[METABOLIC ASPECTS OF PHENYLKETONURIA WITH PARTICULAR ATTENTION TO URINARY ELIMINATION OF SOME PHENOLIC ACIDS].
Explore the source record for details and available documents.
Adolescent↗
SEARCH · Search PubMed
Results for “MANDELIC ACID”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
An improved method for the simultaneous determination of mandelic and phenylglyoxylic acids by gas chromatography.
We present a method that permits the simultaneous analysis of mandelic acid (MA) and phenylglyoxylic acid (PGA) in the urine of workers occupationally exposed to styrene. The method consists of urine extraction in acid medium with chloroform and the subsequent formation of the respective methyl esters. The samples were submitted to gas chromatography using a glass column packed with 10% SP-1000. Recoveries of 66.7% and 95.4% were obtained for MA and PGA, respectively, with limits of quantitation of 0.03 g/L for MA and 0.02 g/L for PGA. The method proved to be precise in terms of both intra-assay and interassay analysis, with coefficients of variation less than 10%.
Chromatography, Gas↗
Comparison of isotopic fractionation in lactic acid and ethanol fermentations.
Pure D(-) and L(+) enantiomers of lactic acid were prepared by fermentation reactions with specific bacteria. In addition, naturally deuterated ethanol was prepared and converted into diastereoisomers using mandelic acid. Various sugars and nutrients were fermented into lactic acid in water having different deuterium contents and ethanol samples were obtained from yeast fermentation of sugars from different botanical origins. The methine and methylene groups in lactic acid and ethanol respectively show similar deuterium contents which are related to that found in the fermentation water. However, the methyl groups of both molecules are significantly different whatever the botanical origin of the carbon source in the fermentation medium.
Biotransformation↗
Participation of a proton-cotransporter, MCT1, in the intestinal transport of monocarboxylic acids.
A molecular mechanism for the intestinal monocarboxylic acid transport was characterized by using a proton/monocarboxylate transporter, MCT1, in Chinese hamster ovary (CHO) cells, first found by Garcia et al. (Cell, 76, 865-873, 1994). Northern blotting analysis showed that MCT1-isomers exist in the rat and rabbit intestinal enterocytes and Caco-2 cells. The expression of [14C]lactic acid uptake by Xenopus laevis oocytes injected with rabbit intestinal mRNA was reduced by hybridizing the mRNA with a MCT1 cDNA of CHO cells before microinjection used as the antisense DNA. [14C]Lactic acid uptake by CHO cells was pH dependent, saturable, stereospecific, and reduced in the presence of acetic acid, benzoic acid, S- and R-ibuprofen, S- and R-mandelic acid, nicotinic acid, pravastatin, propionic acid and valproic acid. In addition, several monocarboxylic acids were transported in pH-dependent and saturable manners. These results suggest that the intestinal MCT1-related protein contributes to a carrier-mediated absorption for organic weak acid compounds.
Animals↗
The time course of mandelic and phenylglyoxylic acid excretion in workers exposed to styrene under model conditions.
Urinary excretion of mandelic and phenylglyoxylic acids by two technicians building glass-reinforced plastic boats has been measured over a 7-day period. Peak excretion of both metabolites occurred several hours after the end of exposure. There was little relationship between urinary mandelic acid concentrations measured at the end of shift and the maximum excretion observed in samples collected after this time. It is suggested that sampling strategies devised to monitor workers exposed to styrene should reflect maximum excretion rates of urinary mandelic acid.
Environmental Exposure↗
Capillary gas chromatographic method for mandelic and phenylglyoxylic acids in urine.
In support of an occupational investigation of styrene exposure, a capillary gas chromatographic method was developed for the quantitation of the styrene metabolites mandelic and phenylglyoxylic acids. The method was based on that of Guillemin and Bauer, in which phenylglyoxylic acid was converted to mandelic acid by reduction before instrumental analysis. The earlier method had to be modified for use with capillary columns; the resulting method was sensitive, selective and reproducible. The detection limit was approximately 0.001 mg/ml urine. Approximately less than 5% relative precision was achieved in the range of 0.05-2 mg/ml urine. Mandelic acid was resolved from other components of urine and from by-products of derivatization.
Air Pollutants, Occupational↗
An enzyme library approach to biocatalysis: development of nitrilases for enantioselective production of carboxylic acid derivatives.
The discovery, from Nature, of a large and diverse set of nitrilases is reported. The utility of this nitrilase library for identifying enzymes that catalyze efficient production of valuable hydroxy carboxylic acid derivatives is demonstrated. Unprecedented enantioselectivity and substrate scope are highlighted for three newly discovered and distinct nitrilases. For example, a wide array of (R)-mandelic acid derivatives and analogues were produced with high rates, yields, and enantiomeric excesses (95-99% ee). We also have found nitrilases that provide direct access to (S)-phenyllactic acid and other aryllactic acid derivatives, again with high yields and enantioselectivities. Finally, different nitrilases have been discovered that catalyze enantiotopic hydrolysis of 3-hydroxyglutaronitrile to afford either enantiomer of 4-cyano-3-hydroxybutyric acid with high enantiomeric excesses (>95% ee). The first enzymes are reported that effect this transformation to furnish the (R)-4-cyano-3-hydroxybutyric acid which is a precursor to the blockbuster drug Lipitor.
Aminohydrolases↗
An assay for mandelate racemase using high-performance liquid chromatography.
Mandelate racemase (EC 5.1.2.2) catalyzes the interconversion of the two stereoisomers of mandelic acid. A fixed-time assay for the quantification of mandelate racemase activity has been developed. The assay involves enzymatic conversion of R-mandelate to S-mandelate (or the reverse reaction) followed by separation and detection of the substrate and product using isocratic reversed-phase high-performance liquid chromatography on a Sumichiral OA-6100 column and absorbance detection. This method offers an economical and efficient alternative to the existing circular dichroism-based and coupled assays.
Chromatography, High Pressure Liquid↗
[Prognosis and determination of the threshold of chronic effect of carbon disulfide and styrene].
Two series of studies were carried out: I--in workers exposed to four different mean annual CS2 concentrations--6 mg/m3; 12 mg/m3; 51 mg/m3 and 247 mg/m3 and II series-in workers exposed to three styrene concentrations--I mg/m3; 40 mg/m3 and 400 mg/m3. The results obtained in series I show the role of the primary toxic effect (inhibition of oxidases with mixed function) and of the adaptation reactions to it with a view to accurate specifying the threshold of chronic CS2 effect. The mathematical expression of the correlation between styrene concentration in air and blood, of phenyl-glyoxylic and mandelic acid in the urine of the exposed subjects enables the prognosis that the threshold of the noxious styrene effect is within the range of 150 mg/m3 to 250 mg/m3. A reduction on CS2 MAC is proposed--from 10 mg/m3 to I mg/m3 and the correction of styrene MAC--from 5 mg/m3 to 30-50 mg/m3.
Adult↗
Exceptional chiral recognition of racemic carboxylic acids by calix[4]arenes bearing optically pure alpha,beta-amino alcohol groups.
Calixarenes bearing optically pure alpha,beta-amino alcohol groups at their lower rim exhibit exceptional and efficient chiral recognition ability in discrimination of racemic mandelic acid, 2,3-dibenzoyltartaric acid and 2-hydroxy-3-methylbutyric acid. [structure: see text]
Amino Alcohols↗
[Coumarin-containing chiral discriminating agents. VII. New crystalline 1H-NMR enantiomeric excess determination reagent for alcohols and amines, (R)-(-)- and (S)-(+)-O-coumarinylmandelic acids].
The Mitsunobu reaction of commercial 4-hydroxycoumarin with both (R)-(-)- and (S)-(+)-tert-butyl mandelates derived from commercial enantiopure mandelic acids furnished (S)-(+)- and (R)-(-)-tert-butyl O-coumarinylmandelates which were, then, treated with trifluoroacetic acid to give novel crystalline optically pure (S)-(+)- and (R)-(-)-O-coumarinylmandelic acids [SCMOH and RCMOH], respectively in good overall yields. Diastereotopic nonequivalence 1H-NMR examination of the resultant esters and amides without any racemization or kinetic resolution by way of a Steglich's procedure (a DCC-DMAP method) has proved each acid to be a useful, efficient and reliable chiral derivatizing agent for the enantiomeric excess determination of chiral alcohols and amines.
Alcohols↗
Metabolism in rats of several carboxylic acid derivatives containing the 3,4-methylenedioxyphenyl group.
The metabolism of the 3,4-methylenedioxy derivatives of mandelic acid (1), phenylacetic acid (2), benzoic acid (3), 3-phenylpropionic acid (4) and cinnamic acid (5) was studied in rats. Following intragastric dosage (1 mmol/kg) the compounds and their metabolites were excreted in the urine within 24 hrs. Recoveries of roughly 85% were obtained. Except for compound (1) which was excreted to a large extent unchanged, glycine conjugates were the major urinary metabolites. Compound (2) formed 3,4-methylenedioxyphenylacetylglycine whereas compounds (3), (4) and (5) were converted to 3,4-methylenedioxybenzoylglycine. No evidence was found with any of the compounds for demethylenation and subsequent excretion of catecholic metabolites.
Animals↗
Biological indicators of exposure in styrene polymerization workers. Styrene in blood and adipose tissue and mandelic and phenylglyoxylic acids in urine.
The concentrations of mandelic and phenylglyoxylic acids, urinary metabolites of styrene, and styrene in blood were determined for 491 styrene polymerization workers. Styrene in subcutaneous fat was determined for 25 workers. The levels of styrene exposure were estimated to be less than 10 ppm, and urinary metabolite and blood styrene concentrations indicated that significant recent exposure (within 4 h) had occurred among workers in areas of styrene polymerization and styrene monomer production. Styrene analysis of subcutaneous fat suggested that the monomer may have been present for as long as 3 d after exposure, a time when urinary metabolites and blood styrene were almost invariably undetectable. All three biological parameters were correlated with recency of exposure and estimated intensity of exposure within job categories.
Adipose Tissue↗
Enantioselective fluorescent recognition of a soluble "supported" chiral acid: toward a new method for chiral catalyst screening.
The long-chain aliphatic-group-substituted mandelic acid 3c, which is soluble only in THF and insoluble in water and many polar/nonpolar organic solvents, has been synthesized. This unique solubility allows 3c to be easily isolated from reaction mixtures and makes it potentially useful for catalyst screening. The fluorescent sensors (R)- and (S)-1 can be used to determine the ees of various samples of 3c generated from a series of catalyst screening experiments. The fluorescence measurements correlate well with the conventional HPLC-chiral column analysis. This work demonstrates that the enantioselective fluorescent recognition of organic substrates can lead to a fundamentally new method for chiral catalyst screening. [reaction: see text]
Catalysis↗
URINARY EXCRETION OF METABOLITES OF CATECHOLAMINES IN NORMAL INDIVIDUALS AND HYPERTENSIVE PATIENTS.
The 24-hour urinary output of 3-methoxy-4-hydroxy mandelic acid (V.M.A.) has been determined in 20 normal adults, 150 hypertensive patients, and four cases of phaeochromocytoma. In this last group estimations of urinary catecholamines and total urinary methylated amines were also performed and the overall results have been compared with the urinary excretory pattern of catecholamines and their metabolites following the injection of radioactive adrenaline and noradrenaline.
Adult↗
Influence of (hydroxy)alkylamino substituents on enantioseparation ability of single-isomer amino-beta-cyclodextrin derivatives in chiral capillary electrophoresis.
A family of single-isomer amino-beta-cyclodextrin (amino-beta-CD) derivatives containing an amino or (hydroxy)alkylamino group in one of the primary positions has been synthesized. The steric effect and hydrogen bond forming ability of the different substituents on enantioseparation of acidic enantiomers has been studied by capillary electrophoresis (CE). Three enantiomeric model compounds (mandelic acid, cis-permethrinic acid, and cis-deltamethrinic acid) having significantly different apparent complex stability constants with beta-CD were applied in the experiments. Dependence of separation selectivity, resolution as well as mobility difference on chiral selector concentration (0.1-20 mM, pH 6.0) was investigated. Each amino-beta-CD showed higher enantioselectivity than the native beta-CD. One hydroxyalkyl group attached to the primary amino N-atom significantly increased both the enantioselectivity and the resolution compared to the primary amino-beta-CD, while two hydroxyalkyl moieties decreased them due to the predominance of steric hindrance. The value of the apparent complex stability constants obtained suited well the mobility difference model (by Wren). On the other hand, the optimum selector concentrations calculated according to the model were slightly lower than the experienced concentrations giving the maximum enantioresolution of enantiomers.
Electrophoresis, Capillary↗
Statistical evaluation of a new method to detect carriers of phenylketonuria.
40 positive heterozygotes and 43 controls were loaded with 200 mg phenylalanine per kilogram body weight. The aromatic acids excreted 2 hrs after the loading were quantified by gaschromatography. The amounts of mandelic acid (MA), 2-hydroxyphenylacetic acid (2HOPAA) and phenylpyruvic acid (PPA) were used for a discriminatory analysis. The MA concentration alone gives a better discrimination than the statistical analysis.
Evaluation Studies as Topic↗
Systematic examination of the signal area precision of a single quadrupole enhanced low mass option (ELMO) MSQ [corrected] mass spectrometer.
To examine the precision of the signal area response of an enhanced low mass option (ELMO) MSQmass spectrometer, operated in the negative electrospray ionization (ESI) mode, extended tests were performed, using flow injection analysis mass spectrometry (FIA-MS). Analytes were nitrate, nitrite, malonic acid, and D,L-mandelic acid. Composition and concentration of injected samples, application of an ASRS anion suppressor and of the cone wash unit, methanol addition to the FIA flow medium, and the voltage bias of the hexapole transfer lens were test variables. Individual test cycles comprised up to 90 injections, processed within 20 h. With a few exceptions the signal response tended to decline over time leading to a loss of more than 80% of the initial signal area in extreme cases. A hexapole radio-frequency (RF) voltage bias of -0.3 V led to an overall low detector response and to high losses of sensitivity over time. Other correlations between the insufficient signal reproducibility and FIA-MS operating conditions could not be established. The test scheme gave hints how to localize the cause of the mass spectrometer malfunction. The repetition of the test scheme after remedying the detected electronic default demonstrated that relative standard deviations less than 5% can be achieved for a sequence of 30 injections if methanol is added to the FIA flow medium and if a suppressor is used. Based on these findings a recommendation is formulated to supplement current test schemes for instrument performance verification by a detector response precision criterion.
Journal Article↗