Affiliation: | a Department of Organic Chemistry, Faculty of Sciences, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon;b Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, D-06120 Halle (Saale), Germany;c Department of Organic Chemistry, Faculty of Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon |