FIGURE 7.

Effects of ROS on UGT activity in LS180 cells. A, control LS180 cells were treated with 0.4 and 4.0 μg/ml catalase for 40 min or with 1.0, 2.0, and 5.0 μm herbimycin-A for 40 min. *, p ≤ 0.01; **, p ≤ 0.001. B, cells were treated with 0.5 or 1.0 mm H₂O₂ for 5 and 10 min. Cells under B were preincubated with 4.0 μg/ml catalase (Cat'ase) or 5.0 μm herbimycin-A (Herb) for 30 min before the addition of 1.0 mm H₂O₂ for an additional 5 or 10 min. Cells were also treated with 50 μm curcumin for 30 min or 250 nm calphostin-C for 30 min before addition of 1.0 mm H₂O₂ for 10 min. UGT activity was measured with eugenol with control value 8431 ± 141 pmol/mg of protein/h. A similar profile was observed with capsaicin as substrate. *, p ≤ 0.01; **, p ≤ 0.001.