Abstract: Three different methods-reduction of nitro-blue tetrezolium, reduction of cyto-chrome C and DMPO-Spin-trapping technique, were utilized to detect the formation of O₂^-· in phosphate-buffered solution, methyl alcohol and dimethyl sulfoxide (DMSO) respectively.As compared with riboflavine photosensitization and autooxidation of pyrogallol both systems for the generation of O₂^-·, the yield of O₂^-· formation by photosensitization reaction of HPD is quite low.It was also found that some soluents such as H₂O and DMSO, have an effect on the measurement of O₂^-·.

Key words: Hematoporphyrin derivative, Superoxide anion radical, Photosen-sitization