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PubMed2003

Determination of volatile aliphatic amines in air by solid-phase microextraction coupled with gas chromatography with flame ionization detection.

Practical aspects of the application of solid-phase microextraction (SPME) to the determination of volatile aliphatic amines in air are described. Analytes included methylamine (MA), ethylamine (EA), dimethylamine (DMA), diethylamine (DEA), trimethylamine (TMA) and triethylamine (TEA). New SPME stationary phases were examined. The effects of relative humidity and temperature on analytes uptake were taken into account in analysis. Gas chromatography (GC) with flame ionization detector (FID) was used for the final analysis.

Air↗

PubMed1989

Safety of intracavernous injections using an alpha-blocking agent.

We tested the possibility of using intracavernous injections of the alpha-blocking agent moxisylyte (6-acetoxy-thymoxy-ethyl-dimethylamine) as treatment of erectile impotence. Laboratory studies proved moxisylyte to be more active than saline (double-blind with crossover) but less active than papaverine (crossover), since it induced prolonged erection in most patients but rigid erection in only a few. However, penile vibration proved to enhance the moxisylyte effects, the combination resulting in rigid erection in 5 of 8 patients tested. Repeated office injections of moxisylyte in 70 patients resulted in clear improvement of impotence during the subsequent weeks in 50 per cent of the psychogenic, and 18 per cent of the organic and mixed impotent patients. Of 91 impotent patients 42 achieved satisfactory intercourse within 2 hours after an office injection, although previously the same dose induced a rigid erection in the office in only 24. Of 37 patients instructed in moxisylyte self-injections 92 per cent achieved successful results without any significant side effect. The main advantage of moxisylyte proved to be its safety, allowing for less compelling precautions than with papaverine: only 2 of the 170 patients injected with moxisylyte at our clinic had prolonged erections, that is 1.1 per cent compared to 14 per cent in a personal series who received papaverine. In regard to the therapeutic applications of intracavernous injection facilitating drugs, such as moxisylyte, should be tried first, with use of the more potent but also more dangerous drugs, such as papaverine, only when impotence fails to improve.

Adult↗

PubMed1988

Relationships between chemical structure and inhibition of choline acetyltransferase by 2-(alpha-naphthoyl)ethyltrimethylammonium and related compounds.

A choline acetyltransferase (ChA) inhibitor with an optimum combination of properties of potency, stability and membrane permeability is required to study several functional aspects of acetylcholine in nervous and non-nervous tissues. Therefore, 2-(alpha-naphthoyl)ethyltrimethylammonium iodide (alpha-NETA), 2-(beta-naphthoyl)ethyltrimethylammonium iodide (beta-NETA), 2-(9'-anthroyl)ethyltrimethylammonium iodide (9'-AETA) and their corresponding tertiary dimethylamine hydrochloride analogs (alpha-NEDA, beta-NEDA, 9'-AEDA) were synthesized and tested for their ChA inhibitory activities. The quaternary ammonium compounds were more potent inhibitors (150 in microM: alpha-NETA, 9; beta-NETA, 76; 9'-AETA, 32) than the corresponding tertiary compounds (150 in microM: alpha-NEDA, 63; beta-NEDA, 1400; 9'-AEDA, 77). The alpha-naphthyl moiety was preferable to the beta-naphthyl- or 9'-anthryl moieties for alignment with the enzyme for inhibition. alpha-NETA and alpha-NEDA exhibited adequate ChA inhibitory potencies for further pharmacological studies and localization of membrane bound ChA. They exhibited fluorescent characteristics of the alpha-naphthyl moiety. Their ChA inhibition was not reversible by dialysis. They were considerably more potent for inhibiting ChA than cholinesterases and carnitine acetyltransferase.

Acetylcholine↗

PubMed2002

Formation of N-nitrosodimethylamine (NDMA) from reaction of monochloramine: a new disinfection by-product.

Studies have been conducted specifically to investigate the hypothesis that N-nitrosodimethylamine (NDMA) can be produced by reactions involving monochloramine. Experiments were conducted using dimethylamine (DMA) as a model precursor. NDMA was formed from the reaction between DMA and monochloramine indicating that it should be considered a potential disinfection by-product. The formation of NDMA increased with increased monochloramine concentration and showed maximum in yield when DMA was varied at fixed monochloramine concentrations. The mass spectra of the NDMA formed from DMA and 15N isotope labeled monochloramine (15NH2Cl) showed that the source of one of the nitrogen atoms in the nitroso group in NDMA was from monochloramine. Addition of 0.05 and 0.5 mM of preformed monochloramine to a secondarily treated wastewater at pH 7.2 also resulted in the formation of 3.6 and 111 ng/L of NDMA, respectively, showing that this is indeed an environmentally relevant NDMA formation pathway. The proposed NDMA formation mechanism consists of (i) the formation of 1,1-dimethylhydrazine (UDMH) intermediate from the reaction of DMA with monochloramine followed by, (ii) the oxidation of UDMH by monochloramine to NDMA, and (iii) the reversible chlorine transfer reaction between monochloramine and DMA which is parallel to (i). We conclude that reactions involving monochloramine in addition to classical nitrosation reactions are potentially important pathways for NDMA formation.

Carcinogens↗

PubMed2003

Role of amination of a polymeric adsorbent on phenol adsorption from aqueous solution.

Adsorption of seven phenols, one aromatic carboxylic acid and one sulfonated aromatic acid from aqueous solution, by a hypercrosslinked polymeric adsorbent (CHA-111) and the derivative animated by dimethylamine was compared. The results of different adsorption isotherms indicated that amino group on the polymeric matrix played a significant role on adsorption of almost all the employed compounds. For most employed compounds adsorption capacities increase to different degree and significantly for those with lower value of pK(a). It may be attributed to the enhanced adsorbent-adsorbate interaction for amino group introduced on the polymeric matrix. The empirical Freundlich isotherm equation was employed to interpret the adsorbent-adsorbate interaction. The adsorption enthalpy change indicated the uptake of phenols on MCH-111 to be an enhanced physical adsorption because of the hydrogen-bonding interaction. Adsorption kinetic study of phenols on CHA-111 and MCH-111 was also conducted and amino group on the matrix will reduce the adsorption rate for change of pore size distribution and loss of macroprous volume as well as the hydration effect on the surface partly.

Adsorption↗

PubMed1997

Detection and identification of NAD-catabolizing activities in rat tissue homogenates.

NAD may be degraded in several ways. A large number of investigations have shown that at least those catabolic routes which involve the formation of ADP-ribose are related to regulatory processes. In this study a rapid assay was utilized that permits identification of NAD-degrading enzymes directly in sodium dodecylsulfate polyacrylamide gels. Enzymatic activities were recovered by washing the gels in the presence of mild detergents such as lauryl dimethylamine N-oxide or Triton X-100. Subsequent incubation of the gels in the presence of the fluorescent analog 1,N6 etheno-NAD visualized NAD-degrading enzymes. Following excision of the fluorescent bands from the gels, the actual activity of the proteins was established by incubating the gel slices with 14C-labeled NAD and subsequent product analysis by thin layer chromatography (TLC). Homogenates from rat renal cortex and spleen were analyzed by this procedure. While in the spleen homogenate only a single band could be 'activity-stained', in the kidney three bands were detected. Kidney proteins with apparent molecular masses of about 210,000 and 105,000 Da were identified as phosphodiesterase and NAD pyrophosphatase (alkaline phosphodiesterase I), respectively. The third protein exhibited an apparent molecular mass of 41,000. The spleen protein (apparent molecular mass 45,000 Da) cleaved NAD to nicotinamide and ADP-ribose identifying it as NAD glycohydrolase. The procedure is suitable to screen for NAD-converting activities in crude extracts. It is specific for proteins which function as monomers or homo-oligomers.

Adenosine Diphosphate Ribose↗

PubMedDate not supplied

Immunomodulatory activity of amphiphilic antimicrobials on mouse macrophages.

A quaternary ammonium salt (1-methyldodecyl)-trimethylammonium iodide, a structurally analogous amine oxide (1-methyldodecyl)-dimethylamine-N-oxide and the amine oxide lacking long alkyl chain trimethylamine-N-oxide were tested for their immunomodulatory activity. Inbred mice strain C57/BL6 were pretreated for 7 days by the compounds under study. The activity of elicited peritoneal macrophages was also tested. Both compounds have a long alkyl chain. In concentrations of 10(-6) M there was a significant increase of the phagocytic, candidacidal and lysozyme activities of the cells. We also observed a suppressed peroxidase activity. The colicidal activity of both the peritoneal and spleen cells were not affected. The amine oxide lacking the long alkyl chain has the same effect at high concentration. A similarity between the effects of the amphiphilic compounds on the macrophages and their antimicrobial efficacy elicits the conclusion that both activities are caused by their ability to interact with the cell membranes.

Adjuvants, Immunologic↗

PubMed2000

Synthesis of ionones and carvone analogues: olfactory properties and preliminary toxicity assays.

Vilsmeier reagents react with alpha/beta-ionones and carvone to produce aldehydes 7-11 in a one-step procedure. The indene derivative 11, which came from the double iminoalkylation of carvone and ring closure with the elimination of dimethylamine, was practically odourless, while all the others had peculiar odours which were very different from the starting material. The cytotoxicity data of 9 and 10, which are the most promising potential perfume ingredients, are also reported.

Alkenes↗

PubMed2001

Cytotoxicity of derivatives from dehydrocrotonin on V79 cells and Escherichia coli.

New derivatives from dehydrocrotonin (DHC, compound I), with the same anti-ulcerogenic properties but less toxicity were synthesised by reducing the cyclohexenone moiety of DHC with NaBH(4) (compound II), by reducing the cyclohexenone and lactone moieties with LiAlH(4) (compound III) and by transforming the lactone moiety into an amide (compound IV) using dimethylamine. The cytotoxicity of these derivatives from DHC was assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), tetrazolium reduction (MTT) and neutral red uptake (NRU). IC(50) values of 540 and 350 microM were obtained for compound II in the NRU and NAC tests, respectively. Compound III was less toxic than the other DHC derivatives (IC(50)=1800 microM) on V79 cells based on NAC assay. Compound IV showed an IC(50) ranging from 350 to 600 microM based on the three endpoints evaluated. The three compounds were less toxic on V79 cells than DHC. DHC, compounds II, III and IV did not change the respiration rate of Escherichia coli on the acute toxicity assay.

Animals↗

PubMed1997

L-Carnitine moiety assay: an up-to-date reappraisal covering the commonest methods for various applications.

L-Carnitine and its esters are typical endogenous substances. Their homeostatic equilibria are effectively controlled by various mechanisms which include rate-limiting enteral absorption, a multicomponent endogenous pool which is regulated according to a mammillary metabolism, an asymmetric body distribution and a saturable tubular reabsorption process leading to renal thresholds. In formal pharmacokinetic and metabolic investigations, the whole L-carnitine pool should be investigated, owing to the rapid interchange process between the various components of the pool. Free L-carnitine, as well as its acyl esters, must therefore be considered from an analytical viewpoint. L-Carnitine, acetyl-L-carnitine and total L-carnitine (the latter as an expression of the whole pool) can easily be assayed by enzyme or radioenzyme methods. Propionyl-L-carnitine and other esters containing fatty acids with more than three carbon atoms can be assayed using various HPLC approaches. Tandem mass spectrometry is another excellent approach to the assay of carnitine and its short-chain, medium-chain and long-chain esters. As L-carnitine contains a chiral carbon atom, the enantioselectivity of the assays is also considered in this review. Metabolites produced by enteral bacteria, namely tri-, di- and mono-methylamine, gamma-butyrobetaine, along with other systemic metabolites, namely trimethylamine N-oxide and N-nitroso dimethylamine, are very important in quantitative and toxicokinetic terms and require specific assay methods. This review covers the commonest methods of assaying carnitine and its esters, their impurities and pre-systemic and systemic metabolites and gives analytical details and information on their applications in pharmaceutics, biochemistry, pharmacokinetics and toxicokinetics.

Carnitine↗

PubMed2001

Protection by thiols of the mitochondrial complexes from 4-hydroxy-2-nonenal.

In the present study, the effects of 4-hydroxy-2-nonenal (HNE) on highly purified pyruvate dehydrogenase complex (PDC) and its catalytic components in vitro and on PDC, alpha-ketoglutarate dehydrogenase complex (KGDC), and the branched-chain alpha-keto acid dehydrogenase complex (BCKDC) activities in cultured human HepG2 cells were investigated. Among the PDC components, the activity of the dihydrolipoamide acetyltransferase-E3-binding protein subcomplex (E2-E3BP) only was decreased by HNE. Dihydrolipoamide dehydrogenase (E3) protected the E2-E3BP subcomplex from HNE inactivation in the absence of the substrates. In the presence of E3 and NADH, when lipoyl groups were reduced, higher inactivation of the E2-E3BP subcomplex by HNE was observed. Purified PDC was protected from HNE-induced inactivation by several thiol compounds including lipoic acid plus [LA-plus; 2-(N,N-dimethylamine)ethylamidolipoate(.)HCl]. Treatment of cultured HepG2 cells with HNE resulted in a significant reduction of PDC and KGDC activities, whereas BCKDC activity decreased to a lesser extent. Lipoyl compounds afforded protection from HNE-induced inhibition of PDC. This protection was higher in the presence of cysteine and reduced glutathione. Cysteine was able to restore PDC activity to some extent after HNE treatment. These findings show that thiols, including lipoic acid, provide protection against HNE-induced inactivation of lipoyl-containing complexes in the mitochondria.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed1999

Neuroprotective effects of alpha-lipoic acid and its positively charged amide analogue.

Elevated levels of extracellular glutamate have been linked to reactive oxygen species mediated neuronal damage and brain disorders. Lipoic acid is a potent antioxidant that has previously been shown to exhibit neuroprotection in clinical studies. A new positively charged water soluble lipoic acid amide analog, 2-(N,N-dimethylamine) ethylamido lipoate HCl (LA-plus), with a better cellular reduction and retention of the reduced form was developed. This novel antioxidant was tested for protection against glutamate induced cytotoxicity in a HT4 neuronal cell line. Glutamate treatment for 12 h resulted in significant release of LDH from cells to the medium suggesting cytotoxicity. Measurement of intracellular peroxides showed marked (up to 200%) increase after 6 h of glutamate treatment. Compared to lipoic acid, LA-plus was more effective in (1) protecting cells against glutamate induced cytotoxicity, (2) preventing glutamate induced loss of intracellular GSH, and (3) disallowing increase of intracellular peroxide level following the glutamate challenge. The protective effect of LA-plus was found to be independent of its stereochemistry. The protective function of this antioxidant was synergistically enhanced by selenium. These results demonstrate that LA-plus is a potent protector of neuronal cells against glutamate-induced cytotoxicity and associated oxidative stress.

Animals↗

PubMed2001

Recombinant Microdochium nivale carbohydrate oxidase and its application in an amperometric glucose sensor.

Biosensors containing recombinant carbohydrate oxidase from Microdochium nivale (rMnO) were developed by means of either chemically modified carbon paste or graphite electrode. 1-(N,N-dimethylamine)-4-(4-morpholine)benzene (AMB) and 1,1'-dimethylferrocene (DMFc) have been used as mediators. The biosensors showed a linear calibration graph up to 18 mM of glucose when operated at 0.04-0.36 V versus a saturated calomel electrode. Almost no change was detected in the sensitivity of the biosensors at pH 7.2-8.1. The biosensors responded to other aldoses in the D-configuration, however, maximal sensitivity of the biosensor was towards D-glucose. The biosensor did not response to polyhydroxylic compounds such as D-mannitol, D-sorbitol and inositol. The advantages of the biosensors based on rMnO in comparison to Aspergillus niger glucose oxidase is a wider linear range, low sensitivity to oxygen and (in some cases) broad specificity.

Aspergillus niger↗

PubMed2002

Synthesis and preliminary biochemical assessment of ethyl-terminated perfluoroalkylamine oxide surfactants.

The synthesis and usefulness in membrane biochemistry of a new class of surfactants have been investigated. 1-Ethyl-2-dimethylamine oxide polar heads were grafted onto a hydrocarbon, a fluorocarbon or an ethyl-capped fluorocarbon hydrophobic tail. The ability of the resulting surfactants to extract and/or to stabilize in aqueous solution a test membrane protein, cytochrome b(6)f, was evaluated. While it is not a detergent, the hemifluorinated derivative efficiently kept purified cytochrome b(6)f soluble, native and functional. The data suggest that alkyl-capped fluorocarbon surfactants provide an interesting alternative to classical detergents for handling membrane proteins in aqueous solutions under non-dissociating conditions.

Cytochrome b Group↗

PubMed2003

Synthesis and antibacterial study of 10, 15, 20-triphenyl-5-(4-hydroxy-3-(trimethylammonium)methyl)phenylporphyrin as models for combination of porphyrin and alkylating agent.

10, 15, 20-Triphenyl-5-(4-hydroxy-3-(trimethylammonium)methyl)phenylporphyrin 4 and its zinc complex 5 have been synthesized and antibacterial activities have been studied for 4 and its derivative. Compound 4 showed stronger inhibition than that of 10, 15, 20-triphenyl-5-(4-hydroxy-3-(dimethylamine)methyl)phenylporphyrin (2) and 10, 15, 20-triphenyl-5-(4-methoxy-3-(trimethylammonium)methyl)phenylporphyrin (6). It is possible that antibacterial activity of compound 4 involved in photoinducing both o-quinone methide intermediate and singlet oxygen formation.

Alkylating Agents↗

PubMed2002

Conformationally constrained ethylenediamines: synthesis and receptor binding of 6,8-diazabicyclo[3.2.2]nonanes.

The synthesis and receptor affinity of 6,8-diazabicyclo[3.2.2]nonanes representing conformationally constrained ethylenediamines are described. The Dieckmann analogous cyclization of the (piperazin-2-yl)propionate 9 provided the bicyclononane 10 only, when the first cyclization product was trapped with chlorotrimethylsilane. 10 was stereoselectively transformed into the bicyclic amines 19a,b and amides 22a,b, which were investigated in competition experiments with radioligands for their sigma(1)-, sigma(2)-, kappa-, and mu-receptor affinities. The (2R)-configured dimethylamine 19a showed promising sigma(1)-receptor affinity (K(i)=23.8 nM) and selectivity, whereas the (2S)-configured (dichlorophenyl)acetamide 22b displayed a sigma-receptor binding profile (sigma(1): K(i)=184 nM; sigma(2): K(i)=263 nM) very similar to the binding profile of the atypical antipsychotic BMY-14802 (26).

Alkanes↗

PubMed2003

Synthesis and biological evaluation of novel carbon-11-labelled analogues of citalopram as potential radioligands for the serotonin transporter.

Three serotonin reuptake inhibitors where the 5-cyano group in citalopram [1-(3-dimethylamino-propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile (1)] was replaced with a methyl, acetyl and piperidinyl carbonyl group, respectively, were synthesized. In a Stille reaction applying [(11)C]methyl iodide the labelled compound [5-methyl-(11)C][3-[1-(4-fluorophenyl)-5-methyl-1,3-dihydroisobenzofuran-1-yl]-propyl]-dimethylamine ([(11)C]-2) was synthesized in 60-90% radiochemical yield. [5-carbonyl-(11)C][1-[1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-yl]-1-piperidin-1-yl-methanone] ([(11)C]-3) was synthesized in 62% radiochemical yield in a palladium mediated cross-coupling reaction utilizing [(11)C]carbon monoxide. The specific activity of [(11)C]-2 was highly dependent on whether the corresponding trimethyltin or tributyltin precursor was applied. In ex vivo rodent studies compound [(11)C]-2 exhibited a good blood-brain barrier (BBB) penetration whereas [(11)C]-3 did not. The brain distribution of [(11)C]-2 was investigated in a non-human primate using PET. There was a rapid uptake of radioactivity into the brain. Accumulation of the radiotracer was in agreement with the known distribution of serotonin transporters. The maximal thalamus to cerebellum ratio of 1.3 was reached after 85 min and the specific binding was partly blocked after pre-treatment with citalopram. Thus, [(11)C]-2 does not exhibit appropriate properties as radioligand for visualization of the serotonin transporter in vivo.

Acetylation↗

PubMed1997

Synthesis and structure-activity relationship studies in a series of 2-substituted 1,3-dioxolanes modified at the cationic head.

To develop ligands that may be useful in exploring muscarinic receptor heterogeneity, we synthesized a series of analogues of 2,2-diphenyl-[1,3]-dioxolan-4-ylmethyl-dimethylamine oxalate and methiodide bearing a modified cationic head. These compounds, when tested on tissues containing the three subtypes M1, M2, and M3, behaved as muscarinic antagonists whose results showed that different substituents on the quaternary and tertiary nitrogen affect affinity and selectivity in different ways. In particular comparison of the affinities of these ligands with those of the reference compounds points out that compounds bearing an ethyl substituent improve the affinity of the molecule at the three subtypes while compounds bearing a phenethyl substituent are more selective for the M3 sites.

Amines↗