Effects of flavonoids on CYP1 expression in RL95-2 endometrial carcinoma cells

► QT, K and M inhibited CYP1 activity dose-dependently with IC50s ranging from 2.2 to 4 μM; AF was inactive. ► CYP1A1 protein amount was decreased in cells co-treated with TCDD and QT, K or M compared to TCDD alone. ► Relatively higher basal CYP1B1 protein was not significantly affected by flavonoid treatments. ► Significant inhibition of induced CYP1A1 or CYP1B1 mRNA was not detected following flavonoid cotreatment. ► Mechanisms of CYP1 inhibition in this cell line are complex and dependent on the CYP gene, AhR inducer and the flavonoid.