1. Department of Organic Chemistry, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde, Cameroon
2. Department of Chemistry, Faculty of Science, University of Ngaoundere, P.O. Box 454, Ngaoundere, Cameroon
3. Institute of Medical Research and Medicinal Plants Studies (IMPM), Ministry of Scientific Research and Innovation, P.O. Box 6163Yaounde, Cameroon
4. Department of Biochemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon
5. Department of General, Organic and Biomedical Chemistry, Faculty of Medicine and Pharmacy, University of Mons NMR and Molecular Imaging Laboratory, B-7000Mons, Belgium