Excretion Of Hippuric Acid Research Articles

Hippuric acid as a significant regulator of supersaturation in calcium oxalate lithiasis: the physiological evidence.

At present, the clinical significance of existing physicochemical and biological evidence and especially the results we have obtained from our previous in vitro experiments have been analyzed, and we have come to the conclusion that hippuric acid (C6H5CONHCH2COOH) is a very active solvent of Calcium Oxalate (CaOX) in physiological solutions. Two types of experiments have been discussed: clinical laboratory analysis on the urine excretion of hippuric acid (HA) in patients with CaOX lithiasis and detailed measurements of the kinetics of the dissolution of CaOX calculi in artificial urine, containing various concentrations of HA. It turns out that the most probable value of the HA concentration in the control group is approximately ten times higher than the corresponding value in the group of the stone-formers. Our in vitro analytical measurements demonstrate even a possibility to dissolve CaOX stones in human urine, in which increased concentration of HA have been established. A conclusion can be that drowning out HA is a significant regulator of CaOX supersaturation and thus a regulation of CaOX stone formation in human urine. Discussions have arisen to use increased concentration of HA in urine both as a solubilizator of CaOX stones in the urinary tract and on the purpose of a prolonged metaphylactic treatment.

Blanching Improves Anthocyanin Absorption from Highbush Blueberry (Vaccinium corymbosum L.) Purée in Healthy Human Volunteers: A Pilot Study

Blueberries ( Vaccinium corymbosum L.) are rich sources of phenolics and anthocyanins (ACNs). We investigated the absorption of ACNs after consumption of one portion (300 g) of minimally processed blueberry purée (P) obtained from blanched (BL) or unblanched (NB) berries. A repeated-measures, crossover design study was conducted on healthy human volunteers. Blood was drawn between baseline and 24 h after BL-P or NB-P consumption, while urine were collected from the day before the experiment up to 48 h. Total plasma ACN content was not significantly different, while phenolics content was higher in BL-P with respect to NB-P. The maximum ACN absorption in plasma was observed after 1.5 h from the intake of the purées and was significantly higher (p ≤ 0.05) after the intake of BL-P. Both products increased the excretion of hippuric acid in urine. In conclusion, blanching had no significant effect on total ACN content and enhanced their absorption from minimally processed purées.

Hippuric Acid in 24-Hour Urine Collections Is a Potential Biomarker for Fruit and Vegetable Consumption in Healthy Children and Adolescents ,

An objective noninvasive biomarker for fruit and vegetable (FV) consumption would help to more reliably characterize the relationship between FV intake and health status in observational studies. Because increases in urinary hippuric acid (HA) were observed after consumption of several FV varieties, we aimed to investigate whether 24-h urinary HA may represent a potential biomarker for FV consumption in children and adolescents. The association of FV and juice (FVJ) intake calculated from 3-d weighed dietary records with 24-h urinary HA excretion was analyzed in 240 healthy children and adolescents and compared with associations of the established biomarkers urinary nitrogen (uN) and urinary potassium (uK) with protein and potassium intake, respectively. Spearman correlation coefficients (r) and cross-classifications were calculated for all diet-biomarker associations. Potential confounders for the HA-FVJ association were examined in linear regression models. In children, correlations of HA with FVJ (r = 0.62), uN with protein (r = 0.64), and potassium intake with uK (r = 0.65) were comparable. In adolescents, the HA-FVJ association was weaker (r = 0.41) compared with the biomarkers uN (r = 0.60) and uK (r = 0.58) (all P < 0.0001). Cross-classification into the same/adjacent quartile by dietary and urinary data were >85% for all analyzed comparisons except for a 75% classification agreement between HA and FVJ in adolescents. Unadjusted and adjusted linear regression models indicated significant (P < 0.0001) HA-FVJ associations in both age groups. FVJ explained more of the variability in HA excretion in children (R2 = 0.38) than in adolescents (R2 = 0.22). Our findings in children showing HA-FVJ associations comparable to those for well-established biomarkers with their respective dietary intakes suggest that HA may represent a useful biomarker for FVJ.

Effects of dietary benzoic acid and sodium-benzoate on performance, nitrogen and mineral balance and hippuric acid excretion of piglets

The objective of this study was to compare the effects of sodium-benzoate (NaB) with those of benzoic acid (BAc) on growth performance of piglets as well as nutrient digestibility, nitrogen and mineral balance, urinary pH, and the urinary excretion of BAc and hippuric acid (HAc). The study was conducted with 120 weaning piglets (6.5 kg body weight), divided in four groups (15 replicates of two piglets each), which received (1) a basal diet (Control), or the basal diet supplemented with (2) 4 g NaB per kg (Group 4NaB), (3) 3.5 g BAc per kg (Group 3.5BAc) or (4) 5 g BAc per kg (Group 5BAc). Performance data were monitored over a 42-day period. Urine and faeces were collected from day 28–33 in metabolic cages with five piglets per treatment. Piglets of Groups 3.5BAc and 5BAc had similarly a considerably improved average daily gain and feed intake (p < 0.05). Performance of Group 4NaB was not significantly different from the other groups. Compared to the Control, the nitrogen retention was only improved in Group 5BAc (p < 0.05); the other groups showed intermediate values. In the supplemented groups, most of the BAc was excreted as HAc in urine, but only Groups 3.5BAc and 5BAc had reduced urinary pH (p < 0.05). Daily intake and faecal and urinary excretion of P and Ca were not affected by the treatment. The molar excess of Na in Group 4NaB was reflected by higher renal excretion of Na compared to the other groups (p < 0.05).

Consumption of Hibiscus sabdariffa L. aqueous extract and its impact on systemic antioxidant potential in healthy subjects

To evaluate health benefits attributed to Hibiscus sabdariffa L. a randomized, open-label, two-way crossover study was undertaken to compare the impact of an aqueous H. sabdariffa L. extract (HSE) on the systemic antioxidant potential (AOP; assayed by ferric reducing antioxidant power (FRAP)) with a reference treatment (water) in eight healthy volunteers. The biokinetic variables were the areas under the curve (AUC) of plasma FRAP, ascorbic acid and urate that are above the pre-dose concentration, and the amounts excreted into urine within 24 h (Ae(0-24) ) of antioxidants as assayed by FRAP, ascorbic acid, uric acid, malondialdehyde (biomarker for oxidative stress), and hippuric acid (metabolite and potential biomarker for total polyphenol intake). HSE caused significantly higher plasma AUC of FRAP, an increase in Ae(0-24) of FRAP, ascorbic acid and hippuric acid, whereas malondialdehyde excretion was reduced. Furthermore, the main hibiscus anthocyanins as well as one glucuronide conjugate could be quantified in the volunteers' urine (0.02% of the administered dose). The aqueous HSE investigated in this study enhanced the systemic AOP and reduced the oxidative stress in humans. Furthermore, the increased urinary hippuric acid excretion after HSE consumption indicates a high biotransformation of the ingested HSE polyphenols, most likely caused by the colonic microbiota.

URINARY EXCRETION OF ANTIOXIDANTS IN HEALTHY HUMANS FOLLOWING QUEEN GARNET PLUM JUICE INGESTION: A NEW PLUM VARIETY RICH IN ANTIOXIDANT COMPOUNDS

In recent years, there has been intense interest in the potential health benefits of dietary derived plant polyphenols and antioxidants. A new variety of Prunus salicina, Queen Garnet plum (QGP), was developed as a high anthocyanin, high antioxidant plum, in a Queensland Government breeding program. Following consumption of 400 mL QGP juice (QGPJ; 1,117 mg anthocyanins) by two healthy male subjects, QGP anthocyanins (cyanidin-3-glucoside and cyanidin-3-rutinoside) were excreted mainly as methylated and glucuronidated metabolites in urine (0.5% of the ingested dose within 24 h). Furthermore, QGPJ intake resulted in a threefold increase in hippuric acid excretion (potential biomarker for total polyphenols intake and metabolite), an increased urinary antioxidant capacity and a decreased malondialdehyde excretion (biomarker for oxidative stress) within 24 h as compared with the polyphenol-/antioxidant-free control. Results from this pilot study suggest that metabolites, and not the native QGP anthocyanins/polyphenols, are most likely the bioactive compounds in vivo.

Evaluation of liver function by co-administration methodology using 13C-labelled benzoic acid and hippuric acid coupled with nuclear magnetic resonance spectroscopy.

The amount of hippuric acid synthesized and excreted in the urine after benzoic acid loading (hippuric acid test) is a useful index of liver function. However, the hippuric acid test gives erroneous results in the event of failure of renal excretory function. A new stable isotope co-administration methodology using nuclear magnetic resonance (NMR) spectroscopy has been developed to overcome this defect. [7-(13)C]Benzoic acid and [glycine carbonyl-13C]hippuric acid ([gly-13C]hippuric acid), each 0.4-0.6 mmol kg(-1) were simultaneously administered intravenously as probes to normal or liver-injured rats and the urine was analysed by 100 MHz 13C NMR spectroscopy. Consequently, urinary excretion of [7-(13)C]hippuric acid formed from [7-(13)C]benzoic acid and [gly-13C]hippuric acid was successfully traced with very simple and convenient procedures. The urinary excretion of [7-(13)C]hippuric acid indicated the combined functions of hippuric acid synthesis and renal excretion, whereas that of [gly-13C]hippuric acid was indicative of renal excretion of hippuric acid only. The heights of resonances for C7 of [7-(13)C]hippuric acid and the glycine carbonyl carbon of [gly-13C]hippuric acid were used to calculate the concentrations of labelled hippuric acids. [7-(13)C]Hippuric acid was excreted more slowly than [gly-13C]hippuric acid by both normal and liver-injured rats. The liver-injured rats excreted the labelled hippuric acids more slowly than the normal rats. The kinetic parameters were computed for the individual rats on the basis of Michaelis-Menten elimination for benzoic acid and first-order elimination for hippuric acid. The maximum rates of metabolism (Vmax) (4.8-5.8 micromol min(-1) kg(-1)) and the renal elimination rate constants of hippuric acid (Kre) (0.010-0.021 min(-1)) in the liver-injured rats were lower than those (Vmax 6.7-11.8 micromol min(-1) kg(-1); Kre 0.026-0.045 min(-1)) in the normal rats. These results have demonstrated that liver function can be evaluated from the Vmax value even though the renal function of hippuric acid excretion (Kre) is impaired. Thus the co-administration methodology is feasible and can remove the defect of the previous hippuric acid test. These results could form the basis for a more convenient and reliable hippuric acid test in man.

Use of Proton NMR for Determining Changes in Metabolite Excretion Profiles Induced by Dietary Changes in the Rat

1H NMR spectroscopy was used to compare the endogenous urinary metabolite profiles of groups of Alp: APfSD (Wistar-derived) and Zucker (obese negative) rats fed different diets. With one of the diets (Special Dietary Services), hippuric acid was found to be absent in urine from both strains of rat whilst another component, 3-(3 hydroxyphenyl) propionic acid (3-HPPA) was identified. Switching either strain of rat from this diet to an alternative (Harlan Teklad) resulted in the appearance of hippuric acid in the urine concomitantly with the disappearance of 3-HPPA. Oral administration of benzoic acid (200 mg kg−1) to animals fed the diet which did not produce urinary hippuric acid resulted in a massive increase in hippuric acid excretion in the urine indicating that the rats retained the capacity to synthesize this material. We conclude that the lack of hippuric acid precursors in the urine along with the presence of 3-HPPA is due to diet and not strain of animal.

Relationships between airborne exposure and urinary metabolites of nail technicians

The study aimed to investigate the occupational exposure to airborne solvents in nail salons and to make clear whether relationships between airborne exposure and urinary metabolite excretion would be still useful as biomarkers. Twenty technicians as exposed group and twenty-one as control group were participated. The airborne solvents, urinary acetone and hippuric acid were determined by gas chromatography, UV-visible spectrometer and GC/MS spectrometry. When evaluated with the addictive effects using geometric mean value of each solvent, overall airborne solvents exposed were very low. Concentrations of urinary acetone and urinary hippuric acid were weakly correlated with those of airborne acetone and airborne toluene. In exposed group, urinary acetone concentration was not significant difference and hippuric acid was only slightly above those in control group. In conclusion, urinary acetone and hippuric acid excretion at low level of airborne acetone and toluene would be inadequate biomarkers.

Effects of dietary benzoic acid on urinary pH and nutrient digestibility in lactating sows

Two experiments were conducted to examine the effect of benzoic acid in the diet of lactating sows on urinary pH and nutrient digestibility. In the first experiment, three levels of benzoic acid in the diet were tested (0.5, 1.0, and 2.0%), while in the second experiment only one dietary level of benzoic acid (0.5%) was used. In the second experiment, the urinary excretion of benzoic acid and hippuric acid was additionally measured. The digestibility was estimated in experiment 1 with HCl-insoluble ash as a marker and in experiment 2 in a total balance period with collection of urine and faeces over 5 days. Supplementation of benzoic acid reduced the urinary pH in a dose dependent manner ( p < 0.01). The relationship between benzoic acid intake and urinary pH response was linear. Dietary benzoic acid at a level of 2% increased the digestibility of organic matter, protein, fat and fiber in the diet. In sows fed the diet supplemented with 0.5% of benzoic acid, 64% of benzoic acid ingested was excreted via urine as hippuric acid, the remainder as unmetabolized benzoic acid.

Anthocyanin Absorption, Metabolism, and Distribution from a Wild Blueberry-Enriched Diet (Vaccinium angustifolium) Is Affected by Diet Duration in the Sprague−Dawley Rat

The effect of wild blueberry consumption on anthocyanin (ACNs) distribution and metabolism in Sprague-Dawley (SD) rats was investigated. Thirty-two rats were fed for 4 or 8 weeks with a control (C) or a wild blueberry-enriched diet (8%) (WB). Anthocyanin profile in plasma, urine, feces, brain, and liver was evaluated by LC-MS/MS, and significantly increased in urine and not in feces after 8 weeks on the WB diet compared to that in 4 weeks, but no anthocyanins were detected in plasma, liver, and brain samples either in the C or WB groups. Metabolites of ACNs were detected in the plasma, urine, feces, and tissues of both the C and WB groups, but the urinary excretion of hippuric acid increased significantly after 4 and 8 weeks of WB consumption. Thus, it seems that ACNs are metabolized by the intestinal microflora to respective phenyl-alkyl acids, which can be further metabolized to benzoic acid. In conclusion, ACNs are bioavailable in rats, and the extent of their metabolism and excretion is based on diet duration. Additionally, urinary hippuric acid content could represent a potential biomarker of ACNs absorption and metabolism in the SD rat under the present experimental conditions.

The metabolic fate of red wine and grape juice polyphenols in humans assessed by metabolomics

The metabolic impact of polyphenol-rich red wine and grape juice consumption in humans was studied using a metabolomics approach. Fifty-eight men and women participated in a placebo-controlled, double-crossover study in which they consumed during a period of 4 wk, either a polyphenol-rich 2:1 dry mix of red wine and red grape juice extracts (MIX) or only a grape juice extract (GJX). Twenty-four-hour urine samples were collected after each intervention. (1)H NMR spectroscopy was applied for global metabolite profiling, while GC-MS was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol-rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis. A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption as) or only a red grape juice dry extract (GJX). 24-h urine samples were collected after each intervention. 1H-NMR spectroscopy was applied for global metabolite profiling, while gas chromatography-mass spectrometry (GC-MS) was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol-rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis (ML-PLS-DA). A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption compared with placebo, whereas no change was found after GJX consumption. GC-MS-based metabolomics of urine allowed identification of 18 different phenolic acids, which were significantly elevated following intake of either extract. Syringic acid, 3- and 4-hydroxyhippuric acid and 4-hydroxymandelic acid were the strongest urinary markers for both extracts. MIX and GJX consumption had a slightly different effect on the excreted phenolic acid profile and on endogenous metabolite excretion, possibly reflecting their different polyphenol composition.

Moderate Champagne consumption promotes an acute improvement in acute endothelial-independent vascular function in healthy human volunteers

Epidemiological studies have suggested an inverse correlation between red wine consumption and the incidence of CVD. However, Champagne wine has not been fully investigated for its cardioprotective potential. In order to assess whether acute and moderate Champagne wine consumption is capable of modulating vascular function, we performed a randomised, placebo-controlled, cross-over intervention trial. We show that consumption of Champagne wine, but not a control matched for alcohol, carbohydrate and fruit-derived acid content, induced an acute change in endothelium-independent vasodilatation at 4 and 8 h post-consumption. Although both Champagne wine and the control also induced an increase in endothelium-dependent vascular reactivity at 4 h, there was no significant difference between the vascular effects induced by Champagne or the control at any time point. These effects were accompanied by an acute decrease in the concentration of matrix metalloproteinase (MMP-9), a significant decrease in plasma levels of oxidising species and an increase in urinary excretion of a number of phenolic metabolites. In particular, the mean total excretion of hippuric acid, protocatechuic acid and isoferulic acid were all significantly greater following the Champagne wine intervention compared with the control intervention. Our data suggest that a daily moderate consumption of Champagne wine may improve vascular performance via the delivery of phenolic constituents capable of improving NO bioavailability and reducing matrix metalloproteinase activity.

Absorption and metabolism of benzoic acid in growing pigs1

Dietary benzoic acid (BA) supplementation causes a pronounced reduction in urinary pH but only small changes in blood pH. The present study aimed to investigate the portal absorption profile, hepatic metabolism of BA, and renal excretion of hippuric acid (HA) underlying the relatively small impact of BA on systemic acid-base status. Eight growing pigs (BW = 63 +/- 1 kg at sampling) fitted with permanent indwelling catheters in the abdominal aorta, hepatic portal vein, hepatic vein, and mesenteric vein were allocated to 4 sampling blocks and randomly assigned to control (CON; nonsupplemented diet) or BA supplementation (B; control diet + 1% BA top-dressed). Feed intake was restricted to 3.6% of BW and the ration divided into 3 equally sized meals offered at 8-h intervals. Blood pH (7.465 and 7.486 +/- 0.004) and urinary pH (4.99 and 7.01 +/- 0.09) were less (P = 0.03 and P < 0.01) in B compared with CON. The arterial concentration, net portal flux, and net hepatic uptake of BA increased (P < 0.01) in B compared with CON. The net portal flux of BA increased (P < 0.01) after feeding with B, but remained positive (P < 0.01) at all sampling times (n = 8). Recovery of dietary BA as increased net portal flux and hepatic uptake of BA was 87 +/- 5% and 89 +/- 15%, respectively. The recovery of dietary BA as urinary excretion of BA and HA was 0.08 +/- 0.02% and 85 +/- 7%, respectively. It is concluded that the small impact of BA supplementation on systemic acid-base status was caused by a protracted BA absorption and efficient hepatic extraction and glycine conjugation in combination with efficient renal clearance of HA. Together, these physiological mechanisms prevented major BA and HA accumulation in body fluids.

Resorption and elimination kinetics of benzoic acid during chemical necrectomy in deep burns

Objective: Chemical necrectomy is an alternative to the surgical or sharp necrectomy for the removal of necrotic parts of the skin in the treatment of deep burns. The aim of our work was to monitor the dynamics of resorption and elimination of benzoic acid applied to the burnt skin. Methods: The set consisted of 10 patients (9 men; 1 woman) aged 25–57 years with IIb-III-degree skin burns. 40% benzoic acid in white petrolatum was applied to the burnt area to the extent of 3–5% of TBSA (total body surface area) for a period of 48 hours. The concentrations of benzoic acid, hippuric acid, and glycine in the serum was monitored at the 10th, 20th, 60th, 120th, 240th and 360th minute thereafter and further at the 12th, 24th, 48th, and 72nd hour; the excretion of hippuric acid in urine was monitored in six 12-hour intervals. Results: The highest concentration of benzoic acid in the serum was detected in the 60th minute sample (0.094±0.074 mmol/L) and of hippuric acid in the 120th minute sample (0.234±0.088 mmol/L) from the application of benzoic acid to the burnt skin. In the period between the 6th and 48th hour, the average concentration of benzoic acid in the serum ranged between 0.042 and 0.03 mmol/L. In this period there was also a significant decrease in serum glycine concentration (p<0.05). During the 48-hour application of benzoic acid to the burnt skin, 46.0–145 mmol of hippuric acid was excreted in urine. Conclusion: Chemical necrectomy with the use of 40% benzoic acid led only to a moderate increase of its concentration in the serum. After its resorption from the wound area it is transformed to hippuric acid, which is promptly excreted in urine.

Delayed and Competitively Inhibited Excretion of Urinary Hippuric Acid in Field Workers Coexposed to Toluene, Ethyl Benzene, and Xylene

The purpose of this study was to investigate whether the metabolic suppression of hippuric acid (HA) occurs in field workers coexposed to toluene, xylene and ethyl benzene. Eleven male spray painters were recruited into this study and monitored for 2 weeks using a repeated-measures study design. The sampling was conducted for 3 consecutive working days each week. Toluene, ethyl benzene, and xylene in the air were collected using 3M 3500 organic vapor monitors. Urine samples were collected before and after work shift, and urinary HA, methyl hippuric acid, mandelic acid, and phenylgloxylic acid concentrations were determined. In the first week, toluene concentrations were 2.66 +/- 0.95 (mean +/- SE) ppm, whereas ethyl benzene and xylene concentrations were 27.84 +/- 3.61 and 72.63 +/- 13.37 ppm, respectively, for all subjects. Pre-work shift HA concentrations were 230.23 +/- 37.31 mg/g creatinine, whereas pre-work shift HA concentrations were 137.81 +/- 14.15 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre-work shift samples than in the pre-work shift samples (p = 0.043). In the second week, toluene concentrations were much lower (0.28 ppm), whereas ethyl benzene and xylene were 47.12 +/- 8.98 and 23.88 +/- 4.09 ppm, respectively, for all subjects. Pre-work shift HA concentrations were 351.98 +/- 116.23 mg/g creatinine, whereas pre-work shift HA concentrations were 951.82 +/- 116.23 mg/g creatinine. Mean urinary HA concentration was significantly greater in the pre-work shift samples than in the pre-work shift samples (p <0.01); a significant correlation (r = 0.565; p = 0.002) was found between pre-work shift urinary HA levels and ethyl benzene exposure. This study showed that urinary HA peak was delayed to next morning for workers coexposed to toluene, ethyl benzene, and xylene; xylene and ethyl benzene probably played competitive inhibitors for metabolism of toluene. The study also presumed that urinary HA became the major metabolite of ethyl benzene at the end of work shift, when the exposure concentrations of ethyl benzene were 2.0 times those of xylene.

Sorghum Bran in the Diet Dose Dependently Increased the Excretion of Catechins and Microbial-Derived Phenolic Acids in Female Rats

Sorghum bran is concentrated with procyanidins (predominately polymers), which may be beneficial for health in humans; however, the bioavailability of procyanidins is not well-understood. Female Sprague-Dawley rats were fed an AIN93G diet containing 0, 5, 10, 20, or 40% Hi-tannin sorghum bran (n = 5-7 for each group) for 50 days. Sorghum bran contained 23.3 mg/g of procyanidins. The urinary excretions of catechin, epicatechin, methylated catechins, and phenolic acids were analyzed using liquid chromatography-tandem mass spectrometry. Sorghum bran dose dependently increased the urinary excretion of catechin (0-2.2 nmol/day) and 3'-O-methylcatechin (0-9.5 nmol/day). Their serum concentrations also increased with dose (range of 0-14 nM for 3'-O-methylcatechin). Among the 14 phenolic acids analyzed, 3,4-dihydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, and 4-hydroxyphenylacetic acid dominated in the serum (1.8-8 micromol/L). In the urine, 3-methoxy-4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, and 3-hydroxyphenylpropionic acid dominated and their excretion increased significantly with the level of sorghum bran in the diet. The summed phenolic acid excretion was 0.8 micromol/day in the control group and increased to 23 micromol/day for 40% sorghum bran group. The hippuric acid excretion ranged from 2.2 to 16.2 micromol/day and peaked in the 10% sorghum bran group. On the basis of chromic oxide, a nonabsorbable marker, total procyanidins and polymers disappeared progressively, and significant degradation occurred in the cecum and colon. Catechins and procyanidins in sorghum were bioavailable; however, bacteria-derived phenolic acids were the predominant metabolites of procyanidins. Procyanidins degraded in the gastrointestinal tract. Depolymerization was not observed.

Metabonomics Approach To Determine Metabolic Differences between Green Tea and Black Tea Consumption

The purpose of this study was to compare the effects of black and green tea consumption on human metabolism. Seventeen healthy male volunteers consumed black tea, green tea, or caffeine in a randomized crossover study. Twenty-four-hour urine and blood plasma samples were analyzed by NMR-based metabonomics, that is, high-resolution 1H NMR metabolic profiling combined with multivariate statistics. Green and black tea consumption resulted in similar increases in urinary excretion of hippuric acid and 1,3-dihydroxyphenyl-2-O-sulfate, both of which are end products of tea flavonoid degradation by colonic bacteria. Several unidentified aromatic metabolites were detected in urine specifically after green tea intake. Interestingly, green and black tea intake also had a different impact on endogenous metabolites in urine and plasma. Green tea intake caused a stronger increase in urinary excretion of several citric acid cycle intermediates, which suggests an effect of green tea flavanols on human oxidative energy metabolism and/or biosynthetic pathways.

Effect of Sodium Benzoate on Change of Urinary Hippuric Acid and Methyl Hippuric Acid among Workers Coexposed to Toluene and Xylene

Objectives: This study was performed to investigate the effect of drink containing sodium benzoate on the change of urinary hippuric acid (UHA) and methyl hippuric acid (UMHA) excretion among workers coexposed to low toluene and xylene. Methods: Study subjects were 55 male shipbuilders who were divided into 3 groups; nonexposed group (n=10, who were not exposed to organic solvent and had drunk sodium benzoate), exposed A group (n=24, who were coexposed to toluene and xylene, and had drunk sodium benzoate), and exposed B group (n=21, who were coexposed to toluene and xylene, and had not drunk sodium benzoate). The study methodology consisted of questionnaire survey, urinary analysis for metabolites of toluene and xylene before and after drinking with or without sodium benzoate, and personal air sampling of toluene and xylene. Results: Before drinking, there was no significant difference in UHA or UMHA between the exposed A and B groups. After 1.5 hour of drinking, UHA of the exposed A group was significantly higher than that of the exposed B group. After 3 hours, however, UHA of the exposed A group was decreased to the level of the exposed B group, regardless of the ambient toluene level. UMHA exhibited no significant difference between the exposed A and B groups regardless of time and ambient toluene level. The regression model showed that drinking of sodium benzoate was positively correlated with UHA after 1.5 hours of drinking, but not after 3 hours. In addition, sodium benzoate didn’t affect UMHA. Conclusions: This study showed that sodium benzoate initially increased UHA temporally but that its effect disappeared after 3 hours. In the medical examination of toluene exposure workers, the ingestion of drink containing sodium benzoate should be forbidden during the 3 hours prior to urinary sampling.

Consumption of both black tea and green tea results in an increase in the excretion of hippuric acid into urine

A major portion of the catechins in green tea is not absorbed in the small intestine. Bacteria in the colon convert nonabsorbed catechins into simpler phenolic compounds, which may also be absorbed. During the production of black tea, most catechins are polymerized to complex molecules called thearubigins. Little is known about the microbial degradation of these complex polyphenols, but hippuric acid has been identified as a major excretion product associated with black tea consumption. To investigate whether green tea and black tea have the same metabolic fate in humans. Seventeen healthy male volunteers were studied with a randomized, full-crossover design. Each intervention period lasted 4 d, ie, a 2-d run-in period with a low-polyphenol diet followed by a 2-d treatment period. Volunteers consumed a daily dose of 6 g green tea solids, 6 g black tea solids, or 360 mg caffeine. Intervention periods were separated by a 10-d washout period. Twenty-four-hour urine samples were collected during the second day of each treatment period. Hippuric acid was analyzed with HPLC-tandem mass spectrometry. The mean excretion of urinary hippuric acid during black tea and green tea consumption was 3.75 +/- 0.28 mmol/24 h and 4.22 +/- 0.28 mmol/24 h, respectively (95% CI for the difference: -0.37 to +1.30 mmol/24 h). The hippuric acid excretion during the control treatment was much lower (1.89 +/- 0.28 mmol/24 h; P < 0.0001, compared with both black tea and green tea). The ingestion of either green tea or black tea results in a major increase in the excretion of hippuric acid into urine.