Insecticidal bisindole alkaloids from leaves of Tabernaemontana divaricata 'Dwaft'

Six undescribed bisindole alkaloids, namely taberdisines A–F (1–6), were isolated from the leaves of Tabernaemontana divaricata 'Dwaft'. Among them, alkaloids 1 and 2 were the first examples of strychnos–iboga type alkaloid with both C–C linkage patterns. Alkaloid 3, a new type of aspidosperma–iboga with a furan-ring, as well as other three undescribed ones was disclosed. Their structures were elucidated by comprehensive spectroscopic analyses. Alkaloids 1 and 5 showed insecticide activity on Sf9 cell and eggs of Spodoptera frugiperda in vivo, which might explain the potential of the plants for insect resistance.