Cephalezomines A–F, Potent Cytotoxic Alkaloids from Cephalotaxus harringtonia var. Nana

Six new alkaloids, cephalezomines A–F (1–6), have been isolated together with known related alkaloids 7–16 from the leaves of Cephalotaxus harringtonia var. nana and the structures were elucidated by spectroscopic data and chemical methods. Cephalezomines A–F (1–6) showed potent cytotoxicity against tumor cells.