1. Phytochemistry and Organic Synthesis Laboratory, Research Center for the Natural and Applied Sciences, University of Santo Tomas, Espana, Manila 1015, Philippines
2. Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, 93053 Regensburg, Germany
3. Plant Sciences Laboratory, Research Center for the Natural Sciences, University of Santo Tomas, Espana, Manila 1015, Philippines
4. Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., Chicago, Illinois 60612-7231, USA
5. Department of Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany