He, Qiu-Qin; Zhang, Xuan; Wu, Hai-Qiu; Gu, Shuang-Xi; Ma, Xiao-Dong; Yang, Liu-Meng; Zheng, Yong-Tang; Chen, Fen-Er Bioorganic and Medicinal Chemistry, 2011, vol. 19, # 18 p. 5553 - 5558 doi: 10.1016/j.bmc.2011.07.037