Photodynamic effects of two hydroxyanthraquinones.
The aim of this work was to investigate the photodynamic action of electron-rich anthraquinones, viz., cynodontin (CYN) and cynodontin-5,8-dimethylether (CYNM). Both optical and EPR methods are used to detect the generation of singlet oxygen. Based on RNO bleaching, relative to rose bengal (RB), singlet oxygen generating efficiencies of CYN and CYNM are derived to be 0.055 and 0.254, respectively. The formation of superoxide anion via electron transfer to O2 was monitored by optical spectroscopy, using SOD-inhibitable cytochrome c reduction assay. The production of O2-* is enhanced in the presence of electron donors such as EDTA and NADH. Photolysis of CYN and CYNM in DMSO, in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), generates a multi-line EPR spectrum, characteristic of spin adduct mixture of O2-* and *OH. Both optical and ESR measurements indicate that O2-* (Type I) and 1O2 (Type II) paths are involved in CYN and CYNM photodynamic action.
Rajendran
M
M
Department of Chemistry, NMSSVN College, Madurai 625 019, Tamil Nadu, India.
Ramasamy
S
S
Rajamanickam
C
C
Gandhidasan
R
R
Murugesan
R
R
D000880:Anthraquinones / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000737:chemistry; D010084:Oxidation-Reduction; D010777:Photochemistry; D013113:Spin Labels; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry
D000880:Anthraquinones; D003497:Cyclic N-Oxides; D013113:Spin Labels; D013481:Superoxides; D017665:Hydroxyl Radical; C001803:tempol; C478048:cynodontin