Bisindolomonoterpenic alkaloids from the stem bark of Strychnos Nux-Vomica exibiting antiplasmodial activity

Strychnos nux-vomica L. (Loganiaceae) is famous for its monomeric alkaloids content, such as strychnine, a convulsant poison. Our laboratory investigates Strychnos species since five decades, and also more recently, the antiplasmodial activity of bisindole alkaloids.

Strychnochrysine (I), previously isolated from the root bark of S. nux-vomica, together with three new bisindolomonoterpenic alkaloids have been isolated for the first time from the stem bark of Strychnos nux-vomica, traditionally used to treat intermittent fever in South East Asia. These longicaudatine-type alkaloids display in vitro antiplasmodial activity against a chloroquine resistant strain and a chloroquine sensitive strain. The most interesting is strychnochrysine showing IC₅₀ around 10µM. The alkaloids could not lead to potent antiplasmodial drug but could be used as tool to investigate original mode of action against Plasmodium.