1. Department of Chemistry, Faculty of Science, University of Maroua, Maroua, Cameroon
2. Department of Chemistry, Higher Teachers’ Training College, University of Maroua, Maroua, Cameroon
3. Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon
4. School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
5. Department of Chemistry, University of Buea, Buea, Cameroon
6. Department of Chemistry, Organic and Bioorganic Chemistry, Bielefeld University, Bielefeld, Germany