Integrated experimental and computational study of Azadirachta indica leaf extract identifies Genistein 8-C-glucoside as a potential inhibitor of Juvenile Hormone Esterase in Spodoptera frugiperda

One significant threat to maize production in the entire world is fall armyworm, Spodoptera frugiperda (J. E. Smith) , as it has a high feeding demand and increasing resistant to synthetic insecticides. The objective of the present study was to evaluate the larvicidal efficacy of neem (Azadirachta indica A. Juss.) leaf extract against Spodoptera frugiperda and to investigating mode of action using bioassay and computational technique. Fresh mature neem leaves were collected from Navrachana University campus, Vadodara, Gujarat, India, shade dried and powdered extracted with methanol using a Soxhlet apparatus. Larvicidal bioassays were performed under laboratory conditions using a leaf-dip method against third-instar larvae of Spodoptera frugiperda . Mortality was recorded at 24, 48, 72, and 96 h post-treatment, and lethal concentration values were estimated using probit analysis. A dose- and time-dependent increase in mortality was observed, with maximum larval mortality of 86.67% at 72 h and 96.67% at 96 h. The LC₅₀ values declined progressively over time, reaching 2.01% at 72 h and 1.22% at 96 h, indicating enhanced toxicity with prolonged exposure. LC-MS analysis of the methanolic extract of the neem leaf identified the Genistein 8-C-glucoside as a bioactive component of the extract. SwissADMET suggested excellent aqueous solubility, high metabolism safety and high polarity. The molecular docking analysis showed that Genistein 8-C-glucoside has a high binding affinity with Juvenile Hormone Esterase (JHE), which was supported by large numbers of hydrogen bonding and 8-C-glucoside-binding with 8-C-glucoside, and 100 ns molecular dynamics simulations were used to show that the ligand-protein complex was stable.