ANTIOXIDANT NUTRIENTS PROTECT AGAINST UVB-INDUCED OXIDATIVE DAMAGE TO DNA OF MOUSE KERATINOCYTES IN CULTURE

Ultraviolet B radiation (UVB) induces oxidative damage in DNA, resulting in the formation of the adduct 8-hydroxydeoxyguanosine. Previous studies from this laboratory have demonstrated a decrease in antioxidant enzyme defenses after UVB radiation in Skh: HR-1 hairless mice, implicating antioxidant status in protection against oxidative damage. The present study was undertaken to examine mechanisms of UVB damage to DNA and modulation by vitamin C, selenite, or Trolox™, a water-soluble vitamin E analog. BALB/c MK-2 mouse keratinocytes were exposed to a dose range of UVB from 4 to 750 mJ/cm 2 . DNA damage in the form of 8OHdG was measured using high-pressure liquid chromatography coupled with electrochemical and UV absorbance detection. Preincubation of the cells for 2days with 0.4 or 0.8 μ g/ml ascorbic acid, 10 or 20 μ g/m1 Trolox™, and 5 or 12.5 μ M selenite resulted in a significant decrease in the number of 8-hydroxydeoxyguanosine adducts per 10 5 deoxyguanines induced by 500 mJ/cm 2 UVB. The results indicate a potential role for antioxidant nutrients in protection against UVB damage to skin cells.