1. Faculty of Science, Department of Chemistry, Université des Sciences et Techniques de Masuku, Franceville, Gabon
2. Faculty of Science, Department of Animal Biology, University of Dschang, Dschang, Cameroon
3. Faculty of Science, Department of Chemistry, The University of Bamenda, Bambili, Cameroon
4. Faculty of Science, Department of Organic Chemistry, University of Yaoundé 1, Yaoundé, Cameroon
5. Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India