Hagihara, Koji; Kashima, Hajime; Iida, Kyoichiro; Enokizono, Junichi; Uchida, Shin-ichi; Nonaka, Hiromi; Kurokawa, Masako; Shimada, Junichi Bioorganic and Medicinal Chemistry Letters, 2007 , vol. 17, # 6 p. 1616 - 1621