1. Department of Chemistry, Faculty of Science, The University of Bamenda, P.O. Box 39, Bambili, Cameroon
2. Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon
3. Department of Chemistry, Higher Teacher Training College, University of Maroua, P.O. Box 55, Maroua, Cameroon
4. Department of Biochemistry, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon
5. Department of Chemistry, Faculty of Science, Scientific and Technical University of Masuku, P.O. Box 943, Franceville, Gabon
6. Department of Chemistry, Bielefeld University, P.O. Box 100131, 33501 Bielefeld, Germany
7. Department of Chemistry, Higher Teacher Training College, University of Yaoundé I, P.O.
Box 47, Yaoundé, Cameroon
8. H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan