Spectrophotometric determination of glutathione and of its oxidation product in pharmaceutical dosage forms

CuSeO3@f-CNFs: A superoxide nanozyme for the selective nanomolar determination of the key cardiovascular biomarker, Glutathione

Nanocomposites that mimic the characteristics of enzymes, commonly as nanozymes, can function as an efficient sensing material with high selectivity towards the targeted biological macromolecule. These nanozymes overcome of the challenges that arise when using natural enzymes as sensing material. This study presents a novel nanozyme, Copper Selenite (CuSeO3) nanoparticles mounted on f-CNF, to electrochemically determine a potential cardiovascular biomarker, Glutathione (GSH). The choice of this material is due to the well-known ability of GSH to form a complex with copper. When a Cu ion enters a healthy cell, it quickly forms a complex with GSH, which then moves to another storage molecule: either a metalloprotein or a chelator. CNF was functionalized using acid to generate functionalized-CNF to enhance biocompatibility and boost conductivity. This was done to provide many active sites for effective integration of CuSeO3 in the nanocomposite preparation. The glassy carbon electrode (GCE) surface was enhanced by introducing CuSeO3@f-CNF nanocomposite, resulting in a significant increase in the current response for GSH in comparison to prior research. CuSeO3@f-CNF/GCE sensor has shown excellent sensing properties, like enhanced stability, selectivity, sensitivity, and reproducibility, for detecting and quantifying GSH. The sensor demonstrated an extensive linear detection range from 62.5 nM to 7785.0 μM, signifying one of the most comprehensive ranges documented to date. It attained a remarkable detection limit (LOD) of 17.6 nM. The sensor's performance was further tested by analyzing genuine biological fluid samples. The nanozyme-modified GCE demonstrated exceptional electrocatalytic efficiency for GSH detection, making it extremely appropriate for real-time monitoring applications.

A nanosecond pulsed laser-ablated MWCNT-Au heterostructure: an innovative ultra-sensitive electrochemical sensing prototype for the identification of glutathione

Here, a scheme that aptly describes the reduction of gold nanoparticles’ crystalline size on the surface of MWCNTs in an aqueous phase to generate a LAMWCNT-Au heterostructure, employing an Nd:YAG laser (energy = 505 mJ and λ = 1064 nm) is developed.

Determination of penicillamine, tiopronin and glutathione in pharmaceutical formulations by kinetic spectrophotometry

A novel and simple method for the determination of penicillamine (PEN), tiopronin (mercaptopropionyl glycine, MPG) and glutathione (GSH) in pharmaceutical formulations by kinetic spectrophotometry has been developed and validated. It is based on the redox reaction where the thiol compound (RSH) reduces Cu^II-neocuproine complex to Cu^I-neocuproine complex. The non-steady state signal of the formed Cu^I- neocuproine complex is measured at 458 nm. The initial rate and fixed time (at 1 min) methods were validated. The calibration graph was linear in the concentration range from 8.0 × 10^‒7 to 8.0 × 10^‒5 mol L^-1 for the initial rate method and from 6.0 × 10^‒7 to 6.0 × 10^-5 mol L^-1 for the fixed time method, with the detection limits of 2.4 × 10^-7 and 1.4 × 10^‒7 mol L^-1, resp. Levels of PEN, MPG and GSH in pharmaceutical formulations were successfully assayed by both methods. The advantages of the presented methods include sensitivity, short analysis time, ease of application and low cost.

Determination of L-glutathione by spot test and spectrophotometric methods based on its interaction with phenazine

This research paper presents simple and quick eco-friendly spot test and spectrophotometric methods for the determination of L-glutathione. The spot test assay is based on the formation of a color complex with phenazine methosulphate and L-glutathione on a thin-layer chromatography plate followed by image analysis using a scanner as a detector. For analysis, the image was converted into red, green, and blue (RGB) histograms. A series of parameters that influenced the color formation were investigated, and under the optimal conditions, a good linearity was observed in the range of 200-1000 μg mL^-1 and 249-1000 μg mL^-1 of L-glutathione with correlation coefficients of 0.9907 for B and 0.9903 for G channels. For the spectrophotometric method, a good linearity was obtained in the range of 2.1-60 μg mL^-1 of L-glutathione concentration with a correlation coefficient of 0.9961. A mechanism of the reaction of L-glutathione with phenazine was proposed and confirmed by Fourier transform infrared and mass spectroscopy.

Sonochemical synthesis of silver nanoparticles anchored reduced graphene oxide nanosheets for selective and sensitive detection of glutathione

Developed here an eco-friendly, one-pot approach toward rapid synthesis of silver nanoparticles anchored reduced graphene oxide (AgNPs_(TMSPED)-rGO) nanosheets via sonochemical irradiation method, using an aqueous solution mixture of GO and AgNO₃ in the presence of N-[3(trimethoxysilyl)propyl] ethylenediamine (TMSPED) without any reducing agent. As synthesized decorated nanosheets was thoroughly characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Pristine AgNPs_(TMSPED), pristine rGO_(TMSPED) and as prepared AgNPs_(TMSPED)-rGO materials were employed to modify the glassy carbon (GC) electrode and demonstrated its excellent electrocatalytic activities towards glutathione (GSH). Voltammetry and amperometry measurements were utilized to assess the electrochemical properties towards the glutathione detection. When the Ag nanoparticles were anchored onto the rGO surface, the observed results illustrated that the electrocatalytic properties of rGO might be enhanced. The resulting sensor exhibits excellent repeatability and long-term stability. Furthermore, AgNPs_(TMSPED)-rGO/GC electrode able to be employed for the selective determination of GSH in amperometric analysis in the presence of ascorbic acid (AA), dopamine (DA), uric acid (UA) and glucose. Finally, this modified electrode was effectively applied to determine glutathione in real samples with good recoveries.

Evaluation of the reactivity of exhaust from various biodiesel blends as a measure of possible oxidative effects: A concern for human exposure

Diesel exhaust particles (DEP) are a major constituent of ambient air pollution and are associated with various adverse health effects, posing a major safety and public health concern in ambient and occupational environments. The effects of DEP from various biodiesel blends on biological systems was investigated using glutathione (GSH) as a marker of possible oxidative effects, based on the decrease in the concentration of GSH at physiological pH. The fluorophoric agent 2,3-naphthalenedicarboxaldehyde (NDA) was used as a selective probe of GSH in the presence of any likely interferents via fluorescence detection. Three different polar solvents (acetonitrile, methanol and water) were used to extract DEP generated during the combustion of different biodiesel blends (5%-99%). Oxidation of GSH to the disulfide (GSSG) was confirmed using electrospray ionization mass spectrometry. A decrease in the concentration of GSH was observed in the presence of DEP extracts from all of the biodiesel blends studied, with reaction rates that depend on the biodiesel blend. Interestingly the reactivity peaked at 50% biodiesel (B50) rather than decreasing monotonically with increased biodiesel content, as was expected. Organic solvent DEP extracts showed wider variations in reactivity with GSH, with methanol extracts giving the largest decrease in GSH concentrations. This may imply a more organic nature of the oxidants in the biodiesel exhaust. It is therefore important to consider ways of reducing concentrations of organic components in biodiesel exhaust that can cause different toxic activity before any blend is offered as a preferred alternative to petroleum diesel fuel.

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.

Rapid and fast strategy for the determination of glutathione in the presence of vitamin B6in biological and pharmaceutical samples using a nanostructure based electrochemical sensor

In this study, we describe the simultaneous determination of glutathione and vitamin B₆in pharmaceutical and biological samples for the first time.

Highly sensitive determination of reduced glutathione based on a cobalt nanoparticle implanted-modified indium tin oxide electrode

Cobalt nanoparticle modified indium tin oxide (CoNP/ITO) electrodes fabricated by ion implantation were applied for the detection of reduced glutathione (GSH).

A high sensitive electrochemical nanosensor for simultaneous determination of glutathione, NADH and folic acid

In the present study, we report electrosynthesis of 4,5-bis(4-chloroanilino)-1,2-benzendiol (BCB) and its application as a selective electrochemical mediator at a surface of carbon paste electrode (CPE) modified ZnO/CNTs nanocomposite as a simple and rapid voltammetric sensor. The sensor showed an efficient catalytic activity for the electro-oxidation of glutathione (GSH), which leads to a lowered overpotential by more than 203 mV compared to unmodified carbon paste electrode. For the mixture containing GSH, nicotinamide adenine dinucleotide (NADH) and folic acid (FA), the electrooxidation signals were well separated. The square wave voltammetry (SWV) currents increased linearly with their concentration at the ranges of 0.006-161, 1.0-650 and 3.0-700 μM, respectively with the detection limits of 0.002, 0.3 and 1.0 μM. Finally, the electrode was successfully applied for the voltammetric determination of analytes in real samples with satisfactory results.

A new strategy for the selective determination of glutathione in the presence of nicotinamide adenine dinucleotide (NADH) using a novel modified carbon nanotube paste electrode

A novel electrochemical sensor for the simultaneous determination of glutathione (GSH) and nicotinamide adenine dinucleotide (NADH) is described. The sensor is based on a carbon paste electrode (CPE) modified with benzamide derivative and multiwall carbon nanotubes. This mixture makes a modified electrode that is sensitive for the electrochemical detection of these compounds. Under optimum conditions and at pH 7.0, oxidation of GSH occurs at a potential of about 330 mV less positive than that at an unmodified CPE. The voltammetric peak currents are linearly dependent on GSH and NADH concentrations in the ranges 0.09-300 μmol L(-1) GSH and 5.0-600 μmol L(-1) NADH. The detection limits found for GSH and NADH were 0.05 μmol L(-1) and 1.0 μmol L(-1), respectively. The electrochemical sensor was also used for the determination of GSH in urine, pharmaceutical and hemolysed erythrocyte samples.

Electrocatalytic activity of 4-nitrophthalonitrile-modified electrode for the l-glutathione detection

The present work describes the substantial electrocatalytic activity of (NC)2C6H3-NHOH/(NC)2C6H3-NO redox couple-modified electrode toward the low voltage detection of l-glutathione (GSH), in neutral medium, at an applied potential of 0.4V versus Ag/AgCl. After optimizing the operational conditions, the sensor provided a linear response range for GSH from 8.0 up to 83.0 micromol L(-1) with sensitivity, detection and quantification limits of 54nA L micromol(-1), 2.7 micromol L(-1) and 8.0 micromol L(-1), respectively. The proposed sensor presented higher sensitivity when compared to other modified electrodes described in the literature and showed a stable response for at least 100 successive determinations. The repeatability of the measurements with the same sensor and different sensors, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n=10. The developed sensor was applied for GSH determination in yeast extract and the results were statistically the same with those obtained by the comparative method described in the literature at a confidence level of 95%.

Electrocatalytic determination of reduced glutathione in human erythrocytes

The determination of reduced glutathione (GSH) in human erythrocytes using a simple, fast and sensitive method employing a glassy carbon electrode modified with cobalt tetrasulfonated phthalocyanine (CoTSPc) immobilized in poly(L: -lysine) (PLL) film was investigated. This modified electrode showed very efficient electrocatalytic activity for anodic oxidation of GSH, decreasing substantially the anodic overpotentials for 0.2 V versus Ag/AgCl. The modified electrode presented better performance in 0.1 mol l(-1) piperazine-N,N'-bis(2-ethanesulfonic acid) buffer at pH 7.4. The other experimental parameters, such as the concentration of CoTSPc and PLL in the membrane preparation, pH, type of buffer solution and applied potential, were optimized. Under optimized operational conditions, a linear response from 50 to 2,160 nmol l(-1) was obtained with a high sensitivity of 1.5 nA l nmol(-1) cm(-2). The detection limit for GSH determination was 15 nmol l(-1). The proposed sensor presented good repeatability, evaluated in terms of the relative standard deviation (1.5%) for n = 10. The modified electrode was applied for determination of GSH in erythrocyte samples and the results were in agreement with those obtained by a comparative method described in the literature The average recovery for these fortified samples was 100 +/- 1)%. Applying a paired Student's-t test to compare these methods, we could observe that, at the 95% confidence level, there was no statistical difference between the reference and the proposed methods.

Electrocatalytic activity of cobalt phthalocyanine CoPc adsorbed on a graphite electrode for the oxidation of reduced l-glutathione (GSH) and the reduction of its disulfide (GSSG) at physiological pH

Modified electrodes coated by adsorbed cobalt phthalocyanines are known to show substantial electrocatalytic activity for the electro-oxidation of several thiols in alkaline aqueous solution. In this context, we explore in this study the electrocatalytic activity of adsorbed cobalt phthalocyanine (CoPc) on ordinary pyrolytic graphite electrode for the oxidation of reduced L-glutathione GSH and the reduction of its disulfide GSSG at physiological pH. To do so, cyclic and rotating disk voltammetries were performed and the amperometric results show that a stable electrochemical sensing material, with good reproducibility and sensitivity (in accordance with the concentrations of GSH expected in biological media), can be easily achieved. This opens the way for the design of an electrochemical sensor able to detect these two analytes in biologically relevant experimental conditions (in terms of pH).

Development of an amperometric biosensor based on glutathione peroxidase immobilized in a carbodiimide matrix for the analysis of reduced glutathione from serum

The development of an amperometric biosensor for the reduced glutathione determination in serum is described. The biosensor is based on glutathione peroxidase (GSH-Px, EC 1.11.1.9) immobilized onto a pyrolytic graphite-working electrode using carbodiimide as enzymatic condensing reagent. This resulted in an amperometric biosensor with good sensitivity and stability. The reduced glutathione (GSH) was enzymatically converted to glutathione disulfide (GSSG) in the presence of hydroperoxide, which was monitored amperometrically by its electrooxidation at +0.65 V vs. SCE (saturated calomel electrode). Glutathione measurement was carried out by maintaining the ratio between GSH and hydrogen peroxide at 2:1 (25 degrees C). The amperometric response of the biosensor was linearly proportional to the GSH concentration between 1.9x10(-5) and 1.4x10(-4) mol/l, in 0.1 mol/l phosphate buffer (pH=7.8), containing 0.1 mol/l KCl and 0.5 mmol/l Na(2)H(2)EDTA, as the supporting electrolyte. In presence of interfering compounds, the recoveries ranged between 97.2% and 110.7%. The biosensor useful lifetime was at least 2 months when it was evaluated after continuous use. Serum samples analyzed by this biosensor showed a good correlation with the results from the spectrophotometric method (Ellman's reagent) used as reference, presenting relative deviations lower than 7.0%. The low apparent Michaelis-Menten constant value, K(M)(app)=1.6 mmol/l, demonstrated that GSH-Px immobilized on pyrolytic graphite exhibited a high affinity to GSH, without loss of enzymatic activity.

Inhibition of poly(ADP-ribose) polymerization preserves the glutathione pool and reverses cytotoxicity in hydrogen peroxide-treated lymphocytes

DNA damage caused by oxygen radicals activates poly(ADP-ribosyl) polymerase (pADPRP), a nuclear enzyme that utilizes NAD+ as substrate. It has been demonstrated that pharmacological inactivation of pADPRP rescues human lymphocytes damaged by oxygen radicals, but not those damaged by equitoxic doses of ionizing radiation. In the present paper we demonstrate that the NAD+ pool decreases after both damaging treatments and is preserved in a similar fashion by pADPRP inhibition. On the contrary, the ATP pool, cell energy charge and reduced thiols are decreased only by the administration of oxygen radicals, and are preserved if poly(ADP)ribosylation is inhibited. In fact, treatment with oxidant agents depletes the cell energy pools owing to the simultaneous demands of the glutathione (GSH)/NADPH cycle and pADPRP-driven NAD+ consumption, while in irradiated cells only the latter mechanism operates. We suggest that, when pADPRP is inhibited, enough energy is available for the preservation of cell thiols, thereby allowing oxidant-treated cells to survive and undergo mitosis. Thus, GSH and energy shortage appear to be the main cause of cell death in oxidant-injured cells.