Enantioselective Acute Toxicity and Bioactivity of Carfentrazone-ethyl enantiomers
The stereoselective herbicidal bioactivity and toxicity toward aquatic organisms of carfentrazone-ethyl enantiomers were investigated. The results showed that there was significant enantioselective acute toxicity toward Selenastrum bibraianum. In addition, S-(−)-carfentrazone-ethyl was 4.8 times more potent than R-(+)-isomer. However, a slight enantioselectivity was observed for Daphnia magna and Danio rerio. The stereoselective herbicidal bioactivity of carfentrazone-ethyl enantiomers was observed by assessing maize root-length inhibition. The results clarified that S-(−)-carfentrazone-ethyl (EC50 1.94 mg/L) > Rac-carfentrazone-ethyl (EC50 2.18 mg/L) > R-(+)-carfentrazone-ethyl (EC50 3.96 mg/L). The herbicidal bioactivity of S-(−)-carfentrazone-ethyl was 2 times higher more than R-(+)-isomer. The mechanism of enantioselective bioactivity was illustrated using molecular simulation software. The GlideScore energies of S-(−)-carfentrazone-ethyl and R-(+)-carfentrazone-ethyl were − 6.15 kcal/mol and − 5.59 kcal/mol, indicating that the S-form has a greater affinity to the active site of protoporphyrinogen oxidase, which is consistent with the results of the bioactive assay. This study can rise the significance of risk assessments for carfentrazone-ethyl herbicide.
KeywordsCarfentrazone-ethyl Chiral pesticides Acute toxicity Bioactivity Molecular simulation
This work was supported by the National Key Research and Development Program of China (Grant No. 2016YFD0200207) and the Project of Science and Technology innovation team from the Anhui Academy of Agricultural Sciences (Grant No. 14C1105).
- Moser H, Vogel C (1991) Optically active N-(1′-methyl-2′-methoxyethyl)-N-chloroacetyl–2-ethyl-6-methylaniline as herbicide US5002606Google Scholar
- OECD (2006) Organization for economic cooperation and development guidelines for the testing of chemicals. Freshwater Alga and Cyanobacteria, Growth Inhibition TestGoogle Scholar
- Organization for Economic Cooperation and Development (OECD) (1995) Report of the final ring test of the Daphnia magna reproduction studyGoogle Scholar
- Organization for Economic Cooperation and Development (OECD) (2013) Guideline for fish embryo acute toxicity (FET) testGoogle Scholar