Nitric oxide release from the S-nitrosothiol zinc phthalocyanine complex by flash photolysis
Braz. j. med. biol. res
;
36(5): 587-594, May 2003. ilus, graf
Article
in English
| LILACS
| ID: lil-331449
RESUMO
The photogeneration of nitric oxide (NO) using laser flash photolysis was investigated for S-nitroso-glutathione (GSNO) and S-nitroso-N-acetylcysteine (NacySNO) at pH 6.4 (PBS/HCl) and 7.4 (PBS). Irradiation of S-nitrosothiol with light (lambda = 355 nm followed by absorption spectroscopy) resulted in the homolytic decomposition of NacySNO and GSNO to generate radicals (GSA and NacySA) and NO. The release of NO from donor compounds measured with an ISO-Nometer apparatus was larger at pH 7.4 than pH 6.4. NacySNO was also incorporated into dipalmitoyl-phosphatidylcholine liposomes in the presence and absence of zinc phthalocyanine (ZnPC), a well-known photosensitizer useful for photodynamic therapy. Liposomes are usually used as carriers for hydrophobic compounds such as ZnPC. Inclusion of ZnPC resulted in a decrease in NO liberation in liposomal medium. However, there was a synergistic action of both photosensitizers and S-nitrosothiols resulting in the formation of other reactive species such as peroxynitrite, which is a potent oxidizing agent. These data show that NO release depends on pH and the medium, as well as on the laser energy applied to the system. Changes in the absorption spectrum were monitored as a function of light exposure
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Photolysis
/
Nitric Oxide
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2003
Type:
Article
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade de São Paulo/BR
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