1. Department of Organic Chemistry, Faculty of Sciences, University of Yaounde 1, Yaounde, Cameroon;
2. Centre for Research on Medicinal Plants and Traditional Medicine, Institute of Medical Research and Medicinal Plants Studies, Yaounde, Cameroon;
3. Department of Chemistry, Faculty of Sciences, University of Ngaoundere, Ngaoundere, Cameroon;
4. Department of Biochemistry, Faculty of Sciences, University of Yaounde 1, Yaounde, Cameroon;
5. Laboratory of NMR and Molecular Imaging, Department of General, Organic Chemistry and Biomedical, University of MONS, Mons, Belgium