Diterpenoid Alkaloids from Two <i>Aconitum</i> Species with Antifeedant Activity against <i>Spodoptera exigua</i>

Abstract

Twenty-five diterpenoid alkaloids were isolated from the roots of two Aconitum species. The structures of seven new C 19 -diterpenoid alkaloids, apetaldines A–G ( 1 – 7 ), and 10 known alkaloids ( 8 – 17 ) from Aconitum apetalum and eight known alkaloids ( 18 – 25 ) from Aconitum franchetii var. villosulum were elucidated via HRESIMS, IR, and NMR data. Alkaloids 1 – 10, 15, 16, and 18 – 25 were screened for their antifeedant activity. Among the compounds tested, chasmanthinine ( 19 ) showed highly potent antifeedant activity with an effective concentration for 50% feeding reduction (EC 50 ) at 0.07 mg/cm 2 . The antifeedant structure–activity relationship of the diterpenoid alkaloids is also discussed.