Substrate-substrate interaction of resorcinol and catechol in upflow anaerobic fixed film – fixed bed reactors in mono and multisubstrate matrices

Biodegradation of resorcinol and catechol was studied in upflow anaerobic fixed film-fixed bed (FFFB) reactors of uniform dimensions in mono and multisubstrate matrices. Cross feeding studies have revealed that phenol was poorly degraded in resorcinol acclimated reactor whereas it was readily degraded in catechol acclimated reactor. Addition of resorcinol along with phenol in a COD ratio 1:3 in resorcinol reactor increased phenol removal efficiency to 95% indicating that resorcinol induces phenol degradation. When both resorcinol and catechol were fed to the resorcinol acclimated reactor, it was observed that resorcinol degradation was inhibited by catechol. Catechol acclimated reactor could degrade phenol readily when added as mono substrate indicating that it may be an intermediate in catechol degradation. In binary mixture studies also catechol reactor could degrade phenol, resorcinol and hydroquinone to 90%. Catechol acclimated reactor exhibits relaxed substrate specificity whereas resorcinol acclimated reactor exhibits rigid substrate specificity for phenol as well as other isomers.     

Synthesis and properties of new photoactivable derivatives of tetrodotoxin

Eight lots of reagent-grade phenol from four companies were tested for capacity to interact with Cu2+ to produce an inactivator or inactivators of the transfective RNA obtained from poliovirions; such capacity to interact with Cu2+ is referred to as cofactor activity. Six of the lots showed cofactor activity; two did not. A review of the data on the phenol lots and of the properties of the impurity or impurities conferring cofactor activity suggested that the active impurity(ies) might be a dihydric or trihydric phenol. Commercial catechol, resorcinol, hydroquinone, orcinol and pyrogallol were tested and found active. The activity of hydroquinone was outstandingly high. Upon serial recrystallization, the activity of catechol, hydroquinone, orcinol and pyrogallol remained constant, but the activity of resorcinol decreased markedly, in stepwise fashion, showing the most of the activity of the commercial resorcinol was due to impurity(ies). Each of catechol, hydroquinone, orcinol, pyrogallol, and the commercial resorcinol was shown to react with Cu2+ to produce inactivator(s). The effective target for inactivator(s) was the RNA and not the transfection process. The kinetics of inactivator(s) production varied for the different phenols, and the inactivator activity of the incubated mixture of pyrogallol and Cu2+ was notably labile.     

Methanogenic degradation of hydroquinone and catechol via reductive dehydroxylation to phenol

Abstract Fermentative degradation of hydroquinone, catechol, and phenol was demonstrated with nearly-homogeneous mixed methanogenic cultures obtained from freshwater sediments and sewage sludge by enrichment with the respective phenolic substrates. Gram-negative short rods predominated in these cultures, together with hydrogen- and acetate-utilizing methanogens. Acetate and methane were the only degradation products. Bacteria enriched with hydroquinone or catechol also degraded phenol and p -hydroxy-benzoate, but not resorcinol or resorcylic acids. Phenol was formed as an intermediate during catechol and hydroquinone degradation, indicating that reductive dehydroxylation was the primary event in degradation of these substrates. Inhibition experiments with bromoethanesulfonate and acetylene indicated that catechol, hydroquinone, and phenol degradation depended on a syntrophic co-operation of fermenting bacteria and hydrogen-oxidizing methanogens.     

Metabolism of hydroquinone by human myeloperoxidase: mechanisms of stimulation by other phenolic compounds.

Hydroquinone, a metabolite of benzene, is converted by human myeloperoxidase to 1,4-benzoquinone, a highly toxic species. This conversion is stimulated by phenol, another metabolite of benzene. Here we report that peroxidase-dependent hydroquinone metabolism is also stimulated by catechol, resorcinol, o-cresol, m-cresol, p-cresol, guaiacol, histidine, and imidazole. In order to gain insights into the mechanisms of this stimulation, we have compared the kinetics of human myeloperoxidase-dependent phenol, hydroquinone, and catechol metabolism. The specificity (Vmax/Km) of hydroquinone for myeloperoxidase was found to be 5-fold greater than that of catechol and 16-fold greater than that of phenol. These specificities for myeloperoxidase-dependent metabolism inversely correlated with the respective one-electron oxidation potentials of hydroquinone, catechol, and phenol and suggested that phenol- and catechol-induced stimulation of myeloperoxidase-dependent hydroquinone metabolism cannot simply be explained by interaction of hydroquinone with stimulant-derived radicals. Phenol (100 microM), catechol (20 microM), and imidazole (50 mM) did, however, all increase the specificity (Vmax/Km) of hydroquinone for myeloperoxidase, indicating that these three compounds may be stimulating hydroquinone metabolism by a common mechanism. Interestingly, the stimulation of peroxidase-dependent hydroquinone metabolism by other phenolic compounds was pH-dependent, with the stimulating effect being higher under alkaline conditions. These results therefore suggest that the interaction of phenolic compounds, presumably by hydrogen-bonding, with the activity limiting distal amino acid residue(s) or with the ferryl oxygen of peroxidase may be an important contributing factor in the enhanced myeloperoxidase-dependent metabolism of hydroquinone in the presence of other phenolic compounds.     

Enhancement of the mutagenicity of polyphenols by chlorination and nitrosation in Salmonella typhimurium.

The hydrolytic products of lignins, humic acids and industrial waste including hydroquinone, catechol, resorcinol, pyrogallol and 1,2,4-benzenetriol are widely distributed in water sources. These polyphenols can interact with chlorine or nitrite to yield new derivatives. Generally, these new products possess more mutagenic potential than their original compounds. Furthermore, the mutagenicity of these polyphenols and their derivatives can be dramatically reduced by rodent liver microsomal enzymes (S9). The mutagenicity of polyphenols is in this order: hydroquinone greater than 1,2,4-benzenetriol greater than pyrogallol, while catechol, resorcinol and phloroglucinol are non-mutagenic. The ultimate product of chlorination or nitrosation of hydroquinone has been identified to be p-benzoquinone. The formation of active oxygen species including superoxide anion and hydrogen peroxide by polyphenols has been demonstrated and this may contribute partly to the molecular mechanisms of polyphenol mutagenicity.     

Enhancing and inhibiting effects of benzenediols on chemiluminescence of a novel cyclometallated iridium(III) complex

A novel chemiluminescence (CL) system, including the cyclometallated iridium(III) complex {tris[1‐(2,6‐dimethylphenoxy)‐4‐(4‐chlorophenyl)phthalazine]iridium}, potassium permanganate and oxalic acid, is proposed for the determination of benzenediols. This method is based on the fact that hydroquinone and catechol exhibited an inhibiting effect, while resorcinol exhibited an enhancing effect on CL intensity. The optimum conditions for CL emission were investigated. Under optimal conditions, the detection limits of hydroquinone, catechol and resorcinol were 6.4 × 10^?8, 2.7 × 10^?9 and 8.1 × 10^?7 mol/L, respectively. The method has been successfully applied to the determination of benzenediols in different types of water sample. The luminophors of the CL systems were all identified as the metal–ligand charge‐transfer (MLCT) excited state of the iridium complex. Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation on the interaction between dihydroxybenzene and Fe3+- H2O2-Rh6G system based on enhancing chemiluminescence.

A highly sensitive flow-injection chemiluminescence (FI-CL) method has been developed for the determination of dihydroxybenzene, based on the hydroxyl radical reaction. Hydroxyl radical (.OH) produced by the reaction of Fe(3+) and H(2)O(2) oxidize rhodamine 6G to produce weak CL. It was observed that catechol and hydroquinone greatly enhanced the weak CL reaction. However, the proposed CL system is not suitable for determination of resorcinol because the enhancement reaction is very slow. The proposed procedure has a linear range of 0.01-2 mg/L for catechol, with a detection limit of 0.006 mg/L, and 0.008-1 mg/L for hydroquinone, with a detection limit of 0.004 mg/L. The possible mechanism of the CL system is discussed.     

Glucosylation of phenolic compounds by Datura innoxia suspension cultures

Datura innoxia grown in suspension cultures can glucosylate simple phenols. Three isomers of dihydroxybenzene (hydroquinone, resorcinol and catechol) were readily converted into their corresponding mono-β-glucosides. Both salicyl alcohol and salicylaldehyde fed to the cells were transformed specifically to isosalicin instead of salicin. Furthermore, the analysis of the cells treated with salicylic acid suggested the formation of its glucose ester in addition to the corresponding monoglucoside. Feeding experiments showed that the cultured cells possess a remarkably high capacity for glucosylation of hydroquinone, which was totally converted into arbutin within 10 hr after administration. The in vitro glucosylation of hydroquinone carried out by the cell-free extract demonstrated that this enzymic reaction requires the presence of UDPG as a high energy donor of glucose.     

Phenolic compounds inhibit the aldose reductase enzyme from the sheep kidney

Aldose reductase (AR) is the key enzyme for the polyol pathway and responsible for sorbitol accumulation during the hyperglycemia. The present article focuses on the role of phenol, pyrogallol, hydroquinone, resorcinol, catechol, and phloroglucinol in in vitro inhibition of AR. For this purpose, AR was purified from the sheep kidney with 5.33 EU mg^?1 specific activity and 0.64% yield using several chromatographic methods. Various concentrations of the compounds were tested on in vitro AR activity. IC₅₀ values were found for phenol, pyrogallol, hydroquinone, resorcinol, catechol, and phloroglucinol as 6.5, 1.13, 5.45, 2.21, 1.8, and 2.09 mM, respectively, and their K_i constant was calculated as 3.45 ± 0.92, 0.96 ± 0.28, 3.07 ± 0.46, 1.59 ± 0.43, 2.5 ± 0.35, and 2.54 ± 0.45 mM, respectively. Pyrogallol showed better inhibitory effect compared to the other compounds. The inhibition mechanisms of all compounds were noncompetitive. In the presents study, in vitro AR inhibition was examined by the phenolic compounds.     

A wounding-induced PPO from cowpea (Vigna unguiculata) seedlings

Polyphenol oxidases (PPO) are induced in cowpea plants by wounding. The highest activity levels were detected 48h after this stimulus in both wounded and neighbor-to-wounded unifoliates of cowpea seedlings; the increase of activity was in the order of 13 to 15-fold, respectively, in comparison to control unifoliates. Multiple molecular forms of active PPO (Mrs 58, 73 and congruent with220kDa) were detected by partially denaturing SDS-PAGE. Wounding-induced cowpea PPO were extracted and purified through (NH(4))(2)SO(4) precipitation and ion-exchange chromatography. The effects of substrate specificity, pH, thermal stability and sensitivity to various inhibitors - resorcinol, EDTA, sodium azide and tropolone - of partially purified soluble PPO were investigated. Purified wounding-induced cowpea PPO (wicPPO) showed the highest activities towards 4-methylcatechol (K(m)=9.86mM, V(max)=24.66 EU [DeltaAmin(-1)]) and catechol (K(m)=3.44mM, V(max)=6.64 EU [DeltaAmin(-1)]); no activity was observed towards l-tyrosine, under the assay conditions used. The optimum pH for wound-induced cowpea PPO was 6.0 with 4-methylcatechol as substrate. The enzyme was optimally activated by 10 mM SDS and was highly stable even after 5 min at 80 degrees C. The most effective inhibitor was tropolone, whereas addition of 10mM of resorcinol, EDTA and sodium azide were able to reduce PPO activities by 40%, 15% and 100%, respectively.     

Anaerobic degradation of aniline and dihydroxybenzenes by newly isolated sulfate-reducing bacteria and description of Desulfobacterium anilini

A new, rod-shaped, Gram-negative, non-sporing sulfate reducer (strain Ani1) was enriched and isolated from marine sediment with aniline as sole electron donor and carbon source. The strain degraded aniline completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Strain Ani1 also degraded aminobenzoates and further aromatic and aliphatic compounds. The strain grew in sulfide-reduced mineral medium supplemented only with vitamin B12 and thiamine. Cells contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P582, but no desulfoviridin. Strain Ani1 is described as a new species of the genus Desulfobacterium D. anilini. Marine enrichments with the three dihydroxybenzene isomers led to three different strains of sulfate-reducing bacteria; each of them could grow only with the isomer used for enrichment. Two strains isolated with catechol (strain Cat2) or resorcinol (strain Re10) were studied in detail. Both strains oxidized their substrates completely to CO2, and contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P 582. Desulfoviridin was not present. Whereas the rod-shaped catechol oxidizer (strain Cat2) was able to grow on 18 aromatic compounds and several aliphatic substrates, the coccoid resorcinol-degrading bacterium (strain Re10) utilized only resorcinol, 2,4-dihydroxybenzoate and 1,3-cyclohexanedion. These strains could not be affiliated with existing species of sulfate-reducing bacteria. A further coccoid sulfate-reducing bacterium (strain Hy5) was isolated with hydroquinone and identified as a subspecies of Desulfococcus multivorans. Most-probable-number enumerations with catechol, phenol, and resorcinol showed relatively large numbers (10(4)-10(6) per ml) of aryl compound-degrading sulfate reducers in marine sediment samples.     

Catechol sensor using poly(aniline-co-o-aminophenol) as an electron transfer mediator

In this work, poly(aniline-co-o-aminophenol) (copolymer) was used as an electron transfer mediator in the electrochemical oxidation of catechol due to its reversible redox over a wide range of pH. The experimental results indicate that the anodic peak potential of catechol at the copolymer electrode is lower than that at the platinum electrode in a solution consisting of catechol and sodium sulfate with pH 5.0, and the activation energy for the electrochemical oxidation of catechol at the copolymer electrode is low (23.6 kJ mol(-1)). These are strong evidence for the electrocatalytic oxidation of catechol at the copolymer electrode. The -OH group on the copolymer chain plays an important role in the electron transfer between the copolymer electrode and catechol in the solution. Based on the catalytic oxidation, the copolymer is used as a sensor to determine the concentration of catechol. The response current of the sensor depends on the concentration of catechol, pH, applied potential and temperature. At 0.55 V (versus saturated calomel reference electrode (SCE)) and pH 5.0, the sensor has a fast response (about 10s) to catechol and good operational stability. The sensor shows a linear response range between 5 and 80 microM catechol with a correlation coefficient of 0.997. It was found that phenol and resorcinol cannot be oxidized at the copolymer electrode at potentials < or =0.55 V, so controlling the sensor potential affords a good way of avoiding the effect of phenol and resorcinol on the determination of catechol.     

Fractionation and Phenol Composition of Cellulose Cigarette Smoke Condensate

Fractionation of smoke condensate and a detailed analysis of phenols in the cellulose cigarette smoke were performed during the course of systematic compositional studies of the smoke. Nearly equal yields of phenolic, acidic and neutral fractions were obtained in fractionation of cellulose cigarette smoke condensate. Thirtyseven phenols were newly identified in the smoke of cellulose cigarette in addition to six phenols ever found in pyrolysis products of cellulose. Semi-quantitative determination of some of these phenols revealed that dihydric phenols, such as catechol, hydroquinone, resorcinol and their alkyl derivatives were the main phenols and monohydric phenols were the minor phenols.     

Some biochemical properties of polyphenol oxidase from celery

Polyphenol oxidase (PPO, EC 1.14.18.1) was extracted from celery roots (Apium graveolens L.) with 0.1 M phosphate buffer, pH 7.0. The PPO was partially purified by (NH4)2SO4 and dialysis. Substrate specificity experiments were carried out with catechol, pyrogallol, L-DOPA, p-cresol, resorcinol, and tyrosine. The Km for pyrogallol, catechol, and L-DOPA were 4.5, 8.3, and 6.2mM, respectively, at 25 degrees C. Data for Vmax/Km values, which represent catalytic efficiency, show that pyrogallol has the highest value. The optimum pH and temperature were determined with catechol, pyrogallol, and L-DOPA. Optimum pH was 7.0 for catechol and L-DOPA, and 7.5 for pyrogallol. Optimum temperatures for maximum PPO activity were 25 degrees C for pyrogallol, 40 degrees C for catechol, and 45 degrees C for L-DOPA. Heat inactivation studies showed a decrease in enzymatic activity at temperatures above 60 degrees C. The order of inhibitor effectiveness was: L-cysteine > ascorbic acid > glycine > resorcinol > NaCl.     

Inhibition by diphenols of the induction of micronuclei by gamma-radiation

A study was made of the influence of diphenols (for instance, resorcinol, hydroquinone, and pyrocatechin) on gamma-radiation induction of micronuclei (1.5 Gy). The position of the diphenol molecule hydroxyl group (the isomeric effect) was shown to influence their antimutagenic activity. This antimutagenic effect of the diphenols is associated with their ability to produce semiquinone and quinone forms which are peculiar for the process of oxidation of pyrocatechin (ortho-) and hydroquinone (para-) as opposed to resorcinol (meta-position of the hydroxyl group).     

Protein engineering of toluene-o-xylene monooxygenase from Pseudomonas stutzeri OX1 for synthesizing 4-methylresorcinol, methylhydroquinone, and pyrogallol

Toluene-o-xylene monooxygenase (ToMO) from Pseudomonas stutzeri OX1 oxidizes toluene to 3- and 4-methylcatechol and oxidizes benzene to form phenol; in this study ToMO was found to also form catechol and 1,2,3-trihydroxybenzene (1,2,3-THB) from phenol. To synthesize novel dihydroxy and trihydroxy derivatives of benzene and toluene, DNA shuffling of the alpha-hydroxylase fragment of ToMO (TouA) and saturation mutagenesis of the TouA active site residues I100, Q141, T201, and F205 were used to generate random mutants. The mutants were initially identified by screening with a rapid agar plate assay and then were examined further by high-performance liquid chromatography and gas chromatography. Several regiospecific mutants with high rates of activity were identified; for example, Escherichia coli TG1/pBS(Kan)ToMO expressing the F205G TouA saturation mutagenesis variant formed 4-methylresorcinol (0.78 nmol/min/mg of protein), 3-methylcatechol (0.25 nmol/min/mg of protein), and methylhydroquinone (0.088 nmol/min/mg of protein) from o-cresol, whereas wild-type ToMO formed only 3-methylcatechol (1.1 nmol/min/mg of protein). From o-cresol, the I100Q saturation mutagenesis mutant and the M180T/E284G DNA shuffling mutant formed methylhydroquinone (0.50 and 0.19 nmol/min/mg of protein, respectively) and 3-methylcatechol (0.49 and 1.5 nmol/min/mg of protein, respectively). The F205G mutant formed catechol (0.52 nmol/min/mg of protein), resorcinol (0.090 nmol/min/mg of protein), and hydroquinone (0.070 nmol/min/mg of protein) from phenol, whereas wild-type ToMO formed only catechol (1.5 nmol/min/mg of protein). Both the I100Q mutant and the M180T/E284G mutant formed hydroquinone (1.2 and 0.040 nmol/min/mg of protein, respectively) and catechol (0.28 and 2.0 nmol/min/mg of protein, respectively) from phenol. Dihydroxybenzenes were further oxidized to trihydroxybenzenes with different regiospecificities; for example, the I100Q mutant formed 1,2,4-THB from catechol, whereas wild-type ToMO formed 1,2,3-THB (pyrogallol). Regiospecific oxidation of the natural substrate toluene was also checked; for example, the I100Q mutant formed 22% o-cresol, 44% m-cresol, and 34% p-cresol, whereas wild-type ToMO formed 32% o-cresol, 21% m-cresol, and 47% p-cresol.     

Degradation of aniline by newly isolated,extremely aniline-tolerant <Emphasis Type="Italic">Delftia </Emphasis>sp. AN3

A bacterial strain, AN3, which was able to use aniline or acetanilide as sole carbon, nitrogen and energy sources was isolated from activated sludge and identified as Delftiasp. AN3. This strain was capable of growing on concentrations of aniline up to 53.8 mM (5000 mg/l). Substituted anilines such as N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 4-methylaniline, 2-chloroaniline, 3-chloroaniline, o-aminoaniline, m-aminoaniline, p-aminoaniline, and sulfanilic acid did not support the growth of strain AN3. The optimal temperature and pH for growth and degradation of aniline were 30 degrees C and 7.0, respectively. The activities of aniline dioxygenase, catechol 2,3-dioxygenase and other enzymes involved in aniline degradation were determined, and results indicated that all of them were inducible. The K (m) and V (max) of aniline dioxygenase were 0.29 mM and 0.043 mmol/mg protein/min, respectively. The K (m) and V (max) of catechol 2, 3-dioxygenase for catechol were 0.016 mM and 0.015 mmol/mg protein/min, respectively. Based on the results obtained, a pathway for the degradation of aniline by Delftiasp. AN3 was proposed. The importance of the strain to the operation of municipal wastewater treatment plants is discussed.     

Simultaneous degradation of p-nitrophenol and phenol by a newly isolated Nocardioides sp

A p-nitrophenol (PNP)- and phenol-mineralizing bacterium (strain NSP41) was isolated from an industrial wastewater and identified as a member of the genus Nocardioides. PNP was degraded via a hydroquinone pathway, and phenol was degraded through a catechol pathway in strain NSP41. Both enzyme systems for the degradation of PNP and phenol were induced simultaneously in the presence of both compounds. Although both enzyme systems were induced at the same time, PNP and phenol were degraded by the hydroquinone and catechol pathway, respectively. However, during the simultaneous degradation in the low phenol concentration, after the exhaustion of phenol, some PNP was transformed by the catechol pathway and 4-nitrocatechol was transiently accumulated. Kinetically, the addition of phenol greatly enhanced the apparent PNP degradation rate, which may be due to the increased cell mass by the assimilation of phenol.     

Evidence that covalent binding of metabolically activated phenol to microsomal proteins is caused by oxidised products of hydroquinone and catechol

The metabolic activation of [14C]phenol resulting in covalent binding to proteins has been studied in rat liver microsomes. The covalent binding was dependent on microsomal enzymes and NADPH and showed saturation kinetics for phenol with a Km-value of 0.04 mM. The metabolites hydroquinone and catechol were formed at rates which were 10 or 0.7 times that of the binding rate of metabolically activated phenol. The effects of cytochrome P-450 inhibitors and cytochrome P-450 inducers on the metabolism and binding of phenol to microsomal proteins, suggest that cytochrome P-450 isoenzyme(s) other than P-450 PB-B or P-450 beta NF-B catalyses the metabolic activation of phenol. Furthermore, reconstituted mixed-function oxidase systems containing cytochrome P-450 PB-B and P-450 beta NF-B were (on basis of cytochrome P-450 content) 6 and 11 times less active in catalysing the formation of hydroquinone than microsomes. The isolated metabolites hydroquinone and catechol bound more extensively to microsomal proteins than phenol and the binding of these was not stimulated by NADPH. The binding occurring during the metabolism of phenol could be predicted by the rates of formation of hydroquinone and catechol and the rates by which the isolated metabolites were bound to proteins.     

Cigarette smoke-induced DNA-damage: role of hydroquinone and catechol in the formation of the oxidative DNA-adduct, 8-hydroxydeoxyguanosine

This study demonstrates the ability of cigarette smoke condensate to generate hydrogen peroxide and to hydroxylate deoxyguanosine (dG) residues in isolated DNA to 8-hydroxydeoxyguanosine (8-OHdG). Both the formation of hydrogen peroxide and that of 8-OHdG in DNA was significantly decreased when catalase or tyrosinase was added to the smoke condensates, and this also occurred when pure hydroquinone or catechol, two major constitutes in cigarette smoke, was used instead of smoke condensate. Moreover, pure hydroquinone and catechol both caused dose-dependent formation of hydrogen peroxide and 8-OHdG, and there was good correlation between the amounts of hydrogen peroxide and 8-OHdG formed. These findings suggest that (i) hydroquinone and catechol may be responsible for the ability of cigarette smoke to cause 8-OHdG formation in DNA, (ii) this oxidative DNA-damage is due to the action of hydroxyl radicals formed during dissociation of hydrogen peroxide and (iii) the hydrogen peroxide in cigarette smoke is generated via autooxidation of hydroquinone and catechol.