Diwu Z, Lown J W
Department of Chemistry, University of Alberta, Edmonton, Canada.
Free Radic Biol Med. 1993 Feb;14(2):209-15. doi: 10.1016/0891-5849(93)90012-j.
When hypericin was illuminated with 580 nm light in aqueous solution, the semiquinone radical, singlet oxygen, and superoxide anion radical were detected. The formation of the semiquinone radical and activated oxygen species and the transformation and competition between them depend on the quinone and oxygen concentrations, irradiation time and intensity, and the nature of substrate. In anaerobic solution containing a high concentration of the quinone, the semiquinone radical was predominantly photoproduced. In contrast, in aerobic solution, singlet oxygen is the principal product in the photosensitization of hypericin. Besides singlet oxygen, superoxide anion radical is generated by the quinone on illumination in aerobic solution via the reduction of oxygen by the semiquinone radical, but to a lesser extent than singlet oxygen. The generation of superoxide anion radical is significantly enhanced by the presence of electron donors.
当金丝桃素在水溶液中用580nm光照射时，可检测到半醌自由基、单线态氧和超氧阴离子自由基。半醌自由基和活性氧物种的形成以及它们之间的转化和竞争取决于醌和氧的浓度、照射时间和强度以及底物的性质。在含有高浓度醌的厌氧溶液中，主要通过光产生半醌自由基。相反，在有氧溶液中，单线态氧是金丝桃素光敏化的主要产物。除单线态氧外，在有氧溶液中光照时，醌通过半醌自由基还原氧产生超氧阴离子自由基，但产生量比单线态氧少。电子供体的存在显著增强了超氧阴离子自由基的产生。
