Superoxide anion is generated from cellular metabolites by solar radiation and its components.
Several endogenous cellular constituents were tested for their ability to produce superoxide anion (O2-) from ground-state molecular oxygen upon irradiation by solar radiation. The pyridine cofactors NADPH and NADH, riboflavin, and the nucleosides 2-thiouracil and 4-thiouridine were found to sensitize the transmission of photon energy from solar radiation and monochromatic radiation (290, 334, 365, and 405 nm) to oxygen, resulting in O2- formation, as detected by superoxide dismutase-inhibitable cytochrome c reduction. Quantum yields for the production of O2- indicate that NADPH is the most efficient and riboflavin the least efficient of the compounds tested. These data indicate that endogenous compounds may participate in the production of O2- by solar radiation and imply that O2- may play a role in sunlight-induced erythema and dermal carcinogenesis.
D000838:Anions; D002273:Carcinogens; D003574:Cytochrome c Group / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D009243:NAD / Q000528:radiation effects; D009249:NADP / Q000528:radiation effects; D012256:Riboflavin / Q000494:pharmacology / Q000528:radiation effects; D013472:Sunlight; D013482:Superoxide Dismutase / Q000528:radiation effects; D013481:Superoxides / Q000096:biosynthesis* / Q000528:radiation effects; D014466:Ultraviolet Rays
D000838:Anions; D002273:Carcinogens; D003574:Cytochrome c Group; D009243:NAD; D013481:Superoxides; D009249:NADP; D013482:Superoxide Dismutase; D012256:Riboflavin