Wu, Gang; Guo, Huan-Fang; Gao, Kun; Liu, Yi-Nan; Bastow, Kenneth F.; Morris-Natschke, Susan L.; Lee, Kuo-Hsiung; Xie, Lan Bioorganic and Medicinal Chemistry Letters, 2008 , vol. 18, # 19 p. 5272 - 5276