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MECHANISM OF PHOTOSENSITIZATION BY PHEOPHORBIDE a STUDIED BY PHOTOHEMOLYSIS OF ERYTHROCYTES AND ELECTRON spIN RESONANCE SPECTROSCOPY
Author(s) -
KUWABARA M.,
YAMAMOTO T.,
INANAM O.,
SATO F.
Publication year - 1989
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1989.tb04074.x
Subject(s) - electron paramagnetic resonance , chemistry , superoxide dismutase , catalase , hemolysis , photochemistry , excited state , oxygen , spectroscopy , resonance (particle physics) , nuclear chemistry , biophysics , oxidative stress , nuclear magnetic resonance , biochemistry , organic chemistry , physics , quantum mechanics , particle physics , nuclear physics , immunology , biology
Phcophorbide a (PPa), a causal substance of food intoxication, when excited by exposure to light wavelengths of over 600 nm, caused the photohemolysis of goat erythrocytes in proportion to the incubation time of the cells. The addition of N‐ 3 , an effective scavenger of 1 O 2 , to the medium markedly inhibited the hemolysis of erythrocytes in a concentration‐dependent manner, whereas the addition of superoxide dismutase (SOD) and catalase, inhibitors of O ‐ 2 and H 2 O 2 generation, respectively, to the medium had little effect on it. Methods for converting 1 O 2 to a nitroxide radical by 2,2,6,6‐tetramethyl‐4‐piperidone (TMPD) and for trapping O ‐ 2 and OH by 5,5‐dimethyl‐l‐pyrroline‐A'‐oxide (DMPO) were employed to observe directly these activated oxygens by electron spin resonance (ESR). The methods provided evidence that only 1 O 2 , was produced by PPa, which was excited by light wavelengths of over 600 nm. Both the addition of N 3 to the solution and the removal of oxygen from the solution inhibited the generation of 1 O 2 . These results led us to conclude that 1 O 2 was mainly responsible for the hemolysis of erythrocytes by photoexcited PPa.