The enhanced levels of ROS could be explained on the one hand by the inhibition of GPx1, which could lead to a ROS accumulation, while on the other hand polysulfides, resulting from a reaction with thiols such as GSH, are known to bring about the formation of H2O2 and subsequently hydroxyl radicals that can cleave nuclear DNA.27 Indeed, we observed with the Comet assay significant increases in strand breaks of DNA only 15 min after exposure of cancer cells to 4. Here, GPX1 is linked to cancer.