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Photosensitized formation of ascorbate radicals by chloroaluminum phthalocyanine tetrasulfonate: An electron spin resonance study
Year:
1992
Source of publication :
Free Radical Biology and Medicine
Authors :
Rosenthal, Ionel
;
.
Volume :
13
Co-Authors:
Kim, H., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, United States
Rosenthal, I., Department of Food Science, The Volcani Center, ARO, P.O. Box 6, Bet Dagan, 50250, Israel
Kirschenbaum, L.J., Department of Chemistry, University of Rhode Island, Kingston, RI 02881, United States
Riesz, P., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, United States
Facilitators :
From page:
231
To page:
238
(
Total pages:
8
)
Abstract:
The chloroaluminum phthalocyanine tetrasulfonate sensitized photooxidation of ascorbic acid to ascorbate radical (A·-)was followed by electron spin resonance (ESR) spectroscopy. In air saturated aqueous media, steady-state amounts of (A·-)are rapidly established upon irradiation. The ESR signal disappears within a few seconds after the light is extinguished-more slowly under constant irradiation as oxygen is depleted. No photooxidation was observed in deaerated media. The effect of added superoxide dismutase, catalase, desferrioxamine, and singlet oxygen scavengers (NaN3 and tryptophan) was studied, as was replacement of water by D2O and saturation with O2. The results are indicative of free radical production by direct reaction between ascorbate ion and sensitized phthalocyanine (a Type I mechanism) in competition with the (Type II) reaction of HA- with singlet oxygen, a reaction which does not produce ascorbate radical intermediates. © 1992.
Note:
Related Files :
Electron Spin Resonance Spectroscopy
ESR
free radicals
Lethrinidae
photosensitizing agent
phthalocyanine
superoxide dismutase
Show More
Related Content
More details
DOI :
10.1016/0891-5849(92)90019-D
Article number:
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
30914
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:58
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Scientific Publication
Photosensitized formation of ascorbate radicals by chloroaluminum phthalocyanine tetrasulfonate: An electron spin resonance study
13
Kim, H., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, United States
Rosenthal, I., Department of Food Science, The Volcani Center, ARO, P.O. Box 6, Bet Dagan, 50250, Israel
Kirschenbaum, L.J., Department of Chemistry, University of Rhode Island, Kingston, RI 02881, United States
Riesz, P., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, United States
Photosensitized formation of ascorbate radicals by chloroaluminum phthalocyanine tetrasulfonate: An electron spin resonance study
The chloroaluminum phthalocyanine tetrasulfonate sensitized photooxidation of ascorbic acid to ascorbate radical (A·-)was followed by electron spin resonance (ESR) spectroscopy. In air saturated aqueous media, steady-state amounts of (A·-)are rapidly established upon irradiation. The ESR signal disappears within a few seconds after the light is extinguished-more slowly under constant irradiation as oxygen is depleted. No photooxidation was observed in deaerated media. The effect of added superoxide dismutase, catalase, desferrioxamine, and singlet oxygen scavengers (NaN3 and tryptophan) was studied, as was replacement of water by D2O and saturation with O2. The results are indicative of free radical production by direct reaction between ascorbate ion and sensitized phthalocyanine (a Type I mechanism) in competition with the (Type II) reaction of HA- with singlet oxygen, a reaction which does not produce ascorbate radical intermediates. © 1992.
Scientific Publication
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