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PubMed2004

In vitro comparative assessment of the scavenging activity against three reactive oxygen species of non-steroidal anti-inflammatory drugs from the oxicam and sulfoanilide families.

The study of the interaction of non-steroidal anti-inflammatory drugs (NSAIDs) with several reactive oxygen species is of great interest in inflammatory conditions where an uncontrolled release of these potentially damaging intermediates has been documented. This study focused on the scavenging of three species (hydroxyl radical, hydrogen peroxide and hypochlorous acid) with several members of the oxicam family and with the sulfoanilide nimesulide. Reaction with hydroxyl radical was assessed by the modified deoxyribose assay, and rate constants were calculated showing values between 0.8 and 1.1 x 10(10) M(-1) s(-1) for oxicams and of about 0.9 x 10(10) M(-1) s(-1) for nimesulide and ibuprofen. These were consistent with those of the literature but in the same range as those for other NSAIDs and for several thiol-containing molecules. The study of hydrogen peroxide scavenging by the horseradish peroxidase (HRP) assay lacked specificity but no interaction could be evidenced by the glutathione peroxidase assay. The scavenging of hypochlorous acid was finally investigated by the recently developed para-aminobenzoic acid assay which demonstrated better performances for meloxicam (1.7 x 10(4) M(-1) s(-1)) as compared to the other oxicams (tenoxicam: 4.0 x 10(4) M(-1) s(-1), piroxicam: 3.6 x 10(4) M(-1) s(-1), lornoxicam: 4.3 x 10(4) M(-1) s(-1)) and nimesulide (2.3 x 10(3) M(-1) s(-1)). These rate constants were, however, lower than those for thiol-containing molecules and ascorbate. These results suggest that the antioxidant properties of NSAIDs could be influenced by a proper pharmacomodulation as far as the scavenging of hypochlorous acid is concerned while the interest is quite limited for the scavenging of hydroxyl radical.

Anilides↗
PubMed1994

Vitamin and amino acid requirements of Lactobacillus plantarum strains isolated from green olive fermentations.

The requirement for essential amino acids and vitamins was determined in wild-type Lactobacillus plantarum strains isolated from green olive fermentation brines. All the strains were found to be auxotrophic with respect to the amino acids but some of them were prototrophic for pyridoxal, p-aminobenzoic acid and/or nicotinic acid. Their growth response to these nutrients was also studied and found to be quite heterogeneous. Nutritional requirement pattern as a criteria for selecting starter cultures is discussed.

Amino Acids↗
PubMed1975

The effect of p-aminosalicyclic acid on iron transport and assimilation in mycobacteria.

p-Aminosalicylic acid inhibits growth of Mycobacterium bovis BCG and Mycobacterium smegmatis more effectively if cells are growing with a sufficiency of iron (more than 1 mu g Fe/ml) in the medium than if cells are deficient in iron (smaller than 0.1 mu g Fe/ml). In iron-deficient cultures formation of mycobactin, an ionophore for iron transport, is strongly inhibited by p-aminosalicylic acid. Uptake of iron into cell suspensions is also inhibited and the activity of several iron-containing enzymes declines in cells exposed to p-aminosalicylic acid during their growth. p-Aminosalicylic acid is about 50 times more effective towards a mutant of M. smegmatis which required mycobactin under iron-deficient growth conditions than towards the wild-type parent. p-Aminosalicylate is taken up into cells by an active process independent of the salicylate uptake system, possibly by the route used for assimilation of p-aminobenzoate. (This could account for why p-aminobenzoic acid, but not salicylic acid, antagonizes the action of p-aminosalicylic acid.) With iron-deficient cells, salicylate assimilation is about 50 times greater than either p-aminosalicylate or p-aminobenzoate but with iron-sufficient cells and with the mycobactin mutant salicylate uptake is negligible whereas p-aminobenzoate and p-aminosalicylate uptakes are unaffected. p-Aminosalicylic acid at 3.3 mM (500 mu g/ml) partially inhibits the uptake of both p-aminobenzoate and, if it is occurring, that of salicylate as well. As p-aminosalicylic acid is always more effective when the intracellular concentration of salicylic acid is low, it probably acts as an anti-metabolite of salicylic acid, not, however, by inhibiting the conversion of salicylic acid to mycobactin, but probably somewhere along the metabolic pathway of iron uptake.

Aminobenzoates↗
PubMed2005

Biochemical and molecular characterization of an azoreductase from Staphylococcus aureus, a tetrameric NADPH-dependent flavoprotein.

Azo dyes are a predominant class of colourants used in tattooing, cosmetics, foods and consumer products. A gene encoding NADPH-flavin azoreductase (Azo1) from the skin bacterium Staphylococcus aureus ATCC 25923 was identified and overexpressed in Escherichia coli. RT-PCR results demonstrated that the azo1 gene was constitutively expressed at the mRNA level in S. aureus. Azo1 was found to be a tetramer with a native molecular mass of 85 kDa containing four non-covalently bound FMN. Azo1 requires NADPH, but not NADH, as an electron donor for its activity. The enzyme was resolved to dimeric apoprotein by removing the flavin prosthetic groups using hydrophobic-interaction chromatography. The dimeric apoprotein was reconstituted on-column and in free stage with FMN, resulting in the formation of a fully functional native-like tetrameric enzyme. The enzyme cleaved the model azo dye 2-[4-(dimethylamino)phenylazo]benzoic acid (Methyl Red) into N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. The apparent Km values for NADPH and Methyl Red substrates were 0.074 and 0.057 mM, respectively. The apparent Vmax was 0.4 microM min(-1) (mg protein)(-1). Azo1 was also able to metabolize Orange II, Amaranth, Ponceau BS and Ponceau S azo dyes. Azo1 represents the first azoreductase to be identified and characterized from human skin microflora.

Amino Acid Sequence↗
PubMed1973

Inhibition of dihydropteroate synthetase from Escherichia coli by sulfones and sulfonamides.

The inhibitory action of various diphenylsulfones and sulfonamides on dihydropteroate synthetase partially purified from Escherichia coli was examined. 4,4'-Diaminodiphenylsulfone (DDS; I(50) = 2 x 10(-5) M) and the monosubstituted derivatives 4-amino-4'-formamidodiphenylsulfone (I(50) = 5.8 x 10(-5) M) and 4-amino-4'-acetamidodiphenylsulfone (I(50) = 5.2 x 10(-5) M) were effective inhibitors of dihydropteroate synthetase activity. Disubstitution of the arylamine groups of DDS (4,4'-diformamidodiphenylsulfone and 4,4'-diacetamidodiphenylsulfone) resulted in complete loss of inhibitory activity. Both DDS (K(I) = 5.9 x 10(-6) M) and sulfadiazine (K(I) = 2.5 x 10(-6) M) were found to be competitive inhibitors of dihydropteroate synthetase. These findings are discussed in regard to the Bell and Roblin theory of structure-activity relationships for p-aminobenzoic acid antagonists.

Aminobenzoates↗
PubMed1997

High-sensitivity detection and postsource decay of 2-aminopyridine-derivatized oligosaccharides with matrix-assisted laser desorption/ionization mass spectrometry.

The sensitivities of oligosaccharide derivatives in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were compared using two matrixes, 2,5-dihydroxybenzoic acid (DHBA) and alpha-cyano-4-hydroxycinnamic acid (CHCA). For this purpose, maltopentaose was tagged with 2-aminopyridine (PA), 4-aminobenzoic acid ethyl ester (ABEE), and trimethyl-(p-aminophenyl)ammonium chloride (TMAPA). DHBA was more advantageous for enhancement than CHCA. Among the derivatives, the sensitivity with the PA-tagged maltopentaose showed a 100-fold improvement over the native one with DHBA as a matrix, while the oligesaccharide derivatized with ABEE and TMAPA gave 30- and 10-fold increases in sensitivity over the underivatized one. To obtain structural information from these derivatized oligosaccharides, postsource decay (PSD) during flight in the field-free drift in MALDI-TOFMS was measured. Predictable and reproducible fragmentation patterns could be obtained in all cases. Furthermore, we found matrix-dependence fragmentation with the PA-labeled oligosaccharide. With CHCA, a simple spectrum ascribable to Y series ions was obtained. On the other hand, both B and Y series ions were clearly observed in the DHBA case. The results demonstrate the usefulness of derivatives for sensitive analysis of oligosaccharides with MALDI.

Aminopyridines↗
PubMed2001

Molecular design and synthesis of artificial ion channels based on cyclic peptides containing unnatural amino acids.

A series of novel cyclic peptides composed of 3 to 5 dipeptide units with alternating natural-unnatural amino acid units, have been designed and synthesized, employing 5-(N-alkanoylamino)-3-aminobenzoic acid with a long alkanoyl chain as the unnatural amino acid. All cyclic peptides with systematically varying pore size, shape, and lipophilicity are found to form ion channels with a conductance of ca. 9 pS in aqueous KCl (500 mM) upon examination by the voltage clamp method. These peptide channels are cation selective with the permeability ratio P(Cl(-))/P(K(+)) of around 0.17. The ion channels formed by the neutral, cationic, and anionic cyclic peptides containing L-alanine, L-lysine, and L-aspartate, respectively, show the monovalent cation selectivity with the permeability ratio P(Na(+))/P(K(+)) of ca. 0.39. On the basis of structural information provided by voltage-dependent blockade of the single channel current of all the tested peptides by Ca(2+), we inferred that each channel is formed from a dimer of the peptide with its peptide ring constructing the channel entrance and its alkanoyl chains lining across the membrane to build up the channel pore. The experimental results are consistent with an idea that the rate of ion conduction is determined by the nature of the hydrophobic alkanoyl chain region, which is common to all the channels.

Amino Acid Sequence↗
PubMed2005

Mono-N-methylation of functionalized anilines with alkyl methyl carbonates over NaY faujasites. 4. Kinetics and selectivity.

[reaction: see text] In the presence of NaY faujasite as the catalyst, the reaction of bifunctional anilines (1-4: XC6H4NH2; X = OH, CO2H, CH2OH, and CONH2) with methyl alkyl carbonates [MeOCO2R': R' = Me or MeO(CH2)2O(CH2)2] proceeds with a very high mono-N-methyl selectivity (XC6H4NHMe up to 99%), and chemoselectivity as well, with other nucleophilic functions (OH, CO2H, CH2OH, CONH2) fully preserved from alkylation and/or transesterification reactions. Aromatic substituents, however, modify the relative reactivity of amines 1-4: good evidence suggests that, not only steric and electronic effects, but, importantly, direct acid-base interactions between substituents and the catalyst are involved. Weakly acidic groups (OH, CH2OH, CONH2, pKa > or = 10) may help the reaction, while aminobenzoic acids (pKa of 4-5) are the least reactive substrates. The solvent polarity also affects the reaction, which is faster in xylene than in the more polar diglyme. The mono-N-methyl selectivity is explained by the adsorption pattern of reagents within the zeolite pores: a B(Al)2 displacement of the amine on methyl alkyl carbonate should occur aided by the geometric features of the NaY supercavities. Different factors account for the reaction chemoselectivity. Evidence proves that the polarizability of the two nucleophilic terms (NH2 and X groups) of anilines is relevant, although adsorption and confinement phenomena of reagents promoted by the zeolite should also be considered.

Journal Article↗
PubMed1996

Medical therapy for ischemic stroke.

Therapy for stroke is undergoing major changes. Many of the changes parallel the advances made in the therapy for myocardial infarction. Acute intervention with cytoprotective and thrombolytic agents is undergoing active investigation. Cytoprotective therapy includes drugs that act to prevent cell death during ischemia and reperfusion. These agents include calpain inhibitors, voltage-sensitive calcium- and sodium-channel antagonists, receptor-mediated calcium-channel antagonists [including N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) antagonists], glutamate-synthesis inhibitors, glutamate-release antagonists, gamma-aminobenzoic acid (GABA) antagonists, 5-HT (serotonin) receptor agonists, gangliosides, antioxidants, growth factors, antiapoptotic agents, and antiadhesion molecules. Thrombolysis is effective in myocardial infarction. Thrombolysis is undergoing evaluation in stroke with streptokinase, anisoylated plasminogen streptokinase activator complex (APSAC), tissue plasminogen activator (t-PA; including recombinant t-PA), urokinase, and single-chain urokinase (scu-PA). Both systemic and selective administration are being evaluated. Preventive therapy with both antiplatelet and anticoagulant drugs sheds new light on how best to stratify patients in terms of a risk-benefit ratio. Continuing public education will be essential as stroke therapy advances.

Brain↗
PubMed1968

Formic hydrogenlyase and the photoassimilation of formate by a strain of Rhodopseudomonas palustris.

A photosynthetic bacterium isolated by enrichment on media containing formate as major source of cell carbon was identified as a strain of Rhodopseudomonas palustris. It grew on a wide range of simple organic compounds including alcohols, fatty acids, and hydroxyacids, on a chemically defined medium with biotin and p-aminobenzoic acid as essential growth factors. The organism grew on formate or photoautotrophically with molecular hydrogen or thiosulfate only in the presence of yeast extract. Ability to photoassimilate formate could be shown only in organisms grown in the presence of formate. The organism contained an inducible formic hydrogenlyase consisting of a soluble formic dehydrogenase, a particulate hydrogenase, and one or more intermediate, but as yet unidentified, electron carriers. The formic hydrogenlyase could be reconstituted from a particulate hydrogenase and a partially purified soluble formic dehydrogenase. Some properties of the formic dehydrogenase and hydrogenase have been compared with that of the formic hydrogenlyase system.

Carbon Dioxide↗
PubMed2006

[Synthesis, characterization and fluorescent properties of o, m, p-(methacrylamido) benzoic acid].

o, m, p- (Methacrylamido) benzoic acid (o, m, p-MAABA) was synthesized from o, m, p-aminobenzoic acid (o, m, p-ABA), elemental analysis and 1H NMR were used to confirm these compounds. The fluorescent properties of the compounds were investigated. The result showed that o, p-MAABA has lambda(ex)max at 358 nm while m-MAABA has lambda(ex)max at 324 nm. Excited at lambda(ex)max, o-MAABA had the strongest fluorescence, while p-MAABA had the weakest, and all of them were round at 420 nm.

English Abstract↗
PubMedDate not supplied

[Intermediary effectiveness of procaine and procaine metabolites following oral administration].

The influence of orally administrated procaine hydrochloride and of its metabolites diethylaminoethanol, monoethylaminoethanol and ethanolamine on specific intermediary processes in rats was tested. While the animals got procaine hydrochloride in a single dose or via food the incorporation rate of amino acids in protein was measured in homogenisates of liver tissue by the incorporation of a mixture of 14C-amino acids. Procaine hydrochloride, the commercial product K. H. 3, as well as diethylaminoethanol, monoethylaminoethanol and ethanolamine increased the amino acid incorporation rate in a dose and time dependent mode, while p-aminobenzoic acid remained without any effect. The dose of procaine hydrochloride inducing a maximal reaction was in the range of 50 to 100 mg/kg b. w. (250 to 500 mg/kg food). The minimal active dose was nearly at 10 mg/kg b. w. Paying regard to a metabolic factor of 10 the effective dose-range is nearly the dose used in experience with human beings to influence geriatric complaints. In the study described here haematoporphyrine (a component of the commercial product K. H. 3, not absorbed) shows no specific intermediary effect. May be it promotes the intestinal absorption of procaine hydrochloride by protection against intestinal hydrolysis. The intermediary effect of procaine hydrochloride is to measure on cellular or subcellular level without compatibility to the activity as a local anaesthetic. With regard to other intermediary effects mentioned in the literature like growth promotion or inhibition of monoamine oxidase activity, it is discussed whether the increase of the hepatic amino acid incorporation rate is corresponding to geriatric experiences made with procaine hydrochloride.

Animals↗
PubMed1997

Rapid determination of p-aminohippuric acid in serum and urine by high-performance liquid chromatography.

We report a simple and rapid HPLC procedure for measuring p-aminohippuric acid in serum and urine. After deproteinization with acetonitrile and addition of p-aminobenzoic acid as an internal standard, the chromatographic run is performed on a C18 column with the absorbance detector set at 275 nm. The separation is carried out in 10 min at a flow-rate of 1.0 ml/min with a mobile phase composed of 7 mmol/l 1-decanesulfonic acid, pH 3.70, and acetonitrile (82:18, v/v). The relationship between p-aminohippuric acid concentration and the p-aminohippuric acid/internal standard peak area is linear up to 100 microg/ml. Within-run precision measured at three different p-aminohippuric acid concentrations ranges from 1.73 to 1.98% in serum and from 0.72 to 1.32% in urine. Between-run precision varies from 1.80 to 4.06% in serum and from 1.05 to 2.66% in urine. Analytical recovery is between 98.26 and 99.44% in serum and from 99.57 to 100.45% in urine. The method is very simple, sensitive, and requires small volumes of sample for the assay (100 microl). Therefore, it could be a useful tool for the analysis of p-aminohippuric acid in the evaluation of renal plasma flow.

Adult↗
PubMed1999

New method for determining the sugar composition of glycoproteins, glycolipids, and oligosaccharides by high-performance liquid chromatography.

A new method is reported that can be performed within a single vessel to analyze the composition of aldose, hexosamine, and sialic acid residues of glycoproteins, glycolipids, and oligosaccharides. Glycoconjugates are treated with sialidase or subjected to mild acid hydrolysis, before being treated with N-acetylneuraminic acid aldolase to convert the free sialic acid residues to their corresponding N-acylmannosamines. The reaction mixture is then successively subjected to acid hydrolysis (in order to produce monosaccharides), N-acetylation, and conversion with p-aminobenzoic acid ethyl ester (ABEE). The ABEE-converted monosaccharides are simultaneously determined by reverse-phase high-performance liquid chromatography. Determination of the sugar compositions of bovine fetuin, II3NeuGc alpha-LacCer, and 3'-sialyllactose with this method was found to be highly accurate. Linearity of the peak area vs. the amount of bovine fetuin ranged from 1 to 50 micrograms in all ABEE-converted monosaccharides. With a slight modification to this method, sialic acid residues can be separately determined as NeuAc and NeuGc. This novel method and its modified version are used to demonstrate the sugar compositions of alpha 1-acid glycoproteins from several sources.

Acetylation↗
PubMed2000

Tissue- and gender-specific expression of N-acetyltransferase 2 (Nat2*) during development of the outbred mouse strain CD-1.

The human N-acetyltransferase (Nat2) genetic polymorphisms have been modeled in mouse strains. We determined the phenotype and genotype of the N-acetyltransferase 2 (Nat2*) gene among outbred CD-1 mice and found a mixed population of heterozygous and rapid and slow homozygous genotypes. Phenotypes determined with p-aminobenzoic acid demonstrated complete concordance of slow and rapid genotype and phenotype. The kidney p-aminobenzoic acid/Nat2-acetylating activity of CD-1 female mice showed a 2.5-fold increase at 80 days of age compared with day 1, whereas males showed a 4.3-fold increase at 25 days and a 5.8-fold increase at 80 days. Immunoblot analysis revealed a 2-fold increase in male kidney Nat immunoreactive protein at 80 days of age, whereas no significant differences were detected in female mice. Likewise, the Nat2 mRNA levels determined by ribonuclease protection assay showed an increase in transcript levels in kidney of male mice during postnatal development, whereas they remained unchanged in females. Gender-associated differences of Nat2 activity, protein, and transcript levels were absent in liver. These observations suggest that the increase in Nat2 enzymatic activity in kidney is accomplished by an increase in transcript. We propose that the observed increase in Nat2 transcript expression in male mice may be a result of androgen regulation during development.

Aging↗