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Single Compound (single + compound)
Selected AbstractsImpacts of heavy metals, polyaromatic hydrocarbons, and pesticides on freeze tolerance of the earthworm Dendrobaena octaedraENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2009Anne-Mette Bindesbøl Abstract Previous studies have shown that the interactions between chemicals and climatic stressors can lead to synergistically increased mortality. In the present study, we investigated the effect of seven common environmental contaminants on survival at ,6 and 15°C as well as on reproduction at 15°C in the earthworm Dendrobaena octaedra. Three classes of chemicals were considered: Heavy metals (nickel, lead, and mercury), polycyclic aromatic hydrocarbons (pyrene and phenanthrene), and pesticides (abamectin and carbendazim). Phenanthrene interacted antagonistically with freezing temperatures, whereas no interaction was observed with any of the tested pesticides. Two of the three tested metals (nickel and mercury) reduced the freeze tolerance synergistically (mercury was especially potent). This suggests that traditional laboratory studies, in which organisms are exposed to increasing concentrations of a single compound under otherwise optimal conditions, may underestimate the toxicity of some metals to field populations living in cold areas. [source] Influence of carbonation on aroma release from liquid systems using an artificial throat and a proton transfer reaction,mass spectrometric technique (PTR,MS)FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2009Maria Ángeles Pozo-Bayón Abstract To determine whether carbonation affects aroma release from liquid systems, carbonated and non-carbonated flavoured model systems were prepared and volatile release was determined under static (equilibrium) and dynamic conditions. A model flavour system was added as a single compound or as a mixture of the six aroma compounds used in this study. Volatile release under dynamic conditions involved using a home-made device simulating an artificial throat, coupled to a proton transfer mass spectrometer (PTR,MS). The results showed that carbonation increased the release of most of the aroma compounds in both static and in dynamic testing conditions. The extent of this effect depended, however, on the physicochemical characteristics of the aroma compounds (the most volatile and most hydrophobic compounds were affected more). Release was also increased if the aroma compounds were added as a mixture rather than as individual compounds. CO2 appears to be a key factor responsible for the enhanced release of flavourings from carbonated liquid systems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Odour-active compounds of Jinhua hamFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2008Huanlu Song Abstract Using DHS, SAFE, GC,O and GC,MS, the odour-active compounds of Jinhua ham were identified and ranked according their odour potencies. For DHS, the ham powder was purged with a nitrogen stream at a flow rate of 50 ml/min for 25 min, 5 min and 1 min, respectively. The effluent of sample headspace was trapped by a Tenax tube, which was placed onto the vessel for GC,O. The most important odorants (FD factor = 125) in Jinhua ham headspace were ethyl 2-methylbutanoate/ethyl 3-methylbutanoate, hexanal, 1-hexen-3-one, 1-octen-3-one, 2-acetyl-1-pyrroline and 2-methoxyphenol, followed by the following odorants (FD factor = 25): 3-methyl butanal, dimethyl trisulphide, 1-nonen-3-one, butanoic acid, phenylacetaldehyde, 3-methylbutanoic acid, 2-methyl(3-methyldithio)furan, , -nonalctone and 4-methylphenol (p -cresol). For SAFE, the ham powder was extracted with diethyl ether, distilled by SAFE and then separated into neutral/basic and acidic fractions. Both fractions were subjected to AEDA. The relatively high-odour impact compounds (Log3FD Factor ,5) of the N/B fraction of SAFE extract of Jinhua ham were 1-octen-one, ethyl 3-methylbutanoate, methional, phenylacetaldehyde, 2-phenylethanol, (E)-4,5-epoxy-(E)-decenal, p -cresol (4-methylphenol); 3-methylbutanal, hexanal, 2-acetyl-1-pyrroline, decanal, (E,Z)-2,6-nonadienal and (E,E)-decadienal. The important odorants of the Ac fraction of SAFE extract of Jinhua ham were butanoic acid, 3-methylbutanoic acid, hexanoic acid, phenylacetic acid and an unknown. It was shown that the aroma of Jinhua ham consisted of a variety of compounds having different odour properties; a single compound could not characterize the aroma of Jinhua ham. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hepatic chemoprotective enzyme responses to 2-substituted selenazolidine-4(R)-carboxylic acidsJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 6 2006Wael M. El-Sayed Abstract In epidemiology and human supplementation studies, as well as many animal models, selenium has shown antitumorigenic activity. The mechanism of action, however, has not been satisfactorily resolved. Selenium supplementation affects many enzymes in addition to those where selenocysteine is an essential component. Such enzymes include cytoprotective detoxifying enzymes, and the regulation of these enzymes by a set of 2-substituted selenazolidine-4(R)-carboxylic acids (SCAs) has been investigated. Following seven consecutive daily doses of these prodrugs of L -selenocysteine, changes in hepatic enzyme activities and/or mRNA levels of glutathione transferase (GST), microsomal epoxide hydrolase (mEH), NAD(P)H-quinone oxidoreductase (NQO), UDP-glucuronosyltransferase (UGT), glutathione peroxidase (GPx), and thioredoxin reductase (TR) have been observed. Among the enzymes examined, UGTs and GPx were found to be the least affected. Among the compounds, 2-oxoSCA produced the most changes and 2-phenylSCA produced the least, none. For no two compounds was the pattern of changes identical, and for a single compound, few changes were reproduced in common by the two routes of administration investigated. In general, more changes were elicited following intraperitoneal (i.p.) administration than with the intragastric (i.g.) route. This dominance was typified by 2-butylSCA and 2-cyclohexylSCA where enzyme activity elevations (TR and mEH with both, NQO with 2-butylSCA) were seen only with the i.p. route. With 2-oxoSCA, however, GST, TR, and NQO activities were found to be elevated independent of route. Only with GST (both routes) and TR (i.p. route), elevations in mRNAs accompanied the 2-oxoSCA elicited elevations of activities at the time of sacrifice. For some enzymes, most notably mEH with compounds administered i.p., elevations in mRNAs were not manifest as increased enzyme activity. Thus, although constituting a closely related series of compounds, each 2-substituted SCA produced its own unique pattern of changes, and for most members, changes were predominant following i.p. administration. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:292,301, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20148 [source] Spasmolytic and antidiarrhoeal properties of the Yucatec Mayan medicinal plant Casimiroa tetrameriaJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 9 2005Michael Heinrich The Maya of the Yucatán peninsula commonly use the leaves of Casimiroa tetrameria for treating gastrointestinal disorders, notably diarrhoea and dysentery, as well as gastrointestinal cramps. The phytochemical investigation resulted in the isolation of 13 compounds: eight polymethoxylated flavonoids (two as minor components with a main constituent), four flavonoid glycosides and one furanocoumarin. In this study we used two well-established models in order to assess the gastrointestinal effects of C. tetrameria extracts and isolated compounds: the USSING-chamber, a pharmacological model for diarrhoea, and the isolated guinea pig ileum, a model for modulatory effects on ileum contraction. Extracts and the class of polymethoxylated flavonoids showed strong inhibitory effects in both models, which provides ex-vivo evidence for the use of this botanical drug in the treatment of several gastrointestinal problems, most notably diarrhoea. The crude extract, polymethoxylated flavonoid-rich fractions and the polymethoxylated flavonoids tested showed prominent antisecretory activity. Polymethoxylated flavonoid-rich fractions also inhibited the histamine-induced contractions in the guinea pig model. The effects are not due to a single compound, but to a large number of structurally related compounds that all contribute to the effect. [source] A simple floral fragrance and unusual osmophore structure in Cyclopogon elatus (Orchidaceae)PLANT BIOLOGY, Issue 4 2009A. P. Wiemer Abstract We studied gland morphology, anatomy and the chemical composition of the floral fragrance in the sweat bee-pollinated orchid Cyclopogon elatus. This is apparently the first such analysis for any Cyclopogon species, and one of very few studies in which both odour and osmophore are characterised in a nectar-rewarding orchid. Structures responsible for floral scent production were localised with neutral red staining and histochemical assays for lipids and starch. Their morphology and anatomy were studied with scanning electron microscopy and light microscopy thin sections, respectively. Fragrance samples were collected using SPME fibres and analysed with GC-MS. Anatomical evidence suggests that two parallel oval-shaped patches of unicellular trichomes on the abaxial surface of the labellum are osmophores. These are rich in stored lipids, while the parenchyma surrounding the vascular bundles contains starch. Only freshly opened flowers produced odours, while buds and withered flowers lacked scent. The chemical composition of the odour was dominated (>99.8%) by a single compound, trans-4,8-dimethyl-nona-1,3,7-triene (DMNT). Gland anatomy and position on the outside of the perianth are unusual for scent glands in general. The presence of DMNT, a nearly ubiquitous compound in herbivore-induced vegetative emissions and one of the major floral volatiles of Yucca, is not surprising in view of hypotheses on the evolutionary origin of flower scents, suggesting that wound volatiles are utilised as kairomonal attractants by florivores whose activities result in pollination. [source] Development of a targeted adductomic method for the determination of polycyclic aromatic hydrocarbon DNA adducts using online column-switching liquid chromatography/tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2010Rajinder Singh Human exposure to polycyclic aromatic hydrocarbons (PAHs) from sources such as industrial or urban air pollution, tobacco smoke and cooked food is not confined to a single compound, but instead to mixtures of different PAHs. The interaction of different PAHs may lead to additive, synergistic or antagonistic effects in terms of DNA adduct formation and carcinogenic activity resulting from changes in metabolic activation to reactive intermediates and DNA repair. The development of a targeted DNA adductomic approach using liquid chromatography/tandem mass spectrometry (LC/MS/MS) incorporating software-based peak picking and integration for the assessment of exposure to mixtures of PAHs is described. For method development PAH-modified DNA samples were obtained by reaction of the anti- dihydrodiol epoxide metabolites of benzo[a]pyrene, benzo[b]fluoranthene, dibenzo[a,l]pyrene (DB[a,l]P) and dibenz[a,h]anthracene with calf thymus DNA in vitro and enzymatically hydrolysed to 2,-deoxynucleosides. Positive LC/electrospray ionisation (ESI)-MS/MS collision-induced dissociation product ion spectra data showed that the majority of adducts displayed a common fragmentation for the neutral loss of 116 u (2,-deoxyribose) resulting in a major product ion derived from the adducted base. The exception was the DB[a,l]P dihydrodiol epoxide adduct of 2,-deoxyadenosine which resulted in major product ions derived from the PAH moiety being detected. Specific detection of mixtures of PAH-adducted 2,-deoxynucleosides was achieved using online column-switching LC/MS/MS in conjunction with selected reaction monitoring (SRM) of the [M+H]+ to [M+H,116]+ transition plus product ions derived from the PAH moiety for improved sensitivity of detection and a comparison was made to detection by constant neutral loss scanning. In conclusion, different PAH DNA adducts were detected by employing SRM [M+H,116]+ transitions or constant neutral loss scanning. However, for improved sensitivity of detection optimised SRM transitions relating to the PAH moiety product ions are required for certain PAH DNA adducts for the development of targeted DNA adductomic methods. Copyright © 2010 John Wiley & Sons, Ltd. [source] Inter-laboratory comparison of elemental analysis and gas chromatography/combustion/isotope ratio mass spectrometry.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 200915N measurements of selected compounds for the development of an isotopic Grob test An inter-laboratory exercise was carried out by a consortium of five European laboratories to establish a set of compounds, suitable for calibrating gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS) devices, to be used as isotopic reference materials for hydrogen, carbon, nitrogen and oxygen stable isotope measurements. The set of compounds was chosen with the aim of developing a mixture of reference materials to be used in analytical protocols to check for food and beverage authentication. The exercise was organized in several steps to achieve the certification level: the first step consisted of the a priori selection of chemical compounds on the basis of the scientific literature and successive GC tests to set the analytical conditions for each single compound and the mixture. After elimination of the compounds that turned out to be unsuitable in a multi-compound mixture, some additional oxygen- and nitrogen-containing substances were added to complete the range of calibration isotopes. The results of ,13C determinations for the entire set of reference compounds have previously been published, while the ,D and ,18O determinations were unsuccessful and after statistical analysis of the data the results did not reach the level required for certification. In the present paper we present the results of an inter-laboratory exercise to identify and test the set of nitrogen-containing compounds present in the mixture developed for use as reference materials for the validation of GC-C-IRMS analyses in individual laboratories. Copyright © 2009 John Wiley & Sons, Ltd. [source] Discovery and Potency Optimization of 2-Amino-5-arylmethyl-1,3-thiazole Derivatives as Potential Therapeutic Agents for Prostate CancerARCHIV DER PHARMAZIE, Issue 7 2009Mikhail Krasavin Abstract A new chemical series was identified via high-throughput screening as having antiproliferative activity on DU-145 human prostate carcinoma cell line (hit compound potency , 2.9 ,M). Medicinal chemistry optimization of two peripheral diversity vectors of the hit molecule, independently, led to SAR generalizations and identification of the ,best' moieties. The latter were merged in a single compound that exhibited an over 100-fold better potency than the hit compound. For the most potent compounds it was confirmed that the observed antiproliferative potency was not associated with the compounds' non-specific cytotoxicity. [source] Secondary metabolite production by the fungal pathogen Eutypa lata: Analysis of extracts from grapevine cultures and detection of those metabolites in plantaAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 2 2006RICHARD LARDNER Eutypa dieback of grapevines is caused by the fungal pathogen Eutypa lata and reduces vineyard longevity worldwide. Early detection could reduce losses due to this disease, so our aim was to identify acetylenic phenol metabolites of E. lata that could prove suitable as chemical markers in an early diagnostic test for the pathogen. Accordingly, secondary metabolite production by 30 isolates of E. lata grown on media derived from canes of three grapevine cultivars was analysed using HPLC. Six metabolites, namely eutypinol, methyl eutypinol, eulatachromene, eutypine, 2- iso -propenyl-5-formylbenzofuran and eulatinol, were detected in culture filtrates. Most abundant were eutypinol and methyl eutypinol, produced by 97 and 83% of isolates, respectively. There was no apparent correlation between secondary metabolite production on media containing milled canes from the three cultivars of grapevine, and the field tolerance of these same cultivars to Eutypa dieback. When various other fungi commonly isolated from grapevine trunks in Australia were grown on milled cane, no secondary metabolites characteristic of E. lata were detected, suggesting such compounds are specific to E. lata. To examine the detection of secondary metabolites in planta, micropropagated grapevine plantlets were treated with purified or crude culture filtrates from nine isolates of E. lata grown on malt yeast broth. Various secondary metabolites were identified in treated plantlets, however, no single compound was detected consistently. Eutypinol was detected in micropropagated grapevine plantlets inoculated with mycelium of E. lata, however, no metabolites were detected in the sap of vines which had been artificially inoculated with the pathogen. [source] Significance testing of synergistic/antagonistic, dose level-dependent, or dose ratio-dependent effects in mixture dose-response analysisENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2005Martijs J. Jonker Abstract In ecotoxicology, the state of the art for effect assessment of chemical mixtures is through multiple dose,response analysis of single compounds and their combinations. Investigating whether such data deviate from the reference models of concentration addition and/or independent action to identify overall synergism or antagonism is becoming routine. However, recent data show that more complex deviation patterns, such as dose ratio,dependent deviation and dose level,dependent deviation, need to be addressed. For concentration addition, methods to detect such deviation patterns exist, but they are stand-alone methods developed separately in literature, and conclusions derived from these analyses are therefore difficult to compare. For independent action, hardly any methods to detect such deviations from this reference model exist. This paper describes how these well-established mixture toxicity principles have been incorporated in a coherent data analysis procedure enabling detection and quantification of dose level,and dose ratio,specific synergism or antagonism from both the concentration addition and the independent action models. Significance testing of which deviation pattern describes the data best is carried out through maximum likelihood analysis. This analysis procedure is demonstrated through various data sets, and its applicability and limitations in mixture research are discussed. [source] Anaerobic transformation of compounds of technical toxaphene.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2003Abstract Technical toxaphene (Melipax) and the single compounds of technical toxaphene (CTTs) 2,2,5- endo, 6- exo, 8,8,9,10- octachlorobornane (B8-806), 2,2,5- endo, 6- exo, 8,9,9,10-octachlorobornane (B8-809), 2,2,5,5,8,9,9,10,10-nonachlorobornane (B9- 1025), 2- endo, 3- exo, 5- endo, 6- exo, 8,8,9,10,10-nonochlorobornane (B9-1679), 2- endo, 3- exo, 5- endo, 6- exo, 8,9,10,10-octachlorobornane (B8-1414), 2- endo, 3- exo, 5- endo, 6- exo, 8,8,9,10-octachlorobornane (B8-1412), and 2- exo, 3- endo, 5- exo, 9,9,10,10-heptachlorobornane (B7-1453) were treated with suspensions of the anaerobic bacterium Dehalospirillum multivorans. After 7 d, more than 50% of technical toxaphene was transformed, and the relative amount of early eluting CTTs increased. After 16 d, only 2- exo, 3- endo, 6- exo, 8,9,10-hexachlorobornane (B6-923), 2- endo, 3- exo, 5- endo, 6- exo, 8,9,10-heptachlorobornane (B7-1001), and a few minor penta- and hexachloro-CTTs were detected in the samples. The result of the transformation was comparable with observations in naturally contaminated sediments and soil. However, the performance with D. multivorans was more simple and reproducible, as well as faster, than use of soil, sediment, or anaerobic sewage sludge. In agreement with reports in the literature, reductive dechlorination at geminal chlorine atoms (gem -Cls) was found to be the major CTT transformation pathway. Experiments conducted with CTTs and gem -Cls at both primary and secondary carbons clarified that the initial Cl -> H substitution takes place at the secondary carbon C2. Furthermore, the 2- endo -Cl position was preferably substituted with hydrogen. In the case of B8-806, the dechlorination at the secondary carbon C2 was approximately 20-fold faster than the subsequent, slow reduction at the primary carbon C8. The three different formerly unknown heptachloro-CTTs, 2- exo, 3- endo, 6- exo, 8,9,9,10-heptachlorobornane (B7-1473), 2- exo, 3- endo, 6- endo, 8,9,9,10-hepatchlorobornane (B7-1461), and 2- exo, 3- endo, 6- exo, 8,8,9,10-heptachlorobornane (B7-1470) were found as intermediates of the B8-806/809 transformation. Treatment of B9-1679 with D. multivorans indicated that gem -Cls on the bridge (C8 and C9) are dechlorinated faster than gem -Cls on the bridgehead (C10). [source] Combined exposure to anti-androgens causes markedly increased frequencies of hypospadias in the ratINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2008S. Christiansen Summary The incidence of hypospadias is increasing in young boys, but it remains unclear whether human exposure to endocrine disrupting chemicals plays a role. Risk assessment is based on estimation of no-observed-adverse-effect levels for single compounds, although humans are exposed to combinations of several anti-androgenic chemicals. In a mixture (MIX) study with three androgen receptor antagonists, vinclozolin, flutamide and procymidone, rats were gavaged during gestation and lactation with several doses of a MIX of the three chemicals or the chemicals alone. External malformations of the male reproductive organs were assessed on PND 47 using a score from 0 to 3 (normal to marked) for hypospadias. Markedly increased frequencies were observed after exposure to a MIX of the three chemicals compared to administration of the three chemicals alone. Anogenital distance at PND 1, nipple retention at PND 13, and dysgenesis score at PND 16 were highly correlated with the occurrence of hypospadias, and MIX effects were seen at doses where each of the individual chemicals caused no observable effects. Therefore, the results indicate that doses of anti-androgens, which appear to induce no hypospadias when judged on their own, may induce a very high frequency of hypospadias when they interact in concert with other anti-androgens. [source] New co-attractants synergizing attraction of Cetonia aurata aurata and Potosia cuprea to the known floral attractantJOURNAL OF APPLIED ENTOMOLOGY, Issue 1 2010J. Vuts Abstract To improve the efficiency of the known floral attractant of Cetonia aurata aurata and Potosia cuprea [3-methyl eugenol, 1-phenylethanol and (E) - anethol] electroantennographic tests were conducted using the antennae of both species. Among synthetic floral compounds eliciting the highest responses from the antennae, geraniol, (±)-lavandulol and ß- ionone, were chosen for field experiments. In field trapping tests in Hungary the addition of (±)-lavandulol to the known attractant resulted in significantly higher catches of both scarabs than the ternary blend alone or the single compounds. Only geraniol resulted in higher catches of P. cuprea when added to the ternary attractant. The addition of ß- ionone to the known attractant decreased catches. In further tests the addition of geraniol in the same single dispenser as the known ternary mixture plus (±)-lavandulol did not increase catches of C. a. aurata and P. cuprea. The improved bait consisting of 3-methyl eugenol/1-phenylethanol/(E) - anethol/(±)-lavandulol described in this study is recommended for use in trapping of C. a. aurata and P. cuprea for agricultural purposes. [source] New technologies for chemical geneticsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S37 2001Leslie A. Walling Abstract Chemical genetics, in which small molecules are used in lieu of mutations to study biological processes, requires large and diverse chemical libraries to specifically perturb different biological pathways. Here we describe a suite of technologies that enable chemical libraries prepared by split-pool solid phase synthesis to be screened in a diverse range of chemical genetic assays. Compounds are synthesized on 500 micron high-capacity polystyrene beads, and arrayed into individual wells of 384-well plates using a hand-held bead arrayer. Compounds are cleaved from synthesis beads using a chemically-resistant ceramic dispensing system, producing individual stock solutions of single compounds. Nanoliter volumes of these solutions are then transferred into assay plates using an array of stainless steel pins mounted on a robotic arm. We have designed reusable 1536- and 6144-well assay plates made of silicone rubber that can be cast in the laboratory and filled by hand. This integrated technology platform enables hundreds of biological assays to be performed from the product of a single synthesis bead, enabling the results of different chemical genetic experiments to be directly compared. J. Cell. Biochem. Suppl. 37: 7,12, 2001. © 2002 Wiley-Liss, Inc. [source] | ||||||||||||||||