Isolation and Structure Characterization of Cytotoxic Phorbol Esters from the Seeds of Croton tiglium.

Nine new and eleven known phorbol esters were isolated from an acetone extract of the seeds of Croton tiglium. Their structures were determined by extensive analysis of spectroscopic data. Eleven of these compounds were evaluated for their inhibition activity on human tumor cell lines HL-60 and lung carcinoma A549. 12-O-Tiglylphorbol-13-acetate (11), 12-O-(2-methyl)-butyrylphorbol-13-aetate (12), and 12-O-tiglylphorbol-13-isobutyrate (13) exhibited strong inhibition activity against both HL-60 and A549 cell lines with IC50 values ≤ 0.02 and ≤ 0.1 µg/mL, respectively. Compound 18 showed strong inhibition activity against the HL-60 cell line with an IC50 value of 0.02 µg/mL. Georg Thieme Verlag KG Stuttgart · New York.