Organic extracts of 20 species of French seaweed have been screened against Trypanosoma brucei rhodesiense trypomastigotes, the parasite responsible for sleeping sickness. These extracts have previously shown potent antiprotozoal activities in vitro against Plasmodium falciparum and Leishmania donovani. The selectivity of the extracts was also evaluated by testing cytotoxicity on a mammalian L6 cell line. The ethyl acetate extract of the brown seaweed, Bifurcaria bifurcata, showed strong trypanocidal activity with a mild selectivity index (IC50 = 0.53 µg/mL; selectivity index (SI) = 11.6). Bio-guided fractionation led to the isolation of eleganolone, the main diterpenoid isolated from this species. Eleganolone contributes only mildly to the trypanocidal activity of the ethyl acetate extract (IC50 = 45.0 µM, SI = 4.0). However, a selective activity against P. falciparum erythrocytic stages in vitro has been highlighted (IC50 = 7.9 µM, SI = 21.6).

No abstract

Thalia geniculata L. (Marantaceae) is an African medicinal plant traditionally used in Benin to treat malaria and other parasitic diseases. There is little ethnobotanical and almost no chemical information available for this species. The phytochemical analysis of the aerial parts of the plant led to the isolation of five compounds, identified as sitoindoside2), stigmasterol (3), β-sitosterol (4), and geranylfarnesol (5). The structural elucidation was achieved using spectrometric methods and by comparison with the literature. Biological activity was evaluated against Plasmodium falciparum, Trypanosoma rhodesiense, Trypanosoma cruzi, and Leishmania donovani. Geranylfarnesol (5) showed significant antiprotozoal activity against P. falciparum and L. donovani, with IC 50 values of 12.7 and 13.2 µM, respectively.

The composition of X. aethiopica root oil is dominated by two dimethylvinylcyclohexene isomers. It differs drastically from the composition of leaf and fruit oils of the same plant. The combination of analytical techniques appeared crucial for a fruitful analysis.