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PubMed2005

Quantitative determination of alkylated quaternary amines and their n-hydroxylated metabolites in an enzyme incubation matrix by liquid chromatography electrospray ionization mass spectrometry.

A simple, rapid and sensitive reversed-phase liquid chromatography method coupled to electrospray ionization mass spectrometry has been developed for studying the in vitro metabolism of the long-chain quaternary ammonium compounds dodecyltrimethylamine, tetradecyltrimethylamine and hexadecyltrimethylamine. Samples were prepared from the biological matrix by a simple protein precipitation stage. The separation was performed using a BDS Hypersil C8 3 microm particle size (100 x 3 mm i.d.) column with a fast gradient separation (60% B to 100% B) using a mobile phase of 10 mm aqueous ammonium acetate (pH 4.0, with 0.06% triethylamine; (A)-acetonitrile (B) at 0.7 mL min(-1). To minimize contamination of the MS source a switching value was used to divert the solvent front to waste. Decylammonium bromide was used as the internal standard and analytes were identified and quantified by positive ion electrospray selected ion monitoring of their intact molecular cations. The assay had a limit of quantitation of 0.25 microm (6.25 pmol on column) and was linear over the range 0.25--100 microm assay concentration for this series of long-chain quaternary amines. The precision of intra- and inter-day assays was better than 19% and the accuracy was between 93 and 109%. The method was used to assess the in vitro metabolism of the quaternary amines by wild-type cytochrome P450 enzyme CYP 4 A 1 and mutants in an artifical membrane system.

Alkylation↗
PubMed1995

Optical detection of macromolecular heparin via selective coextraction into thin polymeric films.

Thin plasticized polymer films, poly(vinyl chloride) doped with a specific ion pairing quaternary ammonium compound, tridodecylmethylammonium chloride, and a lipophilic pH indicator, 3-hydroxy-4-(4-nitrophenylazo)phenyl octadeconate, are shown to exhibit significant and analytically useful optical response toward macromolecular heparin. The response mechanism is based on favorable extraction of heparin into the bulk organic film, owing to the specific ion-pairing complexation reaction between the quaternary ammonium species and the polyanion. A simultaneous coextraction of hydrogen ions results in protonation of the pH chromophore and hence a change in the optical absorbance of the polymeric film. When used in a limited volume/fixed exposure (10 min) detection mode, film absorbances change as a function of the initial heparin concentration in the range of 0.2-3.0 units/mL (1.2-18 micrograms/mL). The practical measurement response time is controlled by heparin diffusion through the stagnant diffusion layer adjacent to the surface of the film as well as within the bulk of the polymer film and is shown to increase with the molecular weight of the heparin species tested. No optical response to heparin is observed when a strong heparin complexing agent (e.g., protamine) is present in the test solution, suggesting that the polymer film can be used to conveniently monitor heparin-protamine (or other antagonist) titrations. The theory relating to the operation of the sensing film in either the equilibrium or the kinetic mode and the selectivity of the optimized film to heparin relative to small anions are presented.

Anions↗
PubMedDate not supplied

Interaction of chlorisondamine with the neuronal nicotinic acetylcholine receptor.

An epitope was found on the alpha2-nicotinic isoform of the neuronal nicotinic acetylcholine receptor that would likely form salt bridges with quaternary ammonium compounds and a cation-pi interaction with the pi-cloud of an aromatic ring. Chlorisondamine, a nicotinic antagonist, exerts a long-lasting, if not permanent, blockade of the ion channel gated by acetylcholine. Blocking of the ion channel prevents nicotine from exerting its rewarding effect on the CNS. Chlorisondamine contains two quaternary ammonium groups and a tetrachloroisoindoline ring. We propose that chlorisondamine interacts with an epitope on the alpha2 isoform of the rat neuronal nicotinic receptor (residues 388-402, GEREETEEEEEEEDE), where one or both of the quaternary ammonium groups of chlorisondamine form a salt bridge with dither a glutamic acid side chain or a phosphate group, whereas the tetrachlorobenzene portion of the tetrachloroisoindoline ring interacts with the guanidinium group of arginine in a cation-pi association: In this work, a new way of probing the interaction of a receptor epitope (alpha2) with organic molecules (chlorisondamine and hexachlorobenzene) was undertaken using matrix assisted laser desorption/ionization mass spectrometry.

Amino Acid Sequence↗
PubMed1985

[Structure-activity relationship in the series of muscarinic acetylcholine receptor antagonists: four types of antagonist-receptor binding].

The data available in literature on the structure-activity relationships in the series of muscarinic antagonists have been analyzed. Three groups of the ammonium compounds are distinguished, each containing a specific chemical structure element. For the antagonist association with the receptor, the binding constant logarithms within each group depend linearly on the partition coefficient (pi) logarithms characterizing their distribution in the water-octanol system. The linear regression coefficients for pi are practically identical. A separate group consists of antagonists that have no ammonium grouping. Four possible modes of antagonist-receptor binding are surmized.

Animals↗
PubMedDate not supplied

Discarding multidrug resistance inducers, the possible role of a biosensing reporter in antimicrobial discovery.

The aim of the present work was to determine whether the luminescence-based reporter plasmid pQacLux could be applied to drug discovery in order to discard compounds with defined properties. Non-pathogenic Staphylococcus aureus RN4220 cells bearing pQacLux were incubated with different concentrations of a disinfectant of common use in hospitals. The in vivo light emission response of the plasmid to the given stimuli was then quantified and compared to a negative control for the construction of dose-response curves. The selected disinfectant provided a convenient model for the activity of quaternary ammonium compounds. In spite of the use of a raw model solution, the system revealed high levels of sensitivity. According to the results obtained, pQacLux could be conveniently used in the first steps of drug development in order to discard all possible multidrug resistance inducers.

Biosensing Techniques↗
PubMed1986

Human antibodies to the antineoplastic drug elliptinium: characterization and structure-activity relationships.

Immune-mediated hemolytic disease is a phenomenon rarely encountered with cancer chemotherapeutic agents. Elliptinium, a tetracyclic ammonium compound used in breast and kidney cancer, can induce antibodies that may result in clinical hemolysis. This study reports the characterization of the elliptinium haptenic determinant by use of two different methodologies: a hemagglutination test and a radioimmunoassay. Binding of 12 analogues or derivatives of elliptinium was also studied. Good correlation between the two methods was obtained, indicating that the determinant is most likely located on the quaternary ammonium-containing ring. Furthermore, the hydrophilicity of the drug appears to be an important factor in the antibody reaction. The mechanism of the binding of elliptinium to its antibodies is discussed.

Alkaloids↗
PubMed1987

Polyclonal antibodies to elliptinium acetate: structure-activity relationships and comparison with human anti-elliptinium IgM.

In order to elucidate the immune-mediated hemolytic disease induced in man by elliptinium acetate, a quaternary ammonium compound with antineoplastic activity, polyclonal antibodies directed against this hapten were raised in rabbits. The coupling step between drug and carrier was performed according to a putative human in vivo hapten conjugation mechanism. Structure-activity relationships of the resulting IgG were compared with the epitope site recognized by human anti-elliptinium IgM by using a panel of twelve elliptinium acetate analogues. Although both antibodies were directed principally against the quaternary ammonium ion, a poor correlation between the cross-reactivity indices was obtained. In fact, it appeared that both antibodies recognized specifically the ammonium group plus different regions of the molecule: the indole ring for human antibodies, the N-alkyl group and its vicinity for rabbit ones. The specificity of the obtained rabbit polyclonal antisera is discussed, with regard to the conjugation mechanism of the drug occurring in man.

Alkaloids↗
PubMed1997

Quantification of the neuromuscular blocking agent rocuronium and its putative metabolite 17-desacetylrocuronium in heparinized plasma by capillary gas chromatography using a nitrogen sensitive detector.

We have developed a sensitive and specific capillary GC (cGC) assay for the quantification of the quarternary aminosteroidal compound rocuronium (roc), a neuromuscular blocking agent, and its putative metabolite 17-desacetylrocuronium (17OH-roc), using 3-desacetylvecuronium (3OH-vec) as an internal standard (I.S.). This novel method has been applied to a pharmacokinetic study with roc, monitoring sixty patients who were classified according to four different body mass index (BMI) groups. The isolation of these drugs from plasma was carried out using a dichloromethane liquid-liquid extraction after ion-pairing of the positively charged ammonium compounds with iodide. To achieve thermal stability, tert.-butyldimethylsilyl-ethers were formed at the 3OH- and 17OH-steroidal positions by reaction with N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide at 70 degrees C overnight. An automated cGC system fitted with a nitrogen sensitive detector with a specially prepared glass phase bead and a computer controlled data handling system was used to analyze and quantify the compounds, which were separated on a DB1 capillary column with helium as the carrier gas and a temperature program ranging from 120 to 300 degrees C. The method is linear for 50-6400 ng/ml for roc and 80-6400 ng/ml for 17OH-roc. The detection limits were 10 ng/ml for roc and 50 ng/ml for 17OH-roc. The lower limit of quantification was 50 ng/ml for roc and 80 ng/ml for 17OH-roc. Intra-assay coefficients of variation (C.V.s) were 10% and 15% and the inter-assay C.V.s 8-18% and 16-21% for roc and 17OH-roc, respectively.

Androstanols↗
PubMed1977

Cholesterol gallstone dissolution rate accelerators I: Exploratory investigations.

Various compounds that might function as cholesterol gallstone dissolution accelerators were studied. The dissolution rates of cholesterol monohydrate pellets in synthetic bile (116 mM sodium cholate-32 mM lecithin) containing the agent at various concentration levels were determined. In the absence of any dissolution rate accelerator, the dissolution kinetics for cholesterol previously were found to be interfacial resistance controlled, and the rates were around 20 times less than the diffusion-controlled rates in the present experiments. Primary, secondary, and tertiary amines and quaternary ammonium compounds were effective accelerators. When the alkyl chain lengths were long enough and/or when the agent concentrations were high enough, the dissolution rates generally approached diffusion-controlled rates. Steroidal amines generally had good activity. Anionic and nonionic surfactants had little or negative activity.

Amines↗
PubMed1981

[Microbiological investigations with decentral dosing apparatuses for disinfectants. Part 1: investigations of cell number (author's transl)].

Cell numbers have been investigated for several months in disinfectant solutions which were measured out with tap water by decentral automatically dosing apparatuses. They differed not only quantitatively but also qualitatively with respect to the products used: With one product on the bases of aldehydes + organic tin compound 3 h after samples have been collected up to 100 bacteria/100 ml could be cultivated. Thus, cell numbers in disinfectant solutions were in the same range of cell numbers of tap water. Sometimes the cell numbers in both substrates seem to go parallel (Fig. 1). The bacterial compositions in both were similar (Table 3); gramnegative, yellow bacteria of the genera Pseudomonas and Flavobacterium dominated. After the disinfectant in one apparatus has been substituted by one which is composed of aldehydes + a quaternary ammonium compound cell numbers rapidly and permanently decreased to the limit of detectability. Only coryneform bacteria survived for a longer time which were characterized (Tab. 4) but not determined taxonomically. Their facultatively methylotrophic growth was conspicuously.

Bacteria↗
PubMed2000

Investigation of the effects of cyclodextrins and organic solvents on the separation of cationic surfactants in capillary electrophoresis.

The use of alpha- and beta-cyclodextrin (CD) to understand and to improve the separation of a series of cationic surfactants, homologues of alkylbenzyldimethyl ammonium compounds (ABDACs) with an alkyl chain of varying length (C10-C18), in capillary electrophoresis (CE) is reported for the first time. Similar to the effects of organic solvents, the presence of alpha- or beta-CD in the running buffer was found to reduce peak tailing/loss for the longer-chain ABDACs. Based on fluorescence measurements, it was found that formation of host-guest complexes occurred between alpha- or beta-CD and various ABDACs, with the likelihood that the hydrophobic alkyl chain including into the CD cavity and the positively charged ammonium group remaining outside the cavity. The effects of alpha- or beta-CD can be interpreted in terms of a shift away from the formation of (1) micelles in the buffer system and (2) surfactant aggregates at the fused-silica capillary walls, as a result of the formation of inclusion complexes between alpha- or beta-CD and ABDACs.

Cations↗
PubMed1991

L-carnitine protection in ammonia intoxication. Effect of aminocarnitine on carnitine-dependent metabolism and acute ammonia toxicity.

Intraperitoneal administration of L-carnitine (16 mmol/kg) was reported by O'Connor et al. (FEBS Lett 166: 331-334, 1984) to fully protect mice from ammonium acetate given at a dose that kills 100% of untreated controls. Other investigators either have failed to observe protection by L-carnitine or have attributed the increased survival to a nonspecific "osmoprotective effect" of quaternary ammonium compounds. In the present studies we have confirmed the protective effect of L-carnitine in acute ammonia intoxication and have shown that D-carnitine and deoxycarnitine, close structural analogs of L-carnitine, are without protective effect. Although D-carnitine and deoxycarnitine do not support L-carnitine-dependent metabolisms, they are transported into tissues and their solutions are osmotically identical to those of L-carnitine; lack of protection by D-carnitine and deoxycarnitine suggests that metabolic rather than nonspecific osmotic effects account for L-carnitine-mediated protection. Further supporting the importance of L-carnitine-dependent metabolisms, we found that mice exhibited increased sensitivity to ammonium acetate when pretreated with DL-aminocarnitine, acetyl-DL-aminocarnitine or palmitoyl-DL-aminocarnitine, potent inhibitors of the carnitine acyltransferases. Interestingly, intraperitoneal injection of hyperosmotic solutions of sodium chloride or sucrose did afford significant protection against subsequently administered ammonium acetate. This phenomenon, which may be due to interference with ammonium acetate uptake from the peritoneal cavity or to reduction of cerebral edema by increased plasma osmolarity, apparently does not play a major role in L-carnitine-mediated protection since, as noted, hyperosmotic D-carnitine and deoxycarnitine solutions were not protective.

Acetates↗
PubMed1998

Hydrolysis of the soft amphiphilic antimicrobial agent tetradecyl betainate is retarded after binding to and killing Salmonella typhimurium.

Hydrolysis of tetradecyl betainate (B14), a fast-acting microbicidal amphiphilic quaternary ammonium compound (QAC) being an ester of betaine and tetradecanol, occurred after binding to Salmonella typhimurium, resulting in release of the water-soluble betaine portion and retention of the lipophilic tetradecanol. The rate of the hydrolysis was significant but retarded in comparison to B14 in solution. As in free solution, the hydrolysis of substance bound to S. typhimurium was increased in an alkaline environment and by heat. At pH 6.0 and 20 degrees C the hydrolysis of bound ester was about 10% after 180 min, whereas at pH 9.0 and 50 degrees C it was about 50% after 60 min. These results are consistent with a model where amphiphilic QACs are inserted into the bacterial outer membrane (OM) with the quaternary ammonium head group facing outwards and the lipophilic portion, including the ester bond, being in the membrane lipid environment enough for retarding the hydrolysis. However, calculation of the mean concentration of B14 in the bacteria at MBC99 (minimum bactericidal concentration required to kill 99% of cells) showed a 7000-8000 times greater concentration than in the medium. At this concentration, when most B14 is considered to be bound to the OM, the available surface area for each molecule was only 2 A2. This is only 6-7% of that required for close packing of the quaternary ammonium head group (30 A2), indicating that a three-dimensional, presumably continuous arrangement was formed. Since B14 is hydrolysed after its binding to bacteria with microbicidal effect, it may be used under conditions where stable QACs might be harmful to the close or the common environment.

Anti-Bacterial Agents↗
PubMed2000

Biological Monitoring of Pesticide Exposure: a review. Introduction.

Pesticides are used worldwide in agriculture, industry, public health and for domestic applications: as a consequence, a great part of the population may be exposed to these compounds. In spite of this extensive use, knowledge on the health risks associated with prolonged exposure is rather poor, and major uncertainties still exist. Epidemiological observations in man have so far produced little conclusive information, mainly because of weaknesses in exposure assessment. Therefore, information on the type and levels of exposure is fundamental in order to better understand and characterize risk to human health. Exposure assessment can be carried out via measurement of environmental concentrations, as well as via determination of the chemical or its metabolites in body tissues (biological monitoring). Besides indices of internal dose, biological monitoring also includes measurements of early effects attributable to interaction between the chemical agent and the human body. Biological monitoring has the advantage, over environmental monitoring, of determining the dose actually absorbed via any possible route: differences in absorption can be taken into account. whether they are due to biological variability or to use of protective equipment. When, in some cases, a combination of occupational and non-occupational exposure occurs, this also can be taken into consideration by biological monitoring. Few reference documents have been published on biological monitoring of pesticides. For this reason, the Office of Occupational Health of the World Health Organization gave ICPS a mandate to prepare a monograph specifically addressed to reviewing methods for biological monitoring of pesticide exposure. This review is based on more than 300 studies published over the period 1980-1999. For the most representative chemical classes, the available biological exposure indices are reported. Both indices of internal dose and. when available, of early effects are discussed. The reported tests were used to monitor exposure of pesticide applicators in agriculture and public health, manufacturing and formulating workers. subjects poisoned after accidental exposure or attempted suicide, volunteers involved in pharmacokinetic studies, as well as sub-groups of the general population exposed to environmentally persistent pesticides. Single chapters deal with organophosphorus insecticides, carbamate pesticides, dithiocarbamates, phenoxyacids, quaternary ammonium compounds. coumarin rodenticides, synthetic pyrethroids, organochlorine pesticides, chlorotriazines, and pentachlorophenol.

Animals↗
PubMed1996

Glutaraldehyde retains its disinfectant properties in presence of hydroxypropylmethyl cellulose (HPMC) gel.

Explanted medical devices are routinely sent to laboratories at the Center for Devices and Radiological Health for analysis. The shipping of these devices presents potential hazards to personnel as well as an opportunity for damage to the devices. In an effort to address these concerns, a viscous disinfecting shipping medium that would limit splashing and cushion a suspended device was proposed. Consequently, we investigated the disinfectant properties of adding a gelling agent, hydroxypropylmethyl cellulose (HPMC) to common disinfectants. We found that the germicidal effectiveness of 2.5% glutaraldehyde in 0.05 M borax when tested against Bacillus subtilis spores was not changed by the addition of 2% HPMC. In addition, HPMC appears to be compatible with 70% ethanol and at least one commercial disinfectant containing a quaternary ammonium compound. Preliminary experiments indicate that an HPMC-disinfectant gel is a potentially useful packaging agent for minimizing the hazards to personnel and materials during shipping of explanted medical devices. The use of such a medium would be subject to guidelines within the context of a program for handling biologically contaminated materials.

Bacillus subtilis↗
PubMed1996

Metabolic alterations in brain autopsies: proton NMR identification of free glycerol.

Metabolic alterations in bovine brain homogenate were examined as a function of post mortem interval (PMI) using high-resolution proton NMR spectroscopy. In particular, while lactate, glutamate, glutamine, creatine and inositols as well as the total concentration of trimethyl-ammonium compounds remained constant, prominent changes due to the hydrolysis of N-acetylaspartate to acetate and aspartate as well as the decomposition of glycerophosphocholine into free choline and glycerol correlated linearly with the duration of PMI (3-195 h). The spectroscopic identification of the latter process was confirmed by proton NMR studies of model solutions as well as of extracts of mammalian brain showing high levels of free glycerol. Since the methylene resonances of glycerol overlap with the proton resonances of myo-inositol, care should be taken in the interpretation of both in vitro and in vivo brain spectra.

Animals↗