Figure 5.

UV generates oxidative free radicals. UV photons interact with atomic oxygen to promote formation of free radical derivatives such as superoxide, hydrogen peroxide and the highly reactive hydroxyl radical. Free radicals avidly attack macromolecules such as protein, lipid, RNA and DNA, altering their structure and interfering with their function. Detoxifying and protective enzymes such as superoxide dismutase, catalase and glutathione peroxidase detoxify and reduce levels of oxidative species in the cell.