Xu, Zi-Chen; Wang, Xiao-Bing; Yu, Wen-Ying; Xie, Sai-Sai; Li, Su-Yi; Kong, Ling-Yi Bioorganic and Medicinal Chemistry Letters, 2014, vol. 24, # 10 p. 2368 - 2373 doi: 10.1016/j.bmcl.2014.03.058