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At least 199 records · Page 11Linked to original sources
PubMed2006

Phenols and amine induced HO* generation during the initial phase of natural water ozonation.

The initial phase of ozone decomposition in natural water (t < 20 s) is poorly understood. It has recently been shown to result in very high transient HO* concentrations and, thereby, plays an essential role during processes such as bromate formation or contaminants oxidation. Phenols and amines are ubiquitous moieties of natural organic matter. Naturally occurring concentrations of primary, secondary, and tertiary amines, amino acids, and phenol were added to surface water, and ozone decomposition as well as HO* generation were measured starting 350 milliseconds after ozone addition. Six seconds into the process, 5 microM of dimethylamine and phenol had generated integral of HO* dt = 1 x 10(-10) M*s and 1.8 x 10(-10) M*s, respectively. With 10 microM dimethylamine and 1.5 mg O3/L, R(ct), (integral of HO*dt/ integral of O3dt) reached 10(-6), which is larger than in advanced oxidation processes (AOP) such as O3/H2O2. Experiments in the presence of HO*-scavengers indicated that a significant fraction of phenol-induced ozone decomposition and HO* generation results from a direct electron transfer to ozone. For dimethylamine, the main mechanism of HO* generation is direct formation of O2*- which reacts selectively with O3 to form O3*-. Pretreatment of phenol-containing water with HOCl or HOBr did not decrease HO* generation, while the same treatment of dimethylamine-containing water considerably reduced HO* generation.

Dimethylamines↗
PubMed1997

Metabolic disposition of [14C]-trimethylamine N-oxide in rat: variation with dose and route of administration.

1. Urine was the major route of excretion of radioactivity (95% dose in 0-24 h) following the oral, intravenous or intraperitoneal administration of [14C]-trimethylamine N-oxide dihydrate (1 mmol/kg body wt) to the adult male Wistar rat. A further 3-4% was voided in the urine during 24-72 h. Only fractional amounts were detected in the faeces, or were retained within tissues 3 days after administration. 2. Biliary secretion of radioactivity was insignificant (0.18% in 0-4 h) but larger amounts were secreted directly into the lumen of the gastrointestinal tract, especially the small intestine (2.6% in 0-1 h). 3. The only radioactive compounds identified in the urine were trimethylamine N-oxide and dimethylamine. Larger amounts of dimethylamine were excreted following oral administration (10%) as opposed to intravenous (2.5%) or intraperitoneal (1.5%) input. This production of dimethylamine occurred over a 100-fold oral trimethylamine N-oxide dose range (0.3-30 mmol/kg body wt). Incubation of trimethylamine N-oxide with gut contents (especially colon and rectum) led to the formation of dimethylamine.

Administration, Oral↗
PubMed1981

Uptake and Concentration of Alkylamines by a Marine Diatom: EFFECTS OF H AND K AND IMPLICATIONS FOR THE TRANSPORT AND ACCUMULATION OF WEAK BASES.

Methylamine, ethylamine, and dimethylamine (10 micromolar) are taken up and concentrated 600 to 6,000-fold by Cyclotella cryptica. Methylamine is concentrated most strongly, and its accumulation and retention are relatively insensitive to external pH but strongly inhibited by 30 millimolar external K(+). Accumulation and retention of ethyl- and dimethylamine, on the other hand, are strongly affected by external pH and less sensitive to external [K(+)]. Intracellular pH, as estimated from neutral red staining and quenching of 9-aminoacridine fluorescence, was between 4 and 5, with the central vacuole being the major acidic compartment. The accumulation of ethyl- and dimethylamine could result from diffusion of the uncharged amine across the membrane(s) and passive equilibration of the charged form (R-NH(3) (+)) inside and outside the cell. Differences in the accumulation ratio and the ion dependence for methylamine uptake relative to ethyl- and dimethylamine uptake suggests that a different mechanism is responsible for the concentration of the simpler amine.

Journal Article↗
PubMed1986

Food-borne amines and amides as potential precursors of endogenous carcinogens.

This paper reviews the experimental results of our research in the past several years and other related papers that have been directed toward the occurrence, biotransformation and epidemiological significance of carcinogenic N-nitroso compounds in biosphere. Endogenous carcinogens are a group of cancer-causing compounds produced in vivo from harmless precursors. This category has been exemplified by the well-known carcinogens, N-nitroso compounds. The significance of naturally occurring amines and amides as precursors of carcinogenic N-nitroso compounds in vivo and their implication in the incidence of human cancer have been investigated and emphasized. Extremely high levels of trimethylamine-N-oxide and dimethylamine were detected in squids and other seafoods. More than 90% of trimethylamine-N-oxide were converted to dimethylamine and trimethylamine on pyrolysis. Low levels of dimethylamine and methylamine were also detected in the fermented soybean products, wines and sauces. Both dimethylamine and trimethylamine are excellent precursors of dimethylnitrosamine. Several naturally occurring aromatic amines especially 2-carboline derivatives such as harman, norharman, harmaline, harmalol, harmine and harmol are mutagenic and become more mutagenic to Salmonella typhimurium after nitrosation. Appreciable amounts of piperidine were detected in the popular spice white and black pepper powders. Under acidic condition, piperidine reacts readily with nitrite to form carcinogenic N-nitroso-piperidine. N-Nitrosophenacetin was formed from the reaction of nitrite with the amide drug phenacetin. This new compound showed strong mutagenicity to Salmonella typhimurium and Sarcina lutea and strong teratogenic activity to Leghorn chicken embryos. Studies have shown that the majority of N-nitroso compounds in the body come from in vivo conversion. Most investigators believe that this endogenous pool of N-nitroso compounds may prove to be a major exposure route in man. The presence of naturally occurring amines and amides in the diet then becomes one of the crucial limiting steps in the formation of endogenous N-nitroso compounds in vivo.

Amides↗
PubMed1977

Biochemical profile of uremic breath.

We attempted to define the substances that contribute to the characteristic "uremic breath" of patients with end-stage renal disease. Breath samples from nine patients underwent direct analysis before and after hemodialysis with use of gas chromatography and confirmation by mass spectrometry, and indirectly assessment by an organoleptic panel. Concentrations of secondary and tertiary amines, dimethylamine and trimethylamine were increased, with subsequent reduction after hemodialysis (dimethylamine from 2.00 +/- 0.19 [S.E.M.] to 0.88 +/- 0.12 microng per 30 minutes, P less than 0.001, and trimethylamine from 0.79 +/- 0.22 to 0.44 +/- 0.15 microng per 30 minutes, P less than 0.003). Treatment with nonabsorbable antibiotics in two patients reduced both serum and breath amine levels without dialysis. Loss of nitrogen via the breath was not quantitatively important. We conclude that uremic breath reflects the systemic accumulation of potentially toxic volatile metabolites, among which dimethylamine and trimethylamine have been positively identified and correlated with the classic fishy odor.

Adult↗
PubMed1981

Microbial formation of secondary and tertiary amines in municipal sewage.

Dimethylamine was formed in municipal sewage that was amended with creatinine, and trimethylamine was formed from choline or phosphatidylcholine. The maximum level of product that accumulated was equivalent to 0.13, 0.096, and 6.7% by weight, respectively, of the added chemicals. No dimethylamine or trimethylamine was detected in sewage amended with betaine, and no dimethylamine was found in sewage that was amended with methylamine and methionine.

Anaerobiosis↗
PubMed1996

Involvement of methyltransferase-activating protein and methyltransferase 2 isoenzyme II in methylamine:coenzyme M methyltransferase reactions in Methanosarcina barkeri Fusaro.

The enzyme systems involved in the methyl group transfer from methanol and from tri- and dimethylamine to 2-mercaptoethanesulfonic acid (coenzyme M) were resolved from cell extracts of Methanosarcina barkeri Fusaro grown on methanol and trimethylamine, respectively. Resolution was accomplished by ammonium sulfate fractionation, anion-exchange chromatography, and fast protein liquid chromatography. The methyl group transfer reactions from tri- and dimethylamine, as well as the monomethylamine:coenzyme M methyltransferase reaction, were strictly dependent on catalytic amounts of ATP and on a protein present in the 65% ammonium sulfate supernatant. The latter could be replaced by methyltransferase-activating protein isolated from methanol-grown cells of the organism. In addition, the tri- and dimethylamine:coenzyme M methyltransferase reactions required the presence of a methylcobalamin:coenzyme M methyltransferase (MT2), which is different from the analogous enzyme from methanol-grown M. barkeri. In this work, it is shown that the various methylamine:coenzyme M methyltransfer steps proceed in a fashion which is mechanistically similar to the methanol:coenzyme M methyl transfer, yet with the participation of specific corrinoid enzymes and a specific MT2 isoenzyme.

Adenosine Triphosphate↗
PubMed1986

Mitochondrial H+-ATPase activation by an amine oxide detergent.

Lauryl dimethylamine oxide activates ATP hydrolysis by the mitochondrial H+-ATPase. Activation is observed in systems with a high content of inhibitor protein as described by Pullman and Monroy (Pullman, M.E., and Monroy, G.C. (1963) J. Biol. Chem. 238, 3762-3769), i.e. Mg-ATP submitochondrial particles and a Triton X-100-solubilized H+-ATPase from the same particles. Detergent activation of ATP hydrolysis is also present in inhibitor-reconstituted systems, i.e. submitochondrial particles, Triton extracts, and soluble F1-ATPase. In submitochondrial particles depleted of inhibitor protein, lauryl dimethylamine oxide induced a biphasic response which is characterized by a drop-in activity induced by relatively low concentrations of LDAO; at higher concentrations the detergent activates to an extent never greater than the initial activity. In inhibitor protein-depleted oligomycin-sensitive Triton extracts, lauryl dimethylamine oxide stimulates ATP hydrolysis to very high values (30 mumol min-1 mg-1). These findings suggest that in addition to the inhibitor protein ATP hydrolysis is controlled by other subunit interactions.

Adenosine Triphosphate↗
PubMed1987

Concurrent generation of methylamine and nitrite during denitrosation of N-nitrosodimethylamine by rat liver microsomes.

With the goal of identifying the organic amine product(s) of enzymatic N-nitrosodimethylamine (NDMA) denitrosation, 4 mM NDMA was incubated with liver microsomes from ethanol-treated rats. The concentrations of dimethylamine and methylamine were determined by derivatization with 2,4-dinitrofluorobenzene followed by gas chromatography-mass spectrometry. There was no net increase in the concentration of dimethylamine during incubation, but the yield of methylamine was equimolar with that of nitrite. Additional incubations of NDMA using acetone-induced microsomes, 1 mM and 0.1 mM substrate, gave methylamine/nitrite ratios of 0.9 and 0.7, respectively, confirming the quantitative linkage between these two products. Control incubations conducted with pure methylamine or dimethylamine indicated that the secondary amine is not a significant intermediate in the metabolic generation of the primary amine. Experiments with 15N-labeled NDMA showed that the methylamine nitrogen came from the amino moiety of the nitrosamine. The results suggest that NDMA metabolism is best viewed as a competition between at least two important pathways, demethylation and the presumably deactivating denitrosation route, a formulation which seems to account for the previously reported detection of methylamine as a urinary metabolite of NDMA and for the production of less than theoretical yields of labeled dinitrogen gas during NDMA metabolism.

Acetone↗
PubMed1986

[Damage to the liver DNA of rats during the endogenous synthesis of N-nitrosodimethylamine].

The damage of liver DNA formation during endogenic synthesis of N-nitrosodimethylamine (NDMA) have been studied after introduction of its precursors, dimethylamine, amidopyrine and sodium nitrite, into the rat stomach. A combined administration of various doses of dimethylamine and nitrite increased the amount of single-strand DNA from 3.0 to 11.3%. The maximum DNA damage after administration of the precursors was observed after 24 h, and after 48 h it decreased to the control level. Pretreatment of rats with dimethylamine or nitrite increased the DNA damage induced by NDMA formation (37.4% and 41.6%, respectively).

Alkylation↗
PubMed1977

[Influence of precursors of endogenously synthesized dimethylnitrosamine on the activity of the demethylase of that carcinogen in rat liver].

Oral administration of dimethylamine, sodium nitrite and a combination of these precursors of endogenously synthesized dimethylnitrosamine to rats increased the activity of demethylase of this carcinogen in the liver microsomes. Under conditions of chronic experiment inclusion of dimethylamine into the diet of rats intensified the demethylase activity even in the presence of casein, an inductor of this enzymatic system. An inhibitor of protein synthesis--actinomycin D prevented an increase of demethylase activity in the microsomal fraction caused by dimethylamine.

Animals↗
PubMed1995

Protein recognition of ammonium cations using side-chain aromatics: a structural variation for secondary ammonium ligands.

A model for the structure of dimethylamine dehydrogenase was generated using the crystal coordinates of trimethylamine dehydrogenase. Substrate is bound in trimethylamine dehydrogenase by cation-pi bonding, but modeling of dimethylamine dehydrogenase suggests that secondary amines are bound by a mixture of cation-pi and conventional hydrogen bonding. In dimethylamine dehydrogenase, binding is orientationally more specific and distinct from those proteins that bind tertiary and quaternary amine groups.

Binding Sites↗
PubMed2001

A novel denitrifying bacterial isolate that degrades trimethylamine both aerobically and anaerobically via two different pathways.

The aerobic and anaerobic degradation of trimethylamine by a newly isolated denitrifying bacterium from an enrichment culture with trimethylamine inoculated with activated sludge was studied. Based on 16S rDNA analysis, this strain was identified as a Paracoccus sp. The isolate, strain T231, aerobically degraded trimethylamine, dimethylamine and methylamine and released a stoichiometric amount of ammonium ion into the culture fluid as a metabolic product, indicating that these methylated amines were completely degraded to formaldehyde and ammonia. The strain degraded trimethylamine also under denitrifying conditions and consumed a stoichiometric amount of nitrate, demonstrating that complete degradation of trimethylamine was coupled with nitrate reduction. Cell-free extract prepared from cells grown aerobically on trimethylamine exhibited activities of trimethylamine mono-oxygenase, trimethylamine N-oxide demethylase, dimethylamine mono-oxygenase, and methylamine mono-oxygenase. Cell-free extract from cells grown anaerobically on trimethylamine and nitrate exhibited activities of trimethylamine dehydrogenase and dimethylamine dehydrogenase. These results indicate that strain T231 had two different pathways for aerobic and anaerobic degradation of trimethylamine. This is a new feature for trimethylamine metabolism in denitrifying bacteria.

Aerobiosis↗
PubMed2005

Complete mineralisation of dimethylformamide by Ochrobactrum sp. DGVK1 isolated from the soil samples collected from the coalmine leftovers.

A bacterial strain DGVK1 capable of using N,N-dimethylformamide (DMF) as sole source of carbon and nitrogen was isolated from the soil samples collected from the coalmine leftovers. The molecular phylogram generated using the complete sequence of 16S rDNA of the strain DGVK1 showed close links to the bacteria grouped under Brucellaceae family that belongs to alphaproteobacteria class. Specifically, the 16S rDNA sequence of strain DGVK1 has shown 97% similarity to Ochrobactrum anthropi LMG 3331 (D12794). This bacterium has also shown impressive growth on dimethylamine, methylamine, formaldehyde and formate that are considered to be the prominent catabolic intermediates of DMF. DMF degradation has led to the accumulation of ammonia and dimethylamine contributing to the increase of pH of the medium. The DMF-grown resting cells of Ochrobactrum sp. DGVK1 have also contributed for the release of ammonia when resting cell suspension was added to phosphate buffer containing DMF. Similar experiments done with the glucose-grown cultures have not produced ammonia and thus indicating the inducible nature of DMF-degrading enzymes in Ochrobactrum sp. DGVK1. Further, dimethylformamidase, dimethylamine dehydrogenase and methylamine dehydrogenase, the key enzymes involved in the degradation of DMF, were assayed, and the activities of these enzymes were found only in DMF-grown cultures further confirming the inducible nature of the DMF degradation. Based on these results, DMF degradation pathway found in Ochrobactrum sp. DGVK1 has been proposed.

Biodegradation, Environmental↗
PubMed1993

Gas chromatographic determination of primary and secondary low-molecular-mass aliphatic amines in urine using derivatization with isobutyl chloroformate.

A simple routine method for the gas chromatographic determination of methylamine, dimethylamine, ethylamine and methylethylamine in urine is presented. The method is based on a two-phase derivatization procedure with isobutyl chloroformate as reagent. The reaction is quantitative in 10 min. We found no artifact formation of either choline or trimethylamine (dietary amine compounds) or of dimethylethylamine or triethylamine (catalyst amines in the industrial setting). The chromatographic behaviour of the amine carbamates was excellent. The recoveries of methylamine, dimethylamine, ethylamine and methylethylamine in spiked urine samples were 82, 89, 100 and 96%, respectively, and the precision (the relative standard deviation) was 3.6, 1.8, 3.3 and 2.0%, respectively. The method was linear for the studied amine carbamates up to 250 mg/l. The endogenous amine concentrations in urine samples from ten normal subjects were: methylamine, 0.9 mg/l (mean; range 0.3-1.5); dimethylamine, 14.7 mg/l (mean; range 4.6-27.6); ethylamine, 0.8 mg/l (mean; range 0.2-2.3); methylethylamine, less than 0.02 mg/l.

Amines↗
PubMed1979

Utilization of trimethylamine and other N-methyl compounds for growth and methane formation by Methanosarcina barkeri.

A number of N-methyl compounds, including several methylamines, creatine, sarcosine, choline, and betaine, were readily fermented by enrichment cultures yielding methane as a major product. Methylamine, dimethylamine, trimethylamine, and ethyldimethylamine were fermented by pure cultures of Methanosarcina barkeri; except for ethyldimethylamine, these amines are considered important substrates of this methanogenic microorganism. Creatine, sarcosine, choline, and betaine were fermented to methane only by mixed cultures. During growth of M. barkeri on methyl-, dimethyl-, or trimethylamine, methanol was not excreted into the medium. The fermentation of trimethylamine gave rise to an intermediary accumulation of methyl- and dimethylamine in the medium. An accumulation of methylamine during the fermentation of dimethylamine was not observed. Methane and ammonia were produced from the three methylamines by M. barkeri in amounts expected on the basis of the appropriate fermentation equations. The growth yield was 5.8 mg of cells (dry weight) per mmol of methane and was not dependent on the kind of methyl compound used as substrate.

Euryarchaeota↗
PubMed1996

Specific roles of methylcobamide:coenzyme M methyltransferase isozymes in metabolism of methanol and methylamines in Methanosarcina barkeri.

An immunochemical approach was employed as a direct test for functional activities of isozymes of methylcobamide:coenzyme M methyltransferase (MT2-M and MT2-A) in the metabolic pathways of methane formation from: methanol, acetate, monomethylamine, dimethylamine, and trimethylamine. Specific removal of the MT2 isozymes from buffer soluble cell extracts of Methanosarcina barkeri was accomplished by use of immobilized, affinity-purified, ovine polyclonal antibodies. Extracts of methanol-grown cells depleted of MT2-M lost entirely the ability to carry out conversion of methanol to 2-(methylthio)ethanesulfonate (methyl-CoM). Methanol:CoM methyl transfer activity was completely restored by addition of purified MT2-M, but no activity was recovered by addition of MT2-A. In contrast, the activity of trimethylamine-grown cell extracts to convert monomethylamine and dimethylamine to methyl-CoM was lost almost entirely by immunosorptive removal of MT2-A. Addition of purified MT2-A, but not MT2-M, to the MT2-A-depleted extract fully reconstituted methyl-CoM formation from both mono- and dimethylamine. Interestingly, in extracts resolved of MT2-A, trimethylamine-dependent methylation of coenzyme M was observed at approximately 20% of the rate of controls not treated with antibody. Furthermore, both isozymes were effective in full restoration of trimethylamine conversion. Tests indicated that neither of the two MT2 isozymes are involved in methane formation from acetate. The results establish that MT2-A plays a specific role in metabolism of methylated amine substrates, whereas, MT2-M functions in methane formation from trimethylamine and methanol.

Cell-Free System↗
PubMed2000

AL-3138 antagonizes FP prostanoid receptor-mediated inositol phosphates generation: comparison with some purported FP antagonists.

The aim of this study was to pharmacologically characterize the antagonist properties of a novel prostaglandin F2alpha (PGF2alpha) analogue (11-deoxy-16-fluoro PGF2alpha; AL-3138) using a variety of second-messenger assays of prostaglandin receptor subtypes. A detailed comparison was made between AL-3138 and some purported FP receptor antagonists such as PGF2alpha dimethylamine, PGF2alpha dimethylamide, glibenclamide and phloretin using the FP receptor-mediated phosphoinositide turnover assay in A7r5 rat thoracic aorta smooth muscle cells and mouse Swiss 3T3 fibroblasts. The potency and efficacy of AL-3138 as an FP receptor agonist were: EC50 = 72.2 +/- 17.9 nM (Emax = 37%) (n = 3) in A7r5 cells and EC50 = 20.5 +/- 2.8 nM (Emax = 33%) (n = 5) in 3T3 cells. Being a partial agonist, the antagonist potency of AL-3138 against fluprostenol in A7r5 cells was determined to be: Ki = 296 +/- 17 nM (n = 3) and Kb = 182 +/- 44 nM (n = 5) (-log Kb = 6.79 +/- 0.1). AL-3138 exhibited very minimal or no antagonistic effects at EP2, EP4, DP and TP prostaglandin receptors. Both PGF2alpha dimethylamide and PGF2alpha dimethylamine were inactive as FP receptor antagonists, whereas phloretin and glibenclamide were very weak and had -log Kb values of 5.28 +/- 0.09 (n = 3) and 3.58 +/- 0.32 (n = 3), respectively. However, phloretin antagonized functional responses of EP2 and DP prostanoid receptors, and also the V1-vasopressin receptor. AL-3138 competed for [3H]PGF2alpha binding to FP receptors with a relatively high affinity (IC50high = 312 +/- 95 nM) matching its functional antagonist potency. In conclusion, AL-3138 is a more potent and selective FP receptor antagonist than glibenclamide, phloretin, PGF2alpha dimethylamide and PGF2alpha dimethylamine and is therefore a unique and novel pharmacological tool to help characterize FP receptor-mediated functions.

3T3 Cells↗