Bibenzyl Derivatives From Leaves of Dendrobium officinale

Nine compounds were isolated from leaves of Dendrobium officinale, including 1 new bibenzyl derivative, denofficin (1), and 8 known structurally related compounds, dendrocandin B (2), dendrocandin U (3), 3,4-dihydroxy-5,4 '-dimethoxy bibenzyl (4), moscatilin (5), 4,4 '-dihydroxy-3,5-dimethoxy bibenzyl (6), (S)-3,4,alpha-trihydroxy-5,4 '-dimethoxy bibenzyl (7), gigantol (8), densiflorol A (9). The structures of these compounds were identified by spectroscopic methods. All isolated compounds were screened for their cytotoxicity against human cervical cancer cell line HeLa cells. Of them, compounds 1-3, 5, 6, and 8 were found to have the capabilities of proliferation inhibition against HeLa cells with half-maximal inhibitory concentration values ranging from 8.0 to 92.4 mu M.