenzoic acid had a stimulating effect comparable to that of gibberellic acid. The aliphatic and phenolic acids appear to be related to plant strategies that influence soil fertility affecting plant growth through rhizodeposition. The role of LMW aliphatic and phenolic acids as molecular markers of ecosystem function is noted.

Abies↗

PubMed2006

Reduction of disinfection by-products precursors by nanofiltration process.

This research is dedicated to determine the rejection ratios of disinfection by-products (DBPs) precursors including resorcinol, phloroglucinol, 3-hydroxybenzoic acid, and tannic acid solution in the presence of calcium by nanofiltration with NF70 membrane. The rejections of these model compounds also were studied at various compositions of a feed solution by changing pH and concentrations of model compounds. It was found that the model compound rejection and membrane permeability increase with pH due to the conformational transformation of ionizable molecules and electric interaction between the model compounds and NF70 membrane. The interactions of model compounds with calcium have no significant effect on model compounds retentions. Because of the complexation of calcium with model compounds, calcium rejection rises with the presence of model compounds and with an increase of pH.

Calcium↗

PubMed2006

Removal of small trihalomethane precursors from aqueous solution by nanofiltration.

The removal of small trihalomethane precursors (THMPs) from aqueous solution by two commercial nanofiltration membranes (NF70 and NF270) was investigated. Resorcinol, phloroglucinol, and 3-hydroxybenzoic acid were selected as model compounds of small THMPs, while tannic acid was chosen as a medium molecular disinfection by-product (DBP) precursor for comparison. The performance of nanofiltration membranes were evaluated by introducing polyethylene glycol (PEG) solutions and uncharged saccharides to estimate molecular weight cut-off (MWCO) and membrane pore radii, respectively. The streaming potential was measured to estimate the membrane surface charge at different pH values, which reveals that the NF270 membrane is more pH-sensitive than the NF70 membrane. The rejections of the above selected THMPs were assessed under various pH values, and the removal efficiencies of THMPs for both membranes at high pH values are reasonably well. Charge exclusion is the prevailing mechanism for the selected small model compounds retended by the negatively charged nanofiltration membranes, while size exclusion and adsorption are controlled mechanisms but not sufficient for the rejection of unionized small organic molecules. In general, the NF270 membrane exhibits the superior permeation rate value, which takes an advantage over the NF70 membrane from the aspect of energy conservation.

Filtration↗

PubMed2005

Changes and subcellular localizations of the enzymes involved in phenylpropanoid metabolism during grape berry development.

The phenylpropanoid pathway yields a variety of phenolics that are closely associated with fruit qualities in addition to structural and defense-related functions. However, very little has been reported concerning its metabolism in fruit. This experiment was designed to assess changes of eleven phenolic acids in grape berry (Vitis vinifera L. cv. Cabernet Sauvignon) and explore both the activities and amounts of three key enzymes--phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate:coenzyme A ligase (4CL)--catalyzing the biosynthesis of these compounds during berry development. Finally, the subcellular localizations of the enzymes within berry tissues were also investigated using immuno-gold electron microscopic technique. The results indicated that the contents of gallic, protocatechuic, gentisic and caffeic acid all changed drastically during berry development, while other compounds containing p-hydroxybenzoic, vanillic, syringic, chlorogenic, p-coumaric, ferulic and sinapic acid varied only slightly. Activities of PAL, C4H and 4CL showed similar pattern changes with two accumulated peaks throughout berry development. In addition, their activities all showed a highly positive correlation with the total contents of phenolic acids, whereas the immunoblotting analysis showed that changes in enzyme activities were independent of the enzyme amounts. Results from the subcellular-localization study revealed that PAL was mainly present in the cell walls, secondarily thickened walls, and the parenchyma cells of the berry mesocarp cells, C4H was found primarily in the chloroplast (plastid) and nucleus and 4CL predominantly in the secondarily thickened walls and the parenchyma cells of mesocarp vascular tissue.

Coenzyme A Ligases↗

PubMed2005

Polypodium leucotomos extract: antioxidant activity and disposition.

The extract of the fern Polypodium leucotomos (PL, Fernblock) is an oral photoprotectant with strong antioxidative properties. Recent studies to determine its chemical composition have shown 4-hydroxycinnamic acid (p-coumaric), 3 methoxy-4-hydroxycinnamic acid (ferulic), 3,4-dihydroxycinnamic acid (caffeic), 3-methoxy-4-hydroxybenzoic acid (vanillic) and 3-caffeoilquinic acid (chlorogenic) to be among its major phenolic components. No conclusive data are available, however, on the H2O2-scavenging capacity of these compounds, or on their absorption and metabolism following their oral intake. In the present work, their antioxidative capacity was assessed by the luminol/H2O2 assay, their absorption studied using Caco-2 cells to resemble the intestinal barrier, and their metabolism investigated using cultured primary rat hepatocytes. The antioxidant capacity of PL components increased in a concentration-dependent manner, with ferulic and caffeic acids the most powerful antioxidants. The apparent permeability results correspond to a human post-oral administration absorption of 70-100% for all tested substances. Coumaric, ferulic and vanillic acids were metabolized by CYP450-dependent mono-oxygenases and partially conjugated to glucuronic acid and sulfate. These phenolic compounds may contribute to the health benefits afforded by this oral photoprotectant.

Animals↗

PubMed1999

Characteristics and occurrence of phenolic phytochemicals.

Phenolic phytochemicals are the largest category of phytochemicals and the most widely distributed in the plant kingdom. The 3 most important groups of dietary phenolics are flavonoids, phenolic acids, and polyphenols. Flavonoids are the largest group of plant phenols and the most studied. Phenolic acids form a diverse group that includes the widely distributed hydroxybenzoic and hydroxycinnamic acids. Phenolic polymers, commonly known as tannins, are compounds of high molecular weight that are divided into 2 classes: hydrolyzable and condensed tannins. Quantification of food phenolics is just beginning, and preliminary results indicate high variability, even within a given food. Phenolics are biologically active compounds that may possess some disease-preventive properties. Evidence for their ability to prevent cancer or heart disease is preliminary and conflicting. The health benefits of phytochemicals have been reported in the popular press, and the public will come to dietitians for answers to their questions about phytochemicals.

Coumaric Acids↗

PubMed1997

Alternative pathways of xanthone biosynthesis in cell cultures of Hypericum androsaemum L.

The biosynthesis of xanthones was studied in cell cultures of Hypericum androsaemum L. We have detected a new benzophenone synthase, for which the preferred substrate is benzoyl-CoA, itself supplied by 3-hydroxybenzoate:coenzyme A ligase. The stepwise condensation of benzoyl-CoA with three molecules of malonyl-CoA, catalyzed by benzophenone synthase, yields 2,4,6-trihydroxybenzophenone. This intermediate is subsequently converted by benzophenone 3'-hydroxylase, a cytochrome P450 monooxygenase. These biosynthetic steps, leading to the formation of 2,3',4,6-tetrahydroxybenzophenone, represent an alternative pathway to that recently proposed for cell cultures of Centaurium erythraea [Peters et al., Planta (1997) in press].

Acyl Coenzyme A↗

PubMed1979

Determination of food preservatives and saccharin by high-performance liquid chromatography.

The quantitative analysis of benzoic and sorbic acid, methyl, ethyl and propyl esters of p-hydroxybenzoic acid and saccharin in foodstuffs is described. These compounds are quantitatively extracted with disposable clean-up columns packed with Extrelut and simultaneously determined by high-performance liquid chromatography on reversed-phase columns. Complicated matrices such as cheese, cake, ketchup and chocolate were tested and recoveries were generally better than 95% in the concentration ranges normally used in the food industry.

Benzoates↗

PubMed1977

Quantitation of patulin pathway metabolites using gas-liquid chromatography.

A gas-liquid chromatographic system which allows most of the metabolites of the patulin pathway to be separated and quantitated has been developed. The metabolites are mostly phenols, and after conversion to their trimethylsilyl derivatives they are efficiently separated on a 3.18 mm O.D. stainless-stell column of 10% QF-1 on Gas-Chrom Q using a temperature programme. The detection limits for the three phenolic acids, 6-methylsalicylic acid, m-hydroxybenzoic acid and gentisic acid are all markedly lower than those obtained in previous systems. The usefulness of the system has been assessed by quantitating the patulin pathway metabolites present in culture filtrates of Penicillium urticae NRRL 2159A.

Chromatography, Gas↗

PubMed1990

Optimization of electrochemical detection in the high-performance liquid chromatography of lignin phenolics from lignocellulosic by-products.

Free phenolic acids and aldehydes (p- and o-hydroxyphenylacetic acid, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, vanillin, syringic acid, p-coumaric acid, syringaldehyde and ferulic acid) were detected in wheat straw extracts by high-performance liquid chromatography with a dual-cell electrochemical detector operated in the redox mode. Phenolics were oxidized with coulometric efficiency in the first cell (+ 1.00 V), then detected by reduction in the second cell (-0.20 V). Compared with the oxidative mode, the reductive detection mode has the advantage of being unaffected by large amounts of interferents eluting at the front of the chromatogram that interfere with the detection of small and early eluting compounds. Hydrodynamic voltammograms in the oxidative, reductive and screen-out modes are presented and the corresponding detection limits for real sample are discussed. Perfect linearity of response was found in the range 5 x 10(-7) - 5 x 10(-5) M and detection limits were of the order of 50-500 fmol injected.

Aldehydes↗

PubMed2002

Interactions of different phenolic acids and flavonoids with soy proteins.

Soy glycinin (SG) and soy trypsin inhibitor (STI) were derivatized by chlorogenic- and caffeic acid (cinnamic acids, C(6)-C(3) structure), and by gallic acid representing hydroxybenzoic acids (C(6)-C(1) structure). Further, the flavonoids, flavone, apigenin, kaempferol, quercetin and myricetin (C(6)-C(3)-C(6) structure) were also caused to react with soy proteins to estimate the influence of the number and the position of hydroxy substituents. The derivatization caused a reduction of lysine, cysteine and tryptophan residues in the soy proteins. The isoelectric points of the derivatives were shifted to lower pH values and formation of high molecular fractions was documented. The derivatives were characterized in terms of their solubility at different pH-values to document the influence on the functional properties. The structural changes induced were studied using circular dichroism (CD), differential scanning calorimetry (DSC), intrinsic fluorescence, and binding of anilinonaphthalenesulfonic acid. The influence of derivatization on the in-vitro digestibility with trypsin, chymotrypsin, pepsin and pancreatin was also assessed. The effect on the trypsin inhibitor activity of all the resulting STI derivatives was studied, the latter being reduced.

Anilino Naphthalenesulfonates↗

PubMed2003

Molecular characterization of an inducible gentisate 1,2-dioxygenase gene, xlnE, from Pseudomonas alcaligenes NCIMB 9867.

Pseudomonas alcaligenes NCIMB 9867 (strain P25X) produces isofunctional enzymes of the gentisate pathway that enables the degradation of xylenols and cresols via gentisate. Previous reports had indicated that one set of enzymes is constitutively expressed whereas the other set is strictly inducible by aromatic hydrocarbon substrates. The gene encoding gentisate 1,2-dioxygenase (GDO), the enzyme that catalyzes the cleavage of the gentisate aromatic ring, was cloned from strain P25X. The GDO gene, designated xlnE, is 1,044 bp, and is part of a 5.4 kb operon which consists of six genes, xlnEFGHID. Transcription of this operon was driven by a sigma 70-type promoter, PxlnE, located 123 bp upstream of the xlnE start codon. Primer extension analysis showed that the xlnE transcription start point is located at the -87 adenine residue. In a P25X xlnE knockout mutant, GDO activity could only be detected when cells were grown in the presence of aromatic substrates, suggesting that xlnE encodes for the constitutive copy of GDO. This was verified by constructing a P25X strain with xlnE transcriptionally fused to a promoterless catechol 2,3-dioxygenase gene. In this strain, catechol 2,3-dioxygenase activity was detected in cells that were grown in the absence of aromatic inducers. However, catechol 2,3-dioxygenase activity increased up to four fold when these cells were grown in the presence of aromatic substrates, in particular 3-hydroxybenzoate. Thus, xlnE is in fact, inducible and the constitutive activity observed under non-inducing conditions was due to its relatively high basal levels of expression.

Amino Acid Sequence↗