Photogeneration of the free radicals and singlet oxygen by chrysophanol from rheum  

作　　者：RAO Jing1,2, XIE Jie1, ZHAO Jingquan1 & ZHU Teng2 1. Key Laboratory of Photochemistry, Center for Molecular Science, Institute of Chemistry, The Chinese Academy of Sciences, Beijing 100080, China 2. University of Science and Technology Beijing, Beijing 10083, China 

出　　处：《Science China Chemistry》2004年第5期381-387,共7页中国科学（化学英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant No.20273079).

摘　　要：In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradia- tion of chryosphanol (MHAQ) with visible light (>430 nm) produced the semiquinone radical anions (MHAQ??), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2 ), trapped by DMPO, were detected. ?? It was proved that O2 was not originated from the singlet oxygen (1O2) but dependent on DMPO, ?? chrysophanol, oxygen and the irradiation time. The singlet oxygen and OH could also be pro- ? duced by the photosensitization of the photosensitizer. These suggest that chrysophanol pos- sesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives ex- tracted from rheum, the relative productivities of O2 were estimated to be 1.8, 1.1 and 1.0 re- ?? spectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14 respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradiation of chryosphanol (MHAQ) with visible light (>430 nm) produced the semiquinone radical anions (MHAQ.?), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2 .?), trapped by DMPO, were detected. It was proved that O2 .? was not originated from the singlet oxygen (1O2) but dependent on DMPO, chrysophanol, oxygen and the irradiation time. The singlet oxygen and.OH could also be produced by the photosensitization of the photosensitizer. These suggest that chrysophanol possesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives extracted from rheum, the relative productivities of O2 .? were estimated to be 1.8, 1.1 and 1.0 respectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14 respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.

关 键 词：chrysophanol  ESR  SEMIQUINONE RADICAL anions  superoxide RADICAL anions  hydroxyl radical  singlet oxygen. 

分 类 号：O641[理学—物理化学]