Planta Med 2006; 72 - P_072
DOI: 10.1055/s-2006-949872

Antiprotozoal activity of Xanthium brasilicum and bioactivity-guided isolation of its active constituents

AMM Nour 1, SA Khalid 2, WE Abdallah 3, M Kaiser 4, R Brun 4, TJ Schmidt 1
  • 1Westfälische Wilhelms-Universität, Institut für Pharmazeutische Biologie und Phytochemie, Hittorfstraße 56, D-48149 Münster, Germany
  • 2University of Khartoum, Department of Pharmacognosy, Faculty of Pharmacy, P.O. box 1996, Khartoum, Sudan
  • 3Medicinal and Aromatic Plants Research Institute, P.O. box 2404-Khartoum, Sudan
  • 4Swiss Tropical Institute, Socinstraße 57, CH-4002 Basel, Switzerland

In the course of a screening of Sudanese Asteraceae against protozoa causing tropical diseases, a crude DCM extract of Xanthium brasilicum Vell. was found highly active against Trypanosoma brucei rhodesiense (East African Sleeping Sickness, IC50 =0.1µg/mL). Bioactivity-guided fractionation yielded two monomeric and two dimeric xanthanolide sesquiterpene lactones (STL 1-4), all highly active. The unusual compound 5 was almost inactive as a pure compound. Compound 1 (8-epixanthatin) showed the lowest IC50 values against T. brucei and Leishmania donovani (visceral Leishmaniasis) of 0.34µM and 0.60µM, respectively. All compounds were reported as constituents of X. pungens [1] but no information on their bioactivity existed. Structure-activity studies with a variety of STL [2] are in progress.

Acknowledgements: A. M. M. Nour acknowledges a scholarship from the German Academic Exchange Service (DAAD).

References: 1. Ahmed, A. A. et al. (1990), Phytochemistry 29: 2211–2215. 2. Schmidt, T. J. et al. (2002), Planta Med. 68: 750–751.