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At least 19 recordsLinked to original sources
PubMed1985

Contact allergy to 3-methylol phenol, 2,4-dimethylol phenol and 2,6-dimethylol phenol.

Thirteen patients with contact allergy to phenol-formaldehyde resins (P-F-R) were patch tested with 3-methylol phenol, 2,4-dimethylol phenol and 2,6-dimethylol phenol. Nine patients reacted to at least 1 compound, all giving positive test responses to 2,4-dimethylol phenol. Seven patients reacted simultaneously to 2,6-dimethylol phenol while only 1 patient reacted to 3-methylol phenol. Negative test responses were noted in 20 controls. Chemical investigation by high pressure liquid chromatography indicated that the compounds tested were pure and separable. The 3 reported sensitizers may, theoretically, be generated during the manufacture of P-F-R. 2,4-Dimethylol phenol and 2,6-dimethylol phenol have been demonstrated and there has been chromatographic evidence of 3-methylol phenol in the P-F-R used in the routine test series at the department.

Benzyl Alcohols↗
PubMed1975

[The phenolics of fruits. VI. The phenolics of currants, gooseberries and blueberries. Changes in phenolic acids and catechins during development of black currants (author's transl)].

Black, red, and white currants, gooseberries and cultivated blueberries contained only small amounts of catechins (total up to 30 mg per kg). Hydroxycinnamic acid derivatives, especially of caffeic and p-coumaric acid, occured mostly in higher concentrations. Furthermore, 4-hydroxygenzoic acid, protocatechuic acid and gallic acid were found after hydrolysis in currants and only protocatechuic acid in gooseberries in different levels. Salicyclic and gentisic acid were found in traces up to 2 mg per kg, occassionally vanillic acid, syringic acid or isoferulic acid. The concentrations of the examined phenolic acids in black currants related to the whole fruit (mg per fruit) increased, and related to fresh weight (mg per 1000 g) decreased during the growth of the fruits with the exception of protocatechuic acid, which appeared mostly in a last stage of the fruit.

Benzopyrans↗
PubMed1976

High-pressure liquid chromatographic separation of 10 benzo(a)pyrene phenols and the identification of 1-phenol and 7-phenol as new metabolites.

The separation of ten isomeric benzo(a)pyrene phenols has been accomplished by the use of high-pressure liquid chromatography utilizing a newly developed recycling technique and new column and solvent systems. Using this new system and comparing the metabolites obtained with authentic standards, we have isolated 1-hydroxybenzo(a)pyrene and 7-hydroxybenzo(a)pyrene and identified them as metabolites formed by rat liver microsomes. In previously reported chromatography systems, the new metabolites migrated with another metabolite, 3-hydroxybenzo(a)pyrene.

Animals↗
PubMed1990

Effect of fluorinated analogues of phenol and hydroxybenzoates on the anaerobic transformation of phenol to benzoate.

The effects of fluorinated analogues on the anaerobic transformation of phenol to benzoate were examined. At greater than or equal to 250 microM 2- or 3-fluorophenol, phenol transformation was delayed. 2-Fluorophenol had no apparent effect on subsequent degradation of benzoate, but benzoate accumulated in the presence of greater than or equal to 250 microM 3-fluorophenol. In contrast, 4-fluorophenol at less than or equal to 2 mM had no effect on either phenol transformation or benzoate degradation. Phenol and 2-, or 3-fluorophenol were transformed simultaneously, but phenol was transformed more rapidly than either fluorophenol. Thus, fluorinated analogues of phenol did not prevent anaerobic transformation of phenol to benzoate. 2-Fluorophenol was converted to 3-fluorobenzoate, and phenol enhanced the rate and extent of its transformation. 3-Fluorophenol was transformed to 2-fluorobenzoate to a limited extent (approximately 3%) when phenol was present. 4-Fluorophenol was not transformed regardless of the presence of phenol. 3-Fluoro-4-hydroxybenzoate, a potential fluorinated intermediate product of para-carboxylation, was transformed rapidly to 2-fluorophenol and 3-fluorobenzoate, irrespective of the presence of phenol, indicating that both dehydroxylation and decarboxylation occurred. Initially, 2-fluorophenol and 3-fluorobenzoate were rapidly formed in an approximate molar ratio of 2:1. Once 3-fluoro-4-hydroxybenzoate was completely removed, the 2-fluorophenol, initially formed, was converted to 3-fluorobenzoate at a slower rate. Thus, phenol enhanced transformation of the fluorinated analogues, and the products of transformation suggested para-carboxylation. 3-Fluoro-2-hydroxybenzoate was not transformed in either the presence or absence of phenol, indicating that ortho-carboxylation did not occur.

Anaerobiosis↗
PubMed1986

Lethal and sublethal effects of chlorine, phenol, and chlorine-phenol mixtures on the mud crab, Panopeus herbstii.

The mud crab, Panopeus herbstii, was acutely exposed (96-hr) to chlorine-produced oxidants (CPO), phenol, and a CPO-phenolic mixture (1:1) to determine lethal and sublethal effects. The 96-hr (LC50) values were determined for each individual compound and mixture. Additionally, whole-animal respiration rates were measured following acute exposure to sublethal concentrations of each compound or mixture. Phenol uptake/depuration rates were measured in the phenol and CPO-phenol mixture concentrations. Results indicated 96-hr LC50 values of 1.06 mg/L for CPO (fiducial limits (FL) = 0.53-2.01 mg/L), 52.8 mg/L for phenol (FL = 45.6-64.5 mg/L), and 184.7 mg/L total toxicant units (TTU) for the CPO-phenol mixture (FL = 143.7-250.2 mg/L TTU). Statistical analysis indicated that the acute toxicity of the CPO-phenol mixture was less than additive. Sublethal studies indicated that only acute exposure to sublethal concentrations of CPO caused altered respiration rates. After 96-hr depuration, metabolic rates in all CPO-exposure crabs generally returned to control rates. Uptake/depuration rate studies indicated significantly lower phenol uptake rates in crabs exposed to the CPO-phenol mixture. These findings suggest that the less-than-additive toxicity of the CPO-phenol mixture may result from lowered uptake/depuration rate kinetics and indicate that the discharge of chlorinated-phenolic waste may not result in additive and/or synergistic interactions, but rather in less-than-additive effects on decapod aquatic species.

Animals↗
PubMed1992

Prostaglandin H synthase kinetics. The effect of substituted phenols on cyclooxygenase activity and the substituent effect on phenolic peroxidatic activity.

A series of p- and m-substituted phenols were examined for their effect on the cyclooxygenase activity of prostaglandin H synthase in 0.1 M phosphate buffer at pH 8.0 and 25.0 +/- 0.1 degrees C. A biphasic response was observed. At low concentrations phenols stimulate, but at higher concentrations inhibit, cyclooxygenase activity. Both enhancement and inhibition are increased by phenolic substituents which are electron-donating, quantified by Hammett sigma constants, and hydrophobic, quantified by Hantsch tau constants. The same series of substituted phenols was also reacted with compound II of prostaglandin H synthase at 4.0 +/- 0.5 degrees C. The compound II data fit the Hammett rho sigma equation; no hydrophobicity factors are required. Phenols inhibit cyclooxygenase activity by interfering with the binding of arachidonic acid to compound I and by competing directly with arachidonic acid as reducing substrates for compound I. Phenols stimulate cyclooxygenase activity by acting as reducing substrates for compound II, thereby accelerating the peroxidatic cycle. Phenols also protect the enzyme from self-catalyzed inactivation, most likely by removing the free radical of prostaglandin G2 by reducing it to prostaglandin G2. Kinetic parameters Km and kcat for cyclooxygenase activity were determined in the presence of phenols. Identical values of Km (15.3 +/- 0.5 mM) and kcat (89 +/- 2 s-1) were obtained regardless of which phenol was employed. Therefore these represent the true Km and kcat values for cyclooxygenase activity.

Animals↗
PubMed1992

Degradation of phenol and phenolic compounds by Pseudomonas putida EKII.

The phenol-degrading strain Pseudomonas putida EKII was isolated from a soil enrichment culture and utilized phenol up to 10.6 mM (1.0 g.l-1) as the sole source of carbon and energy. Furthermore, cresols, chlorophenols, 3,4-dimethylphenol, and 4-chloro-m-cresol were metabolized as sole substrates by phenol-grown resting cells of strain EKII. Under conditions of cell growth, degradation of these xenobiotics was achieved only in co-metabolism with phenol. Phenol hydroxylase activity was detectable in whole cells but not in cell-free extracts. The specificity of the hydroxylating enzyme was found during transformation of cresols and chlorophenols: ortho- and meta-substituted phenols were degraded via 3-substituted catechols, while degradation of para-substituted phenols proceeded via 4-substituted catechols. In cell-free extracts of phenol-grown cells a high level of catechol 2,3-dioxygenase as well as smaller amounts of 2-hydroxymuconic semialdehyde hydrolyase and catechol 1,2-dioxygenase were detected. The ring-cleaving enzymes were characterized after partial purification by DEAE-cellulose chromatography.

Biodegradation, Environmental↗
PubMed1989

Iron absorption and phenolic compounds: importance of different phenolic structures.

The phenolic compounds (phenolic monomers, polyphenols, tannins) are considered to interfere with iron absorption by complex formation with iron in the gastro-intestinal lumen, making the iron less available for absorption. Very little is known about the extent to which different types of phenolic compounds of different size and chemical structure inhibit iron absorption. The relationship between iron absorption and the amount and type of phenolic compounds was studied by the extrinsic tag method. The aims of the studies were as follows: (i) To study the effect of small phenolic compounds with different hydroxylation patterns (gallic acid, catechin, chlorogenic acid) on iron absorption, (ii) To study the effect of different amounts of a hydrolysable tannin containing ten gallic acid residues (tannic acid) on iron absorption. (iii) To study the degree of inhibition of iron absorption by some foods and beverages (oregano, spinach, coffee and tea) in relation to their respective content of iron-binding phenolic groups, measured by a newly developed method. The inhibition of iron absorption by tannic acid was strongly dose-related. The smallest amount (5 mg) inhibited absorption by 20 per cent, 25 mg by 67 per cent and 100 mg by 88 per cent. Gallic acid inhibited iron absorption to the same extent as tannic acid, per mol galloyl groups, whereas no inhibition was observed when catechin was added to the test meal. Chlorogenic acid inhibited iron absorption to a lesser extent. Oregano and tea inhibited iron absorption in proportion to their respective content of galloyl groups, whereas the inhibitory effect of spinach was less marked. The inhibiting effect of coffee was explained mainly by its content of galloyl groups, but also by some other factor, probably chlorogenic acid. It is concluded that the content of iron-binding galloyl groups might be a major determinant of the inhibitory effect of phenolic compounds on iron absorption from the diet, whereas the phenolic catechol groups seem to be of minor importance. The results further suggest that the group of condensed tannins do not interfere with iron absorption.

Absorption↗
PubMed1987

Effect of phenolic acids and phenolics from plant cell walls on rumenlike fermentation in consecutive batch culture.

Information on the interaction between mixed populations in the rumen and plant phenolics is required to fully elucidate the limitations of phenolic compounds on forage digestibility. The objective of this study was to examine the degradation of Italian ryegrass (Lolium multiflorum L.) hay incubated with mixed ruminal populations in consecutive batch culture (CBC) with or without phenolic acids or phenolic compounds extracted from plant cell walls. Each CBC consisted of a series of 10 cultures (3 replicates per culture) inoculated (10%, vol/vol) in sequence at 48-h intervals with microbial suspension from the previous set of cultures. All cultures were grown on a semidefined medium containing Italian ryegrass hay, and each CBC was initiated with an inoculum from the rumen. Rumenlike fermentation characteristics were maintained in control CBCs by repeated inoculum transfer. Treatment CBCs were transferred as described above, but cultures 5, 6, and 7 were incubated in the presence of trans-p-coumaric, cis-p-coumaric, or trans-ferulic acid or phenolics extracted from the cell walls of maize stem or barley straw. Mean apparent dry matter disappearance in control CBC cultures was 495 mg per g of hay, whereas the presence of phenolics reduced the initial dry matter disappearance by 6.3 to 25.6%. trans-p-Coumaric acid and, to a lesser extent, the phenolics from cell walls of maize stem were the most inhibitory compounds for dry matter disappearance and for the production of volatile fatty acids; trans-p-coumaric acid altered the molar ratio of acetate/propionate/butyrate. The CBC further showed variations in the ability of the rumen microbial population to adapt to phenolic compounds.

Animals↗
PubMed1988

Thiol- and pH-modulated slow conformational changes and cooperativity of phenol-binding sites in phenol hydroxylase.

Spectrophotometric titration of phenol hydroxylase (EC 1.14.13.7) with phenol indicated interacting sites for phenol binding. In the absence of added thiol, the cooperativity was positive up to a pH around 8.0 but negative at higher pH values. With added thiol-ethylenediaminetetraacetate, the cooperativity was negative at all investigated pH values. Conversely, a corresponding titration of an enzyme preparation that had been selectively modified in its two most reactive SH groups indicated positive cooperativity at all studied pH values. This selective modification affects the activity of the enzyme to a very minor degree, in contrast to more extensive SH blocking, which displaces flavin adenine dinucleotide with a corresponding loss of activity [Neujahr, H. Y., & Gaal, A. (1975) Eur. J. Biochem. 58, 351-357]. The reactivity of SH groups in the enzyme was significantly decreased after turnover. Thiol treatment restored it to that of the native enzyme. Adding phenol prior to reduced nicotinamide adenine dinucleotide phosphate (NADPH) in the assay of phenol hydroxylase gave immediate linearity and higher initial rates than when NADPH was added first. In the absence of added thiol, there was then a shift of the pH optimum. The results indicate slow conformational changes limiting the rate of the overall reaction. The two most reactive SH groups of phenol hydroxylase, though not participating in any obvious redox reactions, are important for these slow conformational changes and for the cooperativity of phenol-binding sites, wherein the anionic S- forms may be involved (pKa for cysteine is 8.35).

Binding Sites↗
PubMed1992

Carboxylation of phenylphosphate by phenol carboxylase, an enzyme system of anaerobic phenol metabolism.

Several lines of evidence indicate that the first step in the anaerobic metabolism of phenol is phenol carboxylation to 4-hydroxybenzoate; this reaction is considered a biological Kolbe-Schmitt carboxylation. A phenol carboxylase system was characterized by using a denitrifying Pseudomonas strain, K 172, which catalyzes an isotope exchange between 14CO2 and the carboxyl group of 4-hydroxybenzoate. The enzymatic isotope exchange activity (100 nmol min-1 mg-1 of protein) requires Mn2+ and K+. We show that this system also catalyzes the carboxylation of phenylphosphate (the phosphoric acid monophenyl ester) to 4-hydroxybenzoate and phosphate. The specific activity of phenylphosphate carboxylation at the optimal pH of 6.5 is 12 nmol of CO2 fixed min-1 mg-1 of protein. Phenylphosphate cannot be replaced by Mg(2+)-ATP and phenol. The carboxylase activity requires Mn2+ but, in contrast to the isotope exchange activity, does not require K+. The apparent Km values are 1.5 mM dissolved CO2 and 0.2 mM phenylphosphate. Several convenient assays for phenylophosphate carboxylation are described. The isotope exchange reaction and the net carboxylation reaction are catalyzed by the same oxygen-sensitive enzyme, which has a half-life in an air-saturated solution of less than 1 min. Both activities cochromatographed with a protein with a Mr of 280,000, and both activities were induced only after anaerobic growth on phenol. The carboxylation of phenylphosphate suggests that phenylphosphate itself is the physiological CO2 acceptor molecular of this novel CO2 fixation reaction. Alternatively, phenylphosphate could simulate the unknown natural precursor. It is suggested that the formation of an enzyme-bound phenolate anion from the activated phenolic compound is the rate-determining step in the carboxylation reaction.

Adenosine Triphosphate↗
PubMed1988

Effect of phenol and halogenated phenols on energy transfer reactions of rat liver mitochondria.

The in vitro effects of phenol and p-halogenated phenols on mitochondrial energy transfer reactions were examined using isolated rat liver mitochondria. The relationship between physiochemical properties of phenolic compounds and their effects on mitochondria were studied. Phenol and p-halogenated phenols induced the release of K+ ions from mitochondria, suggesting a change in permeability to K+ ions. A decrease in the respiratory control index, an increase in K+ release and stimulation of latent ATPase activity were observed with these compounds in the descending order of p-iodophenol, p-bromophenol, p-chlorophenol, p-fluorophenol and phenol. The concentrations of the phenolic compounds resulting in fifty percent inhibition of the respiratory control index and those resulting in fifty percent release of K+ ions significantly correlated with Hammett's substituent constant (sigma) and the hydrophobic binding constant (pi) of the compounds.

Adenosine Triphosphatases↗
PubMed1987

Human and rat liver phenol sulfotransferase: structure-activity relationships for phenolic substrates.

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of many phenolic drugs. Human liver contains thermostable (TS) and thermolabile forms of PST. Ion exchange chromatography shows that two isozymes of TS PST (peaks I and II) are present in human liver preparations. Rat liver contains four forms of PST that can be separated by ion exchange chromatography. Quantitative structure-activity relationship (QSAR) analysis was used to study phenolic substrates for both human and rat liver PST. Thirty-six substituted phenols were tested as substrates for partially purified human liver TS PST peak I. QSAR analysis resulted in derivation of the following equation: log 1/Km = 0.92 (+/- 0.18)log P - 1.48 (+/- 0.38)MR'4 - 0.64 (+/- 0.41)MR3 + 1.04 (+/- 0.63)MR2 + 0.67(+/- 0.44) sigma- + 4.03 (+/- 0.42). In this equation Km is the Michaelis constant, P is the octanol-water partition coefficient, MR is the molar refractivity of substituents at the 2-, 3-, and 4-positions, and sigma- is the Hammett constant. Values of log 1/Km calculated with this equation were highly correlated with log 1/Km values (r = 0.950) that were observed experimentally. Nine phenols were also tested as substrates for partially purified human liver TS PST peak II. Log 1/Km values for these compounds were significantly correlated for the two isozymes of TS PST (r = 0.992, p less than 0.001). QSAR analysis was also used to derive equations that described the behavior of phenolic substrates for rat liver PST forms I and II. These equations differed substantially from the equation derived for compounds tested with human liver TS PST peak I. Therefore, the characteristics of the active sites of human liver TS PST peak I and rat liver PST forms I and II appear to differ. Application of these equations may make it possible to predict Km values of phenolic substrates for human liver TS PST and for rat liver PST forms I and II.

Animals↗
PubMed1986

Purification and kinetic characterization of a phenol-sulfating form of phenol sulfotransferase from human brain.

The identification of three forms of phenol sulfotransferase (PST) in human brain and the subsequent purification and kinetic characterization of a phenol-sulfating form of the enzyme are described. Two forms of PST which were capable of conjugating phenol and a third form which sulfated dopamine were resolved from one another using DEAE-cellulose chromatography. One of the phenol-sulfating forms (P1-PST) was subsequently purified on Affi-Gel blue and Sephacryl S-200, giving a final purification of almost 390-fold, with an overall yield of approximately 5%. The purified enzyme was sensitive to NaCl and showed an optimum for phenol conjugation at pH 8.5. Kinetic analysis demonstrated that sulfation by P1-PST proceeds via a sequential ordered, bi-substrate reaction mechanism, where 3'-phosphoadenosine-5'-phosphosulfate (PAPS) is the leading substrate. The true Km and Kia values for PAPS were both 0.35 microM, while the true Km value for phenol was 2.8 microM.

Arylsulfotransferase↗
PubMed1978

Polypeptide linkages and resulting structural features as powerful chromogenic factors in the Lowry phenol reaction. Studies on a glycoprotein containing no Lowry phenol-reactive amino acids and on its desialylated and deglycosylated products.

With bovine serum albumin as the reference standard, the armadillo salivary-gland glycoprotein, although containing no chromogenic amino acids and only small amounts of colour-yielding peptides [Chou & Goldstein (1960) Biochem. J. 75, 100-115], is highly reactive in the Lowry phenol protein assay [Wu & Pigman (1977) Biochem. J. 161, 37-47]. After desialylation and Smith degradation of the glycoprotein, the Lowry phenol value increased by 13 and 30% respectively, which suggests that both sialic acid and N-acetylhexosamine exert shielding effects in this reaction. Acid hydrolysis for 30 min decreased the Lowry phenol value by more than 45%, which indicates that the peptide linkages and steric features affect the Lowry phenol reactivity. After hydrolysis for up to 6h, the remaining Lowry phenol value of the partially hydrolysed core protein paralleled the amount of unhydrolysed peptides, inferring that both acid-sensitive and acid-resistant chromophoric peptides are fairly evenly distributed along the whole polypeptide chain. As with bovine serum albumin, more than 80% of the colour yield obtained in the Lowry phenol assay with this glycoprotein is Cu2+-dependent.

Animals↗
PubMed1987

Phenol hydroxylase from yeast. A model for phenol binding and an improved purification procedure.

The binding of phenol to phenol hydroxylase was studied by equilibrium dialysis, spectrophotometric titration and by steady-state kinetics. A binding model with two identical, negatively cooperative, effector/substrate-binding sites per enzyme dimer is proposed. The spectral perturbation caused by phenol and the kinetics of the overall reaction were analysed with relation to the enzyme-phenol complexes of the binding model. The main part of the spectral perturbation as well as of the increase in NADPH oxidation rate was achieved by one molecule of phenol bound per enzyme dimer. The properties of different enzyme-phenol complexes, in terms of spectral changes, hydroxylase activity, oxidase activity and substrate inhibition are discussed. A new purification procedure is described.

Chromatography, Affinity↗
PubMed1985

Biological activity of phenolic compounds. Hepatic cytochrome P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats fed phenolic monomers, polymers, and glycosides.

Eight experiments were conducted to determine effects of a phenolic polymer (Kraft wood lignin, Indulin), phenolic glycosides (cane molasses and wood molasses), and phenolic monomers (vanillin, vanillic acid, ferulic acid, and p-coumaric acid) on liver cytochromes P-450, cytochrome b5, and NADPH cytochrome c reductase in chicks and rats. Chicks fed 6.0% lignin had a higher (P less than 0.01) cytochromes P-450 content than did chicks fed 0% fiber, 6.0% wood cellulose (Solka Floc), or 6.0% arenaceous flour. NADPH cytochrome c reductase activity was not affected by treatment. Chicks fed 12.0% wood molasses had a higher (P less than 0.06) cytochromes P-450 level than did chicks fed 0% fiber or 6.0% wood molasses. Cane molasses incorporated at both 6.0 and 12.0% of the diet induced (P less than 0.05) cytochromes P-450 content over those of control-fed birds. Chicks fed 6.0% lignin, with or without antibiotic (bacitracin:neomycin sulfate, 2:1), had a higher (P less than 0.01) cytochromes P-450 level than did chicks fed control diets, with or without antibiotic. Additionally, chicks fed 6.0% lignin had lower (P less than 0.01) intestinal diaminopimelic acid (DAP) levels than did chicks fed 0% fiber. Rats fed 0% fiber, 6.0% wood cellulose, 6.0% arenaceous flour, or 6.0% lignin exhibited no difference in cytochrome level or activity among treatments. Chicks fed 0.5% vanillin, 0.5% vanillic acid, 0.5% ferulic acid, or 0.5% p-coumaric acid had comparable cytochromes level and activity compared with chicks fed no phenolics. Chicks fed 0.5% p-coumaric acid had lower (P less than 0.05) rates of gain than did chicks fed control or other phenolic-containing diets. Rats fed these phenolics had similar cytochromes P-450 content among treatments.

Age Factors↗