The activity of flavone acetic acid (NSC 347512) on human colon cancer cells in vitro.

Flavone acetic acid (FAA) was incubated for 1 to 48 hr with 3 established human colon cancer cell lines endowed with distinct degrees of phenotypic properties. All 3 lines responded to FAA in almost identical fashion; when incubated with the drug for only 1 hr, an initial decrease in survival was observed for concentrations of 250 micrograms/ml but no further increments in cytotoxicity were elicited when the concentration of FAA was augmented. Increasing the length of treatment yielded relatively modest increments (about 1 log) in cell killing only after an interval of 48 hr and only at the highest concentration (1000 micrograms/ml). Because of these relatively poor cytotoxic effects and because the therapeutic range of FAA is so narrow, we conclude that this agent will not be a valuable contribution to the antitumor arsenal, at least for colon cancer.