In vivo antiplasmodial activity of a crude ethanolic stem bark extract of Nauclea pobeguinii

A crude ethanolic extract of the bark of the African tree Nauclea pobeguinii (Rubiaceae), used in traditional medicine in DR Congo against malaria, containing 5.6% (w/w) strictosamide as the active principle, was evaluated in vivo in the Plasmodium berghei mouse model in a suppressive treatment regimen. The test substance was formulated in PEG400 and orally dosed (PO) at 300mg/kg for two times 5 daily doses. One group received the treatment by the intraperitoneal (IP) route using the same dosing regimen.

The untreated infected control animals all developed typical malaria and died during the course of the experiment (mean survival time (MST): 8.4–11.2 days). The animals treated with chloroquine at 10mg/kg did not develop malaria during dosing, but subsequently relapsed with 2 animals dying before termination of the experiment at day 21.

Treatment with the crude extract, either after oral of intraperitoneal dosing, resulted in moderate depression of parasitaemia during dosing, however quickly followed by a full relapse (MST=about 13 days). At termination of the experiment at day 21, a single survivor in the PO group was apparently cured (no parasitaemia), the single survivor in the IP group showed high parasitaemia and was in a moribund state.

It can be concluded that the crude extract of N. pobeguinii has slight antimalarial potential when administered orally in a suppressive dosing regimen of 2×5 days at 300mg/kg. Its action is likely to be static since full relapse occurs quickly after ending the daily dosing.