1. Department of Organic Chemistry, Faculty of Science, The University of Yaoundé 1, Yaoundé, Cameroon
2. Department of Chemistry, Higher Teacher Training College, The University of Yaoundé 1, Yaoundé, Cameroon
3. Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon
4. Chemical Engineering and Mineral Industries School, University of Ngaoundere, Ngaoundere, Cameroon
5. Chemistry Department, Organic and Bioorganic Chemistry, Bielefeld University, Bielefeld, Germany
6. Department of Chemistry, Faculty of Science, University of Botswana, Gaborone, Botswana