Antiplasmodial and anti-inflammatory activities of Canthium henriquesianum (K. Schum), a plant used in traditional medicine in Burkina Faso

ETHNOPHARMACOLOGICAL RELEVANCE: Canthium henriquesianum (K. Schum) is traditionally used in Burkina Faso for the treatment of malaria, but has not been properly investigated, yet. The aim of this study was to characterize in vitro the antiplasmodial and the anti-inflammatory activity of extracts from Canthium henriquesianum (K. Schum). In parallel, extracts of Gardenia sokotensis (Hutch) and Vernonia colorata (Willd), also traditionally used together in Burkina Faso and already reported with antimalarial activity, were compared. MATERIALS AND METHODS: Plant extracts were tested in vitro for antimalarial activity against chloroquine susceptible (D10) and resistant (W2) strains of Plasmodium falciparum using the lactate dehydrogenase assay. Cell cytotoxicity was assessed on human dermal fibroblast (HDF) by the MTT assay. The selectivity index (SI) was used as the ratio of the activity against the parasites compared to the toxicity of the plant extract against HDF. In vitro cytokine production was assessed by ELISA technique. RESULTS: Canthium henriquesianum aqueous extract had a moderate antimalarial activity (IC₅₀<50µg/ml) with a good selectivity index (SI=HDF/D10>7). Canthium henriquesianum diisopropyl ether extract was the most potent inhibitor of parasite growth with an IC₅₀ 9.5µg/ml on W2 and 8.8µg/ml on D10 and limited toxicity (SI>2). Gardenia sokotensis and Vernonia colorata aqueous extracts were shown to be significantly less active (IC₅₀≥50µg/ml) with substantial toxicity. In addition, when the production of IL-1β and TNFα by lipopolysaccharide (LPS) or hemozoin (malaria pigment) stimulated human THP-1 monocytes was assayed, it was found that the extract of Canthium henriquesianum induced a dose-dependent inhibition of IL-1β, but not of TNFα production, thus confirming its traditional use as antipyretic. By NMR analysis, the chromone was identified as the mostly represented compound in the diisopropyl ether extract of Canthium henriquesianum. Chromone however, was less active as antimalarial than the crude extract and it did not inhibit cytokine production at not toxic doses, indicating that other molecules in the total extracts contribute to the antiplasmodial and anti-inflammatory activity. CONCLUSION: Canthium henriquesianum seems to possess antimalarial activity in vitro and the ability to inhibit the production of the pyrogenic cytokine IL-1β.