1. School of Pharmaceutical Sciences, University of Geneva, 1211 Geneva 4, Switzerland
2. Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, 1211 Geneva 4, Switzerland
3. Swiss Tropical and Public Health Institute, 4002 Basel, Switzerland
4. University of Basel, 4003 Basel, Switzerland
5. Plantasav, B.P. 10308 Niamey, Niger
6. Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G. C., Evin, Tehran, Iran