Imbalance between the production of reactive oxygen species (ROS) and the detoxification of their reactive intermediates by antioxidants causes oxidative stress. Cells must respond to this imbalance before the highly reactive molecules damage cellular structures, particularly DNA. Severe and prolonged oxidative stress can trigger apoptosis and necrosis. Numerous pathological conditions have an oxidative stress component, including cataract, leukemia, melanoma, renal failure, diabetes, cardiovascular diseases and neurodegenerative diseases such as Alzheimer. Signaling pathways downstream of ROS detection phosphorylate the transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) which binds the antioxidant response element within the promoters of genes encoding antioxidant enzymes and detoxifying enzymes. Key Nrf2 target genes include antioxidants such as glutathione peroxidases (GPx) and genes involved in superoxide metabolism. These genes, in addition to some other antioxidants, reduce oxidative stress by breaking down ROS. Analysis of oxidants-antioxidants balance may yield new insights or new approach to how dealing with many diseases and cancer.

This special issue could serve as a background for the diseases which are due to oxidative stress and the role of antioxidants in scavenging the reactive oxygen species.