1. Chemistry Laboratory, Department of Chemistry, Faculty of Science, University of Douala, Douala, Cameroon
2. Department of Chemistry, University of Buea, Faculty of Sciences, Buea, Cameroon
3. Department of Microbial Natural Products (MINS), Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), University of Saarland, Saarbrücken, Germany
4. Process Engineering Laboratory, Department of Chemical Engineering, HTTTC, University of Douala, Douala, Cameroon