1. Department of Chemistry, Faculty of Science , University of Dschang , P.O. Box 67 , Dschang , Cameroon
2. Department of Chemistry , Faculty of Science , University of Dschang , P.O. Box 67 , Dschang , Cameroon , Phone: 00 237 673551059
3. Department of Biochemistry, Faculty of Science , University of Dschang , P.O. Box 67 , Dschang , Cameroon
4. Organic and Bioorganic Chemistry, Department of Chemistry , Bielefeld University , P.O. Box 100131, 33501 , Bielefeld , Germany