The aim of the present study was to evaluate the chemical composition and bioactivity of Uvariopsis congensis Robyns & Ghesq. stem bark extract against Sickle cell disease and associated bacteria. This plant species ingested by wild chimpanzees as medicinal food could inhibit the human hemoglobin S polymerization inducing hemolysis of sickle erythrocytes (as it does by inhibiting the Plasmodium falciparum inducing hemolysis of infected erythrocytes in great apes).

The antisickling and antibacterial activities were assessed according respectively to Emmel and micro-dilution methods. The results revealed that Uvariopsis congensis Robyns & Ghesq. stem bark extract contains various secondary metabolites such as alkaloids, saponins, total polyphenols (87.942±0.536 µg GAE/g), flavonoids (0.623±0.630 µg QE/g), tannins (0889±0.002 µg TAE/g), anthocyanis (0.150±0.017 µg M-3GE/g), leuco-anthocyanins, quinones, terpenes and steroids. Ethanolic extract displayed interesting antisickling activity which was confirmed by the appearance of radius, the increase of the cell area r (p<0.05). The antisickling activity of Uvariopsis congensis Robyns & Ghesq. stem bark extract is dose dependent.

The minimal concentration of normalization (MCN) and the dose of extract for which 50% of the sickled erythrocytes are reversed (ED50) were 100 µg/mL and 0.6 µg/ml respectively. The minimum inhibitory concentrations (MIC) were 250 µg/mL and 500 µg/mL respectively for Escherichia coli ATCC 27195 and Staphylococcus aureus ATCC 33591. The bioactivity of this plant species could be improved by liquid-liquid extraction and chromatographic bio-guided fractionation of ethanolic extract.

This study validates for the first time the in vitro antisickling activity of Uvariopsis congensis Robyns & Ghesq. stem bark extract. The animal self-medication constitutes thus an innovative method which could lead to the discovery of new drugs for the treatment of human ailments like Sickle cell disease.

Auteurs: Koto-te-Nyiwa Ngbolua et all, 2016