Xia, Guangxin; Li, Jianfeng; Peng, Aiming; Lai, Shunan; Zhang, Shujun; Shen, Jingshan; Liu, Zhonghua; Chen, Xinjian; Ji, Ruyun Bioorganic and Medicinal Chemistry Letters, 2005 , vol. 15, # 11 p. 2790 - 2794