Contribution of oxidation reactions to photo-induced damage to cellular DNA

• Published in: Photochemistry and photobiology Vol. 100; no. 5; pp. 1157 - 1185
• Main Authors: Cadet, Jean, Angelov, Dimitar, Di Mascio, Paolo, Wagner, J Richard
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.09.2024
• Subjects: Bases (nucleic acids); Carbonyl compounds; Carbonyls; Cations; Chemical damage; Cyclobutane; Cyclobutane pyrimidine dimers; Deoxyribonucleic acid; DNA; DNA damage; Hydroxyl radicals; Ionization; Irradiation; Laser radiation; Luminous intensity; Melanocytes; Oxidation; Oxidizing agents; Oxygen; Photooxidation; Pyrimidines; Radiation damage; Reactive nitrogen species; Reactive oxygen species; Singlet oxygen; Ultraviolet radiation; base oxidation products; photosensitization; singlet oxygen; base radical cations; reactive oxygen species
• ISSN: 0031-8655; 1751-1097; 1751-1097
• DOI: 10.1111/php.13990

This review article is aimed at providing updated information on the contribution of immediate and delayed oxidative reactions to the photo-induced damage to cellular DNA/skin under exposure to UVB/UVA radiations and visible light. Low-intensity UVC and UVB radiations that operate predominantly through direct excitation of the nucleobases are very poor oxidizing agents giving rise to very low amounts of 8-oxo-7,8-dihydroguanine and DNA strand breaks with respect to the overwhelming bipyrimidine dimeric photoproducts. The importance of these two classes of oxidatively generated damage to DNA significantly increases together with a smaller contribution of oxidized pyrimidine bases upon UVA irradiation. This is rationalized in terms of sensitized photooxidation reactions predominantly mediated by singlet oxygen together with a small contribution of hydroxyl radical that appear to also be implicated in the photodynamic effects of the blue light component of visible light. Chemiexcitation-mediated formation of "dark" cyclobutane pyrimidine dimers in UVA-irradiated melanocytes is a recent major discovery that implicates in the initial stage, a delayed generation of reactive oxygen and nitrogen species giving rise to triplet excited carbonyl intermediate and possibly singlet oxygen. High-intensity UVC nanosecond laser radiation constitutes a suitable source of light to generate pyrimidine and purine radical cations in cellular DNA via efficient biphotonic ionization.