Chern, Jyh-Haur; Chang, Chih-Shiang; Tai, Chia-Liang; Lee, Yen-Chun; Lee, Chung-Chi; Kang, Iou-Jiun; Lee, Ching-Yin; Shih, Shin-Ru Bioorganic and Medicinal Chemistry Letters, 2005, vol. 15, # 19 p. 4206 - 4211 doi: 10.1016/j.bmcl.2005.06.069