Photoadducts and Peroxynitrite: Implications in Pathophysiology and Immunopathology

DNA adducts are a form of DNA damage caused by covalent attachment of a chemical moiety to DNA. Recent evidence suggests associations between the occurrence of adducts formed by specific compounds and various types of toxicity, such as mutation, cancer, and developmental effects. Small DNA or protein adducts can occur both from chemical exposure and from normal metabolic processes. Peroxynitrite is a relatively long-lived oxidant that may serve as an important cytotoxic agent. Its biological effects are due to its reactivity toward many molecules including lipids, amino acids and nucleic acids. In vivo, peroxynitrite formation represents a crucial pathological mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, inflammation, neurodegenerative disorders and cancer.