Antimalarial activity and toxicity evaluation of a quantified **Nauclea pobeguinii** extract
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
Journal of ethnopharmacology. - Lausanne
, p. 10-16
University of Antwerp
Aim of the study To evaluate the in vitro and in vivo antiplasmodial activity and toxicity of the aqueous and 80% EtOH extract of the stem bark of Nauclea pobeguinii (Pob. Ex. Pell.) Petit (Rubiaceae), a plant used in traditional medicine in DR Congo against malaria. Results The 80% EtOH extract from Nauclea pobeguinii stem bark were found to contain (5S)-5-carboxystrictosidine, 19-O-methylangustoline, 3-O-β-fucosyl-quinovic acid, 3-ketoquinovic acid and strictosamide. All compounds were inactive or only moderately active in vitro against Plasmodium falciparum (chloroquine-sensitive Ghana-strain). The aqueous and 80% EtOH extract displayed moderate in vitro activity with IC50 values of 44 and 32 μg/mL, respectively, and without apparent cytotoxicity on MRC-5 cells (CC50 > 64 μg/ml). Daily oral dosing of the 80% EtOH extract, containing 5.6% strictosamide, at 300 mg/kg resulted in 86% reduction of parasitaemia in the 4-day Plasmodium berghei mouse model, and 75% reduction in the Plasmodium yoelii N67 model. Prolonging oral dosing to 2 × 5 days, with an interval of 2 days, and oral administration of the 80% EtOH extract at 300 mg/kg induced 92% reduction of parasitaemia, and a mean survival time of 17 days. Strictosamide, the putative active constituent, may be metabolically activated in the gastrointestinal tract after oral administration. Levels of creatinin, urea, ALAT and ASAT remained unchanged after treatment. No acute toxicity was observed in mice after a single 2 g/kg oral dose, nor after 4 weekly doses. No significant macroscopic or microscopic lesions were observed in heart, lung, spleen, kidney, liver, large intestine and brain. Conclusions These results can partly support and justify the use of Nauclea pobeguinii in traditional medicine in the DR Congo for the treatment of uncomplicated malaria.