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At least 217 records · Page 12Linked to original sources
PubMed1979

Pharmacokinetics and cardiovascular effects in rabbits of a major hydralazine metabolite, the hydralazine pyruvic-acid hydrazone.

The hydrazone of hydralazine and pyruvic acid (HPH) has been recognized as a quantitatively important metabolite of hydralazine in human plasma. We evaluated the disposition of [14C] HPH after its i.v. administration to normal, anephric and probenecid-pretreated rabbits. Renal clearance of HPH in normal rabbits exceeded the glomerular filtration rate by a factor of 3 to 4 and accounted for 80 to 90% of the total body clearance. Active tubular secretion was established by the effect of probenecid pretreatment to reduce the renal clearance of HPH by 80%. Total body clearance of HPH in anephric rabbits was 10% of that of normal animals, emphasizing the minor importance of metabolic conversion for the overall disposition of HPH. HPH in a maximum dose of 50 mumol/kg i.v. had no hypotensive effect in renal hypertensive rabbits and did not interfere with the subsequent hypotensive response to hydralazine. This HPH dose produced plasma levels at least 50 times in excess of those reported in humans after administration of therapeutic doses of parent hydralazine. HPH is consequently of negligible clinical significance, despite the relatively high plasma concentration of this metabolite which occurs after administration of parent hydralazine.

Animals↗
PubMed2004

omega-Amino acid:pyruvate transaminase from Alcaligenes denitrificans Y2k-2: a new catalyst for kinetic resolution of beta-amino acids and amines.

Alcaligenes denitrificans Y2k-2 was obtained by selective enrichment followed by screening from soil samples, which showed omega-amino acid:pyruvate transaminase activity, to kinetically resolve aliphatic beta-amino acid, and the corresponding structural gene (aptA) was cloned. The gene was functionally expressed in Escherichia coli BL21 by using an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible pET expression system (9.6 U/mg), and the recombinant AptA was purified to show a specific activity of 77.2 U/mg for L-beta-amino-n-butyric acid (L-beta-ABA). The enzyme converts various beta-amino acids and amines to the corresponding beta-keto acids and ketones by using pyruvate as an amine acceptor. The apparent K(m) and V(max) for L-beta-ABA were 56 mM and 500 U/mg, respectively, in the presence of 10 mM pyruvate. In the presence of 10 mM L-beta-ABA, the apparent K(m) and V(max) for pyruvate were 11 mM and 370 U/mg, respectively. The enzyme exhibits high stereoselectivity (E > 80) in the kinetic resolution of 50 mM D,L-beta-ABA, producing optically pure D-beta-ABA (99% enantiomeric excess) with 53% conversion.

Achromobacter denitrificans↗
PubMed1979

[Occurrence of pyruvic acid in capsular polysaccharides (K antigens) of klebsiellas].

The capsular polysaccharides of 77 Klebsiella K-types were analysed for the presence of pyruvic acid. One half of the polysaccharides investigated were found to contain between 1.3 and 12% of the keto acid. A comparison between the analyses performed and the calculated values from some pyruvic acid containing polysaccharides of known structure showed that there is only in 5 out of 10 cases a good correlation with a regular substitution of the oligosaccharide repeating units.

Cell Wall↗
PubMedDate not supplied

[The effectiveness of some culture media with pyruvic acid bases for the isolation of mycobacteria from sputum].

The authors have studied the value of culture media based on pyruvic acid (the Dixon medium and an original medium called P.T.) in the isolation of mycobacteria from sputum, as compared with the Löwenstein-Jensen medium. The studies were carried out in two groups of patients: 1043 samples were collected from ambulatory patients and 1740 samples were collected from hospitalized patients. The superiority of the Dixon and of the P.T. media was confirmed by the increased percentage of positive cultures (11% and 20% respectively) as compared with the Löwenstein-Jensen medium. With these media it was possible to isolate mycobacteria 7--14 days earlier than with the other media. On the basis of the results obtained the authors recommend the use, in parallel, especially in those cases when the samples contain only a small number of bacteria, of the Löwenstein-Jensen medium and one of the media based on pyruvic acid.

Culture Media↗
PubMed1973

Isolation of regulatory mutants of the aspartic and pyruvic acid families and their effect on antibiotic production in Streptomyces lipmanii.

Streptomyces lipmanii L100 produces two beta-lactam ring-containing antibiotics: penicillin N and 7-(5-amino-5-carboxy valeramido)-7-methoxy-cephalosporanic acid. These antibiotics are modified tripeptides derived from alpha-aminoadipic acid, cysteine, and valine. Mutants defective either in the biosynthesis or in the control of amino acids belonging to the aspartic and pyruvic acid families were isolated and characterized with regard to their effect on antibiotic synthesis. In a number of these mutants antibiotic synthesis was either completely inhibited or increased up to threefold over wild-type levels.

Anti-Bacterial Agents↗
PubMed1999

Clinical experiences with the use of indole-3-pyruvic acid.

In the last few years, Indol-3-pyruvic acid (IPA) has been subjected to 5 pilot clinical trials in volunteers and a phase II study on patients affected by anxiety, with or without sleep problems. Overall, results indicated a very good safety profile, relief from anxiety and a better quality of sleep in patients treated with IPA. Moreover, the drug showed no withdrawal signs, but positive effects on mood, improving feelings of relaxation, calmness and happiness. The mechanism of action of IPA, depending on increased turnover of some indoles in the CNS, appears clearly distinct from that of benzodiazepines, suggesting that the drug might be used in the treatment of symptoms of mild anxiety and stress experienced by busy and anxious people.

Anti-Anxiety Agents↗
PubMed1991

Analysis of a pyruvic acid acetal-containing polysaccharide by the reductive-cleavage method.

The applicability of the reductive-cleavage method to the analysis of polysaccharides bearing pyruvic acid acetals has been demonstrated. Direct reductive cleavage of fully methylated gum xanthan yielded the expected products, including 1,5-anhydro-4,6-O-[(S)-1-methoxycarbonylethylidene]-2,3-di-O-methy l-D- mannitol. The latter product was not observed when reductive cleavage was performed subsequent to reduction of ester groups in the fully methylated polysaccharide and mild hydrolysis to remove pyruvic acid acetal substituents. Instead, the latter experiment yielded 1,5-anhydro-2,3-di-O-methyl-D-mannitol, establishing the presence in the polysaccharide of terminal (nonreducing) D-mannopyranosyl groups bearing 4,6-O-(1-carboxyethylidene) substituents. The products of reductive cleavage were characterized, where appropriate, by comparison of the gas chromatographic retention times and chemical ionization- and electron ionization-mass spectra of their acetates to those of authentic standards. Alternatively, the products of reductive cleavage could be characterized without resort to comparison with authentic standards by analysis of the 1H-n.m.r. spectra of their benzoates, which were obtained in pure form by high-performance liquid chromatography. By either method of product characterization, this two-step procedure of analysis reveals the presence of pyruvic-acetal residues in polysaccharides and establishes both the identity of the sugar residue to which they are attached and their positions of attachment.

Carbohydrate Sequence↗
PubMed1978

Interference in assays for hydralazine in humans by a major plasma metabolite, hydralazine pyruvic acid hydrazone.

The present study showed that published spectrophotometric and GLC methods for hydralazine in plasma do not distinguish between the drug and a major plasma metabolite, hydralazine pyruvic acid hydrazone. These methods involve the acid treatment of the sample, which hydrolyzes that hydrazone back to hydralazine. A specific GLC assay for the hydrazone was developed and involves its selective extraction from plasma and transformation to 3-trifluoromethyl-s-triazolo[3,4-a]phthalazine. This derivative could be sensitively measured by GLC using an electron-capture detector. With this procedure, it was shown that most "apparent hydralazine" in plasma is the hydrazone, which forms rapidly from hydralazine and endogenous pyruvic acid. Previous work indicated that the hydrazone was inactive when administered intravenously to rabbits.

Chromatography, Gas↗
PubMed1988

Pyruvic-acid-containing polysaccharide in the cell wall of Bacillus polymyxa AHU 1385.

Three acidic polymer fractions with molecular masses of about 16 kDa, 35 kDa and 70 kDa were isolated from lysozyme digests of N-acetylated cell walls of Bacillus polymyxa AHU 1385 by ion-exchange chromatography and gel chromatography. These fractions, containing mannosamine, glucosamine and pyruvic acid in a molar ratio of about 1:1:1 together with glycopeptide components, were characterized as polysaccharide-linked glycopeptides with one, two and more polysaccharide chains. On the other hand, treatment of the cell walls with glycine/HC1 buffer, pH 2.5, at 100 degrees C for 10 min followed by separation of water-soluble products on ion-exchange chromatography gave three polysaccharide fractions, PS-I-III, which contained different amounts of pyruvic acid (0,0.6 and 0.9 residue/mannosamine residue) along with equimolar amounts of mannosamine and glucosamine. Pyruvate-free polysaccharides similar to PS-I were also obtained from PS-II, PS-III and polysaccharide-linked glycopeptides by treatment with 10 mM HC1 at 100 degrees C for 1 h. Results of analyses of these polysaccharide preparations by 1H-NMR and 13C-NMR measurement and methylation, together with data from characterization of fragments obtained by hydrogen fluoride hydrolysis, lead to the most likely structure, ----3)[4,6-O-(1-carboxyethylidene)]ManNAc(beta 1----4)GlcNac(beta 1----, for the acidic polysaccharide of this strain.

Acetylglucosamine↗
PubMed2006

Photoinduced oligomerization of aqueous pyruvic acid.

The 320 nm-band photodecarboxylation of aqueous pyruvic acid (PA), a representative of the alpha-oxocarboxylic acids widely found in the atmospheric aerosol, yields 2,3-dimethyltartaric (A) and 2-(3-oxobutan-2-yloxy)-2-hydroxypropanoic (B) acids, rather than 3-hydroxy-2-oxobutanone as previously reported. A and B are identified by liquid chromatography with UV and ESI-MS detection, complemented by collisionally induced dissociation and 2H and 13C isotope labeling experiments. The multifunctional ether B gives rise to characteristic delta approximately 80 ppm 13C NMR resonances. Product quantum yields are proportional to [PA](a + [PA])(-1) in the range [PA] = 5-100 mM. CO2(g) release rates are halved, while A and B are suppressed by the addition of >1.5 mM TEMPO. A and B are only partially quenched in air-saturated solutions. These observations are shown to be consistent with an oligomerization process initiated by a bimolecular reaction between 3PA and PA producing ketyl, CH3C(OH)C(O)OH, and acetyl, CH3C(O)*, radicals, rather than by the unimolecular decomposition of 3PA into 1-hydroxyethylidene, 3HO(CH3)C: (+CO2), or [CH(3)C(O)* + *C(O)OH] pairs. A arises from the dimerization of ketyl radicals, while B ensues the facile decarboxylation of the C8beta-ketoacid formed by association of acetyl radicals with the ketyl radical adduct of PA. Since the radical precursors to A and B are scavenged by O2 with a low probability per encounter (k(sc) approximately 1 x 10(6) M(-1) s(-1)), PA is able to accrete into multifunctional polar species in aerated aqueous media under solar illumination.

Journal Article↗
PubMed2001

Kinetic modeling of pyruvic acid ozonation in aqueous solutions catalyzed by Mn(II) and Mn(IV) ions.

The ozonation of pyruvic acid (2-ketopropionic acid) in aqueous solutions, catalyzed by Mn(II) and Mn(IV) ions, has been studied at three different pH values (pH = 1.1, 2.0 and 3.0). A mathematical model of the unsteady operation of the experimental reactor has been developed, which takes into account the reactions occurring in the liquid phase and the ozone mass transfer from the gas bubbles. Those reactions have been described with two alternative kinetic models, both made out of four elementary steps. The two kinetic models correlate the experimental data with a fair accuracy, respectively at the lowest and at the highest pH examined. In particular, at pH = 3.0, the ozonation results are inhibited by the acetate ions produced by the reaction itself. This effect has been correctly described in the terms of a complex formed with the low oxidation-state manganese, which successively reacts with the dissolved ozone.

Hydrogen-Ion Concentration↗
PubMed1987

Effects of branched chain amino acids, pyruvate, or ketone bodies on the free amino acid pool and release from brain cortex slices of normal and streptozotocin-diabetic rats.

Brain cortex slices from diabetic rats incubated in Krebs-Ringer-bicarbonate (KRB)--glucose medium show, compared to the normals, a 75% higher glutamine content. Branched chain amino acids (BCAA) added, at 0.5mM each, to this medium increase (53%) the glutamine content in the normal slices but have no effect on the glutamine content in the slices from diabetic rats. When the incubation medium is KRB-pyruvate, glutamine and glutamate contents are lower than in the KRB-glucose medium. The addition of BCAA in the KRB-pyruvate medium partially restores the contents of glutamine in the normal and of glutamine plus glutamate in the diabetic. Keto acids or BCAA added to the incubation medium of normal slices decrease the pool of most of the neutral and acidic amino acids but they do not affect this pool in slices from the diabetic rats. In addition keto acids increase the ratio glutamate in the tissue: glutamate in the medium.

Amino Acids↗
PubMed2003

The enol tautomer of indole-3-pyruvic acid as a biological switch in stress responses.

Indole-3-pyruvic acid (IPA) undergoes in solutions to the keto-enol tautomerism, which appears responsible of its pharmacological effects, as only the enol tautomer is an easy target for oxygen free-radicals and can be transformed directly to kynurenic acid (KYNA). Contrary to expectations, the IPA enol tautomer is rather stable in mammalian tissues, due to the presence of specific tautomerases, favouring the formation of KYNA in the presence of free-radicals. Because of the synergistic effects between glucocorticoids, free-radicals and excitatory aminoacids in chronic stress, the enol tautomer of IPA and KYNA are proposed as physiological metabolites produced in order to shut-off the chronic stress cycle.

Animals↗