- Plant Uptake and Metabolism of Nitrofuran Antibiotics in Spring Onion Grown in Nitrofuran-Contaminated Soil
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Environmental pollution caused by the discharge of mutagenic and carcinogenic nitrofurans to the aquatic and soil environment is an emerging public health concern because of the potential in producing drug-resistant microbes and being uptaken by food crops. Using liquid chromatography-tandem mass spectrometry analysis and with spring onion (Allium wakegi Araki) as the plant model, we investigated in this study the plant uptake and accumulation of nitrofuran from a contaminated environment. Our study revealed for the first time high uptake and accumulation rates of nitrofuran in the edible parts of the food crop. Furthermore, results indicated highly efficient plant metabolism of the absorbed nitrofuran within the plant, leading to the formation of genotoxic hydrazine-containing metabolites. The results from this study may disclose a previously unidentified human exposure pathway through contaminated food crops.
- Wang, Yinan,Chan, K. K. Jason,Chan, Wan
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p. 4255 - 4261
(2017/06/07)
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- Kinetics and mechanism of oxime formation from methyl benzoylformate
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Rate and equilibrium constants for methyl benzoylformate oxime formation were determined as a function of pH over the range from about 0 to 6. The reaction occurs with rate-determining carbinolamine dehydration over the entire range of pH investigated. Specific acid catalysis is dominant at pH 4. Above that value, a pH-independent reaction becomes apparent. This early appearance of an uncatalyzed reaction is interpreted as intramolecular assistance of the ester moiety in carbinolamine dehydration. Copyright
- Malpica,Calzadilla
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p. 945 - 949
(2007/10/03)
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- Syntheses of new unsymmetrical and symmetrical diaryl-sulphides and diarylsulphones containing thiazolinyl and thiazolidinonyl moieties using 4,4′-diacetyldiphenylsulphide
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Condensation of 4,4′-diacetyldiphenyl sulphide (2) with variable amounts of thiosemicarbazide (3) in refluxing ethanol and in the presence of catalytic amounts of dry piperidine afforded only 4-acetylthiosemicarbazone- 4′-acetyldiphenyl sulphide (5). Condensation of 2 with excess semicarbazide hydrochloride (4) in the presence of fused sodium acetate and/or piperidine yielded 4,4′-diacetylsemicarbazone diphenyl sulphide (6), whereas use of equimolar amounts of 2 and 4 afforded 4-acetyl-semicarbazone- 4′-acetyldiphenyl sulphide (7). 4-Acetylsemicarbazone-4′- acetylthiosemicarbazone diphenyl sulphide (8) was also obtained via two different routes. The effect of tautomeric structure 5d is discussed. 4-(4″-phenyl-Δ3-thiazoline-2″-acetylazino) -4′-acetyldiphenyl sulphide (9), 4-(5″-carboxyethyl-4″- thiazolidinone-2″-acetylazino)-4′-acetyldiphenyl sulphide (10), 4-(4″-thiazolidinone-2′-acetylazino)-4′-acetyldiphenyl sulphide (11) and 4-(4″-methyl-Δ3-thiazoline-2″- acetylazino)-4′-acetyldiphenyl sulphide (12) were prepared by interaction of 5 with phenacylbromide, bromodiethylmalonate, chloro ethylacetate and chloroacetone, respectively. Sulphides 9-12 were easily condensed with 3 to afford the corresponding 4-(heterocyclic moiety-2″-acetylazino)-4′- acetylthiosemicarbazone diphenyl sulphides 23-26. Oxidation of the prepared sulphides 5-7, 9-12, 23 and 25-26 using H2O2/glacial AcOH mixtures yielded only 4,4′-diacetyldiphenyl sulphone (13) as the main product in every case, besides 3 and 4 in certain cases. Unsymmetrical and symmetrical sulphones 14-22 were obtained starting from 13. The structures of the synthesized compounds are based on IR, 1H-NMR, 13C-NMR and mass spectral data. A theoretical study on some of the prepared compounds using molecular modeling was carried out.
- Abbady,Abdel-Hafez,Kandeel,Abdel-Monem
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p. 622 - 641
(2007/10/03)
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