Dimeric bisindole alkaloids from the stem bark of Strychnos nux-vomica L.

► Strychnochrysine and 3 alkaloids have been isolated from the stem bark. ► Stereochemistry was confirmed by molecular modelling. ► A description on how to predict the exact conformation by 13C NMR is given. ► The structure of strychnoflavine, previously isolated from the root bark, is given. ► The alkaloids were tested against Plasmodium falciparum and human fibroblasts.