1. Department of Organic Chemistry, Faculty of Science, University of Yaounde I, P. O. Box 812, Yaounde, Cameroon
2. Department of Chemistry, Universität Paderborn, Warburger Straβe 100, 33098 Paderborn, Germany
3. Biology, Chemistry and Environmental Heath Science Department, Benedict College 1600 Harden Street Columbia, SC 29204
4. Department of Chemistry, Higher Teachers’ Training College, University of Yaounde I, BP 47, Yaounde, Cameroon