An improved HPLC measurement for GSH and GSSG in human blood

Visualization and Quantification of Drug Release by GSH-Responsive Multimodal Integrated Micelles

Using molecular imaging techniques to monitor biomarkers and drug release profiles simultaneously is highly advantageous for cancer diagnosis and treatment. However, achieving the accurate quantification of both biomarkers and drug release with a single imaging modality is challenging. This study presents the development of a glutathione (GSH)-responsive polymer-based micelle, PEG-SS-FCy7/PEG-SS-GEM (PSFG), which can precisely localize the tumor using bimodal imaging and prevent drug leakage. These PSFG micelles exhibit a small particle size of 106.3 ± 12.7 nm with a uniform size distribution, and the drug loading efficiency can also be easily controlled by changing the PEG-SS-FCy7 (PSF) and PEG-SS-GEM (PSG) feeding ratio. The PSFG micelles display weak fluorescence emission and minimal drug release under physiological conditions but collapse in the presence of GSH to trigger near-infrared fluorescence and the 19F magnetic resonance imaging signal, allowing for real-time monitoring of intracellular GSH levels and drug release. GSH could synergistically promote the disassembly of the micellar structure, resulting in accelerated probe and drug release of up to about 93.1% after 24 h. These prodrug micelles exhibit high in vitro and in vivo antitumor abilities with minimal side effects. The GSH-responsive drug delivery system with dual-modal imaging capability provides a promising imaging-guided chemotherapeutic platform to probe the tumor microenvironment and quantify real-time drug release profiles with minimal side effects.

LC-MS/MS Analysis of Reaction Products of Arginine/Methylarginines with Methylglyoxal/Glyoxal

Methylglyoxal (MGO) and glyoxal (GO) are toxic α-dicarbonyl compounds that undergo reactions with amine containing molecules such as proteins and amino acids and result in the formation of advanced glycation end products (AGEs). This study aimed at investigating the reactivity of arginine (Arg) or dimethylarginine (SDMA or ADMA) with MGO or GO. The solutions of arginine and MGO or GO were prepared in PBS buffer (pH 7.4) and incubated at 37 °C. Direct electrospray ionization-high-resolution mass spectrometry (ESI-HRMS) analysis of the reaction mixture of Arg and MGO revealed the formation of Arg-MGO (1:1) and Arg-2MGO (1:2) products and their corresponding dehydrated products. Further liquid chromatography (LC)-MS analyses revealed the presence of isomeric products in each 1:1 and 1:2 product. The [M + H]+ of each isomeric product was subjected to MS/MS experiments for structural elucidation. The MS/MS spectra of some of the products showed a distinct structure indicative fragment ions, while others showed similar data. The types of products formed by the arginines with GO were also found to be similar to that of MGO. The importance of the guanidine group in the formation of the AGEs was reflected in similar incubation experiments with ADMA and SDMA. The structures of the products were proposed based on the comparison of the retention times and HRMS and MS/MS data interpretation, and some of them were confirmed by drawing analogy to the data reported in the literature.

Components of the Glutathione Cycle as Markers of Biological Age: An Approach to Clinical Application in Aging

The oxidative-inflammatory theory of aging states that aging is the result of the establishment of a chronic oxidative-inflammatory stress situation in which the immune system is implicated. Among the redox parameters, those involved in the glutathione cycle have been suggested as essential in aging. Thus, the first objective of this study was to determine if several components of the glutathione cycle (glutathione reductase (GR) and glutathione peroxidase (GPx) activities, and concentrations of oxidized glutathione (GSSG) and reduced glutathione (GSH)) in leukocytes) are associated with the biological age (ImmunolAge) estimated using the Immunity Clock in 190 men and women. The second objective was to identify the best blood fraction (whole blood, blood cells, erythrocytes, or plasma) to quantify these components and correlate them with the estimated ImmunolAge. The results show that the oxidative state of peripheral leukocytes correlates with their functionality, supporting the idea that this is the basis of immunosenescence. In blood, the correlations are more significant in the fraction of blood cells with respect to ImmunolAge (positive correlations with GSSG concentration and the GSSG/GSH ratio, and negative correlations with GPx and GR activities). Therefore, blood cells are proposed as the most effective sample to estimate the biological age of individuals in clinical settings.

3-Bromopyruvate elevates ROS and induces hormesis to exert a caloric restriction mimetic effect in young and old rats

CONTEXT

3-Bromopyruvate (3-BP) is a glycolytic inhibitor and a putative caloric restriction mimetic.

OBJECTIVE

We have examined the effect of low-dose administration of 3-BP to rats and assess the CRM effect by measuring an array of biomarkers of oxidative stress.

MATERIALS AND METHODS

Male Wistar young and old rats were administered with a low-dose 3-BP for four weeks.

RESULTS

A significant increase in ROS was observed in 3-BP-treated rats (both young and old), an increase in erythrocyte PMRS (plasma membrane redox system), FRAP (Ferric reducing ability of plasma), catalase and superoxide dismutase activities were also observed. Treatment with 3-BP also reduced protein carbonyl, advanced oxidation protein products, plasma sialic acid, and advanced glycation end products.

CONCLUSION

Short-term 3-BP treatment can provide protection against oxidant stress. We suggest that 3-BP triggers a hormetic response subsequent to an increase in ROS leading to the induction of a protective defense mechanism.

Glutathione Fluorescence Sensing Based on a Co-Doped Carbon Dot/Manganese Dioxide Nanocoral Composite

Glutathione (GSH) is an antioxidant thiol that has a vital role in the pathogenesis of various human diseases such as cardiovascular disease and cancer. Hence, it is necessary to study effective methods of GSH evaluation. In our work, an effective GSH sensor based on a nitrogen and phosphorus co-doped carbon dot (NPCD)-MnO₂ nanocoral composite was fabricated. In addition to utilizing the strong fluorescence of the NPCDs, we utilized the reductant ability of the NPCDs themselves to form MnO₂ and then the NPCD-MnO₂ nanocoral composite from MnO₄^-. The characteristics of the nanocoral composite were analyzed using various electron microscopy techniques and spectroscopic techniques. The overlap between the absorption spectrum of MnO₂ and the fluorescence emission spectrum of the NPCDs led to effective fluorescence resonance energy transfer (FRET) in the nanocoral composite, causing a decrease in the fluorescent intensity of the NPCDs. A linear recovery of the fluorescent intensity of the NPCDs was observed with the GSH level raising from 20 to 250 µM. Moreover, our GSH sensor showed high specificity and sensing potential in real samples with acceptable results.

Determination of glutathione in blood via capillary electrophoresis with pH-mediated stacking

A new approach has been developed for the direct determination of reduced (glutathione [GSH]) and oxidized (glutathione disulfide [GSSG]) GSH in whole blood by means of capillary electrophoresis. Its features include GSH-stabilizing sample preparation, the use of an internal standard, and pH-mediated stacking. Blood stabilized with acid citrate and K₃ EDTA was treated with acetonitrile with N-ethylmaleimide, and then the analytes were extracted with diethyl ether. The total analysis time was 8 min using a 50-µm (i.d.) by 32.5-cm (eff. length) silica capillary. The background electrolyte was 0.075-M citrate Na pH 5.8 with 200-µM cetyltrimethylammonium bromide and 5-µM sodium dodecyl sulfate, and the separation voltage was -14 kV. The quantification limit (S/N = 15) of the method was 1.5 µM for GSSG. The accuracy levels of GSH and GSSG analysis were 104% and 103%, respectively, and between-run precision levels were 2.6% and 3.2%, respectively. Analysis of blood samples from healthy volunteers (N = 24) showed that the levels of GSH and GSSG and the GSH/GSSG ratio in the whole blood were 1.05 ± 0.14 mM, 3.9 ± 1.25 µM, and 256 ± 94, respectively. Thus, the presented approach can be used in clinical and laboratory practice.

The Protective Potency of Medemia argun (An Egyptian Palm) Against Oxidative Stress, and Tissue Injury Induced by γ-Radiation in Rats.. [DOI: 10.21203/rs.3.rs-1973451/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Radiation damages living cells and affect all biological process in human body. Thereby, there is a magnificent interest for protecting patients from the aspect consequences radiotherapy and specialized professional workers by developing a natural antioxidant bio-drugs for amelioration of radiation hazards. Medemia argun (an Egyptian Palm) is a mysterious from northern Sudan and southern Egypt (Nubian desert oases). In ancient Egypt, Medemia argun (MA) dried dates have found in the famed tomb of Tutankhamun. Globally, this is first study related to the metabolomics and biological efficiency of MA in alleviating the harmful effect of γ-irradiation. This work highlights the ameliorative role of MA ethanolic seed’s extract, as a natural promising functional food ingredient in alleviating radiation hazard via its antioxidative properties, anti-inflammatory, antiapoptoic and cell regeneration abilities. In this search, we have estimated the LD50 of MA ethanolic seed’s extract in vivo using male Wistar albino rats. The obtained results showed that 200 mg/kg b.wt. is the recommended dose. Rats were randomly splited into four groups. Group I: Represent as control (normal rats), that were received normal food and water daily for six weeks. Group II. Rats subjected to gamma radiation (6 Gy), a single dose of whole body after one week of the experiment. Group III. Rats were injected intraperitoneally with 200 mg/kg b.wt. of MA ethanolic seed’s extract twice/week for six weeks. Group IV. Rats subjected to gamma radiation (6 Gy), a single dose of whole body after one week of the experiment, then injected intraperitoneally with MA ethanolic seed’s extract (200 mg/kg b.wt.) twice/week for six weeks. Each group contains 15 rats. γ-radiation treatment caused a significant increase in DNA fragmentation, NO, MDA, inflammatory biomarkers (TNF-α, HsP70, IL-6, IL-10, 8-OH-dG, CASP-3, MPC-1, and MMP-9), and liver function (ALT, AST, GGT, ALP, and AFP). Also, there is a significant decrease in GSH, SOD, CAT, POD, T. protein, and albumin. Conversely, MA (200 mg/Kg b.wt.) treatment for 6 weeks effectively reflects most of the altered measurements induced by γ-radiation. The potent therapeutic efficacy of MA was manifested in repairing the DNA fragmentation induced by γ-irradiation and this improvement confirmed by decrease in the concentration of 8-OH-dG. To assess the biological activities and beneficial effect of the ethanolic extract of MA seed’s in ameliorating the radiation hazards in rats, phytochemical analysis, were estimated which revealed presence of many beneficial natural health compounds such as, polyphenols (phenolics and flavonoids), proanthocyanidin (condensed tannins), saponins, protein and carbohydrate. Furthermore, histopathological examinations showed significant adverse deleterious changes in the structure of liver tissue due to exposure to γ-radiation, while treatment with MA maintains the cellular structure of the liver without the appearance of any changes. Biochemical data came to agree with the histopathological observations. There are no published reports of the radioprotective role of Medemia argun in rats. Our results showed that MA can be used during radiotherapy as a natural therapeutic drug due to its valuable nutritional benefits, safe, nature and low cost.

Glutathione production by Saccharomyces cerevisiae: current state and perspectives

Glutathione (L-γ-glutamyl-cysteinyl-glycine, GSH) is a tripeptide synthesized through consecutive enzymatic reactions. Among its several metabolic functions in cells, the main one is the potential to act as an endogenous antioxidant agent. GSH has been the focus of numerous studies not only due to its role in the redox status of biological systems but also due to its biotechnological characteristics. GSH is usually obtained by fermentation and shows a variety of applications by the pharmaceutical and food industry. Therefore, the search for new strategies to improve the production of GSH during fermentation is crucial. This mini review brings together recent papers regarding the principal parameters of the biotechnological production of GSH by Saccharomyces cerevisiae. In this context, aspects, such as the medium composition (amino acids, alternative raw materials) and the use of technological approaches (control of osmotic and pressure conditions, magnetic field (MF) application, fed-batch process) were considered, along with genetic engineering knowledge, trends, and challenges in viable GSH production. KEY POINTS: • Saccharomyces cerevisiae has shown potential for glutathione production. • Improved technological approaches increases glutathione production. • Genetic engineering in Saccharomyces cerevisiae improves glutathione production.

Single-Atom Fe-Anchored Nano-Diamond With Enhanced Dual-Enzyme Mimicking Performance for H2O2 and Glutathione Detection

Glutathione (GSH) is an important antioxidant and free radical scavenger that converts harmful toxins into harmless substances and excretes them out of the body. In the present study, we successfully prepared single-atom iron oxide-nanoparticle (Fe-NP)-modified nanodiamonds (NDs) named Fe-NDs via a one-pot in situ reduction method. This nanozyme functionally mimics two major enzymes, namely, peroxidase and oxidase. Accordingly, a colorimetric sensing platform was designed to detect hydrogen peroxide (H₂O₂) and GSH. Owing to their peroxidase-like activity, Fe-NDs can oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue with sufficient linearity at H₂O₂ concentrations of 1-60 μM and with a detection limit of 0.3 μM. Furthermore, using different concentrations of GSH, oxidized TMB can be reduced to TMB, and the color change from blue to nearly colorless can be observed by the naked eye (linear range, 1-25 μM; detection limit, 0.072 μM). The established colorimetric method based on oxidase-like activity can be successfully used to detect reduced GSH in tablets and injections with good selectivity and high sensitivity. The results of this study exhibited reliable consistency with the detection results obtained using high-performance liquid chromatography (HPLC). Therefore, the Fe-NDs colorimetric sensor designed in this study offers adequate accuracy and sensitivity.

Hierarchical flower-like manganese oxide/polystyrene with enhanced oxidase-mimicking performance for sensitive colorimetric detection of glutathione

Glutathione (GSH) is an important antioxidant and free radical scavenger that converts harmful toxins into harmless substances and excretes them out of the body. In this paper, 3D hierarchical flower-like nanozyme named MnO₂/PS (polystyrene) was successfully prepared by template method for the first time. After the systematical studies, MnO₂/PS nanozyme was evaluated to possess favorable oxidase activity and direct 3,3',5,5'-tetramethylbenzidine (TMB) catalytic ability in the near-neutral environment at room temperature. With the addition of different concentrations of GSH, oxidized TMB can be reduced to TMB with the whole process from blue to nearly colorless be observed by naked eyes. In addition, there is a good linear relationship in the range 1-50 μM and a detection limit of 0.08 μM. The method proposed can be successfully applied to the detection of reduced GSH in tablets and injections with good selectivity and high sensitivity. The analysis results exhibited good consistency with the results obtained by HPLC.

Synergistic Combination of Facile Thiol-Maleimide Derivatization and Supramolecular Solvent-Based Microextraction for UHPLC-HRMS Analysis of Glutathione in Biofluids

Glutathione (GSH) is the most abundant non-protein thiol in biofluids, enabling diverse physiological functions. Among the proposed methods for GSH detection, ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution mass spectrometry (HRMS) has the advantages of high sensitivity and efficiency. In this study, a novel analytical method was developed for the determination of GSH using supramolecular solvent (SUPRAS)-based dispersive liquid–liquid microextraction (DLLME) and UHPLC–HRMS. N-Laurylmaleimide was dissolved in tetrahydrofuran, which served three functions: 1) precipitate the proteins present in the biofluid sample, 2) provide a reaction environment for derivatization, and 3) enable the use of SUPRAS as the dispersing agent. Critical parameters were optimized based on single factor testing and response surface methodology. The established method was validated in terms of linearity, accuracy, precision, and successful quantitative analysis of GSH in saliva, urine, and plasma samples. Experimental results showed that SUPRAS as an extraction solvent was particularly suitable for the extraction of GSH from complex matrices. The current study provides a useful tool for accurate measurements of GSH concentrations, which could potentially be used for clinical diagnostics.

“Turn on” Fluorescence Sensor of Glutathione Based on Inner Filter Effect of Co-Doped Carbon Dot/Gold Nanoparticle Composites

Glutathione (GSH) is a thiol that plays a significant role in nutrient metabolism, antioxidant defense and the regulation of cellular events. GSH deficiency is related to variety of diseases, so it is useful to develop novel approaches for GSH evaluation and detection. In this study we used nitrogen and phosphorus co-doped carbon dot-gold nanoparticle (NPCD–AuNP) composites to fabricate a simple and selective fluorescence sensor for GSH detection. We employed the reductant potential of the nitrogen and phosphorus co-doped carbon dots (NPCDs) themselves to form AuNPs, and subsequently NPCD–AuNP composites from Au3+. The composites were characterized by using a range of spectroscopic and electron microscopic techniques, including electrophoretic light scattering and X-ray diffraction. The overlap of the fluorescence emission spectrum of NPCDs and the absorption spectrum of AuNPs resulted in an effective inner filter effect (IFE) in the composite material, leading to a quenching of the fluorescence intensity. In the presence of GSH, the fluorescence intensity of the composite was recovered, which increased proportionally to increasing the GSH concentration. In addition, our GSH sensing method showed good selectivity and sensing potential in human serum with a limit of detection of 0.1 µM and acceptable results.

Comparison of three methods for in vivo quantification of glutathione in tissues of hypertensive rats

Glutathione (γ-L-glutamyl-L-cysteinyl-glycine, GSH) is a tripeptide that is part of the antioxidant defense system and contributes to numerous redox-regulatory processes. In vivo, reduced GSH and oxidized glutathione disulfide (GSSG) are present in redox equilibrium and their ratio provides important information on the cellular redox state. Here, we compared three different methods for in vivo quantification of glutathione in tissues of hypertensive rats, an accepted animal model of oxidative stress. In the present study, we used hypertensive rats (infusion of 1 mg/kg/d angiotensin-II for 7 days) to determine the levels of reduced GSH and/or GSH/GSSG ratios in different tissue samples. We used an HPLC-based method with direct electrochemical detection (HPLC/ECD) and compared it with Ellman's reagent (DTNB) dependent derivatization of reduced GSH to the GS-NTB adduct and free NTB (UV/Vis HPLC) as well as with a commercial GSH/GSSG assay (Oxiselect). Whereas all three methods indicated overall a decreased redox state in hypertensive rats, the assays based on HPLC/ECD and DTNB derivatization provided the most significant differences. We applied a direct, fast and sensitive method for electrochemical GSH detection in tissues from hypertensive animals, and confirmed its reliability for in vivo measurements by head-to-head comparison with two other established assays. The HPLC/ECD but not DTNB and Oxiselect assays yielded quantitative GSH data but all three assays reflected nicely the qualitative redox changes and functional impairment in hypertensive rats. However, especially our GSH/GSSG values are lower than reported by others pointing to problems in the work-up protocol.

Peroxidase catalytic activity of carbon nanoparticles for glutathione detection

Peroxidases are present widely in microorganisms and plants, and catalyze many reactions. However, the activity of natural peroxidases is susceptible to external conditions. We prepared carbon nanoparticles (CNPs) using an environmentally friendly and simple method. These CNPs were demonstrated to possess intrinsic peroxidase-like activity. CNPs could catalyze the reaction of a peroxidase substrate, 3,3,5,5-tetramethylbenzidine (TMB), in the presence of H₂O₂ to produce a blue solution at 652 nm. CNPs exhibited higher peroxidase activity than that of other carbon-based nanomaterials. Moreover, CNPs retained their high peroxidase activity after being reused several times. Glutathione (GSH) can change the blue color of oxidized TMB into a colorless hue at 652 nm. Based on this fact, qualitative and quantitative approaches were employed to detect GSH using a colorimetric method. This method showed a broad detection range (2.5–50 μM) with a limit of detection of 0.26 μM. This method was shown to be accurate for GSH detection in a cell culture medium compared with that using a commercial assay kit. Our findings could facilitate application of CNPs in biomedical areas.

Peroxidases are present widely in microorganisms and plants, and catalyze many reactions.

Evaluating the Anti-Inflammatory and Antioxidant Effects of Broccoli Treated with High Hydrostatic Pressure in Cell Models

Isothiocyanates (ITCs) are important functional components of cruciferous vegetables. The principal isothiocyanate molecule in broccoli is sulforaphane (SFN), followed by erucin (ERN). They are sensitive to changes in temperature, especially high temperature environments where they are prone to degradation. The present study investigates the effects of high hydrostatic pressure on isothiocyanate content, myrosinase activity, and other functional components of broccoli, and evaluates its anti-inflammatory and antioxidant effects. Broccoli samples were treated with different pressures and for varying treatment times; 15 min at 400 MPa generated the highest amounts of isothiocyanates. The content of flavonoids and vitamin C were not affected by the high-pressure processing strategy, whereas total phenolic content (TPC) exhibited an increasing tendency with increasing pressure, indicating that high-pressure processing effectively prevents the loss of the heat-sensitive components and enhances the nutritional content. The activity of myrosinase (MYR) increased after high-pressure processing, indicating that the increase in isothiocyanate content is related to the stimulation of myrosinase activity by high-pressure processing. In other key enzymes, the ascorbate peroxidase (APX) activity was unaffected by high pressure, whereas peroxidase (POD) and polyphenol oxidase (PPO) activity exhibited a 1.54-fold increase after high-pressure processing, indicating that high pressures can effectively destroy oxidases and maintain food quality. With regards to efficacy evaluation, NO production was inhibited and the expression levels of inducible nitric oxide synthase (iNOS) and Cyclooxygenase-2 (COX-2) were decreased in broccoli treated with high pressures, whereas the cell viability remained unaffected. The efficacy was more significant when the concentration of SFN was 60 mg·mL-1. In addition, at 10 mg·mL-1 SFN, the reduced/oxidized glutathione (GSH/GSSG) ratio in inflammatory macrophages increased from 5.99 to 9.41. In conclusion, high-pressure processing can increase the isothiocyanate content in broccoli, and has anti-inflammatory and anti-oxidant effects in cell-based evaluation strategies, providing a potential treatment strategy for raw materials or additives used in healthy foods.

Optimized Protocol for the In Situ Derivatization of Glutathione with N-Ethylmaleimide in Cultured Cells and the Simultaneous Determination of Glutathione/Glutathione Disulfide Ratio by HPLC-UV-QTOF-MS

Glutathione (GSH) and glutathione disulfide (GSSG) are commonly used to assess the oxidative status of a biological system. Various protocols are available for the analysis of GSH and GSSG in biomedical specimens. In this study, we present an optimized protocol for the in situ derivatization of GSH with N-ethylmaleimide (NEM) to prevent GSH autooxidation, and thus to preserve the GSH/GSSG ratio during sample preparation. The protocol comprises the incubation of cells in NEM containing phosphate buffered saline (PBS), followed by metabolite extraction with 80% methanol. Further, to preserve the use of QTOF-MS, which may lack the linear dynamic range required for the simultaneous quantification of GSH and GSSG in non-targeted metabolomics, we combined liquid chromatographic separation with the online monitoring of UV absorbance of GS-NEM at 210 nm and the detection of GSSG and its corresponding stable isotope-labeled internal standard by QTOF-MS operated with a 10 Da Q1 window. The limit of detection (LOD) for GS-NEM was 7.81 µM and the linear range extended from 15.63 µM to 1000 µM with a squared correlation coefficient R² of 0.9997. The LOD for GSSG was 0.001 µM, and the lower limit of quantification (LLOQ) was 0.01 µM, with the linear (R² = 0.9994) range extending up to 10 µM. The method showed high repeatability with intra-run and inter-run coefficients of variation of 3.48% and 2.51% for GS-NEM, and 3.11% and 3.66% for GSSG, respectively. Mean recoveries of three different spike-in levels (low, medium, high) of GSSG and GS-NEM were above 92%. Finally, the method was applied to the determination of changes in the GSH/GSSG ratio either in response to oxidative stress in cells lacking one or both monocarboxylate transporters MCT1 and MCT4, or in adaptation to the NADPH (nicotinamide adenine dinucleotide phosphate) consuming production of D-2-hydroxyglutarate in cells carrying mutations in the isocitrate dehydrogenase genes IDH1 and IDH2.

Addressing Glutathione Redox Status in Clinical Samples by Two-Step Alkylation with N-ethylmaleimide Isotopologues

Determination of the ratio of reduced to oxidized glutathione is of profound clinical interest in assessing the oxidative status of tissues and body fluids. However, this ratio is not yet a routine clinical parameter due to the analytically challenging interconversion of reduced (free) glutathione to oxidized (bound) glutathione. We aimed to facilitate this ratio determination in order to aid its incorporation as a routine clinical parameter. To this end, we developed a simple derivatization route that yields different isotopologues of N-ethylmaleimide alkylated glutathione from reduced and oxidized glutathione (after its chemical reduction) for mass spectrometric analysis. A third isotopologue can be used as isotopic standard for simultaneous absolute quantification. As all isotopologues have similar chromatographic properties, matrix effects arising from different sample origins can only impact method sensitivity but not quantification accuracy. Robustness, simplified data analysis, cost effectiveness by one common standard, and highly improved mass spectrometric sensitivity by conversion of oxidized glutathione to an alkylated glutathione isotopologue are the main advantages of our approach. We present a method fully optimized for blood, plasma, serum, cell, and tissue samples. In addition, we propose production of N-ethylmaleimide customized blood collection tubes to even further facilitate the analysis in a clinical setting.

The evaluation of glutathione concentration in whole blood of Holstein dairy calves

The aim of this study was to evaluate the concentrations of total (T-GSH), oxidized (GSSG) and reduced glutathione (GSH) in blood of clinically healthy calves, to assess the effect of sex and age together with the type of feeding on its concentrations, and to assess the relationships between glutathione and metabolic indices. A total of 117 Holstein calves at the age of 1 day to 6 months were divided according to age and together with the type of feeding into 4 groups: colostrum and transition milk (n = 20), native milk (n = 39), milk replacer (n = 29) and total mixed ration (n = 29). Blood serum was used for the assessment of the metabolic profile of calves. The concentrations of individual forms of glutathione (mean ± SEM) were as follows: T-GSH: 789.1 ± 19.4 µmol/l, GSSG: 54.2 ± 4.3 µmol/l, GSH: 681.6 ± 15.3 µmol/l, and GSH/GSSG: 41.1 ± 5.9, with the coefficients of variability of 26.6%, 85.3%, 24.3% and 157.4%, respectively. Age and the type of feeding affected GSSG (P≤ 0.01) and GSH/GSSG (P≤ 0.01). The relationships between glutathione and biochemical parameters were mostly weak. T-GSH correlated with creatinine (P≤ 0.05) and chlorides (P≤ 0.05); GSSG correlated with albumin (P≤ 0.01), creatinine (P≤ 0.01), cholesterol (P≤ 0.05), aspartate aminotransferase (P≤ 0.01), alanine aminotransferase (P≤ 0.01), gamma-glutamyltransferase (P≤ 0.05) and calcium (P≤ 0.05); GSH/GSSG ratio correlated with creatinine (P≤ 0.01), cholesterol (P≤ 0.05), aspartate aminotransferase (P≤ 0.05), gamma-glutamyltransferase (P≤ 0.01) and calcium (P≤ 0.05). The evaluation of individual forms of glutathione helps in estimation of redox status in healthy animals and their monitoring can detect the stress extent.

Identification and characterization of reaction products of 5-hydroxytryptamine with methylglyoxal and glyoxal by liquid chromatography/tandem mass spectrometry

RATIONALE

Methylglyoxal (MGO) and glyoxal (GO) are known to be at high levels in humans with diabetes. They react with amine-containing proteins and amino acids to form advanced glycation end products, however, their reactivity with other amine-containing metabolites, such as neurotransmitters, has not been explored. In this study, we aimed at studying the reactivity of 5-hydroxytryptamine (5-HT) with MGO or GO, which may alter the metabolic function of 5-HT.

METHODS

Stock solutions of 5-HT, MGO and GO were made in PBS buffer at pH 7.4 and 5-HT was incubated with MGO or GO at different concentrations. The reactions were also performed at physiological concentrations. The reaction mixtures collected at different incubation times were analyzed by direct ESI-HRMS, LC/MS and LC/MS/MS to detect/characterize the products. Agilent 6545 Q-TOF and Agilent 6420 triple quadrupole mass spectrometers were used for the study, and LC separations were performed on a C18 column.

RESULTS

The direct ESI-HRMS data of the reaction mixtures showed formation of three and four reaction products when 5-HT was reacted with MGO and GO, respectively. All the products showed dominant [M + H]⁺ ions. The products were characterized by HRMS, LC/MS/MS and literature reports on similar compounds. The products can easily be identified by LC/MS based on the accurate mass values together with retention time information. The MS/MS of the reaction products showed structure-indicative fragment ions.

CONCLUSIONS

5-HT reacts with one or two MGO/GO to form a set of reaction products. The reaction between 5-HT and MGO or GO was faster at higher concentrations of MGO/GO (<10 min), and the same products were found even at physiological concentrations (<48 h). The LC/MS/MS (SRM) method can be used to screen the reaction products when present at low levels.

Protective effects of timosaponin BII on oxidative stress damage in PC12 cells based on metabolomics

Peroxide and oxygen free radicals are some of the causes of oxidative stress in brain tissue, and could lead to the change of brain structure and function. In addition, oxidative damage is one of the most important causes of the aging of the vast majority of tissues. The aim of this study is to investigate the protective effect of timosaponin BII on oxidative stress damage of PC12 induced by H₂ O₂ using metabolomics based on the UHPLC-Q-TOF-MS technique. Partial least-squares discriminant analysis method was used to identify 35 metabolites as decisive marker compounds in a preliminary interpretation of the mechanism of the antioxidative effect of timosaponin BII. The majority of these metabolites are involved in the glutathione metabolism, amino acid metabolism, sphingolipid and glycerophospholipid metabolism. Our results suggest that timosaponin BII demonstrates systematic antioxidant effects in the PC12 oxidative damage cell model via the regulation of multiple metabolic pathways. These findings provide insight into the pathophysiological mechanisms underlying oxidative stress damage and suggest innovative and effective treatments for this disorder, providing a reliable basis for the development of novel therapeutic target in timosaponin BII treatment of oxidative stress.

Fluorescence detection of glutathione and oxidized glutathione in blood with a NIR-excitable cyanine probe

Cyanine has been widely utilized as a near infrared (NIR) fluorophore for detection of glutathione (GSH). However, the excitation of most of the reported cyanine-based probes was less than 800 nm, which inevitably induce biological background absorption and lower the sensitivity, limiting their use for detection of GSH in blood samples. To address this issue, here, a heptamethine cyanine probe (DNIR), with a NIR excitation wavelength at 804 nm and a NIR emission wavelength at 832 nm, is employed for the detection of GSH and its oxidized form (GSSG) in blood. The probe displays excellent selectivity for GSH over GSSG and other amino acids, and rapid response to GSH, in particular a good property for indirect detection of GSSG in the presence of enzyme glutathione reductase and the reducing agent nicotinamideadenine dinucleotide phosphate, without further separation prior to fluorescent measurement. To the best of our knowledge, this is the first attempt to explore NIR fluorescent approach for the simultaneous assay of GSH and GSSG in blood. As such, we expect that our fluorescence sensors with both NIR excitation and NIR emission make this strategy suitable for the application in complex physiological systems.

Assessment of glutathione/glutathione disulphide ratio and S-glutathionylated proteins in human blood, solid tissues, and cultured cells

Glutathione (GSH) is the major non-protein thiol in humans and other mammals, which is present in millimolar concentrations within cells, but at much lower concentrations in the blood plasma. GSH and GSH-related enzymes act both to prevent oxidative damage and to detoxify electrophiles. Under oxidative stress, two GSH molecules become linked by a disulphide bridge to form glutathione disulphide (GSSG). Therefore, assessment of the GSH/GSSG ratio may provide an estimation of cellular redox metabolism. Current evidence resulting from studies in human blood, solid tissues, and cultured cells suggests that GSH also plays a prominent role in protein redox regulation via S -glutathionylation, i.e., the conjugation of GSH to reactive protein cysteine residues. A number of methodologies that enable quantitative analysis of GSH/GSSG ratio and S-glutathionylated proteins (PSSG), as well as identification and visualization of PSSG in tissue sections or cultured cells are currently available. Here, we have considered the main methodologies applied for GSH, GSSG and PSSG detection in biological samples. This review paper provides an up-to-date critical overview of the application of the most relevant analytical, morphological, and proteomics approaches to detect and analyse GSH, GSSG and PSSG in mammalian samples as well as discusses their current limitations.

Oxidative stress mediated toxicity of TiO2 nanoparticles after a concentration and time dependent exposure of the aquatic macrophyte Hydrilla verticillata

The present study focused on oxidative stress effects in the aquatic macrophyte Hydrilla verticillata after exposure to titanium dioxide nanoparticles (TiO₂-NPs). Experiments were conducted with different TiO₂-NPs and concentrations (0.1 mg/L and 10 mg/L) in a time-dependent manner (0 h, 24 h, 48 h, 96 h, 168 h). To assess various levels of the oxidative stress response in H. verticillata, the level of hydrogen peroxide (H₂O₂), the ratio of reduced to oxidized glutathione (GSH/GSSG), and activities of the antioxidative enzymes catalase (CAT) and glutathione reductase (GR) were evaluated. Study results imply oxidative stress effects after TiO₂-NP exposure as adaptations in plant metabolism became apparent to counteract increased ROS formation. All TiO₂-NPs caused elevated activities of the enzymes CAT and GR. Moreover, decreased ratios of GSH/GSSG indicated an activation of GSH-dependent pathways counteracting ROS formation. Plants exposed to a bulk-sized control revealed a size-dependent influence on the antioxidative stress response. As H₂O₂ level increases were solely detected after exposure to 10 mg/L TiO₂-NPs and nano-exposed plants showed normalization in its antioxidative stress response after 168h of exposure, it can be suggested that macrophytes are able to cope with currently predicted low-level exposures to TiO₂-NPs.

Metabolomic signature of brain cancer

Despite advances in surgery and adjuvant therapy, brain tumors represent one of the leading causes of cancer-related mortality and morbidity in both adults and children. Gliomas constitute about 60% of all cerebral tumors, showing varying degrees of malignancy. They are difficult to treat due to dismal prognosis and limited therapeutics. Metabolomics is the untargeted and targeted analyses of endogenous and exogenous small molecules, which charact erizes the phenotype of an individual. This emerging "omics" science provides functional readouts of cellular activity that contribute greatly to the understanding of cancer biology including brain tumor biology. Metabolites are highly informative as a direct signature of biochemical activity; therefore, metabolite profiling has become a promising approach for clinical diagnostics and prognostics. The metabolic alterations are well-recognized as one of the key hallmarks in monitoring disease progression, therapy, and revealing new molecular targets for effective therapeutic intervention. Taking advantage of the latest high-throughput analytical technologies, that is, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS), metabolomics is now a promising field for precision medicine and drug discovery. In the present report, we review the application of metabolomics and in vivo metabolic profiling in the context of adult gliomas and paediatric brain tumors. Analytical platforms such as high-resolution (HR) NMR, in vivo magnetic resonance spectroscopic imaging and high- and low-resolution MS are discussed. Moreover, the relevance of metabolic studies in the development of new therapeutic strategies for treatment of gliomas are reviewed.

Role of thiosulfate in hydrogen sulfide-dependent redox signaling in endothelial cells

Recent reports have revealed that hydrogen sulfide (H₂S) exerts critical actions to promote cardiovascular homeostasis and health. Thiosulfate is one of the products formed during oxidative H₂S metabolism, and thiosulfate has been used extensively and safely to treat calcific uremic arteriopathy in dialysis patients. Yet despite its significance, fundamental questions regarding how thiosulfate and H₂S interact during redox signaling remain unanswered. In the present study, we examined the effect of exogenous thiosulfate on hypoxia-induced H₂S metabolite bioavailability in human umbilical vein endothelial cells (HUVECs). Under hypoxic conditions, we observed a decrease of GSH and GSSG levels in HUVECs at 0.5 and 4 h as well as decreased free H₂S and acid-labile sulfide and increased bound sulfide at all time points. Treatment with exogenous thiosulfate significantly decreased the ratio of GSH/GSSG to total sulfide of HUVECs under 0.5 h of hypoxia but significantly increased this ratio in HUVECs under 4 h of hypoxia. These responses reveal that thiosulfate has different effects at low and high doses and under different O₂ tensions. In addition, treatment with thiosulfate also diminished VEGF-induced cystathionine-γ-lyase expression and reduced VEGF-induced HUVEC proliferation under both normoxic and hypoxic conditions. These results indicate that thiosulfate can modulate H₂S metabolites and signaling under various culture conditions that impact angiogenic activity. Thus, thiosulfate may serve as a unique sulfide donor to modulate endothelial responses under pathophysiological conditions involving angiogenesis.NEW & NOTEWORTHY This report provides new evidence that different levels of exogenous thiosulfate dynamically change discrete sulfide biochemical metabolite bioavailability in endothelial cells under normoxia or hypoxia, acting in a slow manner to modulate sulfide metabolites. Moreover, our findings also reveal that thiosulfate surprisingly inhibits VEGF-dependent endothelial cell proliferation associated with a reduction in cystathionine-γ-lyase protein levels.

Simultaneous Quantification of Amino Metabolites in Multiple Metabolic Pathways Using Ultra-High Performance Liquid Chromatography with Tandem-mass Spectrometry

Metabolites containing amino groups cover multiple pathways and play important roles in redox homeostasis and biosyntheses of proteins, nucleotides and neurotransmitters. Here, we report a new method for simultaneous quantification of 124 such metabolites. This is achieved by derivatization-assisted sensitivity enhancement with 5-aminoisoquinolyl-N-hydroxysuccinimidyl carbamate (5-AIQC) followed with comprehensive analysis using ultra-high performance liquid chromatography and electrospray ionization tandem mass spectrometry (UHPLC-MS/MS). In an one-pot manner, this quantification method enables simultaneous coverage of 20 important metabolic pathways including protein biosynthesis/degradation, biosyntheses of catecholamines, arginine and glutathione, metabolisms of homocysteine, taurine-hypotaurine etc. Compared with the reported ones, this method is capable of simultaneously quantifying thiols, disulfides and other oxidation-prone analytes in a single run and suitable for quantifying aromatic amino metabolites. This method is also much more sensitive for all tested metabolites with LODs well below 50 fmol (at sub-fmol for most tested analytes) and shows good precision for retention time and quantitation with inter-day and intra-day relative standard deviations (RSDs) below 15% and good recovery from renal cancer tissue, rat urine and plasma. The method was further applied to quantify the amino metabolites in silkworm hemolymph from multiple developmental stages showing its applicability in metabolomics and perhaps some clinical chemistry studies.

Alpha-Tocopherol Reduces Brain Edema and Protects Blood-Brain Barrier Integrity following Focal Cerebral Ischemia in Rats

OBJECTIVE

This study was conducted to examine the neuroprotective effects of α-tocopherol against edema formation and disruption of the blood-brain barrier (BBB) following transient focal cerebral ischemia in rats.

MATERIALS AND METHODS

Ninety-six male Sprague-Dawley rats were divided into 3 major groups (n = 32 in each), namely the sham, and control and α-tocopherol-treated (30 mg/kg) ischemic groups. Transient focal cerebral ischemia (90 min) was induced by occlusion of the left middle cerebral artery. At the end of the 24-hour reperfusion period, the animals were randomly selected and used for 4 investigations (n = 8) in each of the 3 main groups: (a) assessment of neurological score and measurement of infarct size, (b) detection of brain edema formation by the wet/dry method, (c) evaluation of BBB permeability using the Evans blue (EB) extravasation technique, and (d) assessment of the malondialdehyde (MDA) and reduced glutathione (GSH) concentrations using high-performance liquid chromatography methods.

RESULTS

Induction of cerebral ischemia in the control group produced extensive brain edema (brain water content 83.8 ± 0.11%) and EB leakage into brain parenchyma (14.58 ± 1.29 µg/g) in conjunction with reduced GSH and elevated MDA levels (5.86 ± 0.31 mmol/mg and 63.57 ± 5.42 nmol/mg, respectively). Treatment with α-tocopherol significantly lowered brain edema formation and reduced EB leakage compared with the control group (p < 0.001, 80.1 ± 0.32% and 6.66 ± 0.87 µg/g, respectively). Meanwhile, treatment with α-tocopherol retained tissue GSH levels and led to a lower MDA level (p < 0.01, 10.17 ± 0.83 mmol/mg, and p < 0.001, 26.84 ± 4.79 nmol/mg, respectively).

CONCLUSION

Treatment with α-tocopherol reduced ischemic edema formation and produced protective effects on BBB function following ischemic stroke occurrence. This effect could be through increasing antioxidant activity.

Oxidative stress response of the aquatic macrophyte Hydrilla verticillata exposed to TiO2 nanoparticles

The present study investigated the effects of titanium dioxide nanoparticles (TiO₂ -NPs) on the oxidative stress response in Hydrilla verticillata. Macrophytes were exposed to different concentrations of TiO₂ -NPs (0 mg/L, 0.01 mg/L, 0.1 mg/L, 1 mg/L, and 10 mg/L) for 24 h, based on currently predicted levels of nano-TiO₂ in surface waters. In addition, TiO₂ -NPs with varying crystalline status were used to assess the potential influence of crystalline phases on oxidative stress responses. The level of hydrogen peroxide (H₂ O₂ ), reduced and oxidized glutathione (GSH and GSSG), and activities of the antioxidative enzymes peroxidase (POD), catalase (CAT), and glutathione reductase (GR) were measured and compared with a bulk counterpart. Although POD was not considered to be active, the results imply an activation of the enzymatic defense system, because increased CAT and GR activities were observed. Exposure to bulk TiO₂ revealed lower enzyme activities at all exposure concentrations, suggesting a nano-specific influence on the antioxidative defense mechanisms in H. verticillata. Moreover, all TiO₂ -NP concentrations resulted in a decreased GSH/GSSG ratio, indicating high GSH-dependent metabolic activity to protect against the destructive effects of reactive oxygen species (ROS) generated during nano-TiO₂ exposure. As the level of H₂ O₂ was solely elevated after exposure to 10 mg/L of P25, it appears plausible that the adaptive metabolic mechanisms of H. verticillata are able to cope with environmentally relevant concentrations of TiO₂ -NPs. Environ Toxicol Chem 2016;35:2859-2866. © 2016 SETAC.

Simultaneous assessment of endogenous thiol compounds by LC-MS/MS

Biological thiol compounds are very important molecules that participate in various physiological events. Alteration in levels of endogenous thiols has been suggested as a biomarker of early stage of pathological changes. We reported a chemical derivatization- and LC-MS/MS-based approach to simultaneously determine thiol compounds including glutathione (GSH), cysteine (Cys), N-acetyl cysteine (NAC), homocysteine (Hcy), and cysteinylglycine (CysGly) in biological samples. Thiol-containing samples were derivatized with monobromobimane (mBrB) at room temperature, followed by LC-MS/MS analysis. Assessment of the analytes with baseline separation was completed within 10min, using a gradient elution on a C18 reversed-phase column. Excellent linearity was observed for all analytes over their concentration ranges of 1-400μM. The lowest limits of detection (S/N=3) in a range from 0.31fmol (for NAC) to 4.98fmol (for CysGly) were achieved. The results indicate that this approach was sensitive, selective, and well suited for high-throughput quantitative determination of the biological thiols.

Erythrocyte glutathione transferase: a general probe for chemical contaminations in mammals

Glutathione transferases (GSTs) are enzymes devoted to the protection of cells against many different toxins. In erythrocytes, the isoenzyme (e-GST) mainly present is GSTP1-1, which is overexpressed in humans in case of increased blood toxicity, as it occurs in nephrophatic patients or in healthy subjects living in polluted areas. The present study explores the possibility that e-GST may be used as an innovative and highly sensitive biomarker of blood toxicity also for other mammals. All distinct e-GSTs from humans, Bos taurus (cow), Sus scrofa (pig), Capra hircus (goat), Equus caballus (horse), Equus asinus (donkey) and Ovis aries (sheep), show very similar amino acid sequences, identical kinetics and stability properties. Reference values for e-GST in all these mammals reared in controlled farms span from 3.5±0.2 U/g_Hb in the pig to 17.0±0.9 U/g_Hb in goat; such activity levels can easily be determined with high precision using only a few microliters of whole blood and a simple spectrophotometric assay. Possibly disturbing factors have been examined to avoid artifact determinations. This study provides the basis for future screening studies to verify if animals have been exposed to toxicologic insults. Preliminary data on cows reared in polluted areas show increased expression of e-GST, which parallels the results found for humans.

Immediate stabilization of human blood for delayed quantification of endogenous thiols and disulfides

Endogenous thiols undergo rapid and reversible oxidation to disulfides when exposed to oxidants and are, therefore, suitable biomarkers of oxidative stress. However, accurate analysis of thiols in blood is frequently compromised by their artifactual oxidation during sample manipulation, which spuriously elevates the disulfide levels. Here, we describe a validated pre-analytical procedure that prevents both artifactual oxidation of thiols during sample manipulation and their oxidative decay for months in biosamples that are stored at -80°C. Addition of N-ethylmaleimide to blood samples from healthy donors was used to stabilize whole blood, red blood cells, platelets and plasma disulfides, whereas addition of citrate buffer followed by dilution of plasma with H2O was used to stabilize plasma thiols. The concentrations of thiols and disulfides were stable in all biosamples for at least 6 months when analyzed by UV/Vis HPLC at regular intervals. Only 3 ml of blood were needed to perform the analyses of thiols and disulfides in the different blood fractions. This pre-analytical procedure is reliable for use in both animal and human prospective studies. Its ease of implementation makes the method suitable for application to multicenter studies where blood samples are collected by different sites and personnel and are shipped to specific specialized laboratories.

Halogen mediated voltammetric oxidation of biological thiols and disulfides

The electrochemical generation of the halides, bromine and iodine, in the presence of biologically relevant organosulfur is demonstrated to result in an analytically useful response. In the case of the iodide/iodine redox couple only the thiol causes an increase in the electrochemical oxidative peak current. Conversely, the formed bromine may catalytically oxidise both thiols and disulfides. Hence, the differing reactivities of the halide ions readily allow discrimination between the closely related thiol and disulphide species. For all of the organosulfur species investigated (glutathione, cysteine and homocysteine) micromolar limits of detection are attainable. In the case of the bromine mediated oxidation this sensitivity at least partially arises from the large catalytic amplification, such that, for each disulphide molecule up to ten electrons may be transferred. Ultimately this bromine oxidation results in the formation of the sulfonate species. For the iodine mediated oxidation of the thiols the oxidation proceeds no further than to the formation of the associated disulfide.

The ratio of oxidized and reduced forms of selected antioxidants as a possible marker of oxidative stress in humans

Oxidative stress is an imbalance between reactive oxygen species exposure and the ability of organisms to detoxify the reactive intermediates and to repair the oxidative damage of biologically important molecules. Many clinical studies of oxidative stress unfortunately provide conflicting and contradictory results. The ability of antioxidant systems to adequately respond to oxidative stress can be used in laboratory diagnostics. In the present review, methods using the ratio of reduced and oxidized forms of uric acid, ascorbic acid, glutathione and coenzyme Q10 as suitable indicators of oxidative stress are discussed. From the mentioned publications it is evident that suitable sample preparation prior to analysis is crucial.

Straightforward method to quantify GSH, GSSG, GRP, and hydroxycinnamic acids in wines by UPLC-MRM-MS

A novel, robust and fast ultrahigh performance liquid chromatography–multiple reaction monitoring mass spectrometry method has been developed for the simultaneous quantification of reduced glutathione (GSH), oxidized glutathione (GSSG), grape reaction product (GRP) and hydroxycinnamic acids in wine. The method was evaluated in terms of linearity, precision, accuracy, limits of detection and quantification, stability and matrix effects. Quantitative recovery (74–110%) and satisfactory interday precision (RSD <14%) were achieved for all target compounds. No significant matrix-dependent suppression/enhancement effects were observed. To demonstrate the method applicability, white, rosé and red wine samples with different levels of oxidation were analyzed. Levels of GSH and GSSG varied from 1.63 to 9.91 mg/L and from 0.32 to 3.33 mg/L, respectively. Levels of caftaric acid ranged from 2.57 to 293.07 mg/L. Levels of GRP were between 28.35 and 114.20 mg/L.

Enalapril attenuates ischaemic brain oedema and protects the blood-brain barrier in rats via an anti-oxidant action

1. In the present study, we investigated the effects of postischaemic angiotensin-converting enzyme (ACE) inhibition with enalapril on vasogenic oedema formation and blood-brain barrier (BBB) integrity following transient focal cerebral ischaemia in rats. 2. Cerebral ischaemia was induced by 60 min occlusion of the right middle cerebral artery, followed by 24 h reperfusion. Vehicle and a non-hypotensive dose of enalapril (0.03 mg/kg) were administered at the beginning of the reperfusion period. A neurological deficit score (NDS) was determined for all rats at the end of the reperfusion period. Then, brain oedema formation was investigated using the wet-dry weight method and BBB permeability was evaluated on the basis of extravasation of Evans blue (EB) dye. In addition, oxidative stress was assessed by measuring reduced glutathione (GSH) and malondialdehyde (MDA) in brain homogenates. 3. Inhibition of ACE by enalapril significantly reduced NDS and decreased brain oedema formation (P < 0.05 for both). Disruption of the BBB following ischaemia resulted in considerable leakage of EB dye into the brain parenchyma of the ipsilateral hemispheres of vehicle-treated rats. Enalapril significantly (P < 0.05) decreased EB extravasation into the lesioned hemisphere. Enalapril also augmented anti-oxidant activity in ischaemic brain tissue by increasing GSH concentrations and significantly (P < 0.05) attenuating the increased MDA levels in response to ischaemia. 4. In conclusion, inhibition of ACE with a non-hypotensive dose of enalapril may protect BBB function and attenuate oedema formation via anti-oxidant actions.

A sensitive method for the analysis of glutathione in porcine hepatocytes

BACKGROUND

Reduced glutathione (γ-glutamylcysteinylglycine), GSH, is essential when protecting cells from oxidative stress and also an indicator of disease risk. Reported concentrations of GSH and its oxidized form, glutathione disulfide (GSSG), varies considerably, primarily due to the instability of GSH and various analytical methods.

METHODS

We designed a sensitive method to analyze GSH and GSSG in porcine hepatocytes using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after stabilization with N-ethylmaleimide (NEM). This method includes stable isotope labeled internal standards and simple synthesis of labeled GSSG which commercial sources rarely offer. GSH and GSSG were analyzed in porcine liver biopsies giving a reference interval based on a large number of samples (26 pigs; 3 parallels).

RESULTS

The LC-MS/MS results revealed excellent linearity for both GSH and GSSG, with interday coefficient of variation (%CV) for GSH-NEM and GSSG <10 %. Accuracy for recovery tests was between 95.6% and 106.7% (n = 3) for GSH and between 92.3% and 107.7% (n = 3) for GSSG. The limits of quantification were 0.1 μM for GSH-NEM and 0.08 μM for GSSG. The mean concentration of GSH was 3.5 (95% CI = 1.5-8.1) mmol/liter and of GSSG 0.0023 (95% CI = 0.0003-0.019) mmol/liter.

CONCLUSION

For the first time GSH and GSSG are analyzed in porcine hepatocytes by LC-MS/MS yielding a reference level of GSH and GSSG. The method is reproducible in any laboratory with LC-MS/MS service and will probably be applicable in all soft tissues and cell suspensions, essentially with no modification.

Presumed and actual concentrations of reduced glutathione in preservation solutions

Reduced glutathione (GSH), an important radical scavenger, has been added to various organ preservation solutions. Because GSH oxidizes into oxidized glutathione (GSSG) and only GSH has scavenging capacity, only GSH in the solution at the time of clinical use is relevant. The concentrations of GSH (GSH(conc)) and GSSG(conc) were determined in 2 static preservation solutions--University of Wisconsin (UW) and Celsior--and in 1 machine preservation solution--Kidney Preservation Solution 1 (KPS-1). We determined the half-life (T(1/2)) of freshly added GSH. The GSH(conc) in UW and KPS-1 was 0.006 ± 0.0018 mmol/L and 0.13 ± 0.30 mmol/L, respectively. The GSH(conc) in Celsior was 2.7 ± 0.17 mmol/L. The manufacturers of these solutions reported 3 mmol/L GSH. GSSG(conc) in UW, KPS-1, and Celsior was 1.58 ± 0.61 mmol/L, 1.13 ± 0.16 mmol/L, and 0.24 ± 0.01 mmol/L, respectively. T(1/2) of GSH in UW, KPS-1, and Celsior was 18 days, 86 days, and 83 days, respectively. The actual GSH(conc) in UW and KPS-1 at the time of clinical use was substantially lower than reported by the manufacturer, owing to the relatively short T(1/2) of GSH. For Celsior, the GSH(conc) was maintained. Therefore, addition of fresh GSH to UW and KPS-1 before clinical use is recommended.

Efficacy of screening immune system function in at-risk newborns

This paper explores the introduction of a screening test to highlight impaired immune system status for newborn infants and its efficacy as a preventative clinical measure. Moreover, it is suggested that screening of the infantile immune system has the potential to highlight susceptibility to a range of infant and childhood diseases, bestowing an opportunity to introduce early intervention to reduce the incidence of these diseases. Development of the neonatal immune system is an important health issue, implicated in many childhood problems such as allergies, infection, and autoimmunity. The neonate has a limited immune system and ability to combat bacteria. Depleted levels of the tripeptide reduced glutathione (GSH) have been linked to numerous conditions and its intracellular level is acknowledged as an indicator of immune system function. Introduction of an immune system screening programme for infants is formally reviewed and assessed. Several benefits are reported in the treatment of impaired immune systems, a trial screening programme is proposed for at-risk infants to gather further evidence as to its efficacy. Infants at risk of impaired immune system function include cystic fibrosis, premature infants, and low birth weight infants. The interventions include breastfeeding, milk banks, and appropriate formula to support the immune system.