1. Department of Chemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon
2. Institute of Medical Research and Medicinal Plants Studies (IMPM), Center of Medicinal Plants Studies and Traditional Medicine (CRPMT), P.O. Box 6163, Yaoundé, Cameroon
3. Department of Organic and Bioorganic Chemistry, Lund Institute of Technology, SE 221 00 Lund, Sweden