(untitled) - Jang, M; Cai, L; Udeani, G O; Slowing, K V; Thomas, C F; Beecher, C W. W; Fong, H H. S; Farnsworth, N R; Kinghorn, A D; Mehta, R G; Moon, R C; Pezzuto, J M (Science (Washington, D.C.), 1997)