Concepts of oxidative stress and antioxidant defense in Crohn’s disease

Figure 1 Reactions of superoxide (^•O₂^-) that generate highly reactive oxygen species. ^•O₂^- can be dismutated into H₂O₂, which, in the presence of Fe²⁺, can generate the highly reactive hydroxyl radical, HO^•. ^•O₂^- may react with NO^• to form the strong pro-oxidant peroxynitrite (ONOO^-); alternatively, it may react with HO^• to form singlet oxygen (¹O₂); NADPH: Nicotinamide adenine dinucleotide phosphate.