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PubMed1977

Gas chromatographic determination of pemoline in biological fluids using electron capture detection.

A simple and sensitive gas chromatographic (GC) method for the determination of pemoline in biological fluids, utilizing electron capture detection is described. Plasma samples with a pemoline analog added as internal standard were deproteinized with sulfosalicylic acid, and the supernatants were heated at 80 degrees. The pemoline-dione formed was extracted with benzene, and the extract was analyzed on a gas chromatograph equipped with a tritium foil electron capture detector. Poly A-103 (3%) on Gas-Chrom Q (100-120 mesh) packed in a 3-ft. silanized glass column was used as the stationary phase, with nitrogen serving as carrier gass. Under the same GC conditions, benzene extracts of pemoline-dione from acid-hydrolyzed urine samples were analyzed. Us-ng 1 ml of plasma or urine, the lower limit for the assay was about 0.1 microgram/ml. The method is accurate and reproducible, with a relative standard deviation with +/-4%. Mandelic acid (a metabolite of pemoline) does not interfere with the assay.

Animals↗
PubMed2004

Hydrolysis of nitriles using an immobilized nitrilase: applications to the synthesis of methionine hydroxy analogue derivatives.

Mild and selective hydrolysis of a large range of nitriles leading to carboxylic acids was achieved under neutral conditions by an immobilized and genetically modified enzyme preparation from Alcaligenes faecalis ATCC8750. This immobilized nitrilase has been shown to be an effective catalyst for the stereoselective hydrolysis of mandelonitrile 1a to R-(-)-mandelic acid 1c. This method is particularly useful for the production of hydroxy analogues of methionine derivatives 2c-4c that could have an interest in cattle feeding and for the transformation of compounds containing other acid- or base-sensitive groups 3a-10a. A series of aliphatic dinitriles 11a-15a was hydrolyzed to the corresponding cyano acids. The suitability of the immobilized catalyst as a robust and versatile biocatalyst is discussed, and models to account for the stereoselectivity of the enzymic hydrolysis have been proposed.

Alcaligenes faecalis↗
PubMed1994

Evidence for biosynthesis and catabolism of monoamines in the sea pansy Renilla koellikeri (Cnidaria).

The biosynthesis of catecholamines and indoleamines was investigated in the sea pansy Renilla koellikeri by radiochemical screening of tissue samples exposed in vivo to labelled amino acid precursors and analysed by high-performance liquid chromatography coupled with electrochemical detection. Incubation of sea pansy tissues in [3H]tyrosine resulted in substantial accumulation of radioactivity recovered in chromatograms coeluting with tyrosine and 4-hydroxy-3-methoxy mandelic acid and, to a lesser extent, with 3,4-dihydroxy-phenylalanine, dopamine, norepinephrine, epinephrine, normetanephrine and 3,4-dihydroxyphenyl acetic acid. The catecholamine synthesis inhibitor alpha-methyl-p-tyrosine effectively reduced several of these [3H]tyrosine by-products formed as well as endogenous stores of these amines. Incubations in [3H]tryptophan resulted in large amounts of radioactivity associated with liquid chromatographic peaks coeluting with tryptophan and 5-hydroxytryptophan and lesser amounts with 5-hydroxytryptamine, N-acetyl-5-hydroxytryptamine and 5-hydroxy-3-indole acetic acid. The indoleamine synthesis inhibitor p-chlorophenylalanine reduced the amounts of products formed and depleted stores of the endogenous indoleamines. Enzyme activities which appear to involve tyrosine hydroxylase (EC 1. 12. 16. 2), tryptophan hydroxylase (EC 1. 14. 16. 4) and phenylethanolamine N-methyltransferase (EC 2. 1. 1. 28) were also detected in rachidial tissues by HPLC analysis of reaction products (hydroxylases) and by a radioenzymatic assay (methyltransferase). The sea pansy being a representative of the earliest invertebrates possessing a nervous system, these results support the hypothesis that vertebrate-like enzymatic pathways for the biosynthesis and degradation of monoamine neurotransmitters were conserved throughout evolution.

Animals↗
PubMed1991

[Urinary excretion of 3-methoxy-4-hydroxymandelic acid, 17-hydroxycorticosteroids and 17-ketosteroids in workers producing iron-manganese alloys].

Excretion of suprarenal hormones' metabolites was examined in workers producing ferro-manganese alloys. The subjects were exposed to manganese, iron , chromium compounds, thermal radiation, high temperature and noise. In comparison to the control group, those examined workers had increased excretion of 3-methoxy-4-hydroxy-mandelic acid and 17-hydroxycorticosteroids. It can be assumed that this increase results from organism's physiological adaptation to negative environmental and working conditions.

17-Hydroxycorticosteroids↗
PubMed1998

Clinical efficacy of a chlorous acid preoperative skin antiseptic.

BACKGROUND: Among the ways to reduce the incidence of iatrogenic infectious disease is the use of efficacious preoperative antiseptics. Iodophors and chlorhexidines, the chief presurgical disinfectants today, have various problems with practicality. A new preoperative skin antiseptic has been developed (Alcide Corporation, Redmond, Wash) that involves the mixture of a 0.1% sodium chlorite formulation and an activating preparation of 0.5% mandelic acid to produce chlorous acid and other antimicrobial degradation products. METHODS: Under clinical conditions, the antimicrobial effectiveness of this blended preparation was compared with a chlorhexidine gluconate scrub solution. Using a Latin-square randomization scheme, we treated 2 contralateral abdominal sites and 2 contralateral inguinal sites of healthy male and female volunteers with these antiseptics or the controls of vehicle or activator alone. Microorganisms were harvested and quantified by a standard cylinder-scrub technique. RESULTS: Of 85 volunteers (170 possible sites per test region) screened to meet the USA Food and Drug Administration baseline criteria on population densities of normal flora, 61 abnormal sites and 107 inguinal sites provided suitable data. Against chlorhexidine, the chlorous acid presurgical skin preparation produced superior but statistically equivalent reductions (P > .05) of each volunteer's normal flora at 10 minutes, 30 minutes, and 6 hours after treatment. As many as 4 log reductions were achieved, and activity persisted as long as 6 hours. Compared with chlorhexidine, the chlorous acid product has the practical advantages of a shorter scrub time, less foam, air drying (instead of wiping), and no perceivable residue. CONCLUSIONS: An activated chlorous acid product statistically matched the performance of chlorhexidine gluconate in reducing populations of resident flora on treated skin sites. With an easier and shorter application procedure and strong, long-term antimicrobial activity, the new halogenated antiseptic seems to be a useful and possible efficacious preoperative skin disinfectant.

Adolescent↗
PubMed1977

Analysis of homatropine methylbromide dosage forms.

A stability-indicating method of analysis of homatropine methylbromide in pharmaceutical formulations was developed. This method is based on the formation of a picric acid-quaternary ammonium complex, which is adsorbed on acid-washed diatomaceous earth in alkaline media followed by on-column chloroform extraction. The picrate complex is measured spectrophotometrically at 365 nm. The method was selective for homatropine methylbromide in that there was no interference from its major hydrolytic decomposition products, tropinium methylbromide and mandelic acid.

Methods↗
PubMed2003

Use of short-end injection capillary packed with a glycopeptide antibiotic stationary phase in electrochromatography and capillary liquid chromatography for the enantiomeric separation of hydroxy acids.

A new chiral stationary phase (CSP) was prepared by reacting MDL 63,246 (Hepta-Tyr), a glycopeptide antibiotic belonging to the teicoplanin family, with 5-microm diol-silica particles. The CSP mixed with 5-microm amino silica particles (3:1) was packed into 75-microm fused-silica capillaries for only 6.6 cm and used for electrochromatographic experiments analyzing several hydroxy acid enantiomers. A reversed electroosmotic flow carried both analytes and mobile phase towards the anode in a short time (1-3 min), being baseline resolved all the studied analytes. In order to achieve the fastest enantiomeric resolution of the studied hydroxy acids, the effect of several experimental parameters such as mobile phase composition (organic modifier type and concentration, pH of the buffer and ionic strength), capillary temperature and applied voltage on enantioresolution factor, retention time, enantioselectivity were evaluated. The packed capillary column allowed the separation of mandelic acid enantiomers in less than 72 s with resolution factor Rs=2.18 applying a voltage of 30 kV and eluting with a mobile phase composed by 50 mM ammonium acetate (pH 6)-water-acetonitrile (1:4:5, v/v). The CSP was also tested in the capillary liquid chromatography mode resolving all the studied enantiomers applying 12 bar pressure to the mobile phase [50 mM ammonium acetate (pH 6)-water-methanol-acetonitrile, 1:4:2:3, v/v)], however, relatively long analysis times were observed (12-20 min).

Acids↗
PubMed1998

[Effects of carbon disulfide on neurotransmitter and its metabolites in rats].

OBJECTIVE: In order to study the mechanism of neurotoxic effects of carbon disulfide (CS2) on animal behavior. METHODS: Changes in monoamine transmitter, amino acid transmitter and their metabolites in brain tissues were observed in rats exposed to CS2 at levels of 0, 1,200 and 2,400 mg/m3 respectively, for two months, with high performance liquid chromatography. RESULTS: Indicated that exposure to CS2 could cause decrease in 3-methoxy-4-hydroxy mandelic acid (VMA), increase in 3,4-dioxybenzoic acid, a metabolite of dopamine, and high vanillic acid in rat straitum, decrease in excitatory amino acids and their metabolites (glutamine, aspartic acid and asparagine), with a certain relationship between contents of VMA, aspartic acid and asparagine and changes in neurobehavior. CONCLUSION: Disturbance of neurotransmitter metabolism plays an important role in neurotoxic effects of CS2.

Animals↗
PubMed1996

Determination of the Absolute Configuration of Amines and alpha-Amino Acids by (1)H NMR of (R)-O-Aryllactic Acid Amides.

(R)-O-Aryllactic acid (ROAL) amides derived from alpha-chiral primary amines and alpha-amino acid esters show different chemical shifts in (1)H NMR spectroscopy (300 MHz) depending on their configuration. Molecular mechanics, semiempirical calculations, and (1)H NMR studies suggest that, in solution, these amides prefer an ap-Z conformation with the C(alpha)OAr and C=O groups close to anti-periplanar as in the case of mandelic acid amides. The proposed conformational preference is different from that of the ROAL esters (C(alpha)H and C=O groups in a syn-periplanar conformation). The conformational model for ROAL amides allows the absolute configuration assignment of primary amines and alpha-amino acid esters according to the relative position of the aryl group and the substituents on the amine moiety, and also their enantiomeric composition.

Journal Article↗
PubMed1989

Simultaneous high-performance liquid chromatographic determination of catecholamine-related compounds by post-column derivatization involving coulometric oxidation followed by fluorescence reaction.

A highly selective and sensitive high-performance liquid chromatographic method for the determination of catecholamines (norepinephrine, epinephrine and dopamine) and related compounds (L-DOPA, normetanephrine, metanephrine, 3-methoxytyramine, 3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, homovanillic acid, vanillylmandelic acid, 3,4-dihydroxyphenylethylene glycol, 4-hydroxy-3-methoxyphenylethylene glycol and 4-hydroxy-3-methoxyphenylethanol) with a post-column technique involving coulometric oxidation followed by fluorescence derivatization is described. These compounds, 3,4-dihydroxybenzylamine and ferulic acid are separated within 35 min by ion-pair reversed-phase chromatography using acidic buffers (pH 3.1) with methanol-acetonitrile (3:2, v/v) gradient elution, and then oxidized by a commercial coulometric detector to the corresponding o-quinones, which are converted into fluorescent derivatives by reaction with 1,2-diphenylethylenediamine. The detection limits (signal-to-noise ratio = 3) on-column are 1.5-4 pmol for the two mandelic acids, 600 fmol for L-DOPA and 20-70 fmol for the others.

Catecholamines↗
PubMed1996

Application of a single-compartment model for estimation of styrene uptake from measurements of urinary excretion of mandelic and phenylglyoxylic acids after occupational exposure.

In biological monitoring of styrene, the exposure is usually related to the urinary concentration of mandelic (MA) and/or phenylglyoxylic (PGA) acids in a urine sample taken after the workshift or on following morning. To study this relationship further, a single-compartment mathematical model was developed by which measured occupational repetitive uptake of styrene during a working day was related to measured excretion rates of the urinary metabolites. The model was used in practice to calculate the unknown uptake (dose) from MA and PGA excretion analyzed in urine samples. For comparison, a styrene limit dose was calculated from the exposure limit. Analytical results of samples from plastic boat builders were compared with the limit values.

Chemical Industry↗
PubMed2006

Synthesis and configurational assignment of the amino alcohol in the eastern fragment of the GE2270 antibiotics by regio- and stereoselective addition of 2-metalated 4-bromothiazoles to alpha-chiral electrophiles.

A synthesis of the eastern fragment of the thiazole peptide GE2270 A (1) has been developed. The synthetic approach relies on the regioselective functionalization of 2,4-dibromothiazole (5) via metalation and nucleophilic addition (at C2) or palladium-mediated cross-coupling (at C2 or C4). The stereochemistry at the N-bearing stereocenter was established by coupling of 2-metalated 4-bromothiazoles (4) to enantiomerically pure mandelic acid derivatives. Both the erythro (2) and threo (3) configurated amino alcohols were prepared with high diastereoselectivities depending on the electrophile employed. More specifically, the threo-configurated (S,R)-4-bromothiazolyl beta-amino alcohol 6 was synthesized from O-TBS protected (R)-mandelonitrile in 62% yield. Its N-PMB protected (R,S)-enantiomer 20 was obtained from O-TBS protected (S)-mandelic aldehyde in 67% yield. The erythro-configurated (S,S)-4-bromothiazolyl beta-amino alcohol 29 was prepared from O-TBS protected (S)-ethyl mandelate in four steps and 33% overall yield. The bithiazole moiety in the desired products 2 and 3 was finally established by the regioselective Negishi coupling of 2,4-dibromothiazole (5) and the 4-zincated, N-Boc protected thiazole derivatives of the diastereomeric 4-bromothiazolyl beta-amino alcohols 6 and 29.

Amino Alcohols↗
PubMed1978

Biological monitoring of exposure to styrene by analysis of combined urinary mandelic and phenylglyoxylic acids.

Human volunteers were exposed in an experimental chamber to styrene (4 or 8 hours at 40 to 200 ppm) in order to obtain a quantitative relationship between exposure and urinary elimination of the metabolites mandelic and phenylglyoxylic acids (MA and PGA). For the analysis of PGA a new GC-method was used, based on reductive transformation of the relatively instable PGA into MA, which is stable enough for shipping and handling until final processing. The analysis of the post-exposure elimination shows that spot urine sampled in the morning after exposure and analysed for the sum of MA and PGA is the most reliable index for reflecing a preceding exposure to styrene.

Adult↗
PubMed1976

Serotonin, noradrenaline, dopamine metabolites in transcendental meditation-technique.

The highly significant increase of 5-HIAA (5-hydroxyindole-3-acetic acid) in Transcendental Meditation technique suggests systemic serotonin as "rest and fulfillment hormone" of deactivation-relaxation. Furthermore 5-HT (5-hydroxytryptamine, serotonin) is considered to be the EC-cell (enterochromaffine-cell) hormone requested by Fujita and Kobayashi and its role for EEG synchronisation via area postrema chemoreceptor as anti arousal agent is being discussed. The significant decrease of the catecholamine metabolite VMA (vanillic-mandelic acid) in meditators, that is associated with a reciprocal increase of 5-HIAA supports as a feedback necessity the "rest and fulfillment response" versus "fight and flight". As the adreno medullary tissue serves for hormonal reinforcement of orthosympathetic activity, the Enterochromaffine Cell System (having taken the form of distinct organs in some species as octopus and discoglossus) is suggested to serve via serotonin for humoral reinforcement of parasympathetic activity in deep relaxation.

Adult↗
PubMed1989

Measurement of catecholamines, their precursor and metabolites in human urine and plasma by solid-phase extraction followed by high-performance liquid chromatography with fluorescence derivatization.

A high-performance liquid chromatographic method is described for the determination in human urine and plasma of catecholamines, their precursor and metabolites [amino compounds (norepinephrine, epinephrine, dopamine, normetanephrine, metanephrine, 3-methoxytyramine and L-DOPA), acidic compounds (3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylacetic acid, vanillylmandelic acid and homovanillic acid) and alcoholic compounds (3,4-dihydroxyphenylethyleneglycol and 4-hydroxy-3-methoxyphenylethyleneglycol)]. Urine (0.5 ml) containing 3,4-dihydroxybenzylamine and 4-hydroxy-3-methoxycinnamic acid (internal standards) is deproteinized with perchloric acid, and the resulting solution is fractionated by solid-phase extraction on a strong cation-exchange resin cartridge (Toyopak IC-SP S) into two fractions (amine fraction and acid-alcohol fraction), which include 3,4-dihydroxybenzylamine and 4-hydroxy-3-methoxycinnamic acid, respectively. Plasma (0.7 ml) is deproteinized in the presence of 3,4-dihydroxybenzylamine (internal standard) in the same manner, and the resulting solution is directly used as an acid-alcohol fraction, while an amine fraction is obtained as for urine. Each fraction is subjected to the previously established ion-pair reversed-phase chromatography with post-column derivatization involving coulometric oxidation followed by fluorescence reaction with 1,2-diphenylethylenediamine. The detection limits, at a signal-to-noise ratio of 5, of the compounds measured in urine are 300 pmol/ml for the two mandelic acids, 2-7 pmol/ml for the other acidic and alcoholic compounds, 12 pmol/ml for L-DOPA and 0.6-2 pmol/ml for the other amino compounds; the corresponding values for plasma samples are 80, 0.5-3, 10 and 0.6-3 pmol/ml, respectively.

Catecholamines↗
PubMed2002

Kinetics and thermodynamics of mandelate racemase catalysis.

Mandelate racemase (EC 5.1.2.2) from Pseudomonas putida catalyzes the interconversion of the two enantiomers of mandelic acid with remarkable proficiency, producing a rate enhancement exceeding 15 orders of magnitude. The rates of the forward and reverse reactions catalyzed by the wild-type enzyme and by a sluggish mutant (N197A) have been studied in the absence and presence of several viscosogenic agents. A partial dependence on relative solvent viscosity was observed for values of kcat and kcat/Km for the wild-type enzyme in sucrose-containing solutions. The value of kcat for the sluggish mutant was unaffected by varying solvent viscosity. However, sucrose did have a slight activating effect on mutant enzyme efficiency. In the presence of the polymeric viscosogens poly(ethylene glycol) and Ficoll, no effect on kcat or kcat/Km for the wild-type enzyme was observed. These results are consistent with both substrate binding and product dissociation being partially rate-determining in both directions. The viscosity variation method was used to estimate the rate constants comprising the steady-state expressions for kcat and kcat/Km. The rate constant for the conversion of bound (R)-mandelate to bound (S)-mandelate (k2) was found to be 889 +/- 40 s(-1) compared with a value of 654 +/- 58 s(-1) for kcat in the same direction. From the temperature dependence of Km (shown to equal K(S)), k2, and the rate constant for the uncatalyzed reaction [Bearne, S. L., and Wolfenden, R. (1997) Biochemistry 36, 1646-1656], we estimated the enthalpic and entropic changes associated with substrate binding (DeltaH = -8.9 +/- 0.8 kcal/mol, TDeltaS = -4.8 +/- 0.8 kcal/mol), the activation barrier for conversion of bound substrate to bound product (DeltaH# = +15.4 +/- 0.4 kcal/mol, TDeltaS# = +2.0 +/- 0.1 kcal/mol), and transition state stabilization (DeltaH(tx) = -22.9 +/- 0.8 kcal/mol, TDeltaS(tx) = +1.8 +/- 0.8 kcal/mol) during mandelate racemase-catalyzed racemization of (R)-mandelate at 25 degrees C. Although the high proficiency of mandelate racemase is achieved principally by enthalpic reduction, there is also a favorable and significant entropic contribution.

Amino Acid Sequence↗