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PubMed2002

Subcritical water extraction to evaluate desorption behavior of organic pesticides in soil.

We evaluated the feasibility of extracting organic pesticides in soil using a hot-water percolation apparatus at 105 degrees C and 120 kPa pressure. Efficiency of the method was assessed by extracting six selected pesticides (acetochlor, atrazine, diazinon, carbendazim, imidacloprid, and isoproturon) from previously equilibrated soil at 13.6-65.8 mg/kg concentration range. Studies were performed on brown forest soil with clay alluviation (Luvisol). The method developed was compared to the traditional batch equilibrium method in terms of desorbed amount of pesticides from soil and extraction time. Pesticides in the liquid phase from the batch sorption experiment and in the effluent from the hot-water percolation were quantified by high-performance liquid chromatography with UV detection. The results of the percolation experiment are in close correlation with those of the conventional soil testing method. Desorbed quantities by hot-water percolation were 85% acetochlor, 62% atrazine, 65% carbendazim, 44% diazinon, 95% imidacloprid, and 84% isoproturon, whereas using batch equilibrium method 101, 66, 64, 37, 81, and 90% were desorbed, expressed as the percentage of the adsorbed amount of pesticide on soil following equilibration. The average time for hot-water extraction was 3.45 min, in contrast to the 16 h time consumption of the traditional batch method. The effect of temperature on stability of selected compounds was also evaluated using pesticide-spiked sand without soil. Recoveries of analytes ranged between 84.6 and 91.1% with reproducibility of 7.9-10.2%, except for diazinon, for which recovery was 59.4% with 14.4% relative standard deviation since decomposition occurred at elevated temperature. The percolation process has been described by a first-order kinetic equation. The parameters calculated from the equation provide an opportunity to estimate the amount of compound available for desorption, the rate of desorption processes in the studied soil-pesticide-water system, and modeling the leaching process to obtain additional information on the environmental behavior of the examined pesticide.

Atrazine↗
PubMed1993

Effect of BW B70C, a novel inhibitor of arachidonic acid 5-lipoxygenase, on allergen-induced bronchoconstriction and late-phase lung eosinophil accumulation in sensitised guinea-pigs.

The actions of BW B70C, an orally available, biologically persistent and selective inhibitor of arachidonic acid 5-lipoxygenase, have been examined in two systems of anaphylaxis in actively sensitised guinea-pigs in vivo. In anaesthetised, artificially ventilated animals pretreated with mepyramine and indomethacin to leave only the "peptidoleukotriene-dependent" component (leukotrienes C4, D4 and E4) of the anaphylactic response, direct inhalation of nebulised allergen resulted in a slowly developing bronchoconstriction which was prevented in a dose-dependent manner by BW B70C (2-50 mg/kg p.o.) administered 1 or 6 h before challenge. In conscious animals fasted overnight and then pretreated with mepyramine to prevent death due to acute bronchial anaphylaxis, exposure to nebulised allergen produced slight respiratory symptoms. When blood and lung samples were analysed 4-48 h after allergen provocation a sustained leukocytosis and pulmonary eosinophil accumulation were observed. In contrast, in food-replete conscious animals, the early respiratory symptoms were still observed upon allergen inhalation, but no significant blood leukocytosis or accumulation of eosinophils in the lungs occurred subsequently. The eosinophil influx induced by allergen in fasted animals was assessed both by histological examination and determination of tissue peroxidase content, two measures which demonstrated reasonable agreement. Administration of a single dose of BW B70C (10 mg/kg p.o.) 1 h prior to allergen challenge did not affect the subsequent eosinophil infiltration 24 h later, but 20 mg/kg given in divided doses (-1 and +12 h) produced 67% inhibition of cell accumulation. A single dose of 50 mg/kg (-1 h) had a similar effect (78% inhibition). The potent glucocorticosteroid betamethasone was used as a reference compound, and 4 mg/kg given as a divided dose (-1 and +7) fully inhibited lung inflammation assessed 24 h after provocation with allergen. BW B70C inhibited both acute and allergic bronchoconstriction and late-phase eosinophil accumulation subsequent to allergen inhalation in guinea-pigs. In view of the apparent requirement for sustained plasma levels of BW B70C in order to prevent late-phase eosinophil recruitment to the lung after a single challenge with allergen, it is unclear whether inhibition of 5-lipoxygenase underlies the observed anti-eosinophil accumulation effects of the compound, but the anti-bronchoconstrictor effects are consistent with the known inhibitory activity of BW B70C against 5-lipoxygenase.

Administration, Oral↗
PubMed1986

Mutagenicity of methylisocyanate and its reaction products to cultured mammalian cells.

Methylisocyanate (MIC) induced mutagenic responses in the absence of exogenous activation in the mouse lymphoma cell forward mutation assay at concentrations as low as 8-24 microM. MIC produced predominantly small mutant colonies, suggesting the possibility of clastogenic activity. The intermediate hydrolysis product, methylamine, was also mutagenic without exogenous activation but required several hundred-fold higher concentrations (ca. 3 mM). N,N'-Dimethylurea, the final product in the reaction of methylisocyanate and water, was totally refractory in either the presence or absence of S9 for concentrations up to 57 mM (5 mg/ml). The ethyl ester of N-methylcarbamic acid was also tested since it was the only available analogue to the highly reactive N-methylcarbamic acid intermediate. This compound was mutagenic only in the presence of S9 at doses exceeding 5-40 microM, which suggested the possibility that the free acid, produced by enzymatic hydrolysis, is also mutagenic. The mutagenic activity of the ester resulted solely in the production of small mutant colonies.

Animals↗
PubMed2006

Photocatalytic degradation of phenyl-urea herbicides chlortoluron and chloroxuron: characterization of the by-products by liquid chromatography coupled to electrospray ionization tandem mass spectrometry.

The first stages of the photocatalytic degradation of the compounds chlortoluron [3-(3-chloro-4-methylphenyl)-1,1-dimethylurea] and chloroxuron [3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea], belonging to the class of phenyl-urea herbicides, were investigated using high-performance liquid chromatography (HPLC) coupled to electrospray ionization ion trap tandem mass spectrometry (ESI-IT-MS/MS). Degradation was accomplished under solar radiation, using TiO2 embedded into a polyvinylidene fluoride (PVDF) transparent matrix as a heterogeneous photocatalyst. Aliquots of the chlorinated herbicide solutions were withdrawn at different times and subjected to gradient elution, reversed-phase HPLC separations, specifically optimized to obtain the highest resolution between peaks related to the herbicide degradation by-products. The latter were then investigated using MS detection; in particular, MS/MS measurements were made and structural information was obtained from the interpretation of fragmentation data. Several by-products were identified; the most important ones are hydroxylated compounds arising from the interaction between the two chlorinated herbicides and OH radicals generated at the TiO2 surface under irradiation. Other by-products were generated by slightly different processes, namely demethylation, dearylation and dechlorination, eventually followed by interaction with OH radicals.

Catalysis↗
PubMed2002

Polar organic pollutants in groundwater: experimental approaches to biodegradation during subsoil passage.

A selection of polar organic compounds was investigated for their biodegradation on a laboratory scale fixed-bed bioreactor and the decline of the parent compounds besides the formation of metabolites was monitored. Of particular interest was the investigation into the degradation of pesticides, especially isoproturon (IPU), surfactants and industrial by-products of chemical synthesis. The results from the laboratory degradation experiments are compared to findings in groundwater.

Benzene Derivatives↗
PubMed2005

Phototransformation of methabenthiazuron in the presence of nitrate and nitrite ions.

The influence of nitrate and nitrite ions on the degradation of methabenzthiazuron upon irradiation using artificial solar light has been investigated. The rate of degradation of methabenzthiazuron (1 microM) was accelerated by NO3- (0.1 mM) by a factor of 10. The irradiation of methabenzthiazuron (0.1 mM) in the presence of NO3- (1 mM) or NO2- (0.1 mM) yielded numerous intermediary photoproducts. Mineralization was achieved after prolonged exposure. Some were identified with the help of LC-ESI-MS and flow injection APCI-MS techniques. Both oxidations of the aromatic ring and of the urea chain were observed. The former started by hydroxylation of the ring. Further oxidation of the ring led to cleavage of the benzenic ring with formation of dialdehydic, diacidic and anhydric compounds. Complete removal of the lateral urea chain took place subsequently to demethylation of the terminal methyl group and loss of the CO-NH2 group. Nitration was a minor process. This work shows that the photodegradation of methabenzthiazuron in the presence of nitrate or nitrite ions is highly non-specific.

Benzothiazoles↗
PubMed2001

By-products formation during degradation of isoproturon in aqueous solution. I: Ozonation.

The degradation of the herbicide isoproturon during its ozonation in aqueous solution has been investigated with the aim of identifying intermediate as well as final by-products formed. At ambient temperature, phosphate-buffered (pH = 7) isoproturon aqueous solutions (10, 10(-1) and 10(-3) mg/l) were ozonated in a semi-batch reactor, under a continuous flow of ozonated air whose ozone concentration was 9 and 0.9 mg O3/lair for the highest and the two lower herbicide concentrations respectively. Measured steady-state ozone concentrations during the two sets of experiments (i.e. the highest and the lower isoproturon concentration) were 1.9 and 0.7 mg O3/l. Under all of the above conditions, isoproturon was always completely removed in a period ranging between 5 and 15 min, essentially by reacting with molecular ozone. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses indicate that primary degradation by-products are formed either by introducing OH groups in the aromatic ring and/or in the side-chain substituents, or by breaking down the isopropyl alkyl chain. The results also show that these primary intermediates are successively degraded yielding low molecular weight compounds such as aldehydes, simple organic acids and alpha-oxo-acids, which have been identified by gas chromatography-electron capture detection (GC-ECD), ion chromatography (IC) and GC-MS, respectively. On the basis of the analytical results, a pathway for the degradation of isoproturon by ozone has been proposed.

Chromatography, High Pressure Liquid↗
PubMed2001

Antimutagenic effect of one variety of green pepper (Capsicum spp.) and its possible interference with the nitrosation process.

It is known that the poblano green pepper, a significant component in the Mexican diet, contains certain natural compounds such as chlorophyll, beta-carotene, and vitamins, which have antimutagenic and/or anticarcinogenic properties. Using the somatic mutation and recombination test in wing cells of Drosophila melanogaster, an extract of the poblano pepper (Capsicum spp.) was evaluated to determine its antimutagenic effect against the nitrosation process, simulating the process occurring in the human stomach caused by known food additives. Larvae of 72h old D. melanogaster of standard (ST) and high bioactivation (HB) crosses were exposed in a simultaneous, chronic treatment with the juice expressed from the crushed, whole, fresh pepper fruit, plus the mixture of 20mM methyl urea (MU) and sodium nitrite (SN), mixed with the animals' food. Three doses of pepper juice (12.5, 25, and 50%) were used. The background mutation rate given as spots per wing was 0.36 and 0.48 for ST and HB, respectively. Mutation frequencies produced by the MU and SN mixture was 1.73 (ST) and 26.46 (HB) mutations per wing. The poblano juice decreased the above rates between 40 and 80%, respectively. The experiments suggest that some compounds present in the green pepper may cause this antimutagenic effect by interfering with the nitrosation process. The role of the extract and one of its components, such as vitamin C, in the nitrosation process will be discussed.

Animals↗
PubMed1990

[The pre- and postnatal carcinogenic effect of 3,3-diethyl-1-methyl-1-nitrosourea (DEMNU) in rats following intravenous application].

The pre- and postnatal administration of DEMNU induces a high frequency of tumors when applied via the intravenous route, and the latency periods show a dose dependence (table I). Tumors of the brain, spinal cord and cranial nerves clearly predominate. Furthermore, a large number of neoplasms of kidney, heart and soft tissue was observed (table II). As DEMNU is per se a very stable compound, it is suggested that this agent is metabolized by monooxygenases. 3-Ethyl-1-methyl-1-nitrosourea should be formed as an intermediate product via this pathway, which is relatively stable and might explain the mainly neurotropic carcinogenicity of DEMNU. Species differences in the carcinogenicity of trialkyl-nitrosoureas and the mode of metabolic activation are discussed.

Animals↗
PubMedDate not supplied

Deuterium isotope effect on the toxicokinetics of monomethylamine in the rat.

The single-dose toxicokinetics of monomethylamine has been characterized in the rat by HPLC assay of serial blood samples. Biphasic first-order elimination was observed following an iv bolus dose of 19 mumol/kg with a terminal half-life of 19.1 +/- 1.3 min (mean +/- SE, N = 4). The apparent steady state volume of distribution, systemic blood clearance, and renal blood clearance were 1.21 +/- 0.09 liter/kg, 53.4 +/- 3.5 ml/min/kg, and 5.72 +/- 0.53 ml/min/kg, respectively. The administration of an intragastric dose permitted the calculation of the systemic bioavailability of monomethylamine as 69 +/- 3%. Duplicate experiments using the structural analogue with deuterium atoms substituted for hydrogens on the methyl group revealed a much slower elimination of the compound, although ultimately, 5 times as much was excreted unchanged in the urine. Isotope effects calculated as the ratios of terminal half-life, systemic blood clearance, and systemic bioavailability were 1.9, 2.2, and 1.8, respectively.

Animals↗
PubMedDate not supplied

In vitro cytotoxicity and differential cellular sensitivity of derivatives of diamino acids. II. N1-methyl, N1-allyl, N1-(2-chloroethyl) and N1-propargyl nitrosoureas.

The in vitro cytotoxicity and differential cellular sensitivity of a series of new N1-methyl, N1-allyl, N1-2-chloroethyl and N1-propargyl nitrosourea derivatives of diamino acids were determined in the National Cancer Institute's primary antitumor drug screen. The compounds tested showed an in vitro anticancer activity similar to commercialized nitrosoureas such as CCNU, BCNU, MeCCNU, chlorozotocin, streptozotocin and PCNU. The alkylating moiety of the nitrosoureas seems to play a role in the general selectivity of our compounds. The N1-methyl and N1-2-chloroethyl nitrosourea derivatives are more selective for central nervous system cell lines, the N1-allyl nitrosourea derivatives are more selective for lung cancer cell lines and the N1-propargyl nitrosoureas are more selective for leukemia cell lines.

Amino Acids, Diamino↗
PubMed1986

Gastric antisecretory and pharmacologic properties of N,N-dimethyl-N'-(2-diisopropylaminoethyl)-N-(4,6-dimethyl-2-pyridyl)ur ea (L-634,366).

N,N-Dimethyl-N'-(2-diisopropylaminoethyl)-N-(4,6-dimethyl-2-pyridyl)urea (L-634,366) was selected from a series of pyridylurea compounds with antisecretory activity as a potential therapeutic agent for the treatment of ulcer disease. L-634,366 was an effective inhibitor of gastric secretion evoked by gastrin, histamine and 2-desoxy-D-glucose (2-DG) in conscious dogs. Orally, L-634,366 was slightly less potent than the reference H2 receptor blocker, cimetidine as an inhibitor of secretion evoked by histamine, but was equipotent as an inhibitor of secretion evoked by gastrin and 2-DG. In vitro L-634,366 was a weak antagonist of histamine (H2) receptor responses in the guinea-pig atria and rat uterus; in the atria the antagonism appeared to be noncompetitive. In the anesthetized dog, L-634,366 possessed weak anticholinergic activity as compared to atropine in reducing vagally mediated cardiovascular, antral motor responses and with regard to antagonizing the pressor response to the muscarinic stimulant, McN 343-A. The anticholinergic activity of L-634,366 was lower and more selective than that of pirenzepine or atropine in producing mydriasis in mice, in antagonizing acetylcholine induced bradycardia in guinea-pig atria, methacholine and acetylcholine elicited contractions in the guinea-pig ileum and QNB binding to muscarinic receptors. L-634,366, like carbenoxolone, increased incorporation of 3H-glucosamine in gastric mucous indicating an increase in synthesis or turnover of mucous. L-634,366 is a novel compound possessing a broad spectrum of antisecretory activity; in vitro studies suggested a weak noncompetitive inhibition of the histamine-H2 receptor in atria.

Animals↗
PubMed2002

Ozonation of chlorophenylurea pesticides in water: reaction monitoring and degradation pathways.

The degradation of mono- and dichlorophenylureas under ozone/hydrogen peroxide conditions was investigated in order to establish the effect of the structural parameters. The N-dimethyl phenylureas (mono- and dichloro) appear to differ strongly from the corresponding N-methyl N-methoxy analogues in terms of disappearance of the parent pesticide and evolution of the by-products identified by MS and MS-MS. The degradation rate of the latter is slower by a factor of 2.5 giving rise to additional pathways (hydroxylation of the phenyl ring and carbinolamine intermediate). Experiments with 14C-labelled compounds allow a complete determination of the mass balances obtained after solid-phase-extraction (SPE). This study demonstrates the interest of SPE for reaction monitoring and compares the performances of different types of phases for this purpose used alone or in combination. Mineralisation is also evaluated regarding 14CO2 production and found to contribute up to 20% in the degradation process.

Biodegradation, Environmental↗
PubMed1998

OH radical reactivity of pesticides adsorbed on aerosol materials: first results of experiments with filter samples.

Preliminary results of a new method to investigate the OH radical reactivity of semi-volatile organic compounds (e.g., pesticides) are presented. Terbuthylazine, simazine, sodium benzoate, and bromoxynil were adsorbed on highly disperse silicon dioxide powder as an unreactive carrier at a thickness well below one monolayer. The coated material was suspended in air as an aerosol, sampled on filters, and exposed in an 840-liter Duran chamber to OH radicals, produced by photolysis of hydrogen peroxide in the gas phase. Sunlamps on top of the chamber were used as cold light sources [T(aerosol) approximately 25 degreesC]. OH radical concentrations (10(5)<cOH (cm-3)<3x10(6)) were monitored in the gas phase using a set of four hydrocarbons with well-known OH reactivities as reference compounds. The triazine terbuthylazine (kOH=1.1x10(-11) cm3 s-1) was used as a reference compound in the filter samples. Simazine and isoproturon were found to react with a comparable OH rate constant with respect to terbuthylazine. Sodium benzoate reacts about a factor of 3 slower. Rapid degradation was observed for bromoxynil, explained mainly by photolysis. Besides the characterization and discussion of the experimental setup used, the rate constants obtained are discussed and compared with estimated values.

Aerosols↗
PubMed1993

Solvation of human serum albumin in aqueous alkylurea solutions.

Solvation of human serum albumin in aqueous solutions of urea, methyl-, N,N'-dimethyl-, and ethylurea was studied by density measurements. From the densities at constant molality and constant chemical potential, the preferential solvation parameters of human serum albumin were determined. In all solutions the denaturant is preferentially bound. From preferential solvation data, Gibbs free energies of transfer from water to alkylurea solutions were calculated. Since the enthalpies of transfer were determined previously the entropies of transfer would also be obtained. Based on these and model compound data an attempt is made to identify various interactions involved in solvation. The total binding of denaturant to protein could also be calculated from preferential solvation data. The following major binding sites have been identified: ionic groups on the surface of protein molecules, peptide groups and aromatic side-chains. The correlation between the total number of sites and the number of urea molecules bound is satisfactory.

Calorimetry↗
PubMed2006

Pharmacological characterization and feeding-suppressive property of FMS586 [3-(5,6,7,8-tetrahydro-9-isopropyl-carbazol-3-yl)-1-methyl-1-(2-pyridin-4-yl-ethyl)-urea hydrochloride], a novel, selective, and orally active antagonist for neuropeptide Y Y5 receptor.

We evaluated the pharmacological profiles of FMS586 [3-(5,6,7,8-tetrahydro-9-isopropyl-carbazol-3-yl)-1-methyl-1-(2-pyridin-4-yl-ethyl)-urea hydrochloride], a novel tetrahydrocarbazole derivative as a neuropeptide Y (NPY) Y5 receptor antagonist. This compound showed a highly selective in vitro affinity for Y5 (IC(50) = 4.3 +/- 0.4 nM) relative to other NPY receptor subtypes like Y1 or Y2. Its binding to Y5 was found to be fully antagonistic from cyclic AMP accumulation assays in human embryonic kidney 293 cells. Pharmacokinetic analysis revealed sufficient oral availability and brain permeability of this compound accompanied with clear dose relation. We attempted to assess the selectivity of FMS586 and, thereby, to infer the physiological role of Y5 in the following feeding experiments in normal rats. An intracerebroventricular injection of NPY and Y5-selective agonist peptide induced acute and robust feeding responses in satiated rats, and prior administration of FMS586 at the doses from 25 to 100 mg/kg clearly inhibited these responses by approximately 55 and 90%, respectively. This compound also showed dose-dependent but transient suppression in natural feeding models of both overnight fasting-induced hyperphagia and spontaneous daily intake. FMS586 did not modulate food intake induced by the topical injection of norepinephrine, galanin, or gamma-aminobutyric acid receptor agonist muscimol to the paraventricular nucleus. In addition, we confirmed the Y5-specific activity profile of FMS586 by immunohistochemical analysis. Taken together, we propose not only that our compound potentially expresses specific blockade of central Y5 signals but also that Y5 receptor would certainly contribute to physiological regulation of food intake in normal rats, as suggested from its origin.

Administration, Oral↗
PubMedDate not supplied

In vitro cytotoxicity and differential cellular sensitivity of derivatives of diamino acids. I. N1-methyl, N1-allyl, N1-(2-chloroethyl) and N1-propargyl ureas.

The in vitro cytotoxicity and differential cellular sensitivity of a series of new N1-methyl, N1-allyl, N1-2-chloroethyl and N1-propargyl urea derivatives of diamino acids were determined in the National Cancer Institute's primary antitumor drug screen. The compounds tested showed an in vitro anticancer activity similar to commercialized nitrosoureas such as CCNU, BCNU, MeCCNU, chlorozotocin, streptozotocin and PCNU. The alkylating moiety of the ureas seems to play a role in the general selectivity of our compounds. The N1-methyl and N1-2-chloroethyl urea derivatives are more selective for central nervous system cell lines and the N1-allyl urea derivatives are more selective for lung cancer cell lines. The N1-propargyl ureas did not show any particular selectivity in the 60 human cell lines tested.

Amino Acids, Diamino↗
PubMed2006

Biochemical effects of nonylphenol polyethoxylate adjuvant, Diquat herbicide and their mixture on the three-spined stickleback (Gasterosteus aculeatus L.).

This study examined the response of 7-ethoxyresorufine-O-deethylase, glutathione-S-transferase, glutathione peroxidase, glutathione content, level of thiobarbituric acid reactive compounds and circulating vitellogenin, in three-spined sticklebacks after 21 days of exposure to Diquat herbicide, commercial nonylphenol polyethoxylate adjuvant and mixture between Diquat and adjuvant. The results showed that adjuvant exerted more important oxidative effects than Diquat and that mixture effects were unlike to single additivity. This study argues for ecotoxicological risk assessment of adjuvants and mixtures of adjuvants and pesticides.

Animals↗