Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Benzoates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed1985

Effects of pregnant mare serum gonadotrophin and oestradiol benzoate on enzymes associated with xenobiotic metabolism in immature and hypophysectomized female rats.

Treatment of immature (22-day-old) female Sprague-Dawley rats with pregnant mare serum gonadotrophin (PMSG) resulted in a significant increase in hepatic microsomal cytochrome P-450 concentrations when compared with animals treated with 0.9% (w/v) NaCl solution. Cytochrome P-450 concentrations in microsomes from control and PMSG-treated animals were 0.49 +/- 0.07 and 0.78 +/- 0.18 nmol/mg microsomal protein respectively (mean +/- S.D.). When hypophysectomized rats were treated with PMSG no significant difference was observed between saline-treated and PMSG-treated animals (0.84 +/- 0.06 vs 0.88 +/- 0.08 nmol/mg microsomal protein). Cytochrome b5 concentration and NADPH-cytochrome c reductase and ferricyanide reductase activities were not significantly affected by PMSG treatment. Similar results were obtained when immature and hypophysectomized rats were treated with oestradiol benzoate. Hepatic glutathione (GSH) S-transferase activity was significantly stimulated over control values when hypophysectomized or immature animals were treated with PMSG, oestradiol benzoate or 3-methylcholanthrene. Treatment of animals simultaneously with PMSG or oestradiol benzoate and 3-methylcholanthrene resulted in higher transferase activity than did either treatment alone. Oestradiol benzoate or PMSG treatment of immature female rats resulted in an approximate twofold increase in hepatic aryl hydrocarbon hydroxylase (AHH) activity. However, AHH activity in hypophysectomized animals was not significantly increased by PMSG or oestradiol benzoate treatment. It is concluded that PMSG or oestradiol benzoate treatment of immature female rats resulted in increased total cytochrome P-450 concentration and AHH activity in hepatic microsomes. Glutathione S-transferase activity was also stimulated. Neither PMSG nor oestradiol benzoate stimulated cytochrome P-450 levels or AHH activity in hypophysectomized rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of oestradiol benzoate and tamoxifen on the growth of and induction of progesterone receptors in the uterus and mammary gland of immature pigs.

Intramuscular injection of oestradiol benzoate (0.1, 1 or 10 micrograms/kg per day) and tamoxifen (0.1 or 1 mg/kg per day) to 6-week-old immature pigs for 7 days induced a dose-dependent increase in the wet weight of the uterus and in the total content of uterine DNA, RNA and protein. Both compounds also stimulated a dose-dependent increase in the concentration of progesterone receptors in uterine cytosolic extracts (in terms of either fmol/mg DNA or fmol/g uterus). The concurrent administration of tamoxifen with oestradiol benzoate provoked significant (P less than 0.05) increases in total uterine protein and in the concentration of progesterone receptors (P less than 0.01) compared with treatment with oestradiol benzoate alone. Hence tamoxifen is an oestrogen agonist in the uterus of immature pigs. The effects of oestradiol benzoate and tamoxifen on mammary growth in immature pigs were assessed by image analysis of mammary sections across the gland (in a ventro-dorsal direction through the teat). Oestradiol benzoate at 10 micrograms/kg per day stimulated a fourfold increase in mammary duct area (P less than 0.01), and tamoxifen, at doses of 0.1 or 1 mg/kg per day, stimulated a threefold increase (P less than 0.05). Tamoxifen partially inhibited (P less than 0.05) the effect of oestradiol benzoate. The concentration of progesterone receptors was found to be very heterogeneous in cytosol extracts of mammary tissue of immature pigs and independent of treatment with oestradiol benzoate and/or tamoxifen.

Animals↗
PubMed1982

Subunit structure of oxygenase component in benzoate-1,2-dioxygenase system from Pseudomonas arvilla C-1.

Benzoate-1,2-dioxygenase system from Pseudomonas arvilla C-1 consists of two protein components, benzoate-1,2-dioxygenase reductase and benzoate-1,2-dioxygenase (Yamaguchi, M., and Fujisawa, H. (1980) J. Biol. Chem. 255, 5058-5063). Benzoate-1,2-dioxygenase exhibited two protein bands (alpha and beta) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their molecular weights were estimated to the 50,000 and 20,000, respectively. The intensities of protein staining on polyacrylamide gels suggested that these two subunits were present in equimolar quantities in benzoate-1,2-dioxygenase. Molecular weight of benzoate-1,2-dioxygenase was estimated to be 201,000 by sedimentation equilibrium (Yphantis method). The values of molecular weights of native enzyme and its subunits suggested that the subunit structure of benzoate-1,2-dioxygenase may be alpha 3 beta 3. Cross-linking experiments also suggested the same subunit structure. These two subunits were separated from each other by Ultrogel AcA44 chromatography in the presence of 6 M urea. Amino acid compositions of the two subunits were examined and compared with that of native enzyme. NH2-terminal amino acids of alpha and beta subunits were both serine, and isoelectric points of alpha and beta in the presence of 6 M urea were determined to be pH 5.6 and pH 4.8, respectively. The enzyme contained 8.2 mol of iron and 5.9 mol of labile sulfide/mol of enzyme, suggesting the presence of additional iron atoms besides iron-sulfur clusters. The isolated beta subunit did not contain any significant amounts of iron and labile sulfide, but the alpha subunit contained approximately 2 mol each of iron and labile sulfide and exhibited an absorption spectrum of binuclear iron cluster type.

Amino Acids↗
PubMed2000

Regulation of expression of the Aspergillus niger benzoate para-hydroxylase cytochrome P450 system.

Cytochrome P450 enzyme systems are found throughout nature and are involved in many different, often complex, bioconversions. In the endoplasmic reticulum of the filamentous fungus Aspergillus niger a cytochrome P450 enzyme system is present that is capable of the para-hydroxylation of benzoate. The expression of the two genes encoding the components of this system, the cytochrome P450 gene encoding benzoate para-hydroxylase (bphA) and the gene encoding cytochrome P450 reductase (cprA), is inducible by benzoate. The BPH system was used as a model system to study the mechanisms that result in co-regulation of both components of an eukaryote cytochrome P450 enzyme system. Deletion analysis of the transcription control regions of cprA and bphA resulted in the identification of a region that was involved in benzoate induction of gene expression. The functional competence of the cprA Benzoate Responsive Region thus defined was demonstrated directly by cloning this fragment upstream of a constitutively expressed mini-promoter and analysing expression of the hybrid transcription control region in a lacZ reporter system. Further analysis of cprA gene expression revealed a clear quantitative discrepancy between induction at the protein level (approximately 4-fold) and at the transcription level (> 20-fold). The majority of the transcripts observed after benzoate induction (cprAbeta) were larger then the constitutively expressed cprAalpha transcript. The difference in size between the cprAalpha and cprAbeta transcript is caused by differential promoter use. As the longer cprAbeta transcript carries a small uORF we propose that post-transcriptional regulation of CPR expression underlies the discrepancy in the degree of induction at the protein and transcriptional level. Our results show that regulation of CPR expression is particularly complex, involving regulatory promoter elements, differential promoter use and regulation at the post-transcriptional level.

Amino Acid Sequence↗
PubMed1996

Cytochrome P450rm from Rhodotorula minuta catalyzes 4-hydroxylation of benzoate.

Rhodotorula minuta, a red yeast, produces a cytochrome P450, tentatively named P450rm, catalyzing the formation of isobutene from isovalerate. We found that P450rm interacted with benzoate and the dissociation constant of P450rm for benzoate was 36 microM. A reconstituted system that consisted of purified P450rm and cytochrome P450 reductase catalyzed the 4-hydroxylation of benzoate in addition to the formation of isobutene; the turnover rate was approximately 40 nmol/min/nmol P450rm. The P450rm-monooxygenase system was specific for benzoate and did not catalyze hydroxylation of other aromatic carboxylates. Since only a benzoate 4-hydroxylase that requires tetrahydropteridine has been isolated to date, P450rm appears to be the first isolated cytochrome P450 that acts as a benzoate 4-hydroxylase. The P450rm-monooxygenase system in microsomes of R. minuta might function in the degradation of L-phenylalanine on the pathway to beta-ketoadipate.

Adipates↗
PubMed1992

Sodium benzoate in the treatment of acute hepatic encephalopathy: a double-blind randomized trial.

A prospective randomized double-blind study was conducted to evaluate the efficacy of sodium benzoate in the treatment of acute portal-systemic encephalopathy. Seventy-four consecutive patients with cirrhosis or surgical portasystemic anastomosis and hepatic encephalopathy of less than 7 days duration were randomized to receive lactulose (dose adjusted for 2 or 3 semiformed stools/day) or sodium benzoate (5 gm twice daily). Assessment of response included mental status, asterixis, arterial ammonia level, electroencephalogram and number-connection test. Each was given a score between 0 and 4+. A portal-systemic encephalopathy index was calculated with these scores. Visual, auditory and somatosensory evoked potentials and a battery of psychometric tests for intelligence and memory were also performed to assess improvement. Thirty-eight patients received sodium benzoate; 36 took lactulose. Thirty patients (80%) receiving sodium benzoate and 29 (81%) receiving lactulose recovered; the remaining patients died. Improvement in portal-systemic encephalopathy parameters occurred in both treatment groups and was similar (p greater than 0.1). Electroencephalogram and evoked potentials were not as helpful as mental status in assessing of recovery. Psychometric test scores remained abnormal after recovery of mental status (21 to 42 days) and were probably too sensitive for monitoring of these patients. The incidence of side effects was similar in the two treatment groups. The cost of lactulose for one course of therapy was 30 times that of sodium benzoate. We conclude that sodium benzoate is a safe and effective alternative to lactulose in the treatment of acute portasystemic encephalopathy.

Acute Disease↗
PubMed2001

Purification and characterization of benzoate-para-hydroxylase, a cytochrome P450 (CYP53A1), from Aspergillus niger.

Benzoate-para-hydroxylase (CYP51A or BpH) and NADPH:cytochrome P450 reductase from the filamentous fungus Aspergillus niger were purified to apparent homogeneity, using an overproducing A. niger strain. This is the first membrane-bound fungal cytochrome P450 to be isolated and characterized. Combining BpH with NADPH:cytochrome P450 oxidoreductase in the presence of the phospholipid dilauryl phosphatidylcholine restored the BpH activity, although to only a minor extent. Spectral analysis of BpH showed characteristic spectra for a cytochrome P450. Substrate binding studies with purified BpH as a function of temperature and as a function of pH were performed. Temperature-dependent studies, at pH 8.0, showed that the simplified spin equilibrium model originally proposed for camphor binding to cytochrome P450cam (M. T. Fisher and S. G. Sligar, 1987, Biochemistry 26, 4797-4803) also applies to the benzoate-BpH system. Two equilibrium constants were determined, K(1) for substrate binding without a spin change and K(2) for the spin change of the benzoate-BpH complex. pH-dependent binding studies showed that both K(1) and K(2) increase with pH, indicative of a higher affinity. As K(1) decreases more strongly with pH than K(2), we suggest that benzoate first binds to a binding site on the outside of the protein in a pH-dependent way, followed by transfer to the inside of the protein causing a spin change at the heme iron. The strong pH dependence of K(1) could be the result of the need to break salt bridges at the binding site on the outside of the protein. pH-dependent kinetic studies with microsomes showed that the apparent K(M) values followed the trend observed for benzoate binding to purified BpH, while k(cat) values were virtually constant between pH 6.6 and 8.0 and decreased above pH 8, probably due to loss of productive interaction between BpH and NADPH:cytochrome P450 oxidoreductase. Research into the substrate specificity of BpH showed that BpH can only use benzoic acid and some of its derivatives. Monosubstitution on the phenyl ring is allowed but only at certain positions with specific, not too large groups. Substitution always leads to a lower affinity of the substrate. With one exception, all substrates were converted to their 4-hydroxy derivative. The exception, 3-methoxybenzoate, was demethylated to yield 3-hydroxybenzoate only. The restricted number of substrates and the specificity in catalysis suggest that BpH is not a general-purpose hydroxylase but that its role is confined to benzoate hydroxylation in the beta-ketoadipate pathway of A. niger.

Aspergillus niger↗
PubMed1976

Characterization of a benzoate permease mutant of Pseudomonas putida.

A spontaneous mutant of Pseudomonas putida (PRS 2017) has been isolated which is incapable of growth on benzoate, does not induce the enzymes of the catechol branch of the beta-ketoadipate pathway when grown in the presence of benzoate, cannot accumulate radioactively labeled benzoate, yet grows well with mandelate as sole source of carbon and energy. This strain apparently lacks a benzoate permease, which in the wild type shows a Km of about 0.1 mM for benzoate, is inducible, and is not under the control of the regulatory system which governs the induction of the enzymes of the catechol branch of the beta-ketoadapate pathway. The lesion in PRS2017 is apparently single site and maps near other genes governing benzoate dissimilation.

Adipates↗
PubMed1989

Inhibition of pyruvate carboxylase by sequestration of coenzyme A with sodium benzoate.

Pyruvate-dependent CO2 fixation by isolated mitochondria was strongly inhibited by sodium benzoate. Pyruvate carboxylase was identified as a site of inhibition by limiting flux measurements to assays of pyruvate carboxylase coupled with malate dehydrogenase. Benzoate reduced pyruvate-dependent incorporation of [14C]KHCO3 into malate and pyruvate-dependent malate accumulation by 74 and 72%, respectively. Aspartate-dependent malate accumulation was insensitive to benzoate, ruling out malate dehydrogenase as a site of action. Inhibition by benzoate was antagonized by glycine, which sharply accelerated conversion of benzoate to hippurate. Assays of coenzyme A and its acyl derivatives revealed inhibition to correlate with depletion of acetyl CoA and accumulation of benzoyl CoA. Depletion of acetyl CoA was sufficient to account for greater than 50% reduction in pyruvate carboxylase activity. Competition between acetyl CoA and benzoyl CoA for the activator site on pyruvate carboxylase was insignificant. Results support the interpretation that the observed inhibition of pyruvate carboxylase occurred primarily by depletion of the activator, acetyl CoA, through sequestration of coenzyme A during benzoate metabolism.

Acetyl Coenzyme A↗
PubMed1989

Potentiation of benzoate toxicity by glyoxylate. Inhibition of pyruvate carboxylase and the urea cycle.

It has been proposed that administration of non-nitrogenous precursors to glycine is necessary to realize the full potential of benzoate metabolism as a pathway for disposal of waste nitrogen during ammonia intoxication (Coude et al., Clin Chim Acta 136: 211-217, 1984). However, when glyoxylate, a keto acid precursor to glycine, was administered with benzoate 1 hr prior to a challenge of ammonia, protection against ammonia toxicity was less successful than with benzoate alone. At the cellular and subcellular levels, glyoxylate and benzoate each inhibited the urea cycle in isolated hepatocytes and pyruvate carboxylase in isolated mitochondria. The action of each drug was associated with depletion of aspartate content in isolated hepatocytes and reduction of pyruvate-dependent incorporation of CO2 into aspartate in assays with isolated mitochondria. Depression of aspartate regeneration by inhibition of pyruvate carboxylase is a likely mechanism for impairment of urea cycle activity by both drugs. In whole animals, inhibition of pyruvate carboxylase may contribute to benzoate toxicity and the adverse influence of glyoxylate on benzoate therapy.

Animals↗
PubMed1985

Effects of salicylate and two benzoates on contractions of the field-stimulated guinea-pig vas deferens and atrium.

Na salicylate (3.75-30 mmol/l), Na benzoate (10.5-84 mmol/l) and Na metaiodobenzoate (0.375-0.8 mmol/l) concentration dependently reduced the contractile force of the field-stimulated guinea-pig vas deferens. Contractions elicited by either noradrenaline (0.5 mmol/l) or direct muscle stimulation were also reduced while the maximum twitch response induced by KCl (160 mmol/l) was unaffected. The twitch-inhibiting potency of salicylate and the benzoates correlated to their lipophilicity. The positive inotropic effect of field stimulation of the atrium during the refractory period was not altered by the two benzoates but was reduced by Na salicylate. It is concluded that salicylate and benzoate anions are incorporated into smooth muscle cell membranes of the vas and reduce excitability. No binding seems to occur in membranes of the atrial myocardium or the sympathetic neuron terminals and salicylate or benzoate compounds do not interfere with the liberation of neurotransmitters. In addition to its influence on the cell membrane Na salicylate can diminish contractions by uncoupling oxidative phosphorylation. The use of benzoates can help to distinguish between the two effects.

Animals↗
PubMed1996

Evaluation of media for enumerating heat-stressed, benzoate-resistant Zygosaccharomyces bailii.

A study was undertaken to determine the efficacy of yeast malt extract agar (YMA), acidified YMA (YMAA), acidified tryptone glucose yeast extract agar (TGYA) and Zygosaccharomyces bailii agar (ZBA) for enumerating two strains of Z. bailii (FRR 2227 and FRR 3680) grown and heated in blueberry syrup containing 0, 300 and 600 micrograms/ml sodium benzoate. Cells were heated at 50, 51 or 52 degrees C for 0, 15, 30 or 45 min before spread plating diluted samples on enumeration media and incubating at 30 degrees C for 5 days. Strain FRR 3680 exhibited higher heat resistance than did strain FRR 2227. Regardless of the sodium benzoate concentration in growth and heating media, or the temperature and time of heating, non-selective YMA supported recovery of the highest number of viable cells, followed by TGYA for strain FRR 2227 and TGYA or ZBA for strain FRR 3680. YMAA supported the lowest recovery of heat-stressed cells. The concentration of sodium benzoate in the growth medium did not have a significant effect on tolerance of strain FRR 3680 to heat; however, tolerance of strain FRR 2227 to heat decreased when cells were grown in blueberry syrup containing increased concentrations of sodium benzoate. Regardless of the sodium benzoate concentration in the growth medium, both strains exhibited increased sensitivity when heated in blueberry syrup containing increased concentrations of sodium benzoate. Overall, TGYA was judged best among selective media for enumerating Z. bailii because of its ability to support colony development by heat-stressed cells and because of the ease of counting and differentiating colonies.

Benzoates↗
PubMed1995

Tissue acylcarnitine and acyl-coenzyme A profiles in chronically hyperammonemic mice treated with sodium benzoate and supplementary L-carnitine.

The aim of the present study, was to establish the hepatic profile of acyl-coenzyme A (acyl-CoA) in relation to the hepatic profile of acylcarnitines in chronically hyperammonemic spf mice (hereditary deficiency in ornithine transcarbamylase) treated with sodium benzoate alone or in combination with L-carnitine. The muscular profile of the acylcarnitines and the stability of sarcolemma were also assessed in the same mice. Following administration of sodium benzoate, we observed decreases in hepatic total and free coenzyme A and in acetyl-CoA, which was accompanied by an increase in hepatic acyl-CoA. This treatment also resulted in increased free carnitine, decreased total carnitine, and decreased short and medium chain acylcarnitines in the liver. Increases in plasma creatine kinase levels, muscular free, total, and in short and medium chain acylcarnitines were also observed in this treatment group. In mice receiving a combination of sodium benzoate and L-carnitine, increases in free and total coenzyme A, acetyl-CoA and in free, total and esterified hepatic carnitines were observed. In this treatment group, the plasma level of creatine kinase was found to be reduced, while the free muscular carnitine was increased. Our results indicate that sodium benzoate is implicated in the decrease of total hepatic coenzyme A, through either an inhibition of CoA synthesis or activation of its degradation. The distribution of hepatic coenzyme-A and of hepatic and muscular carnitine (free or esterified) is altered following administration of sodium benzoate which results in a further destabilization of the sarcolemma induced by hyperammonemia. Supplemental treatment with L-carnitine was shown to have a positive effect by increasing hepatic coenzyme A and carnitine levels and restoring the stability of the sarcolemma caused by the treatment of sodium benzoate alone.

Acetylcarnitine↗
PubMed2005

The effects of benzoate, cyclohex-1-ene carboxylate, and cyclohexane carboxylate on biotransformation of o-phthalate in sediment slurries under sulfate-reducing conditions.

It was found in this study that while addition of the predicted intermediate product benzoate did not, addition of cyclohex-1-ene or cyclohexane carboxylate did inhibit the biotransformation of o-phthalate in sulfate-reducing o-phthalate-adapted sediment slurries under a CO2/H2 atmosphere. Biotransformation rates of benzoate were slightly higher than those of o-phthalate in sediment slurries amended with o-phthalate plus benzoate. By using the most probable number (MPN) method to determine the number of o-phthalate transformers, similar growth dynamics of o-phthalate transformers were observed in sediment slurries amended with or without benzoate. The number of benzoate transformers (1x10(9)cellsg-1 of sediment) remained the same in sediment slurries repeatedly amended with a mixture of o-phthalate and benzoate after their transformation. o-Phthalate transformers decreased about three orders (1x10(9) to 1x10(6)cellsg-1 of sediment) of magnitude after biotransformation of o-phthalate, and remained at the low number thereafter until re-amendment with o-phthalate. o-Phthalate transformers increased to 1x10(8)cellsg-1 of sediment just prior to the onset of biotransformation of the o-phthalate.

Bacteria, Anaerobic↗
PubMed2003

Pediatric drug formulations of sodium benzoate: II. Coated granules with a lipophilic binder.

Sodium benzoate is used as a therapeutic agent in the treatment of some rare disorders that predominantly affect children. In preliminary investigations, liquid and semi-solid formulations of sodium benzoate failed because children refuse the oral uptake due to the bad taste of the drug. Recently developed microcapsules with macrogol as a hydrophilic binder raise concern in high-dose treatment regimens because acceptable daily intake limits are exceeded. A novel microcapsule formulation was developed consisting of a lipophilic core with high sodium benzoate load and a saliva-resistant coating. A new powder quality of saturated triglycerides from plant origin was introduced which complies with the Ph. Eur. monograph 'Hard fat'. Sodium benzoate and the triglyceride were mixed and directly extruded at room temperature. The extrudates were spheronized and coated in a fluidized-bed process. The resulting coated granules are small-sized microcapsules and taste neutrally. They can be mixed with food before administration. As the amount of released sodium benzoate is negligible within the first minutes, children do not recognize the bad taste and accept the medication. Recently, sodium benzoate in this novel formulation has been designated by the European Community as an orphan drug in the treatment of non-ketotic hyperglycinemia.

Capsules↗
PubMed1983

Studies on the mechanism of the antifungal action of benzoate.

A method is described for the determination of the pH of intracellular water based on the distribution of [14C]benzoate (0.01 mM) between intra- and extra-cellular water. Benzoate at higher concentrations (2-10mM) enters the yeast cell in the undissociated form, and its neutralization within the cell can cause a shift of the pH of the intracellular water by more than 1 pH unit. Benzoate causes an accumulation of the two hexose monophosphates of yeast glucose fermentation and a decrease in intermediates beyond phosphofructokinase, suggesting inhibition at this stage. Benzoate also causes a concomitant fall in [ATP]. Phosphofructokinase is inhibited to a greater extent than hexokinase at acid pH. There is a relationship between intracellular pH, phosphofructokinase inhibition and CO2 production, suggesting that the antifungal action of benzoate is caused by an accumulation of benzoate at low external pH, which lowers the intracellular pH into the range where phosphofructokinase is sensitive. The subsequent inhibition of glycolysis causes a fall in [ATP] and thus restricts growth.

Adenine Nucleotides↗
PubMed2002

Benzoate X receptors alpha and beta are pharmacologically distinct and do not function as xenobiotic receptors.

The Xenopus benzoate nuclear hormone receptors, BXRalpha and BXRbeta, share 82% identity within their ligand-binding domains and are classified as members of the NR1I2 subfamily that includes the mammalian steroid and xenobiotic receptor, SXR/PXR. Although alkyl benzoates have been identified as endogenous ligands, the exact role of the benzoate receptors in amphibian physiology has not been established. In this report, we show that BXRalpha and BXRbeta are pharmacologically distinct from each other: BXRalpha is more promiscuous than BXRbeta with respect to both ligand specificity and co-activator recruitment. BXRalpha can be transactivated by a number of benzoate derivatives including 4-amino-butylbenzoate (4-ABB), 4-hydroxy-butylbenzoate (4-HBB), 3-hydroxy ethyl benzoate (3-HEB), and benzyl benzoate, but only 4-HBB acts as an agonist for both receptors. Furthermore, BXRalpha-specific agonists such as 4-ABB, chlorpyrifos, and trifluralin act as antagonists on BXRbeta. BXRs are widely distributed in adult tissues but do not show any enrichment in liver and intestine, major sites of SXR/PXR expression that are critical in xenobiotic metabolism. Neither BXR shows the broad specificity toward steroids or xenobiotics exhibited by SXR/PXR. Therefore, we conclude that the BXRs are pharmacologically distinct from each other and unlikely to serve as xenobiotic sensors.

Animals↗
PubMed1986

Effect of benzoate on the metabolism of fructose 2,6-bisphosphate in yeast.

When benzoate (2 mM, pH 3.5) was added together with glucose (0.1 M) to a suspension of Saccharomyces cerevisiae in the stationary phase, it caused a relative increase in the concentration of glucose 6-phosphate and fructose 6-phosphate and a decrease in the concentration of fructose 1,6-bisphosphate. These effects are in confirmation of similar observations made by Krebs et al. [Biochem. J. 214, 657-663 (1983)] and are indicative of an inhibition of 6-phosphofructo-1-kinase. Benzoate also caused an about fourfold relative decrease in the concentration of fructose 2,6-bisphosphate, an increase in that of cyclic AMP with no change in that of ATP. It also greatly decreased the activation of 6-phosphofructo-2-kinase, but not that of trehalase, both of which normally occur upon addition of glucose to a yeast suspension. When added 10 min after glucose, benzoate caused a rapid (within 2-3 min) decrease in fructose 2,6-bisphosphate concentration and in 6-phosphofructo-2-kinase activity. In the presence of benzoate, there was also a parallel decrease in the concentration of fructose 2,6-bisphosphate and in the rate of ethanol production when the external pH was dropped from 5.0 to 2.5, with minimal change in the concentration of ATP. Purified 6-phosphofructo-2-kinase was inhibited by benzoate and also by an acid pH. Experiments with cell-free extracts did not provide an explanation for the rapid disappearance of fructose-2,6-bisphosphate or the inactivation of 6-phosphofructo-2-kinase in yeast upon addition of benzoate.

Adenosine Triphosphate↗