DNA damage by oxygen radical was studied in the systems containing ascorbate or H 2O 2

using ultraviolet-spectrometer

TBA reaction and agarose gel electrophoresis. The absorption in 260nm of DNA decreased. Deoxyribose damage was found in TBA reaction. DNA backbone cleavage was observed in agrose gel electrophoresis. Trace metal ion such as Fe 2+ and so on could accelerate the reactions mentioned above. In all case DNA damage was prevented by a series of HO · scarvages. The role of HO · induced by the above two systems in the DNA damage including base

deoxyribose and backbone degradation was discussed.