PHOTOSENSITIZED PRODUCTION OF SUPEROXIDE ANION BY MONOCHROMATIC (290–405 nm) ULTRAVIOLET IRRADIATION OF NADH and NADPH COENZYMES

Abstract

Abstract— The reduced pyridine coenzymes NADPH and NADH produced superoxide anion(“CK”) from ground state molecular oxygen when irradiated by ultraviolet (UV) radiation extending from 290 to 405 nm as detected by cytochrome c reduction. Superoxide dismutase (SOD), but not catalase or heat‐inactivated SOD, decreased the amount of cytochrome c reduced, indicating that O2− was responsible for the reduction of cytochrome c. Decreased oxygen tension during irradiation also inhibited production of O2−. Quantum yields for the production of the anion were in the region of 10−7 to 10−9 mol per photon. These data indicate that NADH and NADPH can act as type II photosensitizers of both far‐and near‐UV radiation, and that the deleterious biological effects of exposure to these radiations such as erythema and dermal carcinogenesis may be mediated at least in part through the generation of O2−.

Nitric Oxide Fully Protects against UVA-induced Apoptosis in Tight Correlation with Bcl-2 Up-regulation

“…UVA-induced oxidative damage has been reported to occur in lipids (3), coenzymes (4), and DNA (5). On the level of organelles, nucleated mammalian cells exposed to UVA radiation were reported to bear damaged cellular structures, notably the microtubuli (6), the plasma membrane, the nuclear membranes, and the rough endoplasmic reticulum (7,8).…”

Epidermaltrans-urocanic acid and the UV-A-induced photoaging of the skin

“…Absorption of UV-A must induce photobiologic effects within the skin that lead to the visible and histological differences of photoaged skin, and, although the mechanisms by which UV-A-induced photodamage occur have not been completely determined, reactive oxygen species are postulated to play a role (9). The natural shift toward a more prooxidant state in chronologically aged skin then could be exacerbated by absorption of UV-A radiation by endogenous chromophores like NADH͞NADPH (10)(11)(12)(13)(14), tryptophan (15), and riboflavin (9), which then sensitize the formation of reactive oxygen species. Solar radiation has been shown both to reduce the antioxidant population in the skin (16) and to sensitize the production of reactive oxygen species such as singlet oxygen, hydrogen peroxide, and the superoxide anion (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), increasing the potential for reactions like the oxidation of lipids and proteins (17) that influence the degree of cross-linking between collagen and other proteins (9) within the skin.…”

Significance of UV-C Hormesis and Its Relation to Some Phytochemicals in Ripening and Senescence Process

“…Certain plants have repair mechanisms which involve the production of secondary stress metabolites for example, antioxidant compounds such as carotenoids, phenols, flavonoids, and polyamines. The enzyme superoxide dismutase (SOD) is postulated to ameliorate the toxic effects of superoxide and this enzyme is ubiquitously present in aerobic organisms (Cunningham et al, 1985). These compounds, usually present in the plant are generally activated following stress when produced in sufficient abundance in pre-climacteric crops can counteract the effect of DNA and free radical damage (which becomes important with age) and stimulate increase longevity of harvested crops.…”