A series of 2-(3,4,5-trimethoxyphenyl)-3-arylcyclopent-2-ene-1-ones (8a-8e) and their related analogues, including pentenone 9a, pentenol 10a, pentene 12a, and furane 15, were synthesized and evaluated for cytotoxicity against murine and human tumor cell lines. Compounds 8a-c, 8e and 9a showed strong cytotoxicity with IC(50) values in the range of 8-34ng/mL. Compound 8e exhibited significant anti-tumor activity in BDF1 mice bearing Lewis lung carcinoma cells with an inhibition ratio of 59%.