1. Department of Biological Sciences, Faculty of Science, University of Maroua, P.O. Box 814, Maroua, Cameroon
2. Institute of Agricultural Research for Development, P.O. Box 2067, Yaoundé, Cameroon
3. Pharmacognosy Research Laboratories and Herbal Analysis Services, University of Greenwich, London, UK
4. Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, P.O. Box 1364, Yaoundé, Cameroon