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PubMed1985

Serotyping of and hippurate hydrolysis by Campylobacter jejuni isolates from human patients, poultry and pigs in the Netherlands.

Three hundred strains of Campylobacter jejuni, isolated from human patients, poultry and pigs were serotyped according to the Penner-Lauwers system and furthermore tested for hippurate hydrolysis. Serotyping showed a close relationship between human and chicken strains, whereas there was little relationship between human and pig strains. A similar conclusion was drawn from the results of the hippurate hydrolysis test: 86% of human and 94% of poultry strains were positive, whereas 91% of pig strains were negative. These data confirm the conclusions from epidemiological investigations, according to which poultry is a major source of human campylobacteriosis, while pigs are rarely so.

Animals↗
PubMed1993

Effects of smoking and drinking on excretion of hippuric acid among toluene-exposed workers.

In order to investigate possible effects of smoking and drinking on the metabolism of toluene in occupational settings, 206 toluene-exposed men (mean age: 31.4 years) in shoemaking, painting, or surface-coating workshops together with 246 nonexposed control men (36.8 years) were studied for the time-weighted average intensities of exposure to toluene, hippuric acid concentration in shift-end urine samples, and the two social habits of smoking and drinking. The mean daily consumptions of cigarettes and ethanol were about 20 pieces and 10 g among smokers and drinkers, respectively. The geometric mean toluene concentration among the exposed subjects was about 20 ppm, with a maximum of 521 ppm. Regression analysis after classification of the subjects by smoking and drinking clearly demonstrated that the two social habits, when combined, markedly reduce the hippuric acid level in the urine of workers exposed to toluene. There was a significant association between smoking and drinking habits, which hindered separate evaluation of the effects of the two habits on toluene metabolism. Comparison of the present results with the findings reported in the literature, however, suggested that the observed effects may be attributable to smoking rather than to drinking habits.

Adult↗
PubMed1985

The aromatization of cyclohexanecarboxylic acid to hippuric acid: substrate specificity and species differences.

The ability to convert cyclohexanecarboxylic acid to hippuric acid has been studied in liver from guinea pigs, rabbits, rats and mice using a gas chromatographic - mass spectrometric method employing selected ion monitoring. Guinea pig liver showed the highest activity, giving values double of those found in rabbit liver and five times those in rat liver. Only very weak activity was found in mouse liver. (Hydroxymethyl)cyclohexane, cyclohexanealdehyde and alpha-hydroxyethylcyclohexane, which are structurally related to cyclohexanecarboxylic acid but lack the carboxyl group, were not aromatized by guinea pig liver mitochondria. This finding indicates that the carboxyl group is essential for aromatization. Absence of aromatization was also found with the homologs cyclohexaneacetic acid and cyclohexanepropionic acid and with the di-acids trans-1,2- and trans-1,4-cyclohexanedicarboxylic acid. The effect of a methyl group in cyclohexanecarboxylic acid depended on its position. 2-Methyl-1-cyclohexanecarboxylic acid was not aromatized, however the 3- and 4-methyl derivatives underwent aromatization and subsequent conjugation with glycine. The rates of formation of m-methyl- and p-methylhippuric acid were 16% and 9%, respectively, of that found for hippuric acid from cyclohexanecarboxylic acid (8.0 nmol/min/mg protein).

Animals↗
PubMed1977

[Quantitative determination of hippuric acid in urine using high pressure liquid chromatography (author's transl)].

A simple method to determine hippuric acid in urine by high pressure liquid chromatography is described. An ion exchange column is used for the separation. The detection is carried out with a photometer. The analytical criteria of the reliability of the method are tested. The results for the precision and the accuracy of the method meet the guidelines of the statistical quality control. 34 urinary constituents were tested for their interference in order to examine the specificity. Measuring urine samples from 46 normal persons yielded hippuric acid concentrations between 160 and 2010 mg/1. The median was 400 mg/1, equivalent to 357 mg/g creatinine. These results are compared to those given in the literature. Comparative investigations of those urine samples by a gas chromatographic method matched well, with a coefficient of regression of 0.86.

Chromatography, Gas↗
PubMed1992

Assessment of the capabilities of capillary zone electrophoresis for the determination of hippuric and orotic acid in whey.

A rapid method was developed for the simultaneous determination of hippuric and orotic acid in rennet whey by capillary zone electrophoresis using an uncoated capillary utilizing a 0.04 M amino-2-methyl-1,3-propanediol (AMPD)-N,N-bis(2-hydroxyethyl) glycine (BICINE) buffer (pH 8.8) with UV detection at 254 and 280 nm. Whey proteins were removed by ultrafiltration. The method was evaluated for external, internal and standard addition procedures for both peak areas and peak heights. The use of an internal standard (sorbic acid) eliminated injection errors and gave, when applied to peak areas, the same levels for hippuric and orotic acid in those obtained with high-performance liquid chromatography. Relative standard deviations were 1-2%. Peak heights gave erratic results owing to sample matrix effects on peak widths.

Dairy Products↗
PubMed1986

Brain uptake of tryptophan in urease-injected hyperammonemic rats after treatment with benzoate or hippurate.

The tryptophan uptake into forebrain and brainstem was measured in urease-injected rats and in controls after prior application of sodium benzoate or hippurate. Benzoate led to an increased brain uptake index of tryptophan. This effect was additive to the increase in tryptophan uptake effected by the provoked hyperammonemia. In contrast, hippurate did not alter tryptophan uptake across the blood-brain barrier. We conclude that benzoate should be monitored especially when applied intravenously to patients with hyperammonemic coma.

Animals↗
PubMed1981

Prevention of recurrent urinary infections in women: a comparative trial between nitrofurantoin and methenamine hippurate.

We treated 99 female patients suffering from recurrent urinary infections with either 1 gm. methenamine hippurate every 12 hours or 50 mg. nitrofurantoin every 12 hours for intervals of up to 1 year. Monthly microbiological and clinical surveillance was done. Both treatments were effective in reducing the incidence of symptomatic attacks, with nitrofurantoin being more effective. The protective effect of prophylaxis continued after treatment had stopped, suggesting that a permanent beneficial action had been produced. Especially during the first month of treatment methenamine hippurate was tolerated better than nitrofurantoin: 28 per cent discontinued therapy with the latter owing to nausea.

Adult↗
PubMed1978

High-performance liquid chromatographic determination of hippuric acid in human urine.

A method is described for the determination of urinary hippuric acid by high-performance liquid chromatography. The method used ethyl acetate extraction for partial clean up of the urine. The separation was carried out on a reversed-phase column using 20% methanol in 0.01 M aqueous potassium phosphate containing 0.5% acetic acid as a mobile phase. The column effluent was monitored with a UV detector at 254 nm. Hippuric acid was separated from other normal urine constituents in less than 10 min. Metabolites of xylene and styrene did not interfere with the assay. Analytical recoveries from urine were excellent and peak height and concentration were linearly related.

Chromatography, High Pressure Liquid↗
PubMed1975

A difference in the incorporation of 14C into hippurate glycine from DL-(2-14C)-glutamate and DL-(5-14C)glutamate in guinea pigs.

The specific radioactivity of urinary hippurate glycine was determined after injecting guinea pigs with benzoate and either dl-[2-(14)C]glutamate or dl-[5-(14)C]glutamate. The isotope dilution factor for the formation of [(14)C]glycine was significantly greater (30%) with C-2 labelled glutamate. With either form of labelled glutamate the hippurate glycine was largely carboxyl-group labelled. The observations suggest a route for the incorporation of glutamate carbon into glycine that involves C-5 but not C-2. A hypothesis for glycine biosynthesis from l-glutamate is advanced, consistent with these findings, that includes conversion of l-glutamate to 4-hydroxy-2-oxoglutarate, the scission of the latter to glyoxylate and pyruvate, and the formation of glycine by transamination.

Amino Acids↗
PubMed2000

Hippuric acid as a major excretion product associated with black tea consumption.

1. Nine habitual tea-drinking volunteers were recruited and asked to follow a low-polyphenol and low-caffeine diet for 6 days and to provide daily 24-h urine samples. On day 4 of the experiment strong black tea brewed under standardized conditions was re-introduced to the volunteers' diet. 2. 1H-NMR and HPLC profiling of the urine samples indicated that consumption of black tea (6-10 mugs per day) was associated with a significant (p = 0.00017) increase in hippuric acid excretion relative to control, increasing from 153-512 to 742-1374 mg day(-1). The excretion of substantial amounts of hippuric acid has not previously been associated with black tea consumption. 3. For some volunteers, the quantity of benzoic acid processed exceeded the acceptable daily intake (ADI), but this is not considered to constitute any hazard. 4. A mass-balance analysis indicated that the necessary quantity of benzoic acid could not be obtained from the contents of gallic acid, flavanols, flavonol glycosides and theaflavins in black tea even if 100% transformation was obtained, suggesting that the thearubigins (the major and chemically ill-defined polyphenols of black tea) may be an important source.

Adult↗
PubMed1998

Effect of diet on the urinary excretion of hippuric acid and other dietary-derived aromatics in rat. A complex interaction between diet, gut microflora and substrate specificity.

1. A combined in vivo and in vitro study has been devised to investigate an observation, obtained by 1H NMR of urine, that Alp:AprSD (Wistar derived) rats kept under standard husbandry conditions did not excrete urinary hippuric acid (HA). meta-(hydroxyphenyl)-propionic acid ¿m-HPPA¿ was identified as the major aromatic component in urine samples lacking HA. 2. Examination of urine from Alp:APrSD and Zücker (obese negative) rats fed various diets showed that the lack of HA/presence of m-HPPA was due to diet and not to the strain of animal. This observation was reinforced by the demonstration that the administration of benzoic acid (BA) to rats not previously excreting urinary HA resulted in the return of this component to the urinary excretion profile. Thus rats receiving the standard diet were still capable of glycine conjugation. 3. Changing the diet of rats excreting m-HPPA led to the cessation of m-HPPA excretion and the return of HA urine excretion. Interestingly, switching back to the original diet did not cause the loss of HA and the re-emergence of m-HPPA. 4. In vitro studies on the two enzyme systems responsible for glycine conjugation (benzoyl CoA:synthetase and benzoyl CoA:glycine N-acyltransferase) in isolated liver mitochondria showed that m-HPPA did not inhibit either enzyme. However, m-HPPA was not found to be a substrate for the first reaction step explaining why it was found in the urine as the free acid and not as a glycine conjugate. 5. The absence and presence of m-HPPA and hippuric acid is suggested to be due to a combination of differences in dietary precursors of substrates for glycine conjugation and a dietary dependent redistribution of the intestinal microflora responsible for breakdown of plant phenolics and aromatic amino acids. Taken collectively this study emphasises how a simple diet change can cause a profound change in metabolism.

Acyltransferases↗
PubMed2001

Determination of urinary hippuric acid in toluene abuse.

BACKGROUND: Volatile substance abuse is practiced mainly by adolescents and young adults. Its effects are central nervous system excitation followed by central nervous system depression, at times accompanied by seizures. It may cause sudden death as a result of ventricular arrhythmias, reflex vagal inhibition, respiratory depression, and anoxia. Chronic toxicity may involve the nervous system, heart, kidney, and liver. Toluene-based adhesives are among the most commonly inhaled substances. CASE REPORT: A 14-year-old female presented with confusion, hallucinations, and intermittent laughing and crying after having inhaled contact glue several times daily in the course of 5 days. Her condition improved within 3 h. Urinary hippuric acid was 93.9 g/g creatinine indicating heavy toluene exposure (biological exposure index, BEI, is 1.6 g/g creatinine). CONCLUSION: In this patient, urinary hippuric acid was a biomarker for her toluene abuse.

Adolescent↗
PubMedDate not supplied

Simultaneous high-performance liquid chromatographic analysis of hippuric acid and ortho-, meta-, and para-methylhippuric acids in urine.

A high-performance liquid chromatographic assay for the simultaneous analysis of hippuric and methylhippuric acids in urine is described. Compounds are first extracted from acidified urines after addition of o-methylbenzoylalanine (internal standard), using methyl-t-butyl ether. The organic phase is evaporated under nitrogen flow and the residue dissolved in the mobile phase which consisted of 91% potassium phosphate buffer (12.0mM, pH: 2.0), 4.5% methanol, and 4.5% tetrahydrofuran. The method described allows complete separation of meta- and para-methylhippuric acids in less than 20 min using a stainless steel column packed with octadecyl-dimethysilyl silica. The authors used this method to determine the urinary excretion of hippuric and methylhippuric acids in rabbits following exposure to a mixture of toluene and isomers of xylene. Data indicated that under the actual experimental conditions of exposure o-xylene is excreted to a lesser extent as a methylhippuric acid than the meta- and para-xylenes.

Animals↗
PubMed1987

Glycine availability limits maximum hippurate synthesis in growing rats.

The rate-limiting step for hippurate synthesis from sodium benzoate (NaB) was investigated in growing rats. Rats fed a glycine-and serine-free L-amino acid diet were injected daily with saline or varying doses of NaB. Growth was monitored for 4 d, after which time rats were killed and livers were assayed for glycine, serine, benzoyl-CoA, benzoyl-CoA ligase and glycine benzoyl-CoA transferase. In control animals, liver glycine and serine concentrations were 2.18 and 1.63 mumol/g wet wt, respectively; benzoyl-CoA was not detectable. In rats injected with 600 mg NaB/kg body wt per day, liver glycine and serine concentrations decreased to 68 and 78% of control values, respectively, and benzoyl-CoA accumulated (0.52 mumol/g wet wt). As the dose of NaB was increased, liver benzoyl-CoA concentration increased, and growth of the rats was markedly impaired. The activities of benzoyl-CoA ligase and glycine benzoyl-CoA transferase were unchanged after NaB treatment. In a second experiment, rats were treated with growth-impairing doses of NaB. When the diet was supplemented with serine and glycine, growth was normalized, liver glycine and serine concentrations returned to control levels, and benzoyl-CoA accumulation was markedly diminished. These results suggest that glycine availability limits maximum hippurate synthesis in vivo.

Animals↗
PubMed1998

Elevated free fosphenytoin concentrations in uremic sera: uremic toxins hippuric acid and indoxyl sulfate do not account for the impaired protein binding of fosphenytoin.

Fosphenytoin is a new phosphate ester prodrug of phenytoin. Impaired protein binding of phenytoin in uremia has been extensively documented, which prompted us to investigate the protein binding of fosphenytoin in uremic sera. Also studied was the role of uremic toxins hippuric acid and indoxyl sulfate as potential inhibitor of the protein binding of fosphenytoin because these compounds impair protein binding of phenytoin in uremia. Five serum pools were prepared from normal volunteers and five pools from patients with uremia. None of them received phenytoin. The normal serum pools were diluted with saline to mimic the albumin concentration of uremic pool. Both the diluted normal pool and the uremic pool were supplemented with fosphenytoin; after incubation at room temperature for 30 minutes, total and free fosphenytoin concentrations as phenytoin equivalents were measured using fluorescence polarization immunoassay (Abbott Laboratories; Abbott Park, IL, U.S.A.). The authors observed significantly elevated free fosphenytoin concentration in uremic sera compared with that of normal sera in all cases. Because both normal and uremic sera had the same concentrations of albumin, the elevated free fosphenytoin concentration in uremic sera was not caused by hypoalbuminemia. Both indoxyl sulfate and hippuric acid cause significant displacement of phenytoin from protein binding. In contrast, none caused any displacement of fosphenytoin from protein binding.

Anticonvulsants↗
PubMed1978

Long-term prophylaxis with methenamine hippurate in girls with recurrent urinary tract infections.

Twenty girls, aged 5-12 years, with recurrent urinary tract infections, were treated with methenamine hippurate, Hiprex, for a period of 12 months. The number of infections per patient per year was reduced from 3.1 to 0.7 (p less than 0.001). After prophylaxis was stopped this number increased to 1.4 which is a significantly higher incidence than occurred during treatment (p less than 0.05). A few girls complained of the taste but no side-effects were observed. Methenamine hippurate is a useful alternative in long-term prophylaxis against recurrent urinary tract infections in girls.

Child↗
PubMed1981

Hippurate hydrolysis by Legionella pneumophila.

Strains of Legionella pneumophila were shown to hydrolyze sodium hippurate in an overnight test system, but strains of L. bozemanii, L. micdadei, L. dumoffii, and some other organisms similar to the legionellae did not. Although only a small number of strains of legionellae other than L. pneumophila have been classified and tested, the results indicate that the hippurate hydrolysis test may prove useful for differentiating among Legionella species.

Hippurates↗
PubMed1987

Determination of hippurate hydrolysis by gas-liquid chromatography.

A rapid gas-liquid chromatographic procedure was developed to determine hippurate hydrolysis by microorganisms. Bacterial cells were inoculated into 0.4 ml of 1% sodium hippurate and incubated for 2 h at 37 degrees C. Cells were removed by centrifugation, and the benzoate released by enzyme activity was converted to methyl benzoate and analyzed by gas-liquid chromatography. This procedure is sensitive, and its specificity provides a high degree of reliability for organisms with weak hippuricase activity.

Benzoates↗