Differential enantioselectivity of quizalofop ethyl and its acidic metabolite: Direct enantiomeric separation and assessment of multiple toxicological endpoints

Zhang, Xiaoxiang; Wang, Se; Wang, Yu; Xia, Tingting; Chen, Jingwen; Cai, Xiyun

doi:10.1016/j.jhazmat.2010.11.081

Cited by 27 publications

(11 citation statements)

References 42 publications

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“…Yao et al 22 found that R-metalaxyl was about 20-fold more toxic to algae than rac-metalaxyl and that R-metalaxyl was about fourfold more toxic to Daphnia magna than rac-metalaxyl according to the individual 24 h-LC 50 . Zhang et al 23 compared the apparent toxicities of the racemates and the R-(+)-enantiomers of quizalofop ethyl and its primary product-quizalofop acid to Chlorella vulgaris and found that the R-(+)-enantiomers, which were considered to be the herbicidally active forms, were more toxic to the algae. Also, to the alga C. vulgaris, Cai et al 24 found the S-(À)-enantiomer of diclofop was more toxic than the R-(+)-enantiomer by 4.6 times.…”

Section: Results and Discussion Enantioselective Growth Inhibition Ofmentioning

confidence: 99%

Enantioselective Toxic Effects of Hexaconazole Enantiomers Against Scenedesmus Obliquus

Huang

Zhang

et al. 2012

Chirality

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Enantioselectivity in ecotoxicity of chiral pesticides in the aquatic environment has been a subject of growing interest. In this study, the toxicological impacts of hexaconazole enantiomers were investigated with freshwater algae Scenedesmus obliquus. After 96 h of exposure, the EC(50) values for rac-hexaconazole, (+)-hexaconazole, and (-)-hexaconazole were 0.178, 0.355, and 0.065 mg l(-1) , respectively. Therefore, the acute toxicities of hexaconazole enantiomers were enantioselective. In addition, the different toxic effects were evaluated when S. obliquus were exposed to 0.2, 0.5, and 1.0 mg l(-1) of rac-hexaconazole, (+)-hexaconazole, and (-)-hexaconazole during 96 h, respectively. The chlorophyll a and chlorophyll b contents of S. obliquus treated by (-)-hexaconazole were lower than those exposed to (+)-hexaconazole, whereas the malondialdehyde contents of S. obliquus treated by (-)-form were higher than those exposed to (+)-form at higher concentrations. In general, catalase activities were significantly upregulated by exposure to (-)-enantiomer than (+)-enantiomer at all three concentrations. However, superoxide dismutase activities exposed to (-)-hexaconazole were lower than that exposed to (+)-hexaconazole at 0.2 mg l(-1) and 0.5 mg l(-1) . On the basis of these data, the acute toxicity and toxic effects of hexaconazole against S. obliquus were enantioselective, and such enantiomeric differences must be taken into consideration in pesticide risk assessment.

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Section: Results and Discussion Enantioselective Growth Inhibition Ofmentioning

confidence: 99%

Enantioselective Toxic Effects of Hexaconazole Enantiomers Against Scenedesmus Obliquus

Huang

Zhang

et al. 2012

Chirality

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“…Among them the most popular are chromatographic [1][2][3][4][5][6] and spectroscopic methods, and, particularly, nuclear magnetic resonance (NMR). [13][14][15][16] This aspect may become notably relevant in the case of chiral selectors able to encapsulate small molecules, such as cyclodextrins [17][18][19] and resorcinarenes. 11,12 A source of irreproducible chromatographic separation consists of the traces of water or moisture, the content of which is very difficult to control and, in general, constitutes an undesired presence.…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

et al. 2014

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Nuclear magnetic resonance (NMR) investigations on mixtures containing octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E) and each enantiomer of methyl-2-chloropropionate (MCP) ascertained the role of trace amounts of water in the enantiodiscrimination processes. Water is deeply included into the cyclodextrin and favors the formation of the inclusion complex with (S)-MCP, whereas (R)-MCP is only slightly affected, thus causing a significant increase of NMR differentiation. Molecular dynamics simulations were performed to shed light on the possible behavior of Lipodex E in different conditions (i.e., solvent, inclusion complexes), providing energetic and atomistic details that are in agreement with NMR observations.

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“…3,6,7 Moreover, quizalofop-ethyl was documented to be a striking inhibitor against nontarget Toxoplasma gondii ACCase. 8 Zhang recently reported that quizalofop-ethyl and quizalofop-acid exhibited significant enantioselectivity in the apparent toxicities to algae, 9 where the R-enantiomers were more toxic to Chlorella vulgaris than the racemates. The enantiomer-specific profiles of chiral contaminants have become important topics at the forefront of chemistry and toxicology research.…”

Section: Introductionmentioning

confidence: 99%

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

Cheng

et al. 2012

Chirality

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The enantioselective degradation of quizalofop-ethyl and its metabolite quizalofop-acid in two soils, a Wuhan acidic soil and a Baoding alkaline soil, was investigated. The dissipation of quizalofop-ethyl consisted of two phases, a rapidly deceasing first phase that lasted 1 day and a slowly decreasing second phase that extended till the end of the incubation. It is shown that S-quizalofop-ethyl degraded slightly faster than R-quizalofop-ethyl in the two soils. Further incubation of enantiopure enaniomers showed that quizalofop-ethyl was configurationally stable in soil. Quizalofop-acid was produced quickly, and its amount reached a maximum at 1-6 days time and then decreased slowly with half-lives ranging from 11 to 21 days. The results also showed that quizalofop-acid degraded faster in the acidic Wuhan soil than in the alkaline Baoding soil. At last, significant enantiomerization from S-quizalofop-acid to R-quizalofop-acid was observed, and the enantiomerization was fast, resulting in residues enriched with R-quizalofop-acid whatever racemic quizalofop-ethyl or pure enantiomers were initially applied in the soils.

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Differential enantioselectivity of quizalofop ethyl and its acidic metabolite: Direct enantiomeric separation and assessment of multiple toxicological endpoints

Cited by 27 publications

References 42 publications

Enantioselective Toxic Effects of Hexaconazole Enantiomers Against Scenedesmus Obliquus

Enantioselective Toxic Effects of Hexaconazole Enantiomers Against Scenedesmus Obliquus

Synergistic Effects of Trace Amounts of Water in the Enantiodiscrimination Processes by Lipodex E: A Spectroscopic and Computational Investigation

Enantioselectivity in degradation and transformation of quizalofop‐ethyl in soils

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