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At least 271 records · Page 15Linked to original sources
PubMed2002

Synthesis of optically active organoantimony compounds having an (S)-alpha-methylbenzyldimethylamine group and its evaluation for asymmetric reaction.

Novel, enantiomerically pure organoantimony compounds having a C-chiral amine moiety, (S)-(alpha-methyl-2-di-p-tolylstibanobenzyl)dimethylamine [AMSb] (2) and its (eta(6)-arene)chromium complex [AMSb-Cr(CO)(3)] (4), were prepared from common (S)-(alpha-methylbenzyl)dimethylamine (1) via its ortho-lithiated intermediates in short steps. The catalytic activity and enantioselectivity of the ligands 2 and 4 for asymmetric reaction are evaluated, and the optically active (eta(6)-arene)chromium complex 4 has been shown to be an effective ligand for rhodium-catalyzed asymmetric hydrosilylation of ketones.

Benzylamines↗
PubMed1985

Formation and metabolism of nitrosamines in vivo, monitored by 14N-stable isotope labelling.

Microsomal metabolism of N-nitrosodimethylamine entails release of molecular nitrogen; the extent is determined by 15N stable isotope labelling and mass-spectrometric isotope ratio measurements. Exhalation of labelled nitrogen by rats treated with 15N-dimethylamine and nitrite or 15N-nitrite alone indicates that nitrogen may arise from nitrite via two pathways: either directly from nitrosation of primary amines or from secondary and tertiary amines with subsequent enzymic N-demethylation. The overall yield of nitrosamine formation, N-demethylation and nitrogen-release represent about 0.3-6% or the administered dose of dimethylamine (1.1 mmol/kg), depending upon the dose of nitrite (0.55-2.2 mmol/kg). 15N-stable isotope labelling and mass-spectrometric isotope ratio measurements are powerful tools for assessment of endogenous nitrosamine formation from nitrite. One hundred nmol of labelled nitrogen are easily detectable in vivo; with further methodological refinement the limit of detection may be lowered by two orders of magnitude.

Animals↗
PubMed1997

[Study on ion chromatography (IC) for the low-molecular weight amines].

In this paper the retention behaviors of low-molecular weight amines (methylamine, dimethylamine, trimethylamine, ethylamine, propylamine sec-butylamine, n-butylamine, ethanolamine, diethanolamine, triethanolamine) on Ionpac CS12 column were for the first time studied with modern ion chromatograph. The column is usually used for routine analysis of inorganic cations and it strongly retains these organic amines. So they are difficult to be eluted by dilute aqueous HCl alone. The addition of acetonitrile (ACN) as a modifier can improve the peak shape and resolution. Influences of concentrations (ACN & HCl) on separation and detection were investigated separately and the chromatographic conditions were optimized. Aqueous solution of 20 mmol/L HCl containing 1% or 5% ACN (5% for higher molecular weight amines) was used as the eluant with a flow rate of 1.0 mL/min to optimize the column efficiency. In addition to methylamine, ethanolamine and diethanolamine, all other amines can well be separated from each other. According to the structure they may be divided into three classes: (a) methylamine, dimethylamine and trimethylamine; (b) diethanolamine and triethanolamine; (c) ethylamine, propylamine, sec-butylamine and n-butylamine. The three classes of mixtures were separately injected into the IC system and resolutions being obtained by the developed method were: (a) 1.25 and 1.52; (b) 1.20; (c) 2.45, 2.05 and 2.10 respectively. The new method is characterized by rapidity, convenience, sensitivity and simultaneous determination of some inorganic cations. It was separately used for determination of diethanolamine, triethanolamine, NH4+ in explosive samples and of Na+, K+, MgZ+, Ca2+ in water supply with satisfactory results. The retention mechanism of amines on CS12 column and effect of organic modifier were also preliminarily explored.

Biogenic Amines↗
PubMed2004

[Preparation and FTIR properties of amino compounds modified glutaraldehyde crosslinked chitosan resin activated with cyanuric chloride].

The preparation and IR properties of 1-butylamine, dimethylamine, trimethylamine, triethylamine, benzylamine, 4-methylaniline and 4-aminobenzenesulfonic acid modified glutaraldehyde crosslinked chitosan activated with cyanuric chloride were studied. The absorption of nu(O-H) and nu(N-H) at 3430-3440 cm(-1), nu(C-O-C) at 1155 cm(-1), nu(C-OH) at 1030 cm(-1) and nu(C-O) of beta-D-glucose at 899 cm(-1) were not shifted obviously. The absorption of delta(C-H) at 1400-1384 cm(-1) and nu(C-OH) at 1095 cm(-1) varied markedly. The nu(C=N) absorption of crosslinked chitosan was at 1640-1650 cm(-1). The skeleton vibration absorption of 1,3,5-triazine ring was at 803-812 cm(-1) and 1584-1590 cm(-1). With different deacetylation or substitution, the amide I, II, III absorption at 1650, 1600 and 1310 cm(-1) varied obviously. When modified with 1-butylamine, dimethylamine, benzylamine, 4-methylaniline and 4-aminobenzenesulfonic acid, strong absorption of delta(NH3+) appeared at 1517-1530 cm(-1), which was weakened or disappeared when modified with trimethylamine or triethylamine, but a series of new absorption of nu(C-N) appeared at 1400-1500 cm(-1).

Butylamines↗
PubMedDate not supplied

[Serum amine oxidases and gamma-glutamyl transpeptidase activity in burns].

Activities of amine oxidases (benzylamine, 4-nitrobenzylamine, 4-dimethylamine methylbenzylamine used as substrates) and of gamma-glutamyl transpeptidase were studied in blood serum of 72 patients with thermic burns of various intensity and degree. Severity of the disease correlated with the rate of amine oxidases activity alteration. Distinct and long-term decrease in oxidation of benzylamine as well as simultaneous stimulation of 4-dimethylamine methylbenzylamine oxidation were observed in severe forms of the burns disease, thus suggesting the increase in diamine oxidase activity. This phenomenon proved to be an unfavourable prognostic indication of the disease. Alterations in activity of gamma-glutamyl transpeptidase corresponded to severity of the burns disease. Estimation of the enzymatic activity might be used in evaluation of the impairments severity as well as in prognosis of burns disease development.

Adult↗
PubMed1989

Investigations into the biochemical effects of region-specific nephrotoxins.

1H NMR spectroscopy provides a useful initial biochemical screen with which to detect abnormal patterns of metabolites in urine collected from animals with different sites of nephrotoxic lesions. Male Fischer 344 rats were treated with nephrotoxic doses of sodium chromate (pars convoluta of proximal tubule), cisplatin, hexachlorobutadiene, mercury II chloride (pars recta of proximal tubule), propylene imine, and bromoethanamine (renal papilla) in order to induce damage in specific regions of the kidney. Urine was collected for up to 48 hr after dosing and was analyzed by 1H NMR spectroscopy (400 MHz) and conventional biochemical methods to provide biochemical fingerprints of urine in various site-specific nephrotoxic states. Hexachlorobutadiene and HgCl2 produced severe glycosuria and transient enzymuria. 1H NMR urinalysis revealed aminoaciduria, glycosuria, and lactic aciduria after exposure to all proximal tubular toxins except cisplatin, whereas papillary insult resulted in early elevations in urinary trimethylamine N-oxide and dimethylamine, together with later elevations in urinary acetate, succinate, and N,N-dimethylglycine (after propylene imine). Trimethylamine N-oxide and dimethylamine are suggested as novel markers of site-specific renal papillary injury in the rat.

Acetylglucosaminidase↗
PubMedDate not supplied

Determination of N-nitrosodimethylamine levels in some Canadian 2,4-D amine formulations.

Levels of N-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted dimethylamine is removed by cleanup on a silica gel column. The eluates containing NDMA are concentrated, an internal standard of N-nitrosodipropylamine is added, and nitrosamine levels are determined using a gas chromatograph interfaced with a thermal energy analyzer. Recoveries of NDMA and N-nitrosodiethylamine spiked into samples were 103 +/- 16 and 96.3 +/- 9.8%, respectively. Of the 112 samples analyzed, 92 were below 1 part per million (ppm) relative to the amount of 2,4-D in the samples, 16 were between 1 and 5 ppm, and 4 were greater than 5 ppm. The gas chromatographic column used is compared to a conventional packing material for volatile nitrosamine analysis. Formation of NDMA during cleanup and analysis was shown not to occur.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1984

N-nitrosamine formation by intestinal bacteria.

N-Nitrosamine formation by various intestinal bacteria was investigated. N-Nitroso-dimethylamine (NDMA) formation by viable resting cells of Escherichia coli A10 was proportional to the incubation time and the enzyme concentration, while boiled cells were incapable of nitrosation. The enzyme was optimal at pH 7.5 and showed about the same specificities for dimethylamine, diethylamine, dibutylamine, di-isobutylamine, piperidine and pyrrolidine, but high specificity for morpholine. The intestinal bacteria harbouring nitrosating enzyme were mainly aerobic, i.e., Escherichia coli, Proteus morganii, Klebsiella pneumonia and Pseudomonas aeruginosa. Only one of the 32 anaerobic intestinal bacterial species, i.e., Peptococcus asaccharolyticus, was positive. The enzyme activities of these nitrosating bacteria covered a range of 0.06-0.90 nmol NDMA formed per hour per mg protein. These results support the theory of enzymatic catalysis of N-nitrosamine formation by microorganisms and suggest the possibility of endogenous nitrosation in the digestive tract.

Dimethylnitrosamine↗
PubMed1984

[Occurrence of phenolic compounds in the dust of swine stalls and henhouses].

Dust-borne phenols and indols were extracted by ethanol from the sedimentation dust of two pig houses (finishing pigs on half slatted floor resp. piglets on deep litter) and a hen house (3-stage battery cages) and analysed by gas chromatography. In the dust of both pig houses 5 compounds (phenol, p-cresol, p-ethylphenol, indole, skatole) and in the hen house 6 compounds (phenol, p-cresol, 2.6-dimethylamine, 3.4-dimethylamine, indole, skatole) were found. The total amounts of the phenolic compounds came to 275 microgram/g dust (finishing pigs), 111 micrograms/g dust (piglets) and 108 micrograms/g dust (hens). Quantitatively in the finishing pig house p-cresol is well to the fore (53% of the total amount), in the piglet house phenol is dominating (50%) and in the hen house 2.6-dimethylphenol dominates distinctly (83%). The sensory evaluation of the two pig houses showed that the odour intensity in the finishing pig house is distinctly higher than in the piglet house. It seems that the decrease of the odour intensity coincides with the decrease of p-cresol. The results show that animal house dust is an important carrier of trace gases including odorants. The possible influence of dustborne phenol and skatole on the animals is discussed with respect to respiratory affections.

Animals↗
PubMed1984

Alternative bioactivation routes for beta-hydroxynitrosamines. Biochemical and chemical model studies.

The biochemical retroaldol-like fragmentation of beta-hydroxynitrosamines has been investigated further. The extent of fragmentation of 2-hydroxy-2-methylpropyl-methylnitrosamine (HMPMN) to N-nitrosodimethylamine and acetone induced by metabolic activation increases as the NADPH level is decreased. 2-Hydroxy-2-phenylethyl-methylnitrosamine (HPhEMN) undergoes competitive oxidation to 2-oxy-2-phenylethyl-methylnitrosamine (OPhEMN) and fragmentation to benzaldehyde and N-nitroso-dimethylamine in the presence of a metabolic activation system from rat liver. The extent of the oxidation was increased by preinduction of the rats with phenobarbital, or separate addition of NADPH and NAD, but was decreased by addition of dimethyl sulfoxide. The fragmentation was observed most readily when oxidation was inhibited or was not induced by cofactors. When HPhEMN was administered to a rat intraperitoneally, benzaldehyde (fragmentation) was found in the urine with OPhEMN and the substrate, but only the last two substances were found in liver and blood. These experiments provide evidence for retroaldol-like fragmentation of beta-hydroxynitrosamines both in vitro and in vivo. In a related investigation, it was found that N-nitroso-N-4-chlorophenyl-2-aminoethanal (NCAE) is extremely reactive and induces spontaneous generation of 4-chlorobenzenediazonium ion in chloroform, as trapped by 2-naphthol. NCAE reacts with dimethylamine in chloroform, benzene or methanol to give N-nitrosodimethylamine and 4-chloroaniline, among other products. This suggests that beta-nitrosaminoaldehydes produced by the biooxidation of their corresponding alcohols could produce cell alteration through alkylation, deamination or transnitrosation.

Animals↗
PubMed1984

Formation of volatile nitrosamines by drug-nitrite interactions under physiological conditions.

Twenty-eight drugs, most of which are tertiary amines, were tested for the formation of volatile nitrosamines by reaction with nitrite under physiological conditions; the drugs (10mM) were incubated with nitrite ( 40mM ) at pH 3.0, 37 degrees for 1 and 4 hr. The volatile nitrosamines formed were determined by gas chromatography-thermal energy analysis. Of the 28 drugs, 24 formed measurable amounts of volatile nitrosamines that are known carcinogens. The yields of nitrosodimethylamine (NDMA) from aminopyrine (55-65%) and minocycline (11%) were higher than that from dimethylamine under the same conditions. This result suggests that there may be a pathway not involving the secondary amine (dimethylamine) as an intermediate in the formation of NDMA from minocycline as well as from aminopyrine, Tolazamide gave rise to nitrosopiperidine ( NPIP ) in addition to nitrosohexamethyleneimine ( NHXI ), formation of which was expected from the chemical structure of tolazamide, and the yield of NPIP (2-7%) was higher than that of NHXI (0.2-1.2%). Ascorbic acid ( 40mM ) was effective in decreasing the formation of nitrosamines from drugs by reaction with nitrite, although the blocking effects varied between 88 and 100% depending on the drugs tested or on the nitrosamines formed.

Amines↗
PubMed1983

Site and mechanism of covalent binding of 4-dimethylaminophenol to human hemoglobin, and its implications to the functional properties.

4-Dimethylaminophenol, after i.v. injection, rapidly forms ferrihemoglobin and has been successfully used in the treatment of cyanide poisoning. The catalytic ferrihemoglobin formation is terminated by thioether formation of oxidized 4-dimethylaminophenol with reduced glutathione or cysteine 93 beta of hemoglobin. Hereby the physiological functions of human hemoglobin are markedly altered. After binding of two molecules of 4-dimethylaminophenol to tetrameric hemoglobin, the rate of autoxidation is increased about 6-fold. The oxygen affinity is 10 times higher than normal, the Hill coefficient is diminished nearly to unity, and the Bohr effect is reduced by about 50%. The physiologically important allosteric regulation of the oxygen affinity by 2,3-diphosphoglycerate is abolished, and the binding of 2,3-diphosphoglycerate to deoxyhemoglobin no longer functions. By molecular sieving, two alkylated hemoglobins were separated: a hemoglobin fraction with an unchanged low tetramer dimer dissociation, normal electronic spectra, and normal digestibility by carboxypeptidase A; and a second fraction with a high degree of dissociation, altered electronic spectra, and impaired digestibility. A tryptic peptide was isolated containing cysteine 93 beta and histidine 146 beta cross-linked by an arylic compound missing the dimethylamine label. The following reaction mechanism is concluded: Oxy-hemoglobin catalyzes the oxidation of 4-dimethylaminophenol, and the oxidation product, presumably N,N-dimethylquinonimine, is bound covalently to cysteine 93 beta by a thioether linkage. This adduct is unstable and autoxidizes further with the liberation of dimethylamine. The resulting quinoid thioether electrophilically attacks the COOH-terminal histidine of the beta-chain, thereby forming an intramolecular cross-link. By this latter reaction, hemoglobin lacks allosteric transition upon ligation and is obviously frozen in its quaternary R-state.

Aminophenols↗
PubMedDate not supplied

[Oxidation and assimilation pathways of methylated amines in Arthrobacter globiformis].

The oxidation by Arthrobacter globiformis B-175 of tertiary, secondary, and primary amines is catalyzed by specific induced enzymes. Trimethylamine is oxidized to dimethylamine via trimethylamine N-oxide by monooxygenase and demethylase. Dimethylamine is converted to methylamine by another monooxygenase. Methylamine is oxidized to ammonia and formaldehyde by aminoxidase. Formaldehyde is assimilated via ribulose monophosphate cycle, which is confirmed by the presence of hexose-phosphate synthase and by the early and predominant formation of radioactive sugar phosphates during short-term incubation of the cells with labelled methylated amines. Hexose-phosphate synthase was also found in two other strains of A. globiforms (B-126, B-53) which assimilated methylated amines. This methylotroph contains the enzymes of the Krebs cycle which seems to be involved in the synthesis of organic acids. The participation of ammonium nitrogen in anabolic processes is accomplished by reductive amination of alpha-ketoglutarate, glyoxylate, and pyruvate.

Arthrobacter↗
PubMed1998

Proton nuclear magnetic resonance spectral profiles of urine in type II diabetic patients.

Serial urine samples of 33 type II diabetic patients and 20 control subjects were examined by 1H nuclear magnetic resonance (NMR). Metabolites including lactate, citrate, glycine, alanine, hippurate, trimethylamine-N-oxide, and dimethylamine were identified in all subjects although in higher concentrations in diabetic patients. Other analytes, such as creatine, acetate, betaine, and ketone bodies, were found more frequently and in greater concentrations in diabetics than in controls. In addition, although lactate, citrate, alanine, and hippurate concentrations increased with increasing glycosuria and glycohemoglobin, trimethylamine-N-oxide and dimethylamine were present at high concentrations even in diabetics with good metabolic control. 1H NMR spectroscopy permitted us to explore the relationships among the metabolites present in the urine samples and to obtain information about the disease status in type II diabetic patients.

Aged↗
PubMed2002

Identification of substituted sites on MUC5AC mucin motif peptides after enzymatic O-glycosylation combining beta-elimination and fixed-charge derivatization.

A strategy for determination of O-glycosylation site(s) in glycopeptides has been developed using model compounds obtained by enzymatic glycosylation (by human GaNTase-T2 isoform) on peptides derived from the human MUC5AC mucin tandem repeat motif. The beta-elimination-addition reaction (using dimethylamine and concomitantly ethanethiol) on the formerly glycosylated sites through a Michael-type condensation produced efficient deglycosylation with appropriate chemical modification. After N-terminal derivatization by a phosphonium group, peptide sequencing was then carried out by nanospray tandem mass spectrometry experiments. The highly predictable fragmentation pathways of these fixed-charge phosphonium derivatives enable straightforward recognition of glycosylation site(s) based on the mass increment of +44 Da for originally glycosylated threonine compared to the mass of fragments containing nonglycosylated residues.

Amino Acid Sequence↗
PubMed2000

Noninvasive monitoring of citrate, acetate, lactate, and renal medullary osmolyte excretion in urine as biomarkers of exposure to ischemic reperfusion injury.

Injury during the transplant process affects the alloantigen-dependent factors and the alloantigen-independent processes of "chronic" rejection. Consequently, the determination of reliable parameters for the assessment of ischemic damage is essential for the prediction of renal changes after ischemia/reperfusion injury. The aim of this study was to assess the ability of (1)H NMR spectroscopy to predict the early graft dysfunction in an ischemia/reperfusion model after preservation in two standard preservation solutions, Euro-Collins (EC) and University of Wisconsin (UW). The second aim was to specify the role of the UW solution in preventing renal medullary injury. Urine and plasma samples from three experimental groups were examined during 2 weeks: control group (n = 5), EC group (cold flushed and 48-h cold storage of kidney in EC and autotransplantation, n = 12), and UW group (cold flushed and 48-h cold storage of kidney in UW and autotransplantation; n = 12). We also examined these kidneys 30-40 min after implantation and on the sacrifice day. Creatinine clearance was significantly reduced in the EC group during the second week. Fractional excretion of sodium and urine N-acetyl-beta-d-glucosaminidase activity were improved but not significantly different in the preserved groups. Urinary concentrations of the alpha-class glutathione S-transferase were significantly greater in the EC group during the first week after transplantation. The most relevant resonances for evaluating renal function after transplantation determined by (1)H NMR spectroscopy were those arising from citrate, dimethylamine (DMA), lactate, and acetate in urine and trimethylamine-N-oxide (TMAO) in urine and plasma. These findings suggest that graft dysfunction is associated with damage to the renal medulla determined by TMAO release in urine and plasma associated with DMA and acetate excretion. Citrate is also a urinary marker that can discriminate kidneys with a favorable evolution. Our results suggest that (1)H NMR spectroscopy is an efficient technique for detecting ischemic damage when accurate and precise data on graft injury is required. In addition, this study outlines the specific impact of the UW solution against injury to the renal medulla.

Acetic Acid↗
PubMed1996

Comparative subchronic studies on 2,4-dichlorophenoxyacetic acid, amine, and ester in rats.

Forms of 2,4-dichlorophenoxyacetic acid (collectively known as 2,4-D) are herbicides used to control a wide variety of broadleaf and woody plants. Subchronic toxicity studies in rats were conducted on three forms of 2,4-D: the parent form, 2,4-D acid; 2,4-D dimethylamine salt (DMA); and 2,4-D 2-ethylhexyl ester (2-EHE). Doses in the subchronic studies (on an acid equivalent basis) were 0, 1, 15, 100, and 300 mg/kg/day. Major treatment related findings in the three studies included decreases in red cell mass, decreases in T3 and T4 levels, decreases in ovary and testes weights, increases in liver, kidney, and thyroid weights, and cataracts and retinal degeneration (high-dose females). These data demonstrated the comparable toxicities of 2,4-D acid, DMA, and 2-EHE and support a subchronic no-observed-effect level of 15 mg/kg/day for all three forms. In summary, the findings of these studies indicate comparable low subchronic toxicity potentials among representative forms of 2,4-D.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1994

Metabolism and excretion of methylamines in rats.

Experiments were performed with rats to examine the sources and disposition of dimethylamine (DMA), trimethylamine (TMA), and trimethylamine N-oxide (TMAO), all potential substrates for in vivo nitrosation to form N-nitrosodimethylamine (NDMA), a potent carcinogen. When bolus doses of [14C]DMA or [14C]TMA were given ip, recovery of radioactivity in the urine was essentially complete, and respiratory excretion, fecal excretion, and accumulation in tissues of these amines or their metabolites were negligible. Urine analysis following doses of stable isotopes showed that DMA was not converted to TMA or TMAO. Varying amounts of TMA were oxidized to TMAO, the fraction oxidized decreasing at higher doses of TMA. Ingestion and excretion of naturally occurring methylamines were monitored over a 5-day period in separate groups of normal and germ-free rats. The results of these metabolic balance studies indicate that there is net synthesis of DMA by gut bacteria and net consumption of TMAO by endogenous processes. The net intake or excretion of TMA and TMAO observed in normal and germ-free rats is consistent with bacterial synthesis of TMA followed by its almost complete oxidation to TMAO. Blood concentrations of DMA and TMA were measured in rats for 8 hr following < 5, 100, or 1000 mumol bolus i.v. or ip doses of radioisotopes or stable isotopes. At any given dose of DMA or TMA, the decay in blood concentration was approximately monoexponential. At the lowest (most physiologic) dose the apparent volume of distribution (VD) for DMA was larger than that for TMA. Both values of VD greatly exceeded the size of the animals, suggesting that DMA and TMA are highly concentrated at one or more locations in the body. This was confirmed by measurements in tissue homogenates sampled 1 hr after a dose. The overall handling of methylamines by rats is generally consistent with observations in humans. The presence of high local concentrations of DMA and TMA at various extragastric sites merits further investigation in connection with the potential for endogenous nitrosation of these methylamines to form NDMA.

Animals↗