Synthesis and biological evaluation of rationally designed pyrazoles as insecticidal agents.

Abstract

The current research focused on the synthesis of two series of pyrazole derivatives and evaluation of their insecticidal effectiveness. In the first series, seven pyrazole Schiff bases 3a-g were successfully synthesized with yields (79-95%) by condensing phenylfuran-2-carbaldehyde with substituted pyrazole rings. In the second series, eleven amino acid-pyrazole conjugates 6a-k were synthesized utilizing acetic acid, sulfuric acid, morpholine, and EDC. HCl achieving yields of 59% to 94%. The synthesized compounds were assessed for their chemotherapeutic efficacy against locusts and termites by calculating LC₅₀ values, thereby determining their potential as anti-termite and anti-locust agents. Among the eighteen synthesized pyrazole compounds, the Schiff base pyrazole molecules 3f (LC₅₀ = 0.001 μg/mL) and 3d (LC₅₀ = 0.006 μg/mL) demonstrated excellent anti-termite activity compared to the reference drug fipronil (LC₅₀ = 0.038 μg/mL). Pyrazole derivative 6 h with LC₅₀ = 47.68 μg/mL exhibited superior anti-locust activity than the reference drug fipronil (LC₅₀ = 63.09 μg/mL). Additionally, compound 3b, containing NO₂ functionality at the meta position, exhibited notable and significant anti-locust activity with an LC₅₀ values of 100.00 μg/mL. However, the highest mortality was caused by the glycine conjugate of fipronil 6 h of the 2nd series with an LC₅₀ value of 47.68 μg/mL, which also proved to be a potent anti-locust agent. This study explores the efficacy of biologically active pyrazole structures as potential insecticidal agents through a combination of virtual molecular docking analysis and biological experimental investigations. The results demonstrate a strong correlation between the computational predictions and experimental outcomes, suggesting that the pyrazole derivatives exhibit significant insecticidal properties. The findings highlight the potential of these compounds in the development of innovative insecticides, paving the way for future research in pest control strategies.