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PubMed1985

The aromatization of cyclohexanecarboxyl-CoA to hippuric acid by guinea pig liver mitochondria: submitochondrial localization.

The conversion of cyclohexanecarboxyl-CoA to hippuric acid in submitochondrial fractions from guinea pig liver was studied using a gas chromatographic-mass spectrometric method employing selected ion monitoring. Comparison of the activities of the cyclohexanecarboxyl-CoA to hippuric acid converting system (CCoAHC-system) and marker enzymes in the various submitochondrial fractions showed that the CCoAHC-system is localized in the mitochondrial matrix. Partial separation of the inner and outer membranes has been accomplished by treating mitochondria with digitonin in isotonic medium and fractionating the treated mitochondria by differential centrifugation. A digitonin-protein ratio of 2.6 mg of digitonin/10 mg of protein must be used in order to release significant amounts of amine oxidase activity (outer membrane marker) from low speed mitochondrial pellets. This pellet still contained most of the glutamate dehydrogenase activity and was insignificantly contaminated with adenylate kinase. Moderate concentrations of phenazine methosulfate (PMS) greatly stimulated the activity of the CCoAHC-system, even in intact mitochondria (optimal concentration of PMS: 1 mM) whilst higher concentrations (greater than 1 mM) decreased the activity. The formation of hippuric acid in these mitochondrial preparations was linear with time for at least 40 min and linear with respect to protein concentration up to approximately 2.0 mg mitochondrial protein X ml-1.

Acyl Coenzyme A↗
PubMed1984

Benzylamine metabolism at low O2 concentrations. Relative sensitivities of monoamine oxidase, aldehyde dehydrogenase and hippurate synthesis to hypoxia.

The O2 dependence of the metabolism of benzylamine to benzaldehyde, benzoate and hippurate was studied in isolated rat hepatocytes. The initial oxidation to benzaldehyde, catalyzed by monoamine oxidase, had an apparent Kmo2 value of 34 microM in cells and 40 microM in isolated rat liver mitochondria. The conversion of benzaldehyde to benzoate was essentially independent of O2 concentration in spite of the dependence of the reaction upon cytosolic NAD+. The conversion of benzoate to hippurate was half-maximal at 2.4 microM O2 in hepatocytes and at about 0.5 microM O2 in rat liver mitochondria. These values are consistent with the O2 dependence of bioenergetic changes in these preparations and indicate that the O2 dependence of hippurate formation is due to ATP availability for synthesis of benzoyl-CoA. These studies show that the three metabolic processes involved in benzylamine metabolism have markedly different dependences upon O2 and that metabolism of benzylamine by monoamine oxidase is O2 dependent over a physiologically important range.

Aldehyde Oxidoreductases↗
PubMed1988

Determination of benzoic acid and hippuric acid in human plasma and urine by high-performance liquid chromatography.

For patients with inborn errors of urea synthesis, oral administration of sodium benzoate is the usual treatment to increase the nitrogen excretion. Thus, monitoring hippuric acid and benzoic acid simultaneously in human biological fluids is considered to be clinically important. We developed a simple and accurate high-performance liquid chromatographic method for the simultaneous determination of hippuric acid and benzoic acid in human plasma and urine. This method requires no extraction step. Aliquots of urine and plasma are added to a solution of internal standard (o-chlorobenzoic acid) in acetonitrile and directly injected onto a reversed-phase column using an acidic (pH 2.7) eluent and ultraviolet detection at 235 nm. The preliminary plasma concentration-time and urinary excretion rate-time profiles of hippuric acid and benzoic acid from a healthy subject receiving small, medium and large doses of sodium benzoate are reported.

Administration, Oral↗
PubMed1995

Synthesis and preclinical evaluation of technetium-99m-labeled hippurate analogues.

We have synthesized seven 99mTc-labeled hippurate analogues: 99mTc-hippurate. 99mTc-alpha-hydroxyhippurate, 99mTc-m-hydroxyhippurate. 99mTc-o-hydroxyhippurate [99m-salicylglycine (99mTc-SG)], 99mTc-p-hydroxyhippurate, 99mTc-salicylglycylglycine and 99mTc-salicylglycylglycylglycine. All of the 99mTc-hippurates were cleared rapidly from the rat blood and accumulated in the kidney. Of them 99mTc-SG has the desirable biological properties of two diagnostic agents. 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) and 99mTc-dimercaptosuccinate (99mTc-DMSA). A fraction of 99mTc-SG showed a transit time in the kidney and was excreted rapidly into the urine, being similar to 99mTc-MAG3. The binding ratio to the plasma proteins was 96.0% (91.1% in the albumin), being higher than that of 99mTc-DMSA, at 30 min. The lipophilicity revealed far less pH-dependent changes in a range of pH 4.0 to 7.4. 99mTc-SG distributed about 91% in the renal cortex, being similar to that of 99mTc-DMSA. From the present studies, the biological properties of 99mTc-SG suggest that it is a promising agent for measuring renal plasma flow and renal morphology.

Animals↗
PubMed2005

Determination of methenamine, methenamine mandelate and methenamine hippurate in pharmaceutical preparations using ion-exchange HPLC.

An ion-exchange column high-performance liquid chromatography (HPLC) method has been developed for the determination of methenamine in methenamine and methenamine hippurate pharmaceutical preparations. The HPLC method uses a Zorbax SCX-300 column with acetonitrile-0.1M sodium perchlorate monohydrate (pH 5.8) (70:30, v/v) as the mobile phase at the flow rate of 1 mL/min. UV-detection was at 212 nm. The linear concentration plots for methenamine were linear over the concentration range of 0.25-50mM for methenamine and methenamine mandelate standards. The intra-day RSD precision was <1.25%, and for inter-day, <1.85%. The peaks for mandelic acid, hippuric acid and the other ingredients from placebo tablets do not interfere with the analysis for methenamine. The accuracy of this method was shown to be 99-101% by measuring the recovery of methenamine from spiked placebo tablets. The assay of methenamine from methenamine hippurate tablets and from a urinary antiseptic tablet containing methenamine were in the range of 98-102%. This HPLC method is a fast, simple and straightforward method for the analysis of methenamine in pharmaceutical preparations.

Anti-Infective Agents, Urinary↗
PubMed2005

Simple colorimetric semiquantitation method of hippuric acid in urine for demonstration of toluene abuse.

A semiquantitative method for hippuric acid in toluene sniffers' urine was explored by modifying the method by Tomokuni and Ogata. The color of sample urine mixed with pyridine and benzenesulfonyl chloride was yellow, and became reddish by addition of distilled water. Using the color chart, the concentration of hippuric acid could be semiquantitated in a few minutes. The values determined by this method were compared with those obtained by high performance liquid chromatography, showing a coefficient of determination (r2) of 0.8594. This colorimetric method is thus useful for rapid screening for hippuric acid in urine, or toluene sniffing.

Administration, Inhalation↗
PubMed1990

High-performance liquid chromatographic analysis of hippuric acid in human blood plasma.

A method has been developed for the isocratic high-performance liquid chromatographic analysis of hippuric acid in human blood plasma. After the addition of an internal standard (3-methoxysalicylic acid), plasma samples (1 ml) were made alkaline and extracted stepwise with methylene chloride and ethyl acetate. The detection limit was 50 pmol of hippuric acid per ml of plasma. The concentrations of hippuric acid in plasma from house painters (n = 8), with long-term exposure to solvent vapours from alkyd paints, were in the range 1-21 nmol/mol (median 11 nmol/ml). These values were statistically significantly higher than those for controls (n = 9): 2-8 nmol/ml (median 3 nmol/ml).

Acetates↗
PubMed1982

Determination of urinary hippuric acid and o-cresol, as indices of toluene exposure, by liquid chromatography on dynamically modified silica.

Two simple and sensitive high-performance liquid chromatographic methods for the determination of hippuric acid and o-cresol in urine have been developed. The chromatographic system is the same for the two methods and is based on dynamically modified silica. The detection limits were found to be 0.05 mg/ml and 0.05 microgram/ml of urine for hippuric acid and o-cresol, respectively, when using UV detection at 254 nm. The recovery for hippuric acid was about 100% and for o-cresol 33-36%. The detection limit for o-cresol could be lowered by a factor of ten by using fluorescence detection. The methods were used for investigations of the urine from persons exposed to 100 ppm toluene for 6.5 h. The method for o-cresol may also be used for determination of other phenols in urine.

Age Factors↗
PubMed1989

Biosynthesis of hippurate, urea and pyrimidines in the fatty liver: studies with rats fed orotic acid or a diet deficient in choline and inositol, and with genetically obese (Zucker) rats.

The activities of pathways for the biosynthesis of hippurate, urea and pyrimidines in hepatocytes isolated from lean livers were compared with those from three sources of fatty liver: a) the genetically obese Zucker rat, b) Sprague-Dawley rats fed a diet deficient in choline and inositol, and c) Sprague-Dawley rats fed a diet supplemented with orotic acid. The capacity for hippurate synthesis was not significantly affected by fat accumulation, but ureagenesis from saturating ammonia and ornithine was diminished about 50% in all models when fat content rose above 12% wet wt of liver. Pyrimidine biosynthesis under these conditions was similarly diminished with fat accumulation. Ureagenesis was inhibited by sodium benzoate in hepatocytes from lean livers, but not in hepatocytes from fatty livers. Other results suggest that higher rates of ureagenesis than could be achieved with the fatty liver are required in order to demonstrate inhibition by benzoate. Incorporation of [14C]NaHCO3 into orotate was also inhibited by sodium benzoate, but in hepatocytes from fatty as well as lean livers. The metabolic basis for impairment of ureagenesis and pyrimidine biosynthesis in the fatty liver requires further study. That the capacity for hippurate synthesis was not significantly affected suggests a pathway-specific mechanism.

Ammonium Chloride↗
PubMed1998

Disposition of 4-methylbenzoylglycine in rat isolated perfused kidney and effects of hippurates on renal mitochondrial metabolism.

Hippurates tend to accumulate within proximal tubule cells during renal secretion. High intracellular concentrations can alter proximal tubular function or lead to tubular toxicity. In this study we examined the renal disposition of the hippurate 4-methylbenzoylglycine, a compound known for its high renal intrinsic clearance in-vivo. The effect of intracellular accumulation on mitochondrial respiration was also measured in-vitro and compared with that of the 2-methyl and 4-amino analogues. Experiments were performed with either 2.5% pluronic or a combination of 2.2% pluronic and 2% bovine serum albumin (BSA) as oncotic agents. Within the concentration range studied (1-200 microg mL(-1)) tubular secretion seemed to be a function of the amount of unbound drug in the perfusate. Renal excretion data were best fitted by a model in which a Michaelis-Menten term was used to describe active secretion. Parameters obtained after the analysis of renal excretion data were the maximum transport velocity (TM = 55+/-2 microg min(-1)) and the Michaelis-Menten constant for tubular transport (KT = 4.2+/-0.8 microg mL(-1)). The compound accumulated extensively in kidney tissue, ratios up to 600 times the perfusate concentration were reached. Accumulation could be explained by active tubular uptake and data were analysed best by a model similar to the model used to describe renal excretion. Calculated parameters were theoretical maximum capacity (RM =300+/-210 microg g(-1)) and affinity constant for renal accumulation (KA = 5.0+/-4.4 microg mL(-1)). The high intracellular concentrations of 4-methylbenzoylglycine had no effect on kidney function and mitochondrial oxygen consumption. The 2-methyl analogue reduced mitochondrial respiration slightly, but 4-aminobenzoylglycine (p-aminohippurate) caused a significant reduction. In conclusion, this study shows that renal accumulation of a hippurate is determined by the efficiency of its tubular secretion. Whether the high intracellular concentrations affect tubular cell functioning depends on the analogue involved.

Animals↗
PubMed1982

Gas-liquid chromatography technique for detection of hippurate hydrolysis and conversion of fumarate to succinate by microorganisms.

A gas-liquid chromatography technique which allows simultaneous detection of hippuric acid (N-benzoylglycine) hydrolysis and conversion of fumaric acid to succinic acid by microorganisms uses a new medium, hippurate-formate-fumarate broth, and a gas chromatograph equipped with a thermal conductivity detector. This technique gave more reproducible results than other tests used in the study for detecting hippurate hydrolysis and also gave consistent results in detecting succinic acid produced from utilization of fumaric acid.

Bacteria↗
PubMed1989

Evaluation of a disk method for detection of hippurate hydrolysis by Campylobacter spp.

A disk method for detecting hippurate hydrolysis by Campylobacter spp. was evaluated and compared with the conventional tube test used at the Centers for Disease Control (CDC) (G.K. Morris and C.M. Patton, p. 302-308, in E.H. Lennette, A. Balows, W.J. Hausler, Jr., and H.J. Shadomy, ed., Manual of Clinical Microbiology, 4th ed., 1985) and high-performance liquid chromatography (HPLC). A total of 118 Campylobacter strains were tested. Eighty-seven strains (74%) were hippurate positive by the HPLC method, and the remaining 31 (26%) were found to be hippurate negative. By using HPLC as the reference technique, the CDC method showed a sensitivity of 80% and a specificity of 81%; the disk method showed a sensitivity of 93% and a specificity of 94%. The disk method can be performed with a small inoculum of bacteria, did not present problems of interpretation, and showed better results than the CDC method (P = 0.015).

Bacteriological Techniques↗
PubMed1976

Rapid, colorimetric test for the determination of hippurate hydrolysis by group B Streptococcus.

A colorimetric test for the determination of hippurate hydrolysis was developed. Brain heart infusion broth made with 1% sodium hippurate served as the test medium. Hydrolysis was determined by the addition of two chemical developers, M (rhodamine B) and A (uranium acetate). A dark pink color indicated hydrolysis; no color change indicated no hydrolysis. The method was efficacious in either rapid or overnight incubation. One hundred twenty-five strains of group B, 44 strains of group A, 15 strains of group C, and 10 strains of group G Streptococcus were tested. By using the Lancefield method as the standard, there was 100% agreement with both the colorimetric and ferric chloride tests for hippurate hydrolysis, and 96% agreement with the CAMP test.

Hippurates↗
PubMed1977

Measurement by gas chromatography of urinary hippuric acid and methylhippuric acid as indices of toluene and xylene exposure.

A gas chromatographic method was applied to the determination of the urinary glycine conjugates, hippuric, o-, m- and p-methylhippuric acids. These were extracted with ethyl acetate from urine after acidification with hydrochloric acid. The internal standard solution (heptadecanoic acid methanol solution) was added before extraction and a diazomethane-ether-ethanol solution was subsequently added to the dried extracts. The methylated residues were dissolved in methanol and injected into a gas chromatograph as described by Buchet and Lauwerys (1973). By the combined use of gas chromatography and mass spectrometry the methyl esters of hippuric acid and m-methylhippuric acid were identified in the urine of a volunteer who had been exposed to toluene and m-xylene vapours. When the urine specimen contained salicyluric acid (a urinary metabolite of salicylic acid) two sharp peaks were observed. The faster peak coincided with m- or p-methylhippuric acid. The upper limit of urinary hippuric acid concentration in healthy subjects with no occupational exposure was calculated by this method to be 1.026 microgram/ml (fiducial limit 5%) after correction to 1.024 for variation in urinary density.

Adult↗
PubMed1981

Thin-layer chromatography of hippuric and m-methylhippuric acid in urine after mixed exposure to toluene and xylene.

The separation of hippuric and m-methylhippuric acid as toluene and m-xylene metabolites present in urine of people exposed simultaneously to toluene and xylene is described. Chloroform was used for hippuric and m-methylhippuric acid extraction. Satisfactory separation of these metabolites was obtained on TLC plates covered with silica gels and developed in chloroform acetic acid-water (4:1:1);p-dimethylaminobenzaldehyde in acetic acid anhydride was applied to develop the colour. The sensitivity of the method was 6 micrograms hippuric acid per 1 ml urine and recovery was 100% (+/- 1).

Chromatography, Thin Layer↗
PubMed2000

Effect of pantothenic acid on hippurate formation in sodium benzoate-treated HepG2 cells.

Inborn errors of urea synthesis result in hyperammonemia. Sodium benzoate (SB) therapy has been beneficial in the treatment of hyperammonemia. It conjugates with glycine to form hippurate, which is then excreted. SB has also been used to treat children with nonketotic hyperglycinemia (NKH), where glycine is removed, on conjugation, as hippurate. In mammalian liver mitochondria, SB is activated by an ATP-dependent reaction to its CoA ester, before conjugation with glycine. Pantothenic acid (PA) is the precursor of CoA. In this investigation, increasing the amounts of PA increased CoA levels in HepG2 cells. It also significantly increased formation of hippurate in SB-treated cells. These findings suggest a beneficial effect of PA on the SB therapy in children with NKH as well as hyperammonemia.

Cell Line↗
PubMed1982

Secondary prevention of recurrent urinary tract infections. Comparison of the effect of placebo, methenamine hippurate, nitrofurantoin and trimethoprim alone.

290 patients with recurrent urinary tract infection were treated with either placebo, methenamine hippurate, nitrofurantoin or trimethoprim. 38.9% of the patients had chronic pyelonephritis and 23.8% azotemia. During the follow-up period of 1 year 63.2% recurred in the placebo group, 34.2% in the methenamine hippurate group, 25.0% in the nitrofurantoin group and 10.4% in the trimethoprim group. 62.5% of the recurrences in the trimethoprim group were associated with trimethoprim-resistant strains. However, such strains appeared only in 6.5% of the patients treated with trimethoprim, compared with 16.2% in the placebo, 8.3% in the nitrofurantoin and 11.0% in the methenamine hippurate groups. Side-effects were mild and occurred most frequently in the nitrofurantoin group (13.9%).

Clinical Trials as Topic↗
PubMed2003

A survey of urinary hippuric acid and subjective symptoms among occupational low toluene exposed workers.

Biological monitoring of toluene exposure by urinary hippuric acid determination and a subjective symptom survey by self-administered questionnaire were performed in 20 workers at low toluene exposure in factories to evaluate the health hazard including dysfunction of nervous system. Environmental monitoring was carried out using toluene gas detection tubes. Urine samples were collected three times a day in order to measure hippuric acid: first before the commencement of work, then at the end of forenoon work, and lastly at the end of afternoon work. Toluene vapor concentrations of throughout the workday ranged from 15.3 to 31.4 ppm. The urinary hippuric acid concentrations correlated with the toluene concentrations of ambient air (r = 0.58, p = 0.01). The subjective symptoms increased in close association with the exposure to toluene; the prevalence rate of subjective symptoms "during work" in the exposed group was 15 times higher than the rate of the non-exposed group (p < 0.0001). The prevalence rate of subjective symptoms "off-work" in the exposed group was 2.4 times higher than the rate of the non-exposed group (p < 0.0001), and also the prevalence rate of "nineteen symptoms off-work which are apparently related to central nervous system (CNS) and autonomic nervous system (ANS)" in the exposed group was 1.8 times higher than the rate of the non-exposed group (p < 0.05). From these results, these subjective symptoms, which have been believed to be complained in high organic solvent exposure should be reassessed and reconsidered in evaluating the nervous system dysfunction and local irritation in relatively low toluene exposed workers.

Adult↗