Nitric oxide release from the S-nitrosothiol zinc phthalocyanine complex by flash photolysis

Abstract

The photogeneration of nitric oxide (NO) using laser flash photolysis was investigated for S-nitroso-glutathione (GSNO) and S-nitroso-Nacetylcysteine (NacySNO) at pH 6.4 (PBS/HCl) and 7.4 (PBS). Irradiation of S-nitrosothiol with light (l = 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 ISONometer 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 wellknown 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. Correspondence

Nitric oxide- and cisplatin-releasing silica nanoparticles for use against non-small cell lung cancer

“…The total amount of NO released was 37 and 50 μmol/g after 6 days from NO-Si-DETA-cisplatin-AMS1 and NO-Si-DETA-AMS1 samples, respectively. Furthermore, NO release depends on pH and the medium [61]. Small molecule NO donors such as diazeniumdiolates, nitrosothiols, organic nitrites/nitrates and NO-metal complexes have been developed and evaluated for NO storage, release and efficacy against tumor cells [62][63][64][65][66][67].…”

Low-molecular-weight S-nitrosothiols

“…shows the photolysis of GSNO by successive sets of 10 laserpulses (355 nM, 50 mJ/pulse). The photolytic decomposition of S-NO bonds has raised interest in the application of S-nitrosated complexes for photodynamic therapy of cancers [41]. It should be mentioned that S-nitrosothiols are not the only endogenous species showing such photolytic release of NO: Alongside endogenous S-nitrosothiols, also nitrite was shown [42] to contribute significantly to the light-induced release of NO from vascular tissues of rats.…”

Reactive nitrogen/oxygen species production by nitro/nitrosyl supramolecular ruthenium porphyrin complexes

“…Combining these mechanisms on the same platform, which could be able to induce a synergic effect resulting in a considerable improvement of photodynamic action, is strongly desirable. Furthermore, nitric oxide (NO) has been described as an antitumor agent [27,28], which, combined with reactive oxygen species, (ROS) produces a synergistic photodynamic action between ROS and reactive nitrogen species (RNOS) [25,26,29,30]. It was shown that using UV-vis irradiation on a NO-compound leads to tumor destruction [29].…”