A cephalotaxine alkaloid; inhibits the chain elongation phase of translation in eukaryotes; inhibits diphenylalanine formation by rabbit reticulocyte and human placental ribosomes in cell-free assays; binds to human 80S with a Ka value of 2.57 x 107 M-1 (Kd = 38.8 nM); inhibits protein synthesis in vitro in P. falciparum cultured in human erythrocytes (IC50 = 4 nM); inhibits the proliferation of Jurkat acute T cell leukemia (IC50 = 9 nM) and K562 CML cells (IC50 = 408 μg/ml); decreases the number of peripheral leukemia stem cells and increases survival in CML and B-ALL mouse models,