Rotta J C G, Lunardi C N, Tedesco A C
Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeir o Preto, SP, Brasil.
Braz J Med Biol Res. 2003 May;36(5):587-94. doi: 10.1590/s0100-879x2003000500005. Epub 2003 Apr 22.
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 (GS and NacyS ) 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.
利用激光闪光光解技术，在pH值为6.4（PBS/HCl）和7.4（PBS）的条件下，对S-亚硝基谷胱甘肽（GSNO）和S-亚硝基-N-乙酰半胱氨酸（NacySNO）产生一氧化氮（NO）的过程进行了研究。用波长为355nm的光照射亚硝基硫醇（随后进行吸收光谱分析），导致NacySNO和GSNO均裂分解，产生自由基（GS和NacyS）以及NO。使用ISO-Nometer仪器测得，供体化合物在pH 7.4时释放的NO比在pH 6.4时更多。在存在和不存在锌酞菁（ZnPC，一种用于光动力疗法的著名光敏剂）的情况下，NacySNO也被掺入二棕榈酰磷脂酰胆碱脂质体中。脂质体通常用作疏水性化合物（如ZnPC）的载体。加入ZnPC会导致脂质体介质中NO释放量减少。然而，光敏剂和亚硝基硫醇之间存在协同作用，导致形成其他活性物质，如过氧亚硝酸盐，它是一种强氧化剂。这些数据表明，NO的释放取决于pH值、介质以及施加于系统的激光能量。监测吸收光谱随光照的变化情况。
