Kim, Hea Ok; Yoo, Su Jeong; Ahn, Hee Sung; Choi, Won Jun; Moon, Hyung Ryong; Lee, Kang Man; Chun, Moon Woo; Jeong, Lak Shin Bioorganic and Medicinal Chemistry Letters, 2004, vol. 14, # 9 p. 2091 - 2093 doi: 10.1016/j.bmcl.2004.02.039