N-acetyl Glutathione Research Articles

Simultaneous quantification of multiple urinary naphthalene metabolites by liquid chromatography tandem mass spectrometry.

Naphthalene is an environmental toxicant to which humans are exposed. Naphthalene causes dose-dependent cytotoxicity to murine airway epithelial cells but a link between exposure and human pulmonary disease has not been established. Naphthalene toxicity in rodents depends on P450 metabolism. Subsequent biotransformation results in urinary elimination of several conjugated metabolites. Glucuronide and sulfate conjugates of naphthols have been used as markers of naphthalene exposure but, as the current studies demonstrate, these assays provide a limited view of the range of metabolites generated from the parent hydrocarbon. Here, we present a liquid chromatography tandem mass spectrometry method for measurement of the glucuronide and sulfate conjugates of 1-naphthol as well as the mercapturic acids and N-acetyl glutathione conjugates from naphthalene epoxide. Standard curves were linear over 2 log orders. On column detection limits varied from 0.91 to 3.4 ng; limits of quantitation from 1.8 to 6.4 ng. The accuracy of measurement of spiked urine standards was -13.1 to + 5.2% of target and intra-day and inter-day variability averaged 7.2 (± 4.5) and 6.8 (± 5.0) %, respectively. Application of the method to urine collected from mice exposed to naphthalene at 15 ppm (4 hrs) showed that glutathione-derived metabolites accounted for 60-70% of the total measured metabolites and sulfate and glucuronide conjugates were eliminated in equal amounts. The method is robust and directly measures several major naphthalene metabolites including those derived from glutathione conjugation of naphthalene epoxide. The assays do not require enzymatic deconjugation, extraction or derivatization thus simplifying sample work up.

Organic mediator-induced structural transformation in superlattices of monolayer-protected gold nanoparticles

N-acetylglutathione (NAG)-protected gold nanoparticles self-assemble into three-dimensional (3D) face-centered cubic ( fcc)-type superlattices at an air/water interface under highly acidic conditions. To prepare the well-defined superlattices, 1 month’s incubation is at least necessary since the size growth of the as-prepared nanoparticles is essential. Addition of 4-pyridinecarboxyic acid (PyC), a bifunctional hydrogen-bonding mediator, promotes the formation of the superlattices, which are created for about 2 weeks’ storage. Interestingly, PyC-induced nanoparticle superlattices are in a body-centered tetragonal ( bct) structure. The fcc-to- bct phase transformation would be due to stronger interaction between NAG and PyC than that between NAG molecules on the gold nanoparticle surfaces.

Gold Nanoparticle Superlattices: Novel Surface Enhanced Raman Scattering Active Substrates

We developed a cheap and rapid method for the fabrication of 3D nanoparticle superlattices (SLs) of Au@SGAN and Au@MSA (N-acetyl glutathione (SGAN) and mercaptosuccinic acid (MSA) protected gold nanoparticles, respectively) in gram scale, at a liquid−liquid interfaces under flowing nitrogen gas. While available methods take several weeks to make crystalline SLs, the present route makes them in a day. Morphology of these crystals was examined with scanning electron microscopy (SEM), and their structures were probed using transmission electron microscopy (TEM). The surface enhanced Raman scattering (SERS) studies of these crystals were done using crystal violet (CV) molecules as the analyte which exhibited a detection limit of 10−8 M. The SERS spectrum was used to map the Raman images of the superlattce crystals. SERS from the edges of the crystal showed more enhancement than from the flat surfaces, which is in good agreement with theoretical reports of such anisotropic structures. The sides of the crystals are not sharp, and they show corrugations at the nanometer scale. This helps to produce more “hot spots” at the edges, which result in larger electric field enhancement from these locations. The enhancement factors (EF) for Au@MSA and Au@SGAN SLs were calculated to be around 1.47 × 106 and 3.60 × 105, respectively. More enhancements from Au@MSA SL compared to that of Au@SGAN could be attributed to the smaller chain length of the MSA molecule, which allows closer analyte approach to the nanoparticle surface.

Chemometric and Microscopic Analyses for the Size Growth of Monolayer-Protected Gold Nanoparticles during Their Superlattice Formation

Superlattices of gold nanoparticles have been produced at an air/solution interface under a highly acidic condition. The nanoparticle surface is protected by N-acetylglutathione (NAG). During the course of the superlattice formation, size growth of nanoparticles was observed: The superlattices were composed of nanoparticles of 6.6 nm in core diameter, whereas the as-prepared nanoparticles had the core diameter of 1.4 nm. The growth kinetics was pursued by the time evolution of the UV-vis absorption spectra for the sample solution. The change in the absorption spectral profiles was so small that we conducted principal-component analysis (PCA), which is known as a chemometric technique to resolve (or extract) spectra of minute chemical species submerged in the original spectra. Scanning transmission electron microscopy (STEM) corroborated the PCA results, yielding a successful explanation of the growth scheme of the NAG-protected gold nanoparticles.

Fivefold Symmetry in Superlattices of Monolayer-Protected Gold Nanoparticles

Three-dimensional (3D) superlattices of gold nanoparticles were prepared at an air/solution interface. The surface of the gold nanoparticles used is protected by N-acetylglutathione (NAG). Morphological studies revealed that the superlattices formed fivefold symmetric structures such as pentagonal rod, decahedron, and icosahedron, which were probably developed by multiple twinning. Moreover, high-resolution surface images of the superlattices in fivefold symmetry showed excellent ordered arrangements of nanoparticles with both close-packed and non-close-packed structures.

Antiangiogenesis efficacy of nitric oxide donors.

Angiogenesis is a complex process involving endothelial cell migration, proliferation, invasion, and tube formation. Inhibition of these processes might have implications in various angiogenesis-mediated disorders. Because nitric oxide (NO) is known to play a key role in various vascular diseases, the present study was undertaken to determine the role of NO in angiogenesis-mediated processes using the NO donor, S-nitroso N-acetyl penicillamine (SNAP) and S-nitroso N-acetyl glutathione (SNAG). The antiangiogenic efficacy of these NO donors was examined using in vivo and in vitro model systems. The in vitro studies demonstrated the ability of SNAP to inhibit cytokine fibroblast growth factor (FGF2)-stimulated tube formation and serum-induced cell proliferation. The inhibitory effect on cell proliferation by SNAP concentrations above the millimolar range was associated with significant shifts in the concentration of NO metabolites. Furthermore, using the mouse Matrigel implant model and the chick chorioallantoic membrane (CAM) models, SNAP demonstrated maximal inhibitory efficacy (85-95% inhibition) of cytokine (FGF2)-induced neovascularization in both in vivo models. SNAP and SNAG resulted in 85% inhibition of FGF2-induced neovascularization in the mouse Matrigel model when given at 5 mg/kg/day infusion in minipumps during 14 days and 87% inhibition of angiogenesis induced by FGF2 in the CAM when administered a single dose of 50 microg. Thus, NO donors might be a useful tool for the inhibition of angiogenesis associated with human tumor growth, or neovascular, ocular, and inflammatory diseases.

On the Synthesis and Characterization of N-Formyl Glutathione and N-Acetyl Glutathione

Treatment of glutathione (GSH) with formic acid and acetic anhydride leads to preparation of crystalline N-formyl GSH. This is the first characterized preparation of N-formyl GSH; this product was previously erroneously thought to he N-acetyl GSH. Authentic N-acetyl GSH (crystalline) was prepared by treating GSH with acetic acid and acetic anhydride. The N-acylated derivatives were characterized by 1H NMR and mass spectroscopy.