Construction of an immobilised acetylcholinesterase column and its application in screening insecticidal constituents from Magnolia officinalis

Abstract

Application of a matrix-immobilised target enzyme for screening inhibitors is widely used in drug development, but there are few studies in insecticide discovery. In this paper, an economical and effective immobilised acetylcholinesterase (AChE) column was prepared using the sol-gel embedment method, which was further combined with high-performance liquid chromatography for screening the AChE inhibitors and insecticidal compounds from complex natural products. AChE inhibitory constituents magnolol and honokiol were isolated from the ethanol extract of Magnolia officinalis, with IC50 values of 0.069 and 0.057 mM respectively. In an in vivo bioassay, magnolol and honokiol showed insecticidal activity against Nilaparvata lugens, with LC50 values of 0.324 and 0.137 mM, which are comparable with that of commonly used insecticide chlorpyrifos (0.233 mM). Moreover, molecular docking was carried out against a homology model of N. lugens AChE. The complexes showed that magnolol and honokiol placed themselves nicely into the active site of the enzyme and exhibited an interaction energy that was in accordance with our activity profile data. These results demonstrate that magnolol and honokiol have great applied potential to be developed as natural insecticides, and an immobilised AChE column is very useful as a rapid screening tool for target enzymes towards potent inhibitors.