What is glutathione?
Glutathione (reduced form, GSH; L-glutathione) is a tripeptide thiol compound synthesized endogenously in cells and present at millimolar concentrations in the cytosol — making it the most abundant low-molecular-weight thiol in mammalian cells. It is catalogued under CAS number 70-18-8 with a molecular formula of C₁₀H₁₇N₃O₆S and a molecular weight of 307.32 g/mol. Glutathione is studied in research for its role as the primary substrate in the glutathione peroxidase (GPx) redox cycle, as a nucleophilic co-substrate for glutathione S-transferases in Phase II metabolism research, and as the defining variable in assays that measure cellular redox state through the GSH/GSSG ratio. The compound is supplied as a lyophilized powder for laboratory research and is intended solely for research purposes, not for human use. Ever Vital carries glutathione at 99.8% purity by HPLC.
What is the molecular structure of glutathione?
Glutathione is a linear tripeptide composed of three amino acid residues: L-glutamate, L-cysteine, and glycine. The defining structural feature is the gamma-glutamyl peptide bond linking glutamate to cysteine: rather than a standard alpha-peptide bond at the alpha-carboxyl group, glutamate is connected to cysteine through its gamma-carboxyl (side-chain carboxyl) group. This unusual linkage is what distinguishes glutathione from a conventional tripeptide and is responsible for its resistance to most intracellular peptidases. Only gamma-glutamyl transpeptidase, expressed on the outer face of certain cell membranes, can cleave this bond. The cysteine residue carries the thiol group (-SH) that is the chemically reactive site in glutathione biochemistry — this thiol can be oxidized to a disulfide with a second glutathione molecule, generating GSSG (glutathione disulfide), and reduced back by glutathione reductase in a NADPH-dependent reaction that completes the redox cycle.
How does glutathione function in the cellular redox cycle?
The glutathione redox cycle is a central mechanism for managing hydrogen peroxide and lipid hydroperoxides in cells. The cycle involves two main enzymes. Glutathione peroxidases (GPx1–8) catalyze the reduction of hydroperoxides at the expense of GSH: two molecules of GSH donate electrons to reduce one molecule of H₂O₂ to water, producing GSSG. Glutathione reductase (GR) then regenerates GSH from GSSG using NADPH as the reductant, completing the cycle and maintaining the intracellular GSH pool. This cycle is studied in cell culture using defined GSH concentrations and GPx activity assays, with GSH depletion or GSSG accumulation serving as measurable indicators of oxidative flux. Research applications include characterizing how different oxidative stressors affect cycle kinetics, identifying compounds that modulate GPx or GR activity, and determining threshold GSH concentrations at which cellular protection mechanisms are saturated in specific cell types.
What are glutathione S-transferases, and how is glutathione used in Phase II metabolism research?
Glutathione S-transferases (GSTs) are a family of cytosolic and membrane-bound enzymes that catalyze the conjugation of glutathione's thiol group to electrophilic substrates — a reaction that is the defining step in Phase II biotransformation. By attaching GSH to electrophilic compounds (including reactive metabolites, xenobiotics, and certain endogenous lipid peroxidation products), GSTs convert them into polar, water-soluble conjugates that can be further processed for cellular export. Published research uses isolated GST isoforms with defined glutathione concentrations to characterize substrate specificity and concentration-response relationships for specific electrophilic substrates. GST research has relevance across several fields including toxicology, xenobiotic metabolism, and pharmacology, where the efficiency of Phase II conjugation influences the metabolic fate of test compounds in cell models. The alpha, mu, pi, and theta GST classes are each studied for distinct substrate profiles and tissue distribution patterns.
How do researchers measure the GSH/GSSG ratio?
The ratio of reduced glutathione (GSH) to its oxidized disulfide form (GSSG) is the standard operational measure of cellular redox state in cell biology and oxidative stress research. Under homeostatic conditions, the GSH/GSSG ratio in the cytosol is maintained at approximately 100:1 or higher, meaning the reduced pool strongly predominates. Shifts in this ratio toward lower values — more GSSG relative to GSH — indicate increased oxidative flux. Measurement methods include DTNB-based spectrophotometric assays, HPLC with fluorescent derivatization, enzymatic recycling assays using glutathione reductase, and mass spectrometry for simultaneous quantification of both species. Each method requires careful sample handling because GSH auto-oxidation can alter the measured ratio during processing. Research using Ever Vital's glutathione as a reference standard in these assays requires material at consistent, high purity — 99.8% by HPLC — to ensure that measured concentrations in assay buffers accurately reflect the intended experimental conditions.
What does published research describe about glutathione and reactive oxygen species in cell models?
Published research examines glutathione in cell models primarily as the mechanistic substrate in oxidative stress responses. When cells are exposed to hydrogen peroxide, lipid hydroperoxides, or reactive nitrogen species in vitro, the GPx cycle is activated and GSH is consumed proportionally to the oxidative load. Studies measure the kinetics of GSH depletion and GSSG accumulation to characterize the cell's oxidative buffering capacity under different stress conditions and in different cell types. In models where GSH synthesis is inhibited — typically via buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase — researchers examine which downstream effects appear specifically when the GSH pool is reduced, allowing mechanistic attribution of cellular responses to the glutathione redox system. These studies frame glutathione biochemistry at the level of enzyme kinetics and cellular redox signaling, not as a proxy for clinical outcomes. Ever Vital makes no therapeutic claims regarding glutathione.
How does glutathione interact with the thioredoxin system?
The glutathione system and thioredoxin (Trx) system are the two principal cellular thiol-disulfide redox systems, and they interact both directly and through shared downstream targets. Thioredoxins are small redox proteins that reduce disulfide bonds in target proteins using their own cysteine residues, and they are regenerated by thioredoxin reductase (TrxR) using NADPH — paralleling the GR/NADPH mechanism that regenerates GSH. Under conditions where one system is inhibited or depleted, the other can partially compensate for specific redox substrates, though each system has distinct protein targets and compartment-specific roles. Research examining the cross-talk between these systems uses compounds that selectively deplete or inhibit one pathway at a time, with glutathione as a defined variable in GST- and GPx-dependent arms of the experiment. This research architecture clarifies which redox processes depend on each system and how they interact in the context of oxidative stress models. See the longevity research compound categories overview for the broader redox research landscape.
What is the relationship between glutathione and the mercapturic acid pathway?
The mercapturic acid pathway is the sequence of enzymatic reactions through which GST-derived glutathione conjugates are converted to N-acetyl-L-cysteine conjugates (mercapturic acids) for export and eventual urinary excretion in whole-organism models. Following GSH conjugation by a GST, the gamma-glutamyl group is cleaved by gamma-glutamyl transpeptidase (GGT), the glycine residue is removed by a dipeptidase, and the remaining cysteine conjugate is N-acetylated by cysteine conjugate N-acetyltransferase to produce the mercapturic acid. This pathway is studied in hepatocyte and kidney cell culture models to characterize the complete biotransformation trajectory of electrophilic test compounds, using glutathione as the initiating substrate for GST conjugation. Published research on the mercapturic acid pathway informs Phase II metabolism characterization in toxicology and xenobiotic research and relies on well-characterized, high-purity glutathione for reproducible GST activity assays.
How should glutathione be handled for research use?
Glutathione is supplied as a lyophilized powder and is stored at −20°C to maintain the integrity of the reduced thiol form. The cysteine thiol group is susceptible to air oxidation, producing GSSG over time if the compound is stored improperly or in solution. Research handling best practices include minimizing exposure to oxygen during preparation steps, working under nitrogen if the application demands strict reduced thiol concentrations, preparing solutions fresh where feasible, and aliquoting the lyophilized stock to avoid repeated opening of the primary container. Acidic conditions (pH 2–4) stabilize the reduced form in solution but may not be compatible with all assay systems. This article does not provide preparation or solution-making protocols; handling procedures are determined by the investigator according to experimental requirements. For guidance on interpreting batch-level analytical documentation, see the Ever Vital guide on reading a Certificate of Analysis.
How does Ever Vital source glutathione?
Ever Vital supplies glutathione (reduced, L-glutathione) as a research-grade compound at 99.8% purity by HPLC, with mass spectrometry identity confirmation on every batch. It is available in a 1500mg size at $70, making it one of the higher-volume compounds in the catalog — consistent with its role as a substrate consumed at meaningful quantities in GPx cycle assays, GST activity assays, and GSH/GSSG measurement experiments. A batch-specific Certificate of Analysis ships with every order as standard. Researchers can access specifications, current pricing, and documentation on the glutathione product page, or browse the full research catalog at all compounds. For researchers working across the cellular redox space, Ever Vital also carries NAD+ at 99.8% purity — the primary coenzyme for glutathione reductase's NADPH-generating upstream pathways. All material is intended for laboratory research use only and is not for human use.
This compound is a research chemical intended for laboratory and scientific research purposes only. It is not a drug, supplement, or food, and is not intended to diagnose, treat, cure, or prevent any disease. Ever Vital does not sell products intended for human use. Researchers are responsible for compliance with all applicable local, state, and federal regulations.