1. Graduate School, University of Santo Tomas, Manila 1015, Philippines
2. Palawan State University, Tiniguiban Heights, Puerto Princesa City 5300, Palawan, Philippines
3. Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340, United States
4. Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
5. Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60612, United States
6. Phytochemistry Laboratory, Research Center for the Natural and Applied Sciences, University of Santo Tomas, Manila 1015, Philippines