In vivo Antimalarial and Antitrypanosomal Activity of Strychnogucine B, a Bisindole Alkaloid from Strychnos icaja.

Strychnogucine B is a bisindole alkaloid previously isolated from that possesses promising antiplasmodial properties. This compound was synthesized in four steps from (-)-strychnine. As no acute toxicity was observed at the highest tested cumulative dose of 60 mg/kg, its antimalarial activity was determined intraperitoneally at 30 mg/kg/d in a murine model. In the Peters's 4-d suppressive test, this alkaloid suppressed the parasitaemia by almost 36% on day 5 and 60% on day 7 compared to vehicle-treated mice. In addition to this interesting antimalarial activity, it showed moderate antitrypanosomal activity but no activity in an acute model. It was also inactive on promastigotes. This highlights its selective antimalarial efficacy and leads to further investigation to assess its potential as new antimalarial lead compound.