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פותח על ידי קלירמאש פתרונות בע"מ -
PHOTOSENSITIZED FORMATION OF ASCORBATE RADICALS BY RIBOFLAVIN: AN ESR STUDY
Year:
1993
Source of publication :
Photochemistry and Photobiology
Authors :
רוזנטל, יונל
;
.
Volume :
57
Co-Authors:
Kim, H., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland, 20892, United States
Kirschenbaum, L.J., Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, 02881, United States
Rosenthal, I., Department of Food Science, The Volcani Center, ARO, Bet Dagan, 50250, Israel
Riesz, P., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland, 20892, United States
Facilitators :
From page:
777
To page:
784
(
Total pages:
8
)
Abstract:
Abstract— The riboflavin‐sensitized photooxidation of ascorbate ion (HA‐) to ascorbate radical (A‐) was followed by electron spin resonance (ESR) spectroscopy in conjunction with oxygen depletion measurements. 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. Similar results were obtained with other flavins and when ascorbyl palmitate was substituted for HA‐. 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 ascorbate free radical production via direct reaction between ascorbate ion and triplet riboflavin in the presence of O2. While the presence of superoxide ion tends to reduce the steady‐state concentration of A‐, competition from the reaction of HA‐ with singlet oxygen is less apparent in this system (at HA‐≥ 1 mM) than in the previously studied aluminum phthalocyanine tetrasulfonate‐photosensitized reaction. Copyright © 1993, Wiley Blackwell. All rights reserved
Note:
Related Files :
chemistry
Electron Spin Resonance Spectroscopy
free radicals
Kinetics
light
methodology
riboflavin
עוד תגיות
תוכן קשור
More details
DOI :
10.1111/j.1751-1097.1993.tb09210.x
Article number:
Affiliations:
Database:
סקופוס
Publication Type:
מאמר
;
.
Language:
אנגלית
Editors' remarks:
ID:
24882
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:10
Scientific Publication
PHOTOSENSITIZED FORMATION OF ASCORBATE RADICALS BY RIBOFLAVIN: AN ESR STUDY
57
Kim, H., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland, 20892, United States
Kirschenbaum, L.J., Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, 02881, United States
Rosenthal, I., Department of Food Science, The Volcani Center, ARO, Bet Dagan, 50250, Israel
Riesz, P., Radiation Oncology Branch, National Cancer Institute, NIH, Bethesda, Maryland, 20892, United States
PHOTOSENSITIZED FORMATION OF ASCORBATE RADICALS BY RIBOFLAVIN: AN ESR STUDY
Abstract— The riboflavin‐sensitized photooxidation of ascorbate ion (HA‐) to ascorbate radical (A‐) was followed by electron spin resonance (ESR) spectroscopy in conjunction with oxygen depletion measurements. 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. Similar results were obtained with other flavins and when ascorbyl palmitate was substituted for HA‐. 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 ascorbate free radical production via direct reaction between ascorbate ion and triplet riboflavin in the presence of O2. While the presence of superoxide ion tends to reduce the steady‐state concentration of A‐, competition from the reaction of HA‐ with singlet oxygen is less apparent in this system (at HA‐≥ 1 mM) than in the previously studied aluminum phthalocyanine tetrasulfonate‐photosensitized reaction. Copyright © 1993, Wiley Blackwell. All rights reserved
Scientific Publication
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