Screening of natural compounds for inhibitory activity on colon cancer cell migration.

We examined the effects of 75 kinds of natural compounds, such as alkaloids, phenylpropanoids, flavonoids, steroids and terpenoids on the in vitro migration and proliferation of colon 26-L5 cells, in comparison with anti-cancer drugs used for chemotherapy. Twenty-three of the 75 compounds inhibited markedly tumor cell migration. Among the 23 compounds, evodiamine showed the most potent and selective inhibitory activity on tumor cell migration with an IC50 value of 1.25 microg/ml, which was about 20 times lower than that for tumor cell proliferation. The migratory inhibition reached about 70% at 10 microg/ml of evodiamine. On the other hand, most of anti-cancer drugs tested, except for paclitaxel, had little effect on tumor cell migration at the concentrations strongly inhibiting tumor cell proliferation. Paclitaxel suppressed tumor cell migration in a concentration-dependent manner and achieved about 70% inhibition at 10 microg/ml with a marginal effect on cell proliferation. These results suggest that evodiamine and paclitaxel may be regarded as leading compounds for anti-metastatic agents acting through the inhibition of tumor cell migration without cytotoxicity.