Systemic enantioselectivity study of penthiopyrad: enantioselective bioactivity, acute toxicity, degradation and influence on tomato

Abstract

BACKGROUND: In order to promote the green development of agriculture, it is important to study the enantioselective effect of chiral pesticides. The bioactivity of the chiral fungicide penthiopyrad (PEN) racemate and enantiomers against phytopathogens, toxicity to non-target organisms, effect on tomato fruit growth and maturation, and environmental fate in tomato cultivation were evaluated at an enantioselective level in this study. RESULTS:The results indicated that at the same efficacy, the optically pure S-(+)-PEN could lower the dosage of racemate by 20-96%. The S-enantiomer had low toxicity to earthworms. Besides, the S-(+)-PEN did not cause significant abiotic stress to the tomato and increased fruit fresh weight and size via modulating the contents of plant hormones. However, the content of hydrogen peroxide (H 2 O 2 ), superoxide (O 2 − ) and malondialdehyde in the R-enantiomer treatment group was significantly higher than the control group. The effect of the racemate on tomato fruit was between the enantiomers. Furthermore, compared to R-(−)-PEN and racemate, the S-enantiomer degraded more quickly in tomato fruit, leaves, and soil, reducing the danger of human exposure. CONCLUSION:The S-enantiomer is highly effective and less toxic. The development of enantiomer pure S-(+)-PEN products might be an efficient and low-risk strategy. The results lay the foundation for comprehensive evaluation and proper application of PEN.

Enantioselective Behaviors of Chiral Fungicide Penthiopyrad in Five Kinds of Crops and Whole-Age Dietary Risk Assessments

“…cinerea (EC 50 , 2.29 μg/L) and S. sclerotiorum (EC 50 , 1.10 μg/L) were 5.07 and 22.8 times higher than R -(−)-penthiopyrad (EC 50 , 11.6 and 25.1 μg/L), respectively . For Chlorella pyrenoidosa, Lemna minor, and Daphnia magna, the EC 50 or LC 50 (median lethal concentration) values of R -(−)-penthiopyrad (11.3–18.5 mg/L) were 1.97, 5.95, and 9.20 times higher than S -(+)-penthiopyrad (1.37–9.36 mg/L), respectively, but for Eisenia fetida, R -(−)-penthiopyrad (LC 50 , 0.530 μg/cm 2 ) was 2.08 times more toxic than S -(+)-penthiopyrad (LC 50 , 1.10 μg/cm 2 ) .…”

“…toxic than S-(+)-penthiopyrad (LC 50 , 1.10 μg/cm 2 ) 12. According to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), the penthiopyrad toxicity for crustacea (D. magna), algae, or other aquatic plants (C. pyrenoidosa, L. minor) is category acute 2 and 3 (low to moderate toxicity).…”