1. Atta-ur-Rahman Institute for Natural Product Discovery, Universiti Teknologi MARA Selangor Branch, Puncak Alam Campus, 42300 Bandar Puncak Alam, Selangor Malaysia
2. Department of Chemistry, Faculty of Science, University Malaya, 50603 Kuala Lumpur, Malaysia
3. Department of Chemistry, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Semarahan, Sarawak, Malaysia
4. School of Pharmacy, International Medical University, Jalan Jalil Perkasa 19, Bukit Jalil, 57000 Bukit Jalil, Kuala Lumpur, Malaysia
5. Natural Products Inc., Evanston, Illinois 60203, United States