Nematicidal effect against Bursaphelenchus xylophilus of harmine quaternary ammonium derivatives, inhibitory activity and molecular docking studies on acetylcholinesterase

In the present study, we have investigated nematicidal effects against Bursaphelenchus xylophilus and inhibition potential, molecular docking of 43 harmine derivatives on acetylcholinesterase in vitro and in vivo. Among them, harmine quaternary ammonium derivatives 10 , 11 , 12 and 13 displayed promising nematicidal effects with 48 h LC 50 values of 1.63, 1.63, 1.75 and 1.44 μg/mL, respectively and remarkable inhibition effects on acetylcholinesterase (IC 50 values are 0.92, 0.90, 0.82, 0.07 μg/mL in vitro and 17.16, 14.56, 13.63, 3.06 μg/mL in vivo, respectively). The structure–activity analysis indicated that the presence of the methyl group in 1–position, the electron–donating substituents in 2–and 9–positions, bromine in 6–position, and the electron–withdrawing substituents in 7–position of carboline ring, could enhance the nematicidal effect and inhibition of acetylcholinesterase. Moreover, a molecular model was provided for the binding between compound 13 and the active site of acetylcholinesterase based on the computational docking results and helps us to optimize these new leading compounds.