Antifeedant Activity of Camptothecin and its Semisynthetic Derivatives Against Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) Larvae
The antifeedant activities of camptothecin 1 and its semisynthetic derivatives 2-12 were evaluated against an
economically important pest, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). Simple chemical conversions were
carried out on the natural camptothecin obtained from a Chinese medicinal plant Camptotheca acuminate. These conversions
focused on different functional modified sites in the camptothecin skeleton considered to be important for the biological
activity. Among all the tested compounds, compounds 4, 5, 7 and 8 displayed more promising antifeedant activity
than camptothecin 1. Especially compound 7 was found to exhibit exceptionally potent antifeedant activity with AFC50
values of 92.03μg/mL, compared to 1 and toosendanin, a commercial insecticide derived from Melia azedarach (IC50
528.40μg/mL and 91.68μg/mL, respectively). The different antifeedant activity range of compounds 1–12 indicated that
variation of chemical structures in the camptothecin skeleton markedly affected the activity profiles of this compound
class, and some preliminary SAR information has been observed from it.
Keywords: Camptothecin, antifeedant activity, Spodoptera litura, Structure-activity relationships.
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