What Is Glutathione?
Glutathione (GSH) is a tripeptide composed of gamma-glutamic acid, cysteine, and glycine (γ-Glu-Cys-Gly). It is the most abundant low-molecular-weight thiol in mammalian cells, with intracellular concentrations typically in the millimolar range (1–10 mM). As the cell’s primary endogenous antioxidant, glutathione coordinates a broad range of redox-dependent processes and has become one of the most studied molecules in cellular biology, with research spanning oxidative stress, detoxification, immune function, and aging.
Molecular Structure and Properties
- Full name: L-gamma-glutamyl-L-cysteinylglycine
- Molecular formula: C₁₀H₁₇N₃O₆S
- Molecular weight: 307.3 Da
- Key feature: Thiol (-SH) group on the cysteine residue — the chemically active centre responsible for its antioxidant and conjugation functions
- Redox forms: GSH (reduced, active), GSSG (glutathione disulphide, oxidised)
- Regeneration: GSSG reduced back to GSH by glutathione reductase, using NADPH as the electron donor
Primary Mechanism: Reactive Oxygen Species Neutralisation
Glutathione’s primary antioxidant function involves direct and enzyme-catalysed neutralisation of reactive oxygen species (ROS) and reactive nitrogen species (RNS):
Glutathione Peroxidase (GPx) pathway:
- GPx enzymes use GSH to reduce hydrogen peroxide (H₂O₂) and organic hydroperoxides (ROOH) to water and alcohols
- 2 GSH + H₂O₂ → GSSG + 2 H₂O (GPx-catalysed)
- This is the primary route of H₂O₂ detoxification in most cell types
Direct radical scavenging:
- GSH can directly donate a hydrogen atom to free radicals, neutralising hydroxyl radicals (·OH) and superoxide (O₂·⁻)
- The resulting glutathionyl radical (GS·) reacts with another GS· to form GSSG, which is then recycled by glutathione reductase
Glutaredoxin (Grx) system:
- GSH serves as the electron donor for glutaredoxins, which reduce protein disulphide bonds and mixed disulphides — protecting protein cysteine residues from irreversible oxidation
Phase II Detoxification and Xenobiotic Conjugation
Glutathione is central to Phase II metabolic detoxification. Glutathione S-transferases (GSTs) catalyse the conjugation of GSH’s thiol group to electrophilic xenobiotics, carcinogens, and reactive metabolites, rendering them more water-soluble for excretion:
- GSH conjugation marks compounds for export via multidrug resistance proteins (MRPs) and subsequent processing to mercapturic acid derivatives for urinary excretion
- This pathway detoxifies reactive metabolites of drugs, environmental pollutants, and endogenous reactive aldehydes (4-HNE, malondialdehyde)
- GST and GSH activity is a primary focus of hepatocyte research and liver toxicology models
The GSH/GSSG Ratio as a Redox Biomarker
The ratio of reduced glutathione (GSH) to oxidised glutathione (GSSG) is one of the most widely used indicators of intracellular redox state. In healthy cells, the GSH/GSSG ratio is typically maintained above 100:1. During oxidative stress, this ratio falls as GSH is consumed and GSSG accumulates — a measurable endpoint used in oxidative stress research models and toxicology assays.
Key Research Areas
Oxidative stress models: Glutathione is the primary experimental variable in cellular oxidative stress research. GSH depletion (via buthionine sulfoximine, BSO) and exogenous GSH supplementation are standard techniques for establishing dose-response relationships between redox state and cell viability, gene expression, and signalling pathway activation.
Liver biology and hepatocyte research: The liver is the primary site of glutathione synthesis and export. GSH depletion in hepatocyte models underlies acetaminophen hepatotoxicity research and broader drug-induced liver injury (DILI) studies. GSH replacement models are used to study liver protection mechanisms.
Immune cell function: T lymphocyte activation and proliferation are dependent on adequate intracellular GSH levels. GSH depletion inhibits T cell receptor signalling and IL-2 production, making glutathione a research variable in immunology models examining lymphocyte function.
Neuroprotection research: Neurons are particularly vulnerable to oxidative stress due to high mitochondrial activity and limited catalase expression. Glutathione research in neuronal models is relevant to neurodegenerative disease biology, where GSH depletion is an early feature in Parkinson’s disease and Alzheimer’s disease models.
Cancer research: Elevated GSH in tumour cells is associated with resistance to chemotherapy agents that act via oxidative mechanisms. Research examining GSH depletion strategies as sensitisers for cytotoxic agents is a significant area in cancer cell biology.
Sourcing Glutathione for Research
R&D Peptides supplies Glutathione 1500mg as a lyophilised research compound with a batch-specific Certificate of Analysis. Supplied strictly for in vitro research use only.
For quality and testing standards, see our quality and testing page, or browse our full Longevity & Anti-Ageing research compound range.
All content on this page is for educational and informational purposes only. Glutathione is supplied by R&D Peptides strictly for in vitro research use. It is not intended for human or veterinary administration, and no therapeutic claims are made or implied.
