High-performance liquid chromatographic method to analyze picomole levels of glutathione, cysteine and cysteinylglycine and its application to pre-cancerous rat livers

Glutathione

Glutathione is an endogenous peptide with antioxidant and other metabolic functions. The nomenclature, formulae, elemental composition, and appearance and uses of the drug are included. The methods used for the synthesis and biosynthesis of glutathione are described. This profile contains the physical characteristics of the drug including: solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The spectral methods that were used for both the identification and analysis of glutathione include ultraviolet spectrum, vibrational spectrum, 1H and 13C nuclear magnetic resonance spectra, and mass spectrum. The profile also includes the compendial methods of analysis and the other methods of analysis that are reported in the literature. These other methods of e-analysis are: potentiometric, voltammetric, amperometric, spectrophotometric, specrtofluorometric, chemiluminescence, chromatographic and immunoassay methods. The stability of and several reviews on drug are also provided. More than 170 references are listed at the end this comprehensive profile on glutathione.

Fast and simultaneous analysis of biothiols by high-performance liquid chromatography with fluorescence detection under hydrophilic interaction chromatography conditions

A method for analyzing biothiols based on high-performance liquid chromatography (HPLC)-fluorescence detection under hydrophilic interaction chromatography (HILIC) conditions has been developed. Thiols were derivatized with nonfluorescent ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate (SBD-F), which selectively reacts with the thiol groups to furnish the corresponding fluorescent SBD-thiols. Among the six different kinds of HILIC columns examined, the ZIC-HILIC column with sulfobetaine groups in the stationary phase proved to be the best for the separation of SBD-thiols. Eight thiols-N-acetylcysteine, cysteamine, homocysteine, cysteine, cysteinylglycine, glutathione, γ-glutamylcysteine, and internal standard N-(2-mercaptopropionyl)glycine-were baseline-separated within 10 min. The detection sensitivity was improved partly due to the increase in the SBD-thiol fluorescence owing to the acetonitrile-rich mobile phase used. The detection limits at a signal-to-noise ratio of 3 were 0.02-3.4 nmol l(-1). The method could successfully quantify six thiols in a human plasma sample, while cysteamine could not be detected. Both the intra- and interday precisions were below 4% for homocysteine, cysteine, cysteinylglycine, glutathione, and γ-glutamylcysteine except for N-acetylcysteine. This method should be a useful tool for investigating the relationship between sulfur metabolism and related diseases, since a multicomponent system consisting of different thiol compounds could be analyzed simultaneously with high sensitivity within a short time.

Lighting-up of the dye malachite green with mercury(II)-DNA and its application for fluorescence turn-off detection of cysteine and glutathione

This work describes a novel strategy for the highly sensitive and selective detection of cysteine (Cys) and glutathione (GSH) based on the Hg(2+)-AGRO100-malachite green (MG) complex system. The dye MG, which has a very low quantum yield in aqueous solution by itself, can bind with the thymine-rich DNA AGRO100 in the presence of Hg(2+) ions to generate a striking fluorescence intensity enhancement of 1000-fold. As sulfur-containing amino acids, Cys and GSH effectively sequester Hg(2+) ions from the Hg(2+)-AGRO100-MG complex structure to switch the 'lit-up' chemosensor to the 'off' state (about a 50-fold fluorescence intensity decrease), thus providing a facile, but effective, method to probe for Cys/GSH. The fluorescence titration, UV absorption, CD, and Raman spectra provide some insight into the structural and chemical basis for the enhancement effect. The formation of the Hg(2+)-AGRO100-MG complex significantly affects the electronic structure and conformation of the MG molecule by leading to an extended π system, which is the likely origin of the observed striking fluorescence intensity enhancement. Notably, the proposed sensing platform exhibits exquisite selectivity and sensitivity toward Cys/GSH with limits of detection of 5 nM for Cys and 10 nM for GSH, respectively. Furthermore, the straightforward assay design avoids labeling of the probe, uses only commercially available materials, and still displays comparable sensitivity and excellent selectivity.

Determination of glutathione in hemolysed erythrocyte with amperometric sensor based on TTF-TCNQ

BACKGROUND

GSH has a relevant role in human metabolism as an indicator of disease risks. An amperometric sensor for glutathione (GSH) determination is described as an alternative method featuring simple construction procedure and short time analysis.

METHOD

The developed sensor was used to determine glutathione at low potential using a TTF-TCNQ complex.

RESULTS

The sensor exhibits a linear response range from 5 to 340 micromol/l under applied potential of 200 mV vs. SCE. The sensitivity and detection limit were 90.1 microA l/mmol cm(2) and 0.3 micromol/l, respectively.

CONCLUSION

When the sensor was tested in hemolysed erythrocyte samples for GSH determination, a good correlation in results was observed between the sensor and the spectrophotometric method. The sensor showed recovery values between 98% and 102%.

Poly(oxyethylene) based surface coatings for poly(dimethylsiloxane) microchannels

Control of surface properties in microfluidic systems is an indispensable prerequisite for successful bioanalytical applications. Poly(dimethylsiloxane) (PDMS) microfluidic devices are hampered from unwanted adsorption of biomolecules and lack of methods to control electroosmotic flow (EOF). In this paper, we propose different strategies to coat PDMS surfaces with poly(oxyethylene) (POE) molecules of varying chain lengths. The native PDMS surface is pretreated by exposure to UV irradiation or to an oxygen plasma, and the covalent linkage of POE-silanes as well as physical adsorption of a triblock-copolymer (F108) are studied. Contact angle measurements and atomic force microscopy (AFM) imaging revealed homogeneous attachment of POE-silanes and F108 to the PDMS surfaces. In the case of F108, different adsorption mechanisms to hydrophilic and hydrophobic PDMS are discussed. Determination of the electroosmotic mobilities of these coatings in PDMS microchannels prove their use for electrokinetic applications in which EOF reduction is inevitable and protein adsorption has to be suppressed.

Capillary electrophoresis of glutathione to monitor oxidative stress and response to antioxidant treatments in an animal model

Glutathione plays a central role in metabolism and antioxidant defence. Several factors can influence the analytical efficiency and rapidity of the quantitative determination of glutathione. Procedures in sample pre-treatment have been compared in order to minimize analytical errors. Capillary electrophoresis has been chosen as a more adequate technique for obtaining a rapid and simple method for glutathione and glutathione disulfide determination in the blood and liver of the rat. The methods, once optimised, have been validated and applied for monitoring the oxidative stress in an animal model, such as the rat made diabetic by streptozotocin injection, when the animals are treated with antioxidants and compared with the corresponding controls.

Simultaneous Determination of Tryptophan and Glutathione in Individual Rat Hepatocytes by Capillary Zone Electrophoresis with Electrochemical Detection at a Carbon Fiber Bundle−Au/Hg Dual Electrode

A method for single-cell analysis was developed by combining capillary zone electrophoresis (CZE) with electrochemical detection (ECD) using a dual electrode consisting of two different types of electrode material (carbon fiber and Au/Hg). In this method, the parallel mode was used. Different potentials were applied to both electrodes of the dual electrode. Tryptophan and glutathione, which could not be simultaneously detected by normal CZE-ECD, could be simultaneously and selectively detected by CZE-ECD at the dual electrode in one run, respectively. The CZE-ECD system with the dual electrode was applied to determine them in individual rat hepatocytes.

Analytical methods to investigate glutathione and related compounds in biological and pathological processes

Reduced glutathione (GSH, gamma-L-glutamyl-L-cysteinylglycine) is a fundamental low-molecular mass antioxidant that serves several biological functions. Upon enzymatic and non-enzymatic oxidation, GSH forms glutathione disulfide (GSSG) and, under particular conditions, may generate other oxidative products. The determination of GSH, its precursors, and metabolites in several bio-matrices is a useful tool in studying oxidative stress. Many separative and non-separative methods have been developed and improved for the assay of GSH and related compounds. At present, high-performance liquid chromatography and capillary electrophoresis are the most used separative techniques to determine GSH and congeners. The review will deal with analytical methods developed over the last few years for the determination of GSH and related compounds, and with the procedures performed in sample pre-treatment in order to minimize analytical errors. Since GSH, GSSG, and related compounds lack of strong chromophores or fluorophores, it is advantageous, in many assays, to derivatize the compounds in order to improve the detection limit with UV-Vis and to allow fluorescence, thus the most commonly used labeling agents are also described.

Surface modification of poly(dimethylsiloxane) microfluidic devices by ultraviolet polymer grafting

Poly(dimethylsiloxane) (PDMS)-based microfluidic devices are increasing in popularity due to their ease of fabrication and low costs. Despite this, there is a tremendous need for strategies to rapidly and easily tailor the surface properties of these devices. We demonstrate a one-step procedure to covalently link polymers to the surface of PDMS microchannels by ultraviolet graft polymerization. Acrylic acid, acrylamide, dimethylacrylamide, 2-hydroxylethyl acrylate, and poly(ethylene glycol)monomethoxyl acrylate were grafted onto PDMS to yield hydrophilic surfaces. Water droplets possessed contact angles as low as 45 degrees on the grafted surfaces. Microchannels constructed from the grafted PDMS were readily filled with aqueous solutions in contrast to devices composed of native PDMS. The grafted surfaces also displayed a substantially reduced adsorption of two test peptides compared to that of oxidized PDMS. Microchannels with grafted surfaces exhibited electroosmotic mobilities intermediate to those displayed by native and oxidized PDMS. Unlike the electroosmotic mobility of oxidized PDMS, the electroosmotic mobility of the grafted surfaces remained stable upon exposure to air. The electrophoretic resolution of two test peptides in the grafted microchannels was considerably improved compared to that in microchannels composed of oxidized PDMS. By using the appropriate monomer, it should be possible to use UV grafting to impart a variety of surface properties to PDMS microfluidics devices.