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PubMed2002

[Use of column and thin layer chromatography for detection of vanillyl mandelic acid in urine].

The excretion of vanillylmandelic acid was measured by column chromatography of urinary samples on aluminum oxide with subsequent thin-layer chromatography on silica gel. Use of aluminum oxide allowed application of greater urine samples (up to 0.1% of 24-h diuresis) onto chromatographic plates and essentially improved the quality of separation of vanillylmandelic acid from other phenylcarbonic acids by thin-layer chromatography, as well as the specificity and reproducibility of measurements.

Aluminum Chloride↗
PubMed1977

[Thin layer chromatography screening test for semiquantitative detection of 4-hydroxy-3-methoxy mandelic acid (HMMA) in urine without extraction (author's transl)].

A thin layer chromatography (TLC) screening test is described, which allows the semiquantitative determination of HMMA in urine samples. From the collected 24 hour urine a measured sample is applied without extraction to a special TLC plate, which is developed in one dimension. In comparison to a series of graded standard solutions the daily HMMA output can be estimated semiquantitatively. In 102 patients over 18 years of age, suffering from high blood pressure, the daily HMMA output was estimated by both the Pisano method (Pisano, J.J., Crout, J.R. & Abraham, D. (1962), Clin. Chim. Acta 7,285--291) and the TLC method. Coincident results with both methods were obtained in 99 of these cases. The residual 3 cases show pathological results with the Pisano method and results in the normal range or the warning range, respectively, with the TLC method. These cases can probably be classified as false positive results of the Pisano method. The TLC method is recommended as a screening test for estimating the daily HMMA excretion.

Chromatography, Thin Layer↗
PubMed1978

Urinary excretion of aromatic acids in hyperphenylalaninemic states: response to a protein challenge.

A protein challenge (3g/kg) was given to 15 hyperphenylalaninemic patients for 4 days and urinary excretion of aromatic phenylalanine metabolites (e.g. phenylpyruvic acid; mandelic acid; ortho-hydroxy-phenylacetic acid) was studied by quantitative gas chromatographic analysis. Two groups of patients, different in their serum phenylalanine pattern, could be distinguished from the pattern of urinary aromatic acid excretion. In the first group, the aromatic acid excretion declined towards the end of the challenge whereas aromatic acid excretion increased throughout the challenge in the second group. The differences could be ascertained by statistical analysis.

Adolescent↗
PubMed1989

[Method for simultaneous determination of six metabolites of toluene, xylene and ethylbenzene, and its application to exposure monitoring of workers in a printing factory with gravure machines].

For the biological monitoring of exposure to solvent composed of toluene, xylene, and ethylbenzene used in a printing factory with gravure machines, we developed a HPLC method for the simultaneous determination of urinary metabolites of this solvent, i.e. hippuric acid, o-, m-, and p-methylhippuric acid, mandelic acid and phenylglyoxylic acid. Except for phenylglyoxylic acid, urinary concentrations of the metabolites determined by the present method correlated well with the air concentrations of the respective solvent components. Hence the present method is useful in monitoring solvent exposure. In 91 workers of the printing factory and 53 control subjects, we also determined the concentrations of some phenolic metabolites and confirmed that o-cresol is a useful indicator for monitoring toluene exposure.

Benzene Derivatives↗
PubMed1982

High-performance liquid chromatography for the quantitative determination of the urinary metabolites of toluene, xylene, and styrene.

A new high-pressure liquid chromatography (HPLC) method for simultaneous quantitative determination of the urinary metabolites of toluene, m-xylene, and styrene (hippuric acid, m-methylhippuric acid, phenylglyoxylic acid, mandelic acid) is described. The extraction procedure was performed on acidified urines, after addition of 4-hydroxybenzoic acid as internal standard, using a butylchloride/isopropanol mixture and drying 0.5 ml of the organic layer under nitrogen flow. The residue obtained was dissolved in 0.1 ml water/acetonitrile and 5 microliters were injected into an HPLC apparatus equipped with a 0.26 X 25 cm HC ODS SIL X column. Absorbance measures were performed at 225 nm throughout the investigation. All metabolites were clearly separated in a short time (12 min) and the amounts of other urinary compounds affecting the analysis were so small that the measurement of low concentrations of the urinary metabolites could be easily performed. Linear calibration curves were obtained from 0.1 to 3 mg/ml and a correlation coefficient greater than 0.99 was found between concentrations of the standards and areas of the peaks. Statistical analysis confirms that this method, which has a high reproducibility, is simple, reliable, and useful for the biologic monitoring of industrial exposure to aromatic compounds.

Chromatography, High Pressure Liquid↗
PubMed2003

Use of ionic liquids in a lipase-facilitated supported liquid membrane.

A lipase-facilitated transport of 4-phenoxybutyric acid, 3-phenoxypropionic acid, 2-phenylpropionic acid, 2-phenoxybutyric acid, mandelic acid and 2-amino-2-phenylbutyric acid was carried out using a supported liquid membrane based on room temperature ionic liquids. There were marked differences in the permeate fluxes of various organic acids due to the substrate specificity of the lipases. The maximum permeate flux (44 x 10(-2) mmol cm-2 x h) was obtained using 4-phenoxybutyric acid as the substrate and 1-n-butyl-3-methylimidazolium hexafluorophosphate as the liquid membrane phase.

Carboxylic Acids↗
PubMed1998

The stereo inversion of 2-arylpropionic acid non-steroidal anti-inflammatory drugs and structurally related compounds by Verticillium lecanii.

The fungus Verticillium lecanii has previously been shown to be capable of inverting the chirality of ibuprofen and 2-phenylpropionic acid from the (R)-enantiomer to the corresponding (S)-antipode, a phenomenon also observed in mammalian systems including man. An investigation is reported here into the substrate specificity of the enzyme system present in V. lecanii using the following 2-arylpropionic acids: ibuprofen, ketoprofen, indoprofen, suprofen, flurbiprofen and fenoprofen, together with the structurally related compounds 2-phenylbutyric acid, 2-phenoxypropionic acid, mandelic acid, atrolactic acid, etodolac and alpha-methoxyphenylpropionic acid. The results demonstrated that V. lecanii is capable of inverting the chirality of all the 2-arylpropionic acids investigated. All were inverted in the (R) to (S) direction with the exception of ketoprofen, where inversion was observed in the reverse direction. Using the structurally related compounds as substrates, the size of the alkyl substitutent at the alpha-carbon at the methyl group, and the presence of the methyl group at the chiral centre, were found to be critical. These results suggest that V. lecanii could be used as a basis for the production of pure enantiomers of the 2-arylpropionic acids in commercial biotransformations.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Conversion of phenylalanine to benzaldehyde initiated by an aminotransferase in lactobacillus plantarum

The production of benzaldehyde from phenylalanine has been studied in various microorganisms, and several metabolic pathways have been proposed in the literature for the formation of this aromatic flavor compound. In this study, we describe benzaldehyde formation from phenylalanine by using a cell extract of Lactobacillus plantarum. Phenylalanine was initially converted to phenylpyruvic acid by an aminotransferase in the cell extract, and the keto acid was further transformed to benzaldehyde. However, control experiments with boiled cell extract revealed that the subsequent conversion of phenylpyruvic acid was a chemical oxidation step. It was observed that several cations could replace the extract in the conversion of phenylpyruvic acid to benzaldehyde. Addition of Cu(II) ions to phenylpyruvic acid resulted not only in the formation of benzaldehyde, but also in the generation of phenylacetic acid, mandelic acid, and phenylglyoxylic acid. These compounds have been considered intermediates in the biological conversion of phenylalanine. The chemical conversion step of phenylpyruvic acid was dependent on temperature, pH, the availability of cations, and the presence of oxygen.

Journal Article↗
PubMed1981

[Biotransformation of zipeprol (Mirsol) in humans. Gas chromatographic/mass spectrometric studies, using ammonia as a selective reactant gas (author's transl)].

After oral application of Zipeprol (Mirsol) the unchanged drug and nine degradation products were detected in human urine; six of them could be identified. All identified metabolites were detected in the alkaline urine fraction; after acid hydrolysis N-(2-hydroxyethyl)-piperazine was found as an artifact. With respect to the presented results, biotransformation of Zipeprol in man mainly follows three degradation routes: 1. alpha-cleavage leading to metabolite M4; 2. cleavage of the exocyclic N-C-bond of the piperazine ring leading to metabolites M3, M5, M6; 3. benzylic cleavage leading to benzylalcohol (M1); oxidation leading to 2-hydroxy-2-phenylacetic acid (mandelic acid, M2).

Ammonia↗
PubMed1996

[Studies on the evaluation of exposure to industrial chemicals].

Among the biological exposure indices of lead, lead in plasma was the most direct indicator of current exposure. Lead mobilized into plasma as well as in urine could be used as an indicator of the internal dose of lead. The ratio of non-treated to restored activity of delta-aminolevulinic acid dehydratase (ALA-D) was a more specific index than ALA-D activity itself at low levels of lead exposure, excluding the familial or genetic variation in the activity. The methods using HPLC for determining heme intermediate improved the evaluation of the lead effect: delta-aminolevulinic acid in plasma, blood, and urine (ALA-P, ALA-B, and ALA-U), coproporphyrin in urine, and zinc protoporphyrin in blood (ZP). ROC (Receiver operating characteristic) curve analyses indicated that the diagnostic values for lead exposure decreased in the order ALA-D ratio > ALA-D activity = ALA-P > ALA-U = ZP. Pyrimidine 5'-nucleotidase activity or pyrimidine nucleotide concentrations in blood was also useful for the monitoring or diagnosis of lead intoxication. Using the HPLC method with inclusion compounds in the mobile phase, hippuric acid, methylhippuric acids, mandelic acid and phenylglyoxylic acid could be simultaneously determined in the urine of workers exposed to a mixture of toluene, xylenes, and ethylbenzene. The correction of the urinary metabolite concentration for specific gravity or creatinine allowed the more specific evaluation of the solvent exposure. In the biological monitoring of chlorinated hydrocarbons such as trichloroethylene, prolonged excretion of the metabolites resulted in a bias between metabolite concentrations and TWA levels of the solvent in a day. The background levels of 2,5-hexanedione (HD) were affected by acid hydrolysis conditions, age, sex and lipid metabolism. Substances hydrolyzed to HD in urine from non-exposed subjects were different from HD detected in the workers exposed to n-hexane. Urinary concentrations of N-acetyl-S-(N-methylcarbamoyl) cysteine (AMCC) served as an index of the average exposure to N, N-dimethylformamide during several preceding work days and may indicate the internal dose, while N-methylformamide may be an index of daily exposure. A simple and rapid method for the determination of urinary alkoxyacetic acids was recently developed for the biological monitoring of workers exposed to glycolethers and their acetates. Urinary butoxy acetic acid (free plus conjugated ones) could be simply determined by gaschromatography after acid hydrolysis of urine. The urinary acetone or methanol concentration determined by the head space technique was also useful for the biological monitoring of workers exposed to isopropanol and/or acetone, or methanol, respectively. Evaluation of exposure to the solvents described above could be carried out by comparing the urinary metabolite concentrations with reference values and the biological exposure index values which were defined as the urinary metabolite concentration corresponding to the threshold value for each solvent.

1-Propanol↗