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 <b>IVc</b> and <b>Vi</b> against <i>Plutella xylostella</i>, with LC₅₀ values of 16.68 and 16.21 μg/mL, respectively, outperforming the positive controls toosendanin and rotenone. Compounds <b>Vg</b>, <b>Vi</b>, and <b>Vj</b> exhibited remarkable antifeedant activity against <i>P. xylostella</i> with AFC₅₀ values of 8.24, 6.02, and 14.16 μg/mL, respectively, which were comparable to commercial antifeedant agent toosendanin. Furthermore, compounds <b>IVc</b>, <b>IVg</b>, and <b>Vj</b> showed prominent growth inhibitory activity against <i>Mythimna separata</i> 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.