1. NUS Graduate School for Integrative Sciences and Engineering 21 Lower Kent Ridge, University Hall, Tan China Tuan Wing, #04-02 Singapore 119077 Singapore
2. Experimental Drug Development Centre 10 Biopolis Road, Chromos, #05-01 Singapore 138670 Singapore
3. Department of Chemistry National University of Singapore Singapore 117543 Singapore
4. State Key Laboratory of Bioactive Substances and Functions of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation Institute of Materia Medica Peking Union Medical College and Chinese Academy of Medical Sciences Beijing 100050 China