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PubMed1985

[Pharmacokinetic and pharmacological studies on cetraxate, an anti-ulcer agent].

Cetraxate hydrochloride was administered either orally or intravenously to rabbits, and its concentration in body fluids was determined by using the HPLC method. Cetraxate was easily hydrolyzed in the gastrointestinal tract and blood, and it was metabolized to p-hydroxyphenylpropionic acid (PHPA) and a new metabolite, p-hydroxybenzoic acid (PHBA). After oral administration of cetraxate hydrochloride, a large amount of unchanged drug was distributed to the gastric wall. PHPA was distributed in all the organs examined, excluding the brain. To determine whether or not the anti-ulcer action of cetraxate hydrochloride was due to the unchanged drug, PHPA, or tranexamic acid, studies with aspirin and water-immersion -induced gastric ulcers in rats were performed. As a result, it was found that tranexamic acid had an anti-ulcer action similar to that of cetraxate hydrochloride.

Animals↗
PubMed2004

Prediction of the charge states of folded proteins in electrospray ionization.

Earlier work from this laboratory dealt with the observation that the charge states of non-denatured proteins can be decreased by use of buffer salts in which the gas-phase basicity of conjugate base B, GB(B), of the buffer cations is high. A theoretical model was developed and applied to several small proteins. The predictions of the charge states were found to be in good agreement with those observed experimentally. Because the computational model is based on the charge residue model (CRM), the observed agreement lends support for the CRM. In the present work, the same model is applied to recent data by Catalina et al. who showed that very large charge reductions are achieved with very high GB(B) proton sponges. Their data included lysozyme but also the very much larger proteins, p-hydroxybenzoate hydroxylase (PHBH), 90 kDa and glutamate synthase (GLTS), 166 kDA. The present work examines the performance of the model for the much stronger bases and the very much larger proteins. It is found that the predictions of the charge states agree well for the small protein lysozyme but somewhat less well with the experimental results for PHBH and GLTS. The causes for the lack of good agreement with the large proteins are examined.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1988

Enzymatic dehalogenation of 4-chlorobenzoate by extracts from Arthrobacter sp. SU DSM 20407.

In extracts from Arthrobacter sp. SU DSM 20407 an enzyme was detectable, that converted 4-chlorobenzoate into 4-hydroxybenzoate. This conversion was also observed when no oxygen was present in the reaction mixture. Boiling for 5 min destroyed the enzyme activity. 4-Bromo- and 4-iodobenzoate were substrates for the enzyme too, but not 4-fluorobenzoate, 4-chlorophenylacetate and 4-chlorocinnamic acid. The enzyme showed optimum activity at 16 degrees C and at pH 7-7.5. The specific activity in the extracts varied between 0.5 and 5 mU/mg of protein. Zn2+ and Cu2+ inhibited the enzyme, while H2O2 slightly activated. In contrast to all other 4-chlorobenzoate dehalogenases described before the enzyme was not inhibited by EDTA, nor was it activated by Mn2+. Other divalent ions also had no effect. The molecular mass of the enzyme was 45,000 +/- 5,000 Da as judged by gel-filtration.

Arthrobacter↗
PubMed1987

Kinetic enzymatic method for automated determination of HDL cholesterol in plasma.

A sensitive fixed-time kinetic enzymatic method for the measurement of high density lipoprotein cholesterol is described, as adapted for the Cobas Bio centrifugal analyser (Hoffmann LaRoche). The Boehringer Mannheim cholesterol esterase/cholesterol oxidase/peroxidase/3,4-dichlorophenol kinetic reagent was modified by the inclusion of 2,4,6-tribromo-3-hydroxybenzoic acid which reacts with hydrogen peroxide and 4-aminophenazone to produce a quinone-imine dye with a greater molar absorptivity than that produced with phenol. The method has been developed for the determination of HDL fractions isolated with polyethylene glycol 6000, for which a reagent of high sensitivity is required. The method is linear to at least 3.88 mmol/l of HDL cholesterol and the coefficients of variation for within-run and day-to-day precision were less than 3.0%. Correlation of the kinetic HDL cholesterol method with an equilibrium method was good (R = 0.9980). The assay is rapid, inexpensive and large numbers of specimens can be processed conveniently.

Autoanalysis↗
PubMedDate not supplied

Inhibition of pancreatic lipase by phenolic acids--examination in vitro.

The influence of addition 2,4,6,8, and 10 microM of benzoic and cinnamic acids and selected phenolic acids (salicylic, p-hydroxybenzoic, gentisic, protocatechuic, vanillic, syringic, o-coumaric, p-coumaric, caffeic, ferulic, sinapic) on the activity of pancreatic lipase was examined in vitro. The strongest inhibition activities were observed with caffeic, ferulic and benzoic acid, while sinapic and gentisic acids produced the lowest inhibition.

Animals↗
PubMed1988

Enzymatic determination of high density lipoprotein phospholipid using a sensitive reagent and a Cobas Bio Centrifugal Analyzer.

A sensitive enzymatic method for the measurement of high density lipoprotein choline-containing phospholipids (HDL-pc) was adapted to a Cobas Bio Centrifugal Analyzer. The Boehringer Mannheim phospholipase D/choline oxidase/peroxidase reagent was modified by the inclusion of 2,4,6,-tribromo-3-hydroxybenzoic acid (TBHBA) which reacts with hydrogen peroxide and 4-aminophenazone to produce a quinone-imine dye with a fourfold greater molar absorption than that produced with phenol. The method has been developed for the determination of HDL fractions isolated with polyethylene glycol 6000, for which a reagent of high sensitivity is required. The method is linear to 5.5 mmol/l of HDL-pc and the CVs for within-run and day-to-day imprecision were less than 3.5%. Correlation of HDL cholesterol (HDL-c) with HDL-pc values in 200 healthy subjects was good (r = 0.9024). The mean (+/- SD) HDL-pc value for men was 1.12 (+/- 0.26) and for women, 1.34 (+/- 0.29) mmol/l. The assay is inexpensive and large numbers of specimens can be processed rapidly and conveniently.

Bromobenzoates↗
PubMed1979

Metabolism of beclamide, N-benzyl-3-chloropropionamide, in man.

1. Following oral administration of [14C]beclamide to human subjects there was almost complete elimination of radioactivity in the urine within 48 h. 2. Less than 1% of the administered dose was excreted unchanged. 3. The major metabolites were (a) N-(4-hydroxybenzyl)-3-chloropropionamide, (4-hydroxybeclamide; c. 56%), which was eliminated to a small extent in the free form and as a sulphate but mainly as a glucuronide, and (b) hippuric acid (c. 20%). 4. Six minor metabolites were also detected, of which the following were identified: benzoic acid (up to c. 7%), N-(4-hydroxybenzyl-3-chloro-2-hydroxypropionamide, (dihydroxy-beclamide; c. 2%, mostly as a glucuronide) and 4-hydroxybenzoic acid (c. 0.6%, partly as a glucuronide).

Adult↗
PubMed1982

Identification of phenolic acids in human urine by ion monitoring.

1. Two-different double derivatization techniques and two different g.l.c. systems were used to separate isomeric phenolic carboxylic acids in normal human urine. 2. Carboxylic acids were converted into n-butyl esters and phenolic functions into trifluoroacetic acid esters. 3. n-Butyl trifluoroacetoxybenzoates were separated by g.l.c. and detected by mass spectrometric single-ion monitoring. 4. Trifluoroacetates were hydrolysed under mild conditions, and liberated phenolic groups were subjected to flash methylation. 5. n-Butyl methoxybenzoates were separated by g.l.c. and detected by flame ionization. 6. All derivatives were identified by comparison of retention times and mass spectra with those of authentic reference standards. 7. The urine of a normal vegetarian volunteer was examined. 8. The presence of meta- and para-hydroxybenzoic acids, vanillic acid and isovanillic acid was confirmed by unambiguous techniques.

Chromatography↗
PubMed1991

Human liver sulphotransferase and UDP-glucuronosyltransferase: structure-activity relationship for phenolic substrates.

1. Human liver sulphotransferase and UDP-glucuronosyltransferase were studied with phenol, methyl-, ethyl-, propyl-, butyl-, phenyl-, nitro-, amino-phenols and hydroxybenzoic acids as substrates. 2. The Michaelis-Menten constants (Km) and the maximum velocities of reaction (Vmax) of sulphotransferase and UDP-glucuronosyltransferase for each substrate were measured. 3. The Km values for sulphotransferase varied over 5000-fold whereas they varied over 25-fold for UDP-glucuronosyltransferase. 4. Sulphotransferase and UDP-glucuronosyltransferase have different structure-activity relationships with phenolic substrates.

Adult↗
PubMed1997

Bis[2-(4-carboxyphenoxy)carbonylethyl]phosphinic acid (BCCEP): a new reagent for hemoglobin modification.

The synthesis and hemoglobin cross-linking studies of a novel organic reagent, bis[2-(4-carboxyphenoxy)carbonylethyl]phosphinic acid (BCCEP; 2) has been reported. The reagent was synthesized in four steps from hydroxybenzoic acid. The tri-sodium salt of BCCEP was employed to cross-link oxyHb, and the product was purified by DEAE-cellulose chromatography. The purified material was analyzed by SDS-PAGE, IEF, and HPLC analyses, which clearly showed the formation of covalent, intramolecular cross-links. While SDS-PAGE analyses of individual bands pointed to the molecular weight range of 32 kDa, the HPLC analyses suggested that the cross-links had formed between beta 1-beta 2 subunits. The oxygen equilibrium measurements and the Hill plots were performed on the purified bands to assess oxygen affinity as well as cooperativity of oxygen binding of the modified hemoglobins. All bands corresponding to modified hemoglobins showed significantly reduced oxygen affinity as compared with that of cell-free hemoglobin, as desired. The modified hemoglobins, however, exhibited somewhat reduced oxygen-binding cooperativity as contrasted with human stroma-free hemoglobin. Molecular dynamics simulation studies (Insight II/Discover/Biosym) on the Reagent-HbA0 complex suggested that the most likely amino acid residues involved in the cross-linking are Lys82 or N-terminal Val1 on one of the beta chains, and Lys144 on the other.

Chromatography, DEAE-Cellulose↗
PubMedDate not supplied

Reduction of hydroxyl radical generation in a rat hindlimb model of ischemia-reperfusion injury using crosslinked hemoglobin-superoxide dismutase-catalase.

The effects of PolyHb (intermolecularly crosslinked hemoglobin) and PolyHb-SOD-CAT (intermolecularly crosslinked hemoglobin, superoxide dismutase and catalase) on the production of hydroxyl radical was studied using a rat hindlimb model of ischemia-reperfusion. Hydroxyl radical generation was assessed by an indirect assay based on the hydroxylation of 4-hydroxybenzoate. The hydroxylation product, 3,4 dihydroxybenzoate (3,4 DHBA), was analyzed by high performance liquid chromatography and electrochemical detection. The identification of 3,4 DHBA was confirmed by analysis of authentic standard and an in vitro hydroxyl radical generation system. Ischemia was induced in both hindlimbs by ligation of the infrarenal aorta. After a 4hr ischemic period, hindlimbs were simultaneously perfused with PolyHb-SOD-CAT (5 g/dl) into one limb and PolyHb (5 g/dl) into the other limb via femoral arterial catheters. Each perfusate also contained the hydroxyl radical trap, 4-hydroxbenzoate (5 mM). Femoral venous effluents were analyzed for the presence of the 3,4 DHBA. Data indicates that greater 3,4 DHBA production occurs during PolyHb perfusion as compared to PolyHb-SOD-CAT. These preliminary results show that perfusion with PolyHb-SOD-CAT may alleviate oxidative stress in a model of ischemia-reperfusion.

Animals↗
PubMed1979

Bilirubin acidity. Titrimetric and 13C NMR studies.

Acidimetric titration of bilirubin IX-alpha, dissolved in excess aqueous sodium hydroxide, showed that two protons are dissociated with pK values well below 7 and that one or several additional acidic groups titrate with pK around 12.9. Precipitation of the nearly insoluble acid precluded determination of the two lower pK values by titration in aqueous solution. In dimethyl sulfoxide solution, four acidic protons were demonstrated, titrating two by two without precipitation. 13C NMR spectra of bilirubin IX-alpha were recorded and complete assignments were made by comparison with the spectra of bilirubin XIII-alpha and mesobilirubin etc. Such spectra, recorded after addition of 2 and 4 mol of base per mol of bilirubin IX-alpha, showed that both carboxyl groups are titrated by the first 2 mol of base, and both lactams by the following 2 mol of base. Cotitrations of bilirubin IX-alpha with other acids, o- and m-hydroxybenzoic acid and 2-pyridone, were used to determine relative pK values in dimethyl sulfoxide solution, and pK values for the four acidic protons of bilirubin IX-alpha in aqueous solution were calculated from the Born equation. Both carboxyl groups exhibited pK = 4.4, and both lactams pK = 13.0, in good agreement with values expected from the chemical structure of the bilirubin molecule. The implications of these findings for understanding the mechanism of bilirubin neurotoxicity are discussed.

Bilirubin↗
PubMed1981

Inhibition of brain glutamate decarboxylase by 4,5-dihydroxyisophthalic acid and related compounds.

Hydroxybenzoic and phthalic acids and their related compounds were tested for inhibitory activity to brain glutamate decarboxylase. Of mono-, di-, and trihydroxybenzoic acids, gallic acid was the most inhibitory, giving 50% inhibition at a concentration of 0.17 mM. Dihydroxybenzoic acids were less inhibitory than the trihydroxyacids but more than monohydroxybenzoic acids. Of the phthalic acid-related compounds tested, 4,5-dihydroxyisophthalic acid was the most potent inhibitor, producing 50% inhibition at 0.61 microM. The inhibition of these compounds was competitive with respect to L-glutamate. The Ki values were 0.02, 1.2 and 4.9 microM for 4,5-dihydroxyisophthalic acid, 5-hydroxyisophthalic acid and gallic acid, respectively. When administered intraventricularly to mice, 4,5-dihydroxyisophthalic acid produced a significant decrease in the gamma-aminobutyric acid content of the brain, resulting in induction of convulsions.

Animals↗
PubMed1981

Thielavin A and B, new inhibitors of prostaglandin biosynthesis produced by Thielavia terricola.

Two potent inhibitors of prostaglandin biosynthesis, thielavin A (C31H34O10) and B (C29H30O10), were isolated from cultures of Thielavia terricola. Both of these compounds were shown to be structurally related to depsides, thus consisting of three hydroxybenzoic acid groups. Concentrations required for 50% inhibition of the conversion of 14C-arachidonic acid into prostaglandins F2 alpha plus E2 by microsomes of ram seminal vesicles were 12 microM for thielavin A and 9 microM for thielavin B, respectively. Of the enzymatic steps involved in prostaglandin synthesis, thielavin A specifically inhibited the conversion of arachidonic acid into prostaglandin H2, while prostaglandin E2 synthesis from the endoperoxide was the most sensitive to thielavin B. Thromboxane A2 synthesis from prostaglandin H2 in bovine platelet microsomes were inhibited by 50% at concentrations of 150 and 350 microM of thielavin A and B, respectively. Thielavin B was significantly effective on carrageenan-induced oedema of rats when administered intravenously but on on oral administration. The anti-inflammatory activity was not detectable with thielavin A either on intravenous injection or on oral administration.

Animals↗
PubMed1991

TAN-931, a novel nonsteroidal aromatase inhibitor produced by Penicillium funiculosum No. 8974. II. Structure elucidation, chemical modification and biological activity.

The structure of TAN-931, a novel nonsteroidal aromatase inhibitor, was determined by chemical reactions and spectral analyses including 2D NMR experiments to be 4-(2,6-dihydroxybenzoyl)-3-formyl-5-hydroxybenzoic acid. Several derivatives of TAN-931 were prepared, and it was found that the 3-formyl and 2'- and/or 6'-hydroxyl groups play an important role in its inhibitory activity. Among the compounds synthesized, 4-(2,6-dihydroxybenzoyl)-3-formyl-5-methoxy-N,N-dimethyl-benzamide was found to be more effective than TAN-931 when administered orally.

Administration, Oral↗
PubMed1999

Kelletinin A, from the marine mollusc Buccinulum corneum, promotes differentiation in Hydra vulgaris.

The effects of kelletinin A [ribityl pentakis (p-hydroxybenzoate)] (KA), a natural compound isolated from the marine gastropod Buccinulum corneum, were studied in vivo in Hydra vulgaris during regeneration. KA caused a marked increase of regenerated tentacle numbers (ATN) and promoted transdifferentiation of epithelial cells into battery cells, and nematocyte differentiation. Morphological data were correlated to changes in acid and alkaline phosphatase levels, enzymes that have been described as regeneration markers.

Acid Phosphatase↗
PubMed2000

Hydroxyl radical production in the cortex and striatum in a rat model of focal cerebral ischemia.

BACKGROUND: Increases in hydroxyl radical production have been used as evidence of oxidative stress in cerebral ischemia/ reperfusion. Ischemia can also induce increased dopamine release from the striatum that may contribute to hydroxyl radical formation. We have compared hydroxyl radical production in the cortex and striatum as an index of oxidative stress in a rat model of focal cerebral ischemia with cortical infarction. METHODS: Using a three vessel occlusion model of focal cerebral ischemia combined with bilateral microdialysis, hydroxylation of 4-hydroxybenzoate (4HB) was continuously monitored in both hemispheres in either the lateral striatum or frontoparietal cortex. The ischemia protocol consisted of one hour equilibration, 30 min of three vessel occlusion, then release of the contralateral common carotid artery (CCA) for 2.5 h. RESULTS: Induction of ischemia resulted in a 30-fold increase in dopamine release in the lateral striatum. Compared to the nonischemic striatum, the ratio of the hydroxylation product 3,4-dihydroxybenzoate (34DHB) to 4HB (trapping agent) in the ipsilateral striatum increased significantly 30 min after ischemia induction. In contrast, during the 30 min of three vessel occlusion there was no increase in the ratio in the cortex. Following the release of the contralateral CCA, the ratio from the ischemic cortex increased significantly compared to sham-operated animals. However, under all circumstances, the 34DHB/4HB ratio was greater in the striatum than in the cortex. CONCLUSION: The increase in the 34DHB/4HB ratio in the lateral striatum coincides with the increased dopamine release suggesting a role for dopamine oxidation in the increased production of hydroxyl radicals. The significant increase in the ratio from the ischemic cortex compared to that from the sham-operated animals is consistent with increased oxidative stress induced by ischemia. However, the lower 34DHB/4HB ratio in the cortex which does not receive dopaminergic innervation compared to the striatum suggests a different mechanism for hydroxyl radical production. Such an alternate mechanism may represent a more toxic oxidative insult that contributes to infarction.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Flavonoids and free phenolic acids from Phytolacca americana L. leaves.

In the leaves of Phytolacca americana L. flavonoid compounds: kaempferol 3-O-beta-D-glucopyranoside, kaempferol 3-O-beta-D-xylopyranosyl (1-->2)-beta-D-glucopyranoside, kaempferol 3-O-alpha-L-rhamnopyranosyl (1-->2)-beta-D-glucopyranoside, kaempferol 3-O-diglucoside and quercetin 3-O-glucoside were identified by chemical and spectroscopic methods and using co-chromatography, phenolic acids: p-hydroxybenzoic, vanillic, synapic, p-coumaric ferulic and caffeic were also confirmed.

Flavonoids↗