Anti-plasmodial activity of Dicoma tomentosa (Asteraceae) and identification of urospermal A-15-O-acetate as the main active compound

• Published in: Malaria Journal
• Main Authors: Jansen Olivia, Tits Monique, Angenot Luc, Nicolas Jean-Pierre, De Mol Patrick, Nikiema Jean-Baptiste, Frédérich Michel
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2012
• Subjects: Antiplasmodial; Asteraceae; Melampolide; Burkina Faso; Dicoma tomentosa; Natural compound; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/1475-2875-11-289; https://doaj.org/article/69667e97e6a6409f9f1fe9029c20af3b

Abstract Background Natural products could play an important role in the challenge to discover new anti-malarial drugs. In a previous study, Dicoma tomentosa (Asteraceae) was selected for its promising anti-plasmodial activity after a preliminary screening of several plants traditionally used in Burkina Faso to treat malaria. The aim of the present study was to further investigate the anti-plasmodial properties of this plant and to isolate the active anti-plasmodial compounds. Methods Eight crude extracts obtained from D. tomentosa whole plant were tested in vitro against two Plasmodium falciparum strains (3D7 and W2) using the p-LDH assay (colorimetric method). The Peters’ four-days suppressive test model ( Plasmodium berghei- infected mice) was used to evaluate the in vivo anti-plasmodial activity. An in vitro bioguided fractionation was undertaken on a dichloromethane extract, using preparative HPLC and TLC techniques. The identity of the pure compound was assessed using UV, MS and NMR spectroscopic analysis. In vitro cytotoxicity against WI38 human fibroblasts (WST-1 assay) and haemolytic activity were also evaluated for extracts and pure compounds in order to check selectivity. Results The best in vitro anti-plasmodial results were obtained with the dichloromethane, diethylether, ethylacetate and methanol extracts, which exhibited a high activity (IC 50 ≤ 5 μg/ml). Hot water and hydroethanolic extracts also showed a good activity (IC 50 ≤ 15 μg/ml), which confirmed the traditional use and the promising anti-malarial potential of the plant. The activity was also confirmed in vivo for all tested extracts. However, most of the active extracts also exhibited cytotoxic activity, but no extract was found to display any haemolytic activity. The bioguided fractionation process allowed to isolate and identify a sesquiterpene lactone (urospermal A-15-O-acetate) as the major anti-plasmodial compound of the plant (IC 50 < 1 μg/ml against both 3D7 and W2 strains). This was also found to be the main cytotoxic compound ...