Showing papers on "Benzoic acid published in 1994"

Purification and characterization of a ferulic acid esterase (FAE-III) from Aspergillus niger: Specificity for the phenolic moiety and binding to microcrystalline cellulose

Abstract: An inducible ferulic acid esterase (FAE-III) has been isolated, purified and partially characterized from Aspergillus niger after growth on oat spelt xylan. The purification procedure utilized ammonium sulphate precipitation, hydrophobic interaction and anion-exchange chromatography. The purified enzyme appeared almost pure by SDS-PAGE, with an apparent M r of 36000. A single band, corresponding to a pl of 3·3 was observed on isoelectric focusing. With methyl ferulate as substrate, the enzyme had a specific activity of 67 IU (mg protein)-1, pH and temperature optima of 5 and 55–60 °C, respectively, and a Km of 2·08 mM and a V max of 175 μmol min-1 (mg protein)-1. The enzyme was also active upon methyl sinapinate, methyl-3,4-dimethoxy cinnamate and methyl p-coumarate, but not benzoic acid methyl esters or methyl caffeate. Similarly, Streptomyces olivochromogenes FAE showed activity against methyl ferulate, methyl sinapinate and methyl p-coumarate, but at a level 420-fold less (on methyl ferulate) than the A. niger esterase. No activity was detected against the benzoate methyl esters. For both enzymes, this shows the necessity for C-3 on the phenol ring to be methoxylated and the aliphatic region of the substrate to be unsaturated. The specific activity of FAE-III on destarched wheat bran was 31 U (mg protein)-1 in the presence of Trichoderma viride xylanase and 3 U (mg protein)-1 in the absence. Apparent pH dependent binding of A. niger FAE-III to microcrystalline cellulose was also demonstrated.

Transcellular transport of benzoic acid across Caco-2 cells by a pH-dependent and carrier-mediated transport mechanism.

Abstract: The pH-dependent transcellular transport of [14 C]benzoic acid across a Caco-2 cell monolayer is shown to be mediated by a monocarboxylic acid-specific carrier-mediated transport system, localized on the apical membrane. Evidence for the carrier-mediated transport of benzoic acid includes (a) the significant temperature and concentration dependence, (b) the metabolic energy dependence, (c) the inhibition by unlabeled benzoic acid and other monocarboxylic acids, (d) countertransport effects on the uptake of [14C]benzoic acid, and (e) effects of a proteinase (papain) and amino acid-modifying reagents. Furthermore, since carbonylcyanide p-trifluoromethoxyphenylhydrazone and nigericin significantly inhibited the transport of [14C] benzoic acid, the direct driving force for benzoic acid transport is suggested to be the inwardly directed proton gradient. From these results, together with previous observations using intestinal brush border membrane vesicles, the pH dependence of the transcellular transport of certain organic weak acids across Caco-2 cells is considered to result mainly from a proton gradient-dependent, carrier-mediated transport mechanism, rather than passive diffusion according to the pH-partition theory.

Biosynthetic Pathway for Veratryl Alcohol in the Ligninolytic Fungus Phanerochaete chrysosporium

Abstract: Veratryl alcohol (VA) is a secondary metabolite of white-rot fungi that produce the ligninolytic enzyme lignin peroxidase. VA stabilizes lignin peroxidase, promotes the ability of this enzyme to oxidize a variety of physiological substrates, and is accordingly thought to play a significant role in fungal ligninolysis. Pulse-labeling and isotope-trapping experiments have now clarified the pathway for VA biosynthesis in the white-rot basidiomycete Phanerochaete chrysosporium. The pulse-labeling data, obtained with 14C-labeled phenylalanine, cinnamic acid, benzoic acid, and benzaldehyde, showed that radiocarbon labeling followed a reproducible sequence: it peaked first in cinnamate, then in benzoate and benzaldehyde, and finally in VA. Phenylalanine, cinnamate, benzoate, and benzaldehyde were all efficient precursors of VA in vivo. The isotope-trapping experiments showed that exogenous, unlabeled benzoate and benzaldehyde were effective traps of phenylalanine-derived 14C. These results support a pathway in which VA biosynthesis proceeds as follows: phenylalanine → cinnamate → benzoate and/or benzaldehyde → VA.

The bacterial degradation of benzoic acid and benzenoid compounds under anaerobic conditions: Unifying trends and new perspectives

Abstract: Simple homocyclic aromatic compounds are extremely abundant in the environment and are derived largely from lignin. Such compounds may enter anaerobic environments and several groups of bacteria, exhibiting diverse energy-yielding mechanisms, have evolved the capacity to overcome the thermodynamic stability of the benzene nucleus and degrade aromatic compounds under these conditions. Over the last few years considerable advances have been made in our understanding of the biochemical strategies underlying the bacterial degradation of aromatic compounds in anoxic environments. The study of the biochemistry, and more recently the molecular genetics of the photosynthetic bacterium Rhodopseudomonas palustris and several strains of denitrifying pseudomonads, has provided the greatest insight into the mechanism and regulation of aromatic degradation under anaerobic conditions. Research has centred around the anaerobic degradation of benzoic acid. This involves the initial activation to form benzoyl-Coenzyme A, reduction of the aromatic nucleus - a reaction that has only recently been demonstrated in vitro - and the subsequent degradation of the alicyclic intermediates. Recently, much information regarding the exact nature of these intermediates has been obtained. Also through recent studies, it has become increasingly clear that benzoyl-CoA is a central metabolic intermediate during the anaerobic degradation of structurally diverse aromatic compounds. The initial metabolism of these compounds involves the formation of a carboxyl group on the aromatic nucleus (if necessary) and the synthesis of the respective Coenzyme A thioester; this results in the direct formation of benzoyl-Coenzyme A rather than benzoate. In many cases of anaerobic aromatic degradation studied in batch culture, aromatic intermediates are transiently excreted into the medium. It is argued that the study of this phenomenon may facilitate the understanding of the regulation and kinetics of the aromatic degradative pathways.

Initial reactions in the anaerobic oxidation of toluene and m-xylene by denitrifying bacteria.

Abstract: Pseudomonas sp strain T and Pseudomonas sp strain K172 grow with toluene under denitrifying conditions We demonstrated that anaerobic degradation of toluene was initiated by direct oxidation of the methyl group Benzaldehyde and benzoate accumulated sequentially after toluene was added when cell suspensions were incubated at 5 degrees C Strain T also grows anaerobically with m-xylene, and we demonstrated that degradation was initiated by oxidation of one methyl group In cell suspensions incubated at 5 degrees C 3-methylbenzaldehyde and 3-methylbenzoate accumulated after m-xylene was added Toluene- or m-xylene-grown strain T cells were induced to the same extent for oxidation of both hydrocarbons In addition, the methyl group-oxidizing enzyme system of strain T also catalyzed the oxidation of each isomer of the chloro- and fluorotoluenes to the corresponding halogenated benzoate derivatives In contrast, strain K172 only oxidized 4-fluorotoluene to 4-fluorobenzoate, probably because of the narrow substrate specificity of the methyl group-oxidizing enzymatic system During anaerobic growth with toluene strains T and K172 produced two transformation products, benzylsuccinate and benzylfumarate About 05% of the toluene carbon was converted to these products

Aza-Claisen rearrangements initiated by acid-catalyzed Michael addition

Abstract: The reaction of allylic amines with dimethyl acetylenedicarboxylate is subject to protic acid catalysis and affords 15, the product of Michael addition and aza-Claisen rearrangement. The sequence involves Michael addition of 4c or 19-21 to generate an intermediateN-alkenyl ammonium salt 14 that undergoes a charge-accelerated rearrangement to 15. Toluenesulfonic acid is a useful catalyst for the Mickael addition step. Benzoic acid is not effective because the intermediate 14 is competitively dealkylated by the benzoate counterion. In one case, the intermediate N-alkenylammonium ion 18 has been detected by 1 H NMR spectroscopy and has been observed to undergo the aza-Claisen rearrangement at -20 o C

Hydrogen-peroxide-producing system of Pleurotus eryngii involving the extracellular enzyme aryl-alcohol oxidase

Abstract: The effect of benzyl alcohol, benzaldehyde and benzoic acid on the production of extracellular hydrogen peroxide (H2O2) by the ligninolytic fungusPleurotus eryngii was investigated. It was found that an equilibrium between oxidative and reductive reactions of these compounds is established, leading to the continuous production of H2O2. A multienzymatic cyclic system is proposed in which H2O2 is produced extracellularly by the action of aryl-alcohol oxidase on benzyl alcohol, the most abundant compound after redox reactions, and to a lower extent on benzaldehyde. The oxidation products of these reactions, benzaldehyde and benzoic acid, are reduced by intracellular dehydrogenases.

Ab initio studies of free and monohydrated carboxylic acids in the gas phase

Abstract: Simple carboxylic acids, R-COOH (R=methyl, ethyl, vinyl, phenyl, and hydroxyphenyl), and the monohydrates of acetic and benzoic acids have been studied in the gas phase using ab initio quantum chemical methods. HF/6-31G * and MP2/6-31G * geometry optimizations prove that calculations at the MP2 level reproduce well the available experimental gas-phase structures. In the most stable conformation of the free acids the acid hydrogen is syn to the carbonyl oxygen. Conformers with an anti acid hydrogen are local energy minima for the aliphatic acids and for the nonplanar benzoic acid; however, arrangements with an sp 2 hybridized β carbon and with a planar heavy atom skeleton correspond to transition structures

Retinobenzoic Acids. 6. Retinoid Antagonists with a Heterocyclic Ring

Abstract: Several candidate retinoid antagonists were designed on the basis of the ligand superfamily concept and synthesized. Retinoidal activities of these benzimidazole and benzodiazepine derivatives were examined by assay of differentiation-inducing activity on human promyelocytic leukemia cell line HL-60. The parent benzimidazole derivative, 4-(5,6,7,8-tetrahydro-5,5,8,8- tetramethylnaphth-[2,3-d]imidazol-2-yl)benzoic acid (7a), and related compounds with a small alkyl group instead of the hydrogen on the nitrogen (1N) atom of the imidazole ring exhibited retinoidal activity, and the potency strongly depended on the bulkiness of the substituent. The compounds having a phenyl or benzyl group on the nitrogen lacked differentiation-inducing activity on HL-60 cells and acted as antagonists to the potent retinoid 4-[(5,6,7,8-tetrahydro-5,5,8,8- tetramethyl-2-naphthalenyl)carbamoyl]benzoic acid (Am80). Among the compounds possessing a seven-membered heterocyclic ring as a linking group, 4-(5H-7,8,9,10-tetrahydro-5,7,7,10,10- pentamethylbenzo[e]- naphtho[2,3-b][1,4]diazepin-13-yl)benzoic acid (16) also exhibited the antagonistic activity. The binding abilities of these compounds to retinoic acid receptors alpha and beta were consistent with their potency for the inhibition of HL-60 cell differentiation induced by the retinoid Am80.

The Carboxylic Acid Group as an Effective Director of Ortho-Lithiation

Abstract: Treatment of PhCO 2 H in tetrahydrofuran with 2.2 equiv of a 1:1 sec-butyllithium/N,N,N',N'-tetramethyl-1,2-ethylenediamine complex at -90 o C gave o-LiC 6 H 4 CO 2 Li, which was treated with electrophiles to give o-RC 6 H 4 CO 2 H (R=Me, SMe, Cl, Br) in good yields

Selective Oxidation of Toluene to Benzaldehyde by O2 with Visible Light in Barium(2+)- and Calcium(2+)-Exchanged Zeolite Y

Abstract: High selectivity has been demonstrted upon visible light induced oxygenation of toluene to benzaldehyde in alkaline earth exchanged zeolite Y. We attribute the tight product control to mainly two factors. One is access to the C{sub 6}H{sub 5}CH{sub 3}-O{sub 2} excited charge-transfer state by light of sufficiently long wavelength to prevent loss of product control by photofragmentation of primary products or by homolysis of the proposed hydroperoxide intermediate. The second is confinement of benzyl/HO{sub 2} radical pairs to the zeolite matrix cage, which suppresses indiscriminate attack of these radicals and forces them to combine. The Co{sup 3+}-catalyzed radical oxidation of toluene by O{sub 2} in solution used currently in an industrial process for benzaldehyde synthesis lacks this selectivity, mainly because of continued oxidation of the aldehyde to benzoic acid. 24 refs., 2 figs.

Inhibitor binding to the binuclear active site of tyrosinase: temperature, pH, and solvent deuterium isotope effects.

Abstract: Competitive inhibition of the monophenolase reaction of tyrosinase by a variety of compounds was investigated with respect to temperature and pH. Derivatives of benzoic acid as well as p-nitrophenol were the best inhibitors. Toluene and several N-heterocycles were all weak inhibitors. Thermodynamic parameters of toluene inhibition were qualitatively different from those of aromatic acids and were consistent with a hydrophobic binding site for toluene. Inhibition by both aromatic acids and p-nitrophenol was strongly pH-dependent over the range 5.1-8.0, with inhibitor binding favored at lower pH. In contrast, toluene binding and indazole binding were pH-independent while benzimidazole binding was favored at higher pH. For both carboxylic acids and p-nitrophenol, inhibitor binding was quantitatively accounted for by assuming the protonated, electrically neutral form of the inhibitor is the reactive species. A solvent deuterium isotope effect on the binding of benzoic acid was observed. A proton inventory study indicated that a single proton transferred from benzoic acid to a site with a fractionation factor of 0.64 +/- 0.02 accounts for the isotope effect. The identity of the proton acceptor and possible mechanistic implications are discussed.

Effect of lipid unsaturation on the antioxidative activity of some phenolic acids

Abstract: Antioxidative properties ofp-hydroxybenzoic, vanillic, syringic, 3,4-dihydroxybenzoic,p-coumaric, ferulic, sinapic and caffeic acids were studied in the concentration range 0.02–0.20 wt% during autoxidation at 100°C of lard and sunflower oil methyl esters (MEL and MESO, respectively). In both lipid systems, the derivatives of benzoic acid had weaker inhibiting properties than did the corresponding analogues of cinnamic acid. The effectiveness and strength of the antioxidative action were considerably lower in the lipid system MESO, which was rich in linoleic acid and was more easily oxidized. Thep-hydroxybenzoic, vanillic, syringic andp-coumaric acids in this system exercised no inhibiting effect. We established that the molecules of the investigated phenolic acids initiated the chain radical process of autoxidation, and the formed antioxidant radicals propagated the chains as a result of the reaction with the lipid substrate. These reactions proceeded at a higher rate in MESO than in MEL.

Zeolite Catalyzed Aromatic Acylation and Related Reaches

Abstract: The development of catalytic procedures in aromatic acylation is a priority because the current industrial methods apply stoichiometric or excess amounts of metal chlorides or mineral acids as “catalysts”. The paper reviews zeolite catalysis in this field and subsequently focusses on the acylation of phenols. Here, two reaction steps are involved: esterification and the so-called Fries rearrangement; both reactions are catalyzed by H-zeolites. The Fries rearrangement has been studied over various zeolites using phenyl acetate as a standard reactant. For the combined reaction especially the system resorcinol/benzoic acid has been examined with several catalysts. Zeolite H-Beta was found to be the best catalyst. When more bulky reactants are involved the new MCM-41 zeolitic material is a promising catalyst.

Kinetics and hydrolysis mechanism of chlorsulfuron and metsulfuron‐methyl

Abstract: In acidic media, hydrolysis of chlorsulfuron and metsulfuron-methyl occurs via two consecutive reactions which were followed by ultraviolet spectrophotometry. For these two reactions, the pseudo-first-order rate constants increase proportionally to the concentration of hydronium ion in the more acidic media and to the square of this concentration at higher pH values. A kinetic study by HPLC shows that the first reaction leads to the formation of 4-methoxy-6-methyl-1,3,5-triazin-2-amine and (o-chlorophenylsulfonyl) carbamic acid for chlorsulfuron or (o-methoxycarbonylphenylsulfonyl) carbamic acid for metsulfuronmethyl. The second reaction is the conversion of these sulfonylcarbamic acids to sulfonamides and carbon dioxide. The complete lack of saccharin and of o-sulfamoyl benzoic acid proves that the ester function of the methoxycarbonyl group is stable. The lack of general acid-base catalysis and a solvent deuterium isotope effect less than unity are consistent with a rate-determining cleavage of the protonated substrate. In the basic pH range (10–14) a single reaction occurs, the nucleophilic substitution of the methoxy group on the triazine by a hydroxide group.

Use of water and EDTA extractions to estimate available (free and reversibly bound) phenolic acids in Cecil soils.

Abstract: Sterile and microbe reinfested Cecil Ap and Bt soil materials amended with 0 to 5 µmol/g of ferulic acid,p-coumaric acid,p-hydroxybenzoic acid, or vanillic acid were extracted after varying time intervals with water, EDTA, or NaOH to characterize sorption of cinnamic and benzoic acid derivatives and to determine the effectiveness of water and EDTA extractions in estimating concentrations of free and reversibly bound phenolic acids in soils Basic EDTA (05 M, pH 8) extractions and water extractions provided good estimates of both free and reversibly bound cinnamic acid derivatives, but not of benzoic acid derivatives Neutral EDTA (025 M, pH 7) and water extractions, however, were effective for both cinnamic and benzoic acid derivatives Rapid initial sorption of both cinnamic and benzoic acid derivatives was followed by slow long-term sorption of the cinnamic acid derivatives Slow long-term sorption was not observed for the benzoic acid derivatives The amount of sorption of phenolic acids in soil materials was directly related to the concentration of phenolic acids added to soil materials The addition of a second phenolic acid to the soil materials did not substantially affect the sorption of each individual phenolic acid Sodium hydroxide extractions, which were made only after phenolic acids in phenolic acid-amended and non-amended soil material were depleted by microbes, confirmed that neutral EDTA and water extractions of soils can be used to make accurate estimates of baseline (residual) levels of free and reversibly bound phenolic acids available to soil microbes and, thus, potentially to seeds and roots

Novel bis(naphthalic anhydrides) and their polyheteroarylenes with improved processability

Abstract: Novel bis(naphthalic anhydrides) containing “bridging” groupings and/or bulky substituents are reviewed. Reactions of these compounds with aromatic diamines and bis(o-phenylene diamines) led to the formation of polynaphthylimides and polynaphthoylenebenzimidazoles combining solubility in organic solvents with high thermal, heat and chemical resistance.

Production of Benzaldehyde and Benzyl Alcohol by the Mushroom Polyporus tuberaster K2606

Abstract: The culture conditions of Polyporus tuberaster K2606 were investigated to find conditions with which much benzaldehyde and benzyl alcohol would be obtained. Strain K2606 reduced benzoic acid as well as L-phenylalanine to benzaldehyde and benzyl alcohol in high yield. The conversion rate of benzoic acid was about 60%. Two other metabolites of L-phenylalanine, 3-phenylpropionic acid and 3-phenylpyruvic acid, were reduced to benzaldehyde and benzyl alcohol as well. Veratryl alcohol, a secondary metabolite of L-phenylalanine, was not detected. Benzaldehyde produced by strain K2606 was reduced to benzyl alcohol, which was slowly converted again into benzaldehyde when culture with shaking continued

Catalytic oxidation of toxic organics in supercritical water

Abstract: Oxidation of some toxic organic compounds in supercritical water is investigated in the presence of a solid catalyst in an isothermal plug flow fixed-bed reactor. Comparison between catalyzed and non-catalyzed oxidations indicates that the conversions are much higher when the catalyst is present. It is also found that the heterogeneous oxidation route forms less intermediate products during the decomposition of organics such as benzoic acid and 1-methyl-2-pyrrolidone in carbon dioxide.

Anaerobic degradation of pimelate by newly isolated denitrifying bacteria.

Abstract: Summary: A C7 dicarboxylic (pimelic) acid derivative is postulated as an intermediate in anaerobic degradation of benzoate. Four strains of Gram-negative, nitrate-reducing bacteria capable of growth with both pimelate and benzoate as sole carbon and energy source were isolated. The metabolism of strain LP-1, which was enriched from activated sludge with pimelate as substrate, was studied in detail. This strain grew only with oxygen or with oxidized nitrogen compounds as electron acceptor. In the presence of nitrate, a wide range of substrates excluding C1 compounds was degraded. The new isolate was catalase- and oxidase-positive, and had one single polar flagellum. Strain LP-1 was tentatively classified within the family Pseudomonadaceae. The catabolism of pimelate and benzoate was studied in cell-free extracts of strain LP-1. Both acids were activated with coenzyme A in a Mg2+- and ATP-dependent reaction. The corresponding acyl-CoA synthetases were specifically induced by the respective growth substrate. Pimelate was also activated by CoA transfer from succinyl-CoA. Pimelyl-CoA was oxidized by cell-free extracts in the presence of potassium ferricyanide. Degradation to glutaryl-CoA and acetyl-CoA proceeded by a sequence of β-oxidation-like reactions. Glutaryl-CoA dehydrogenase and glutaconyl-CoA decarboxylase activities were expressed in cells grown with pimelate or benzoate, indicating the specific involvement of these enzyme activities in anaerobic degradation of these two acids. Enzyme activities responsible for further degradation of the resulting crotonyl-CoA to acetyl-CoA via classical β-oxidation were also detected.

Effect of lignin-related phenols and their methylated derivatives on the growth of eight white-rot fungi.

Abstract: When various lignin-related para-phenolic benzoic acids, para-phenolic cinnamic acids, para-phenolic phenylpropionic acids, the corresponding unsubstituted and 4-O-methylated derivatives, and 4-hydroxyl substituted benzaldehydes were tested on the growth of eight white-rot fungi, methylation of the 4-hydroxy substituent resulted, in most cases, in increased inhibition of fungal growth. This effect was most notable with monomethoxylated compounds. When the aromatic ring contained additional methoxyl substituents, the toxicity of the 4-O-methylated derivative was less pronounced. Marked inhibition of fungal growth was also observed with aromatic compounds lacking a para-substituent. Higher concentrations of aromatic aldehydes were manifestly more toxic than the corresponding carboxylic acid.

Side-Chain Liquid Crystalline Ionomers. 1. Preparation through Alkaline Hydrolysis and Characterization

Abstract: Side-chain liquid crystalline ionomers were obtained through alkaline hydrolysis of liquid crystalline polyacrylates. In the case of a polyacrylate bearing a phenyl benzoate moiety in the mesogenic group, partial hydrolysis using sodium hydroride was found to be highly selective and give the sodium salt of benzoic acid; as for a polyacrylate containing a biphenyl moiety in the side group, a hydrolysis reaction resulted in the sodium salt of acrylic acid. Increasing the content of ionic groups led to a systematic depression of the nematic to isotropic transition temperature. On the other hand, ionic aggregation had little effect on the nematic to isotropic transformation enthalpies as well as the glass transition temperatures of these new materials, in particular for ionomers based on the polyacrylate containing a biphenyl moiety in the side group

Phenylacetic acid benzylamides

Abstract: The present application relates to the uses of phenylacetic acid benzylamides and new (S)(+)-2-ethoxy-4-[N-[1-2-piperidino-phenyl)-3-methyl-1-butyl]-aminocarbonylmethyl]-benzoic acid and the salts thereof, which have valuable pharmacological properties, namely an effect on the intermediate metabolism, but particularly the effect of lowering blood sugar.

Structure and conductivity of liquid crystal channel‐like linic complexes of taper‐shaped compounds

Abstract: Molecular packing and electrical conductivity were studied in complexes of alkali trifluoromethanesulphonates with low-molar or polymeric compounds containing both taper-shaped mesogens were esters of either 3,4,5-tris [p-(n-dodecan-l-yloxy) benzyloxy] benzoic acid (I) or 3, 4, 5-tris (n-dodecan-l-yloxy) benzoic acid (II). In the hexagonal columnar liquid crystal phase the tapered mesogens fan out from the centre of the column, with the ionic receptors forming the central channel and the aliphatic tails constituting the continuum matrix. In the case of side-chain polymethacrylates the column core also contains the backbone chain. The DC conductivity σ of unoriented samples increases greatly at the crystal-columnar transition, with only a minor further change upon columnar-isotropic transition. σ was in the range 10−9 − 10−6 in the columnar phase 40–90 °C, whilst the activation energies for conduction were between 28 kcal mol−1 for the crown ether and only 2 kcal mo−1 for the complex of LiCf3SO3 with the non-polymeric ester of tri(ethylene oxide) with I.