Cytotoxic Phorbol Esters of Croton tiglium

Chemical investigation of the seeds of Croton tiglium afforded eight new phorbol diesters (three phorbol diesters, 1–3, and five 4-deoxy-4α-phorbol diesters, 4–8), together with 11 known phorbol diesters (nine phorbol diesters, 9–17, and two 4-deoxy-4α-phorbol diesters, 18 and 19). The structures of compounds 1–8 were determined by spectroscopic data information and chemical degradation experiments. The cytotoxic activities of the phorbol diesters were evaluated against the SNU387 hepatic tumor cell line, and compound 3 exhibited the most potent activity (IC₅₀ 1.2 μM).