Cytotoxicity and Cell Cycle Specificity of Homoharringtonine

Abstract

The plant alkaloid, homoharringtonine, isolated from Cephalotaxus harringtonia is cytotoxic to HeLa, KB, and L cells growing in monolayer cell cultures. This effect appears to be cell-cycle specific. In synchronized KB cells, protein synthesis was preferentially inhibited in the G 1 and G 2 phases (70 and 45% inhibition, respectively) as might be expected for a protein-synthesis inhibitor.