1. Department of Chemistry, M/C 0212, Virginia Tech, Blacksburg, Virginia 24061-0212, USA
2. College of Pharmacy, Division of Medicinal Chemistry and Pharmacognosy, The Ohio State University, Columbus, OH 43210, USA
3. Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri 63166-0299, USA
4. Missouri Botanical Garden, B.P 3391, Antananarivo 101, Madagascar
5. Centre National d'Application des Recherches Pharmaceutiques, B.P 702, Antananarivo 101, Madagascar