The backs of the animals were shaved 2 days prior to the start of the experiment. The animals were divided into three groups (n = 10 for each group). Group I animals served as controls. These animals received acetone (200 μl/mouse) application only. Group II animals received two topical applications of 0.24% 9, 10-dimethylbenz[a]anthracene (DMBA) in acetone (200 μl/mouse) over a period of 1 week, followed by 5 nmol 12-O-tetradecanoylphorbol-13-acetate (TPA) in acetone (50 μl/mouse) twice weekly for 24 weeks. The mice of group III were treated as Group II mice, except that they were treated with 4'-demethylepipodophyllotoxin (DMEP) (200 μl of the solution in acetone at a concentration of 1 μg/ml), 30 min prior to application of the above dose of TPA twice weekly for 24 weeks.

4'-demethylepipodophyllotoxin (DMEP) showed cytotoxicity activity against five human tumor cell lines (i.e., BGC-823, KB, HepG2, K-562, and HL-60) and a normal human cell line (i.e., HK-2) The EC50s of DMEP against these tumor cell lines ranged from 0.31 to 398 uM.