Relationships between Insecticidal Activity of 6-Alkylthio-2-pyridyl Methanesulfonates and Acetylcholinesterase Inhibition of their Sulfone Derivatives against Nephotettix cincticeps

Structure-Activity Studies of Methanesulfonate Insecticides (Part 4)

Abstract

The inhibitory activity (I₅₀) of fifteen sulfone analogs of 6-alkylthio-2-pyridyl methanesulfonates was measured against acetylcholinesterase preparations from Ageo and Izumi strains of Nephotettix cincticeps. The insecticidal activity of 6-alkylthio derivatives to both strains was highly related to the acetylcholinesterase-inhibitory activity of the corresponding sulfones when hydrophobicity factors (log k′) of the molecule perhaps participating in the transport process were taken into account. Variations in insecticidal activity was due to the total of structure-activity relationships in enzyme inhibition and transport process. The combination of hydrophobicity and steric parameter terms was quite similar in the two strains.