Fig. 1. The effect of extracts from iodine-biofortified lettuce (1000 μg mL⁻¹) on ROS level in human gastric adenocarcinoma cell line (AGS), colorectal adenocarcinoma cell line (HT-29) and normal colon epithelial cell line (CCD 841 CoN). * vs. negative control (NC) when p < 0.01; + vs. control lettuce when p < 0.01. Cells were treated for 24 h with 1000 μg mL⁻¹ extract from non-enriched lettuce (control lettuce), or KIO₃-fortified lettuce, or 5-ISA-fortified lettuce, or 3,5-diISA-fortified lettuce, or synthetic 5-ISA, or synthetic 3,5-diISA, or 200 μM menadione as positive control.