Cephalotaxus alkaloids are natural products characterized by pentacyclic structure.
These alkaloids are commonly found in the plum yew species (Cephalotaxus), especially in the Japanese plum-yew.
The most important representative is cephalotaxin. Other notable representatives include harringtonine and homoharringtonine.
Harringtonine and homoharringtonine exhibit antitumor activity and act against murine leukemia cells. They serve as protein and DNA biosynthesis inhibitors and are used against acute myelocytoxic leukemia.