Benzoylformate Research Articles

Cytogenetic biomarkers, urinary metabolites and metabolic gene polymorphisms in workers exposed to styrene

The present study comprised a biomonitoring study in 95 workers occupationally exposed to styrene and 98 unexposed controls, employing an integrated approach involving biomarkers of exposure, effect, and susceptibility. Airborne styrene was evaluated at workplace, and urinary styrene metabolites, mandelic acid (MA), phenylglyoxylic acid (PGA), vinylphenols (VPTs) and phenylhydroxyethylmercapturic acids (PHEMAs), were measured as biomarkers of internal dose. Cytogenetic alterations were evaluated by analysing the frequency of chromosomal aberrations (CAs) and micronucleated binucleated cells (MNBN) in peripheral blood lymphocytes. The micronucleus assay was coupled with centromeric fluorescence in situ hybridization to distinguish micronuclei (MN) arising from chromosomal breakage (C- MN) from those harboring whole chromosomes (C+ MN). The possible influence of genetic polymorphisms of xenobiotic-metabolizing enzymes involved in styrene biotransformation (EPHX1, GSTT1, GSTM1, GSTP1) and NAT2 on the cytogenetic endpoints was investigated. The exposed workers showed a significantly higher frequency of MNBN (13.8+/-0.5% versus 9.2+/-0.4%; P<0.001) compared to control subjects. The effect appeared to concern both C- and C+ MN. A positive correlation was seen between the frequency of C+ MN and urinary level of MA+PGA (P<0.05) and VPTs (P<0.001). Chromosome-type CAs positively correlated with airborne styrene level and VPTs (P<0.05), whereas chromatid-type CAs correlated with PHEMAs (P<0.05). Workers bearing GSTM1 null genotype showed lowered levels of PHEMAs (P<0.001). The GSTT1 null genotype was associated with increased MNBN frequencies in the exposed workers (P<0.05) and the fast activity EPHX genotype with a moderate decrease in both MNBN and CAs in the controls. Our results suggest that occupational exposure to styrene has genotoxic effects that are potentiated by the GSTT1 gene deletion. These observations may have relevance considering the risk of lymphatic and haematopoietic malignancies tentatively associated with styrene exposure.

Synthesis, Characterization and Fluorescence of Terbium (III) Complexes with Phenylglyoxylic Acid and 2,2-Dipyridine, 1, 10-Phenanthroline, Triphenyl Phosphine Oxide

Three new complexes TbL 3dipy(H 2O) 2, TbL 3phen(H 2O) 2 and TbL 2(TPPO) 2NO 3 were synthesized (L = phenylglyoxylate ion, dipy = 2, 2-dipyridine, phen = 1, 10-phenanthroline, TPPO = Triphenyl phosphine oxide). Elemental analysis, conductivity, IR spectra, and 1HNMR spectra studies were performed. IR spectra indicate that the carboxylate ion of phenylglyoxylate is coordinated to the Tb (III) ion as an unidentate ligand. In 1HNMR, the signals of different hydrogens in phenylglyoxylate ion shift upfield. The excitation and emission spectra of the three solid complexes were recorded at room temperature, in which the optimum excitation wavelengths are 361.0, 359.0 and 367.0 nm for these three complexes, respectively. Four emission bands due to the 5D 4– 7F j(j = 6, 5, 4, 3) transitions were observed for TbL 3dipy(H 2O) 2(489.0, 545.0, 584.0, 620.0 nm) and TbL 3phen(H 2O) 2(490.0, 544.0, 583.0, 620.0 nm). Under the same conditions, only one emission band due to the 5D 4– 7F 5 transition was observed for the complex TbL 2(TP-PO) 2NO 3. The emission intensity of TbL 3dipy(H 2O) 2 is the strongest among the three complexes.

Simultaneous HPLC Determination of Urinary Metabolites of Toluene, Xylenes, and Ethylbenzene; and Its Application to Biological Monitoring of Tunisian Workers Exposure

A simple, sensitive, and reproducible high performance liquid chromatographic procedure is described for the simultaneous determination of urinary metabolites of several aromatic hydrocarbons: mandelic and phenylglyoxylic acids from ethylbenzene; hippuric acid from toluene, and methylhippuric acids from xylenes. The employed mobile phase and the chromatographic conditions allowed relatively low detection limits (0.1 to 0.2 mg/L). The method was tested on 33 workers in the paint industry and on 33 nonoccupationally exposed Tunisian subjects. A significant difference of metabolite concentrations was found between the two groups. In the exposed group, most of the measured levels were lower than the biological exposure indices.

Voltammetric Determination of Phenylglyoxylic Acid in Urine Using Graphite Composite Electrode

A composite electrode prepared from graphite powder and epoxy resin was applied as a working electrode for the determination of phenylglyoxylic acid (one of the metabolites of styrene) in human urine. Cathodic differential pulse stripping voltammetry was used and optimum conditions have been found giving the limit of determination about 5 mg L−1. All results were compared with those obtained using hanging mercury drop electrode. For the confirmation of suggested mechanism of the electrochemical reaction the elimination voltammetry with linear scan was used.

Influence of genetic polymorphisms of styrene-metabolizing enzymes and smoking habits on levels of urinary metabolites after occupational exposure to styrene

Here we evaluate the influence of individual genetic polymorphisms of drug-metabolizing enzymes as well as body mass index (BMI) and lifestyle (smoking, alcohol consumption) on urinary metabolites after occupational exposure to styrene. Seventy-three workers exposed to styrene in a reinforced-plastics workplace were studied. The personal styrene exposure in the air and the urinary styrene metabolites mandelic acid and phenylglyoxylic acid were measured. The subjects’ genetic polymorphisms in the genes that encode the styrene-metabolizing enzymes CYP2E1, CYP2B6, EPHX1, GSTM1, GSTT1 and GSTP1 were determined. Neither genotype nor lifestyle significantly affected urinary metabolites. There was, however, an interaction between the CYP2E1 genotype and smoking. Among non-smokers, urinary styrene metabolites were significantly decreased in subjects with c1/c1 alleles of CYP2E1 as compared with those with the c1/c2 genotype. There was no significant difference in urinary metabolites among smokers. When the combined influence of the CYP2B6 genotype and the predicted activity of EPHX1 were examined, urinary metabolites in subjects with low enzyme activity were lower than in those with medium or high activity after high styrene exposure (≥50 ppm). The results suggest that genetic susceptibility and lifestyle should be considered in biological monitoring of exposure to styrene.

Synthesis of New Chiral Hydroxy Oxazolines and Their Use in the Catalytic Asymmetric Phenyl Transfer to Aldehydes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Bioreduction of phenylglyoxylic acid to R-(−)-mandelic acid by Saccharomyces cerevisiae FD11b

Screening from 40 microorganisms belonging to different taxonomical groups ( Saccharomyces cerevisiae, Lactoballius, Streptococcus faecalis and Candida albicans) was performed to select the strain with high production rate of R-(−)-mandelic acid (R-MA). A sp. strain S. cerevisiae FD11b with high yield and enantiomeric excess (e.e.) and little byproducts was obtained by means of UV-mutation breeding. In the optimal conditions of pH 6.5, 32 °C, anaerobic and glucose supply rate ( F glu) 0.0833 mmol gdw −1 h −1, the strain FD11b showed a high specific MA production rate ( q p = 0.35 mmol gdw −1 h −1) and enantioselectivity (e.e. = 97.1%). The phenylglyoxylic acid (PGA) concentration showed a remarkable effect on the apparent activity of MA dehydrogenase. The specific production rate ( q p) reached the maximum at 30–40 mM of PGA concentrations. At higher concentrations of PGA more than 40 mM, the q p decreased obviously in a linear way. However, the e.e. of R-MA kept about 95–96.5%, when the PGA concentration was below 60 mM, even at the concentration of PGA 80 mM, the e.e. was still higher than 90%. A modified Monod type equation based on a hypothesis of substrate inhibition could fit the experimental data well. The estimated maximum specific production rate ( q pm) and saturation constant ( K s) were 0.431 mmol gdw −1 h −1 and 5.88 mM, respectively.

Preparation of ( S)-mandelic acids by enantioselective degradation of racemates with a new isolate Pseudomonas putida ECU1009

An enantioselective ( R)-mandelate degrading bacterium, Pseudomonas putida ECU1009, was newly isolated from soil. The degradation activity of the bacterial cells was significantly enhanced by supplementing an optimal amount of racemic mandelic acid (0.4%), benzoylformic acid (0.4%), or benzoic acid (0.2%) to the culture medium as the enzyme inducer. Using the resting cells as a biocatalyst, three kinds of ( S)-mandelic acids 1– 3 were prepared with high isolated yields and enantiomeric excesses. Moreover, in a one-pot fermentation–transformation process using 1.25% ( RS)-mandelic acid as the sole carbon/energy source for cultivation of the bacterium, ( S)-mandelic acid 1 was accumulated after 48 h of bioconversion with 46.5% yield and >99% ee.

Synthesis, structure and catalase-like activity of new dicopper(II) complexes with phenylglyoxylate and benzoate ligands

The preparation and characterization of dimeric Cu 2(bpy) 2(phga) 4 (bpy: 2,2′-bipyridine; phgaH: phenylglyoxylic acid) and Cu 2(ba) 4(bpy) 2 (baH: benzoic acid) complexes are described. Crystallographic characterization of the Cu 2(bpy) 2(phga) 4 complex has shown that the coordination geometry around copper(II) ions is distorted square pyramidal (monoclinic, P21/ c, a = 11.7440(4) Å, b = 20.9020(10) Å, c = 9.3980(10) Å, α = 90.00°, β = 93.2240(10)°, γ = 90.00°, V = 2303.3(3) Å 3, Z = 4). These complexes were found to exhibit catalase-like activity.

Selective oxidations by nitrosating agents: Part 2: Oxidations of alcohols and ketones over solid acid catalysts

The reactivity of a nitrosating agent (N 2O 3) on oxidations of alcohols and the methyl group of acetophenone were tested. Active electrophylic surface nitrosonium ions (NO +) was detected on H 2SO 4/SiO 2 catalysts by Raman spectroscopy, suggesting a surface ionic mechanism of oxidation in agreement with the one proposed in acid aqueous solutions. Alcohols are selectively oxidized to ketones and aldehydes in high yield, useful for synthetic applications, at 25 °C in 1,2-dichlorethane and using commercial sulfonated styrene divinyl benzene resins (Amberlyst 15 ®) as catalysts. In addition, nitrous acid ester has been observed as intermediates according to an ionic mechanism by surface NO +. Under the same reaction conditions, acetophenone is selectively oxidized to benzoyl cyanide in high yield and selectivity. The comparison with oxidation carried out in aqueous solution of HNO 2, where benzoyl formic acid was obtained, suggests that the differences in the final products are likely due to the specific stabilizing effect of each solvent. Moreover, the reactivity of the intermediates isolated in aqueous systems implies that α-nitroso-acetophenone is a probable reaction intermediate also in aprotic heterogeneous systems.

Selective oxidations by nitrosating agents: Part 1: Oxidations of ketones in concentrated sulfuric acid

Selective oxidations by nitrous acid in aqueous sulfuric acid towards alkyl side chains of enolizable ketones are reported. The conversion reagents–products in different experimental conditions is explored and the reaction path of the compounds involved as intermediates is tested. Side-chain oxidations are particularly successful for substrates with one site or with equivalent sites of oxidation. Thus, 95% of benzoylformic acid from acetophenone and 60% of 1,2-cyclohexanedione from cyclohexanone are obtained at ∼78 and at ∼40% H 2SO 4, respectively. Kinetic ( k obs) and thermodynamic ( k°) rate constants of acetophenone are also determined, the latter by using the acidity dependence of the rates, the equilibria involving the reacting species and the departure from the ideality of the catalytic acid system. Details of the process between enolizable ketones and electrophilic species in concentrated aqueous acid solutions are discussed.

Electrochemical Characterization of Benzoyl Formic Acid at Glassy Carbon Electrode in Ionic Liquid: [emim]Br

AbstractThe direct electrochemical reduction of benzoyl formic acid was investigated in ionic liquid, 1‐ethyl‐3‐methylimidazolium bromide ([emim]Br), using cyclic voltammetry and chronocoulometry. The diffusion coefficient (D) and the transfer coefficient (α) of benzoyl formic acid in [emim]Br were obtained.

Synthesis of new chiral hydroxy oxazolines and their use in the catalytic asymmetric phenyl transfer to aldehydes

Starting either from benzoylformic acid or ethyl oxamate and enantiopure β-amino alcohols, several chiral α-hydroxy oxazolines have been prepared by short synthetic routes. Subsequently, they have been employed in the catalytic asymmetric phenyl transfer to various aldehydes, using a mixture of triphenylborane and diethylzinc as the phenyl source. The corresponding secondary alcohols were obtained with good enantioselectivities (up to 81% ee) and up to 92% yield.

The dimethyldioxirane-mediated oxidation of phenylethyne

The product pattern found for the dimethyldioxirane-mediated oxidation of phenylethyne strongly depends on the reaction conditions. Dimethyldioxirane generated in situ from caroate (HSO(5)(-)) and acetone in acetonitrile-water furnishes phenylacetic acid as the main product. With solutions of dimethyldioxirane in acetone, mandelic acid and phenylacetic acid are mainly formed. The relative abundances of the two acids depend on the residual water present in the dimethyldioxirane-acetone solution. Application of thoroughly dried solutions of the reagent effects increased formation of mandelic acid. When phenylethyne is oxidized by dimethyldioxirane transferred into tetrachloromethane, to minimize traces of water even further, oligomeric mandelic acid is obtained. The results are rationalized by the initial formation of phenyloxirene, which is known to equilibrate with phenylformylcarbene and benzoylcarbene. Subsequent Wolff rearrangement produces intermediate phenylketene, which can be trapped by water as phenylacetic acid or suffer from further oxidation to the alpha-lactone of mandelic acid. The alpha-lactone can either react with water to yield mandelic acid or, under anhydrous conditions, to yield oligomeric mandelic acid. In addition to mandelic acid and phenylacetic acid phenylglyoxylic acid, benzoic acid and benzaldehyde are observed as reaction products. The formation of phenylglyoxylic acid by transfer of two oxygen atoms to the unrearranged carbon skeleton of phenylethyne followed by oxygen insertion into the aldehydic C-H bond of the intermediately formed phenylglyoxal is discussed. In a second pathway this acid is formed by partial oxidation of mandelic acid. Benzaldehyde and benzoic acid are explained as products of the oxidative degradation of the alpha-lactone by dimethyldioxirane. Under in situ conditions benzoic acid is also formed by caroate initiated oxidative decarboxylation of phenylglyoxylic acid and/or intermediate phenylglyoxal.

Determination of urinary styrene metabolites in the general Italian population by liquid chromatography-tandem mass spectrometry.

To apply mass spectrometry-based techniques for the determination of background levels of metabolites of widespread organic solvents, such as styrene, in unexposed subjects from the general population. The study population consisted of 129 healthy Italian subjects, not occupationally exposed to styrene (67 men; 37% smokers). Urinary levels of mandelic acid (MA) and phenylglyoxylic acid (PGA) were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using LC-MS/MS, we were able to detect the peaks of MA and PGA in 100% of samples. The distribution of styrene metabolites was log-normal, the geometric means of MA and PGA concentrations being 0.443 mg/g creatinine [geometric standard deviation (GSD) 2.34] and 0.107 mg/g creatinine (GSD 3.49), respectively. The reference intervals estimated for MA and PGA were 0.084-2.339 and 0.009-1.238 mg/g creatinine, respectively. The application of highly sensitive and selective mass spectrometry-based analytical techniques could be useful in the definition of reference values for metabolites of organic pollutants and for better assessment of low-level occupational exposure to organic solvents.

Selective oxidations by nitrosating agents in liquid and solid acid catalysts

The oxidative properties of N2O3 and NO+ ion towards methyl or methylene groups of enolizable ketones are tested at 25°C in homogeneous and heterogeneous acid systems. The results in concentrated aqueous sulphuric acid show that reasonable good yields (∼95%) of benzoylformic acid from acetophenone are obtained at selected acidity ranges. A kinetic study for the conversion reagents–products and a thermodynamic treatment of the rates was also attempted by using the acidity dependence of rates, the equilibria of the reacting species and the departure from the ideality of the catalytic acid system. On the replacement of aqueous acid solutions with solid acids, benzoyl cyanide is instead obtained, with high yields and selectivity over catalysts with suitable acidic properties. Additional studies of different ketones and of certain alcohols are also reported.

Ruthenium(II) Complexes Bearing Carboxylato and 2‐Oxocarboxylato Ligands

AbstractThe syntheses of ruthenium(II) acetato and benzoato complexes [Ru(bdmpza)(O2CCH3)(PPh3)] (6) and [Ru(bdmpza)(O2CPh)(PPh3)] (7) [bdmpza = bis(3,5‐dimethylpyrazol‐1‐yl)acetate] are reported. The complexes 6 and 7 are synthesized in high yield from [Ru(bdmpza)Cl(PPh3)2] (1) and thallium acetate (2) or thallium benzoate (3). In a similar substitution reaction a benzoylformate complex [Ru(bdmpza){O2CC(O)Ph}(PPh3)] (8) is obtained from 1 and thallium benzoylformate (4). Reaction of 6 or 7 with benzoylformic acid also yields 8. In analogous reactions several 2‐oxocarboxylato ruthenium(II) complexes [Ru(bdmpza){O2CC(O)R}(PPh3)] (9: R = CH2CH2CO2H, 10: R = Me, 11: R = Et) can be obtained. The low‐spin ruthenium(II) complexes 8 to 11 exhibit a purple or brownish‐red colour caused by MLCT transitions and thus a HOMO−LUMO gap which is almost identical to that of high‐spin 2‐oxoglutarate dependent iron oxygenases. 6 crystallises as a water adduct, 6·H2O and 8 forms an acetonitrile adduct 12. Crystal structures of the water adduct 6·H2O and 8 were obtained. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2004)

Selective oxidations by nitrosating agents in liquid and solid acid catalysts

The oxidative properties of N 2 O 3 and NO + ion towards methyl or methylene groups of enolizable ketones are tested at 25 °C in homogeneous and heterogeneous acid systems. The results in concentrated aqueous sulphuric acid show that reasonable good yields (∼95%) of benzoylformic acid from acetophenone are obtained at selected acidity ranges. A kinetic study for the conversion reagents–products and a thermodynamic treatment of the rates was also attempted by using the acidity dependence of rates, the equilibria of the reacting species and the departure from the ideality of the catalytic acid system. On the replacement of aqueous acid solutions with solid acids, benzoyl cyanide is instead obtained, with high yields and selectivity over catalysts with suitable acidic properties. Additional studies of different ketones and of certain alcohols are also reported.

New data on enantiomeric excess versus conversion during enantioselective hydrogenation of activated ketones on a platinum catalyst

The initial transient period (ITP) was studied in the enantioselective hydrogenation of activated ketones (ethyl pyruvate, pyruvaldehyde dimethyl acetal, methyl benzoyl formate) on Pt-alumina (E4759) catalyst modified by cinchonidine (CD) or dihydrocinchonidine (DHCD) under mild experimental conditions in toluene (hydrogen pressure: 1 bar, temperature: 253–298 K, modifier concentration: 0.001–1 mmol/L). The effects of temperature, modifier concentration, different pretreatments of the catalyst, and structure of the reactants on the relationship of the enantiomeric excess (ee) and conversion were studied. Our results suggest that the ITP is affected not only by impurities/contaminants present in the catalytic system but also by the competitive adsorption of reactants, modifier, and solvent. Consequently it may not be excluded that the ITP can be considered an intrinsic feature of this type of enantioselective hydrogenation reaction.

Cytogenetic markers, DNA single-strand breaks, urinary metabolites, and DNA repair rates in styrene-exposed lamination workers.

The effect of occupational exposure to styrene on frequencies of chromosomal aberrations and binucleated cells with micronuclei and on single-strand break levels in peripheral blood lymphocytes was studied in 86 reinforced plastic workers and 42 control individuals (including 16 maintenance workers with intermittent, low-dose exposure). In these individuals, the irradiation-specific DNA repair rates and the repair rates of 8-oxoguanines were investigated. We assessed the exposure by measuring the concentrations of styrene in air and in blood and of mandelic acid, phenylglyoxylic acid, 4-vinyl phenol conjugates and regioisomeric phenyl hydroxyethyl mercapturic acids in urine. All these parameters correlated with one another. No clear relationship was found between the styrene exposure and the frequencies of chromosomal aberrations. Binucleated cells with micronuclei were moderately related to the parameters of styrene exposure. We found a negative correlation between all exposure parameters and single-strand breaks. The positive correlation between exposure parameters and DNA repair rates suggests that particular DNA repair pathways may be induced by styrene exposure.