DAMAGE TO PBR322 DNA PHOTOSENSITIZED BY HYPOCRELLIN-A IN LIPOSOMES AND ITS DERIVATIVE IN SOLUTION

Single-strand breaks of plasmid pBR322 DNA photoinduced by hypocrellin A (HA) in liposomes and by sodium salt of 14-dehydroxy-15-deacetyl-hy pocrellin A-13-sulfonate (13-SO3Na-DDHA) in aqueous solution have been investigated by agarose gel electrophoresis. Upon irradiation with vi sible light, DNA damage was observed under oxygen and under argon with both HA and 13-SO3Na-DDHA. The mechanisms of DNA damage in liposomes and solution have been studied. In photosensitization by HA in liposom es, the hydroxyl radical . OH is the main agent responsible for DNA da mage. During photosensitization by 13-SO3Na-DDHA in buffer solution, O -1(2) and . OH are both involved in the DNA cleavage. Comparative stud ies with the two sensitizers are also discussed.