Synthesis, Insecticidal Activities, Toxicity Assessment, and Environmental Implications of (R)- and (S)-Proline-Derived Chiral Neonicotinoid Derivatives

Abstract

Neonicotinoid insecticides are widely employed in pest control, but their potential environmental implications demand the exploration of safer and more sustainable alternatives. This study encompasses a comprehensive assessment of the synthesis and toxicity of potential insecticide proline-derived chiral neonicotinoid derivatives, explicitly focusing on elucidating their environmental implications. Toxicity evaluation contained multiple models, including brine shrimp (Artemia salina), zebrafish (Danio rerio), and murine models compared with the commonly used insecticide dinotefuran. Enantioselective toxicity was observed in the brine shrimp assay, with the R-enantiomer demonstrating lesser toxicity compared to the S-enantiomer and dinotefuran. In the zebrafish model, dinotefuran induced developmental abnormalities, such as delayed hatching and vertebral column malformation, while the R-enantiomer exhibited relatively lower sensitivity. The murine LD₅₀ study in mice revealed lower toxicity levels for proline-derived insecticides than dinotefuran. Moreover, these chiral neonicotinoid derivatives were successfully synthesized by optimizing the synthetic routes. The synthesis involved specific starting materials and reaction steps, following established protocols. This study contributes valuable insights into the toxicity profiles of proline-derived chiral neonicotinoid derivatives and underscores the significance of assessing their environmental implications. The synthesized compounds provide a foundation for developing safer and more sustainable insecticides to mitigate the environmental risks associated with prevailing pest control practices.