Optimisation of natural neolignan as pesticide candidates: semisynthesis and insecticidal potential of honokiol derivatives bearing dual phenyl-urea/-thiourea moieties

Currently, the development of novel agrochemicals based on natural products is a favourable initiative to address the potential risks of traditional synthetic pesticides. Reported herein are two series of novel phenylurea-/phenylthiourea-containing honokiol derivatives and their pesticidal activities against two typical agricultural pests. The bioassay results underscored the pronounced larvicidal activities of compounds IVc and Vi against Plutella xylostella, with LC50 values of 16.68 and 16.21 μg/mL, respectively, outperforming the positive controls toosendanin and rotenone. Compounds Vg, Vi, and Vj exhibited remarkable antifeedant activity against P. xylostella with AFC50 values of 8.24, 6.02, and 14.16 μg/mL, respectively, which were comparable to commercial antifeedant agent toosendanin. Furthermore, compounds IVc, IVg, and Vj showed prominent growth inhibitory activity against Mythimna separata with LC50 values of 0.15, 0.19, and 0.22 mg/mL, respectively, exceeding those of toosendanin and rotenone. Accordingly, these potent compounds hold potential as novel agrochemicals for crop protection.