1. Laboratory of Natural Products Chemistry; Department of Chemistry; Faculty of Science; University of Dschang; P.O. Box 67 Dschang Cameroon
2. Department of Biochemistry; Faculty of Science; University of Dschang; P.O. Box 67 Dschang Cameroon
3. Institute of Natural Medicine; University of Toyama; 2630-Sugitani Toyama 930-0194 Japan