Inhibition of growth and induction of alkaline phosphatase in colon cancer cells by flavonols and flavonol glycosides.

We observed previously that quercetin can increase the activity of the differentiation markers alkaline phosphatase and dipeptidyl peptidase in Caco-2 colon cancer cells. In the present work, we compared the effects of quercetin on cell proliferation and differentiation with the action of related flavonols and quercetin glycosides. Relative to the action of quercetin, effects on growth and enzyme activities did not always follow parallel trends but quercetin 3-glucoside was notably more potent in both respects while quercetin rutinoside was less active. Of the compounds examined, baicalein and myricetin caused the greatest production of hydrogen peroxide when incubated with the medium. Flavonols can have pro-oxidant effects, but our data suggested that this action was not the sole determinant of growth inhibitory or differentiating effects on Caco-2 cells. Our data indicated that effects of quercetin on colon cancer cell lines can be greatly affected by glycoside modification.