Fig. 3.

The effect of food-derived polyphenols on endogenous antioxidant enzymes. (A) Thioredoxin reductase activity was measured 24 h after treatment of OVCAR3 with food-derived polyphenols and sulforaphane at their maximal effective dose (MED) and half of MED (hMED). (B) The effect of food polyphenols and sulforaphane on the protein expression level of NQO1 was assessed by immunoblotting after treatment at the MED and hMED (left panel) and 20, 50 nM, and 2 μM of polyphenols (right panel) for 24 h. The results of the densitometric analysis of the blots are shown in the lower panel. Full, non-adjusted blots are available in Supplementary Fig. 2. (C) The NQO1 mRNA level was measured by RT-qPCR. Values are the mean ± SE, n = 3. An asterisk (*) represents a significant difference (p < 0.05) compared to the vehicle control.