This is a working overview of oxidized glutathione, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It contains an unusual gamma-glutamyl bond between glutamate and cysteine, which resists cleavage by many peptidases. The reduced form, GSH, carries a thiol group on cysteine and is the dominant intracellular form in most cells. Its structure allows it to participate in redox reactions and to serve as a sulfur donor. The oxidized form, GSSG, consists of two GSH molecules joined by a disulfide bond.
In cells, glutathione helps maintain the reducing environment of the cytosol and supports enzymes that counteract reactive oxygen species. It acts as a cofactor for glutathione peroxidases, which reduce hydrogen peroxide and lipid peroxides, and for glutathione S-transferases, which conjugate electrophiles. The ratio of GSH to GSSG is often used as an indicator of oxidative stress, although the ratio can vary by compartment and cell type. Glutathione also stores cysteine, an amino acid that can be limiting for protein synthesis and antioxidant defense.
Glutathione is a small sulfur-containing peptide built from glutamic acid, cysteine, and glycine. Its distinctive feature is a gamma-glutamyl bond between glutamate's side-chain carboxyl group and cysteine's amino group. This linkage resists ordinary peptidases and helps the molecule remain stable inside cells. The reduced thiol form, often abbreviated GSH, is the dominant intracellular species. The oxidized disulfide dimer, GSSG, forms when two reduced molecules link through their cysteine sulfur atoms. The balance between these forms is a common redox indicator.
In living systems, glutathione occurs in millimolar concentrations in many cell types, while extracellular levels are generally much lower. The liver holds a substantial share of the body's total pool, and the molecule participates in reduction, detoxification, and amino acid transport. It also serves as a cofactor for enzymes such as glutathione peroxidase and glutathione S-transferase. Because the cysteine residue supplies a reactive thiol, glutathione can donate electrons and become oxidized. Cells regenerate reduced glutathione through glutathione reductase using NADPH.
Commercial glutathione is produced by microbial fermentation or chemical synthesis, then purified. Reduced and oxidized grades are offered separately, with purity specifications often exceeding 98 percent. The compound appears in foods such as fresh fruits, vegetables, and meats, although cooking and processing can lower amounts. Oral, topical, and inhaled forms are discussed in research and consumer contexts, but absorption and tissue delivery remain active areas of study. Regulatory status varies by country and intended use.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | For reduced glutathione; the oxidized dimer has two sulfur atoms. |
| Molar mass | 307.32 g/mol | Calculated for the reduced form. |
| Appearance | White to off-white crystalline powder | Typical for solid reagent; solutions are usually colorless. |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar organic solvents. |
| Typical storage | -20 °C, desiccated, protected from light | Limits oxidation, moisture uptake, and degradation. |
Glutathione is a small tripeptide built from glutamic acid, cysteine, and glycine. Its peptide bond between glutamate and cysteine involves the gamma-carboxyl group rather than the usual alpha-carboxyl group. This structure gives the molecule a reactive thiol on the cysteine residue. The reduced form, often abbreviated GSH, is the predominant intracellular species in many cell types. Because the thiol can donate electrons, glutathione participates in redox chemistry and in the conjugation of reactive molecules.
Cells synthesize glutathione through two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine, and glutathione synthetase adds glycine to form the complete tripeptide. Breakdown occurs through gamma-glutamyl transpeptidase and subsequent peptidase reactions, forming the gamma-glutamyl cycle. Within cells, glutathione also forms a disulfide-linked dimer called GSSG when two GSH molecules react. The balance between GSH and GSSG is widely used as an indicator of oxidative conditions, although the ratio can vary by compartment and tissue.
Quantification of glutathione in biological or food samples commonly uses liquid chromatography coupled to ultraviolet, fluorescence, electrochemical, or mass spectrometric detection. Because the thiol group oxidizes readily, samples are often acidified or derivatized immediately after collection to stabilize reduced glutathione. Enzymatic recycling assays and colorimetric kits offer higher throughput but generally lower specificity than chromatographic methods. Mass spectrometry can distinguish glutathione from related thiols and allow simultaneous measurement of oxidized forms. Reported concentrations depend strongly on sample type, extraction procedure, and analytical platform.
Glutathione reference materials are sensitive to oxygen, light, and elevated temperature. Solid material is typically stored desiccated at -20 °C or below, while solutions require tighter control because thiol oxidation proceeds faster in liquid form. Aqueous solutions are often prepared fresh, kept cold, and protected from air; some protocols add acid or chelating agents to slow metal-catalyzed oxidation. Repeated freeze-thaw cycles can accelerate degradation and should be avoided. Stability data vary by matrix, so laboratories usually verify performance with their own storage conditions.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group. This unusual linkage protects the molecule from many common peptidases. The cysteine side chain carries a thiol group that can undergo reversible oxidation. Because of this thiol, glutathione participates in redox reactions and helps maintain the reducing environment inside most cells in living systems.
In cells, glutathione exists mainly in a reduced form called GSH. When two GSH molecules react, they form oxidized glutathione, or GSSG, which contains a disulfide bond. The ratio of GSH to GSSG is often used as an indicator of oxidative stress. Enzymes such as glutathione peroxidase and glutathione reductase help cycle the molecule between these two states. This cycling supports antioxidant defense, detoxification of reactive molecules, and regulation of certain signaling pathways.
Quantifying glutathione requires distinguishing GSH from GSSG and preventing oxidation during sample preparation. Common approaches include the enzymatic recycling assay, often called the Tietze method, which measures total glutathione after converting GSSG to GSH. HPLC with ultraviolet or fluorescence detection and LC-MS/MS can separate and quantify both forms, sometimes after derivatization of the thiol group. Blood, plasma, and tissue samples differ in matrix and baseline concentrations, so method validation must account for recovery, linearity, and interference. No single assay is universally standard.
Glutathione is most stable as a dry powder stored cool and dry, but its thiol group is readily oxidized in solution. Aqueous preparations at neutral or alkaline pH lose GSH faster because the thiolate form reacts with dissolved oxygen and metal ions. Acidic conditions, chelating agents, and oxygen exclusion can slow oxidation, while repeated freeze-thaw cycles promote degradation. Light exposure and trace metals also contribute to loss. Laboratories typically validate stability for their own matrices because degradation rates depend on pH, temperature, concentration, and container materials.
=== Pre-release === SFM was developed internally at Valve in 2005 and most of it was based on the code from the in-game demo playback tool found in Source. SFM was used to make Day of Defeat: Source trailers with effects that could not be achieved in real-time. The tool was used extensively for certain promotional materials for the release of Team Fortress 2, particularly the Meet the Team trailers. This version of SFM, which ran using Source's in-game tools framework, was unintentionally leaked during the public beta of Team Fortress 2 in September 2007. By 2010, the entire interface was re-implemented using Qt 4 and given its engine branch for further development. Before SFM was released to the public, Team Fortress 2 carried a simplified version of SFM known as the "Replay Editor", which was limited to capturing the actual events occurring throughout a player's life. It provided no ability to modify actions, repeat segments, or apply special effects beyond those already used in-game. However, arbitrary camera angles were possible, such as tracking the movements of other players in action at the time. The Replay Editor also allowed users to upload completed videos to YouTube. On June 27, 2012, SFM became available on a limited basis through Steam, the same day the final Meet the Team video "Meet the Pyro" was released. The open beta for Windows was released as of July 11, 2012. From 2011 to 2018, Valve operated a competition known as the Saxxy Awards for community-made SFM animations.
On 29 March, Trump stated that he would prefer to "take the oil in Iran". He proposed taking Iran's oil export center, Kharg Island, claiming that the United States could capture the territory "very easily", and implying that the US could occupy it for some time. On 30 March, Trump said that if a deal were not reached soon and the Strait of Hormuz reopened, the US would strike all of Iran's power plants, oil wells, Kharg Island, and possibly all its desalinization plants, although the feasibility and strategic value of some of Trump's threats were contested. On the same day Turkey and NATO intercepted the fourth missile directed towards Turkish territory. Iran denied firing a missile at Turkey, claiming that it was a false flag attack. The US began flying B-52 bombers over Iranian territory for the first time, indicating its confidence of air supremacy over Iran. The US used bombers to target an ammunition depot and air base in Isfahan, causing large explosions. U.S-allied Gulf states such as Saudi Arabia, the UAE, Kuwait, and Bahrain reportedly pushed Trump to continue the war until there are significant changes in Iran's leadership. American journalist Shelly Kittleson was kidnapped in Baghdad by Kata'ib Hezbollah—the strongest faction within the PMF—who demanded that the Iraqi government release several detained members of the group. On 1 April, Mehr News Agency, a semi-official Iranian government news outlet, reported that policy expert and former foreign minister Kamal Kharazi was seriously injured and his wife was killed in an airstrike which hit his home.
(2026) report fossil evidence from the Pyvykha Mountain site (Ukraine) indicative of coexistence of archaeocetes of at least two different body size categories in the same locality during the middle Eocene, and interpret the studied cetaceans as likely to be close relatives of the ancestors of Neoceti. Van Rompaey et al. (2026) describe fossil material of Brevirostrodelphis aff. dividum and Brevirostrodelphis sp. from the Berchem Formation (Belgium), providing evidence of presence of members of this genus in the North Sea Basin and their trans-Atlantic distribution during the Miocene, and reinterpret the type specimen of Phocaenopsis sheynensis as a specimen of Kentriodon sp. The first porpoise fossil material from the western North Atlantic is reported from the Pliocene strata near Charleston (South Carolina, United States) by Kofranek et al. (2026). Tanaka et al. (2026) report the first discovery of fossil material of a toothed whale from the Miocene (Burdigalian to Langhian) strata of the Korematsu Formation (Japan). Buchholtz et al. (2026) report evidence of links between sternal shape and feeding behaviors in extant baleen whales, and reconstruct the transition from raptorial predation to filter feeding during the evolutionary history of baleen whales on the basis of the study of sternal morphology in extinct members of the group. Strauch & Pyenson (2026) report the discovery of fossil material of cf. Salishicetus from the Oligocene or Miocene strata of the Vaqueros Formation (California, United States).
Sources: en.wikipedia.org
=== Pregnancy and breastfeeding === Spironolactone can cross the placenta. It has been found in the breast milk of lactating mothers, but only very small amounts of spironolactone and its metabolite canrenone enter breast milk, and the amount received by an infant during breastfeeding (<0.5% of the mother's dose) is considered to be insignificant. A study found that spironolactone was not associated with teratogenicity in the offspring of rats. Because it is an antiandrogen, however, spironolactone could theoretically have the potential to cause feminization of male fetuses at sufficient doses. In accordance, a subsequent study found that partial feminization of the genitalia occurred in the male offspring of rats that received doses of spironolactone that were five times higher than those normally used in humans (200 mg/kg per day). Another study found permanent, dose-related reproductive tract abnormalities rat offspring of both sexes at lower doses (50 to 100 mg/kg per day). In practice however, although experience is limited, spironolactone has never been reported to cause observable feminization or any other congenital defects in humans. Among 31 human newborns exposed to spironolactone in the first trimester, no signs of any specific birth defects were seen. A case report described a woman who was prescribed spironolactone during pregnancy with triplets and delivered all three (one boy and two girls) healthy; no observable feminization occurred in the boy.
The Ukrainian Defence Ministry said that its forces had retaken about 20sq km (7.5sq miles) of territory from Russian forces in the north and south of the outskirts of Bakhmut in recent days while acknowledging continued Russian advances inside the city. The Wagner Group's head Yevgeny Prigozhin claimed that an American citizen was killed fighting in Bakhmut, in a video posted on Telegram that showed him inspecting a body and what he claimed to be US identification documents. In Kharkiv Oblast, two people where killed in another bout of Russian shelling in Dvorichna. South African President Cyril Ramaphosa said both Presidents Putin and Zelenskyy had agreed to receive an African mission that would propose a peace plan. He said the plan was backed by the presidents of Senegal, Uganda and Egypt and that UN Secretary-General António Guterres, the United States and the United Kingdom had also been briefed. The commander of the land forces of the South African National Defence Force, Lieutenant-General Lawrence Mbatha, visited Moscow. A Moscow court sentenced Colombian resident and Russian passport-holder Alberto Enrique Giraldo Saray to five years and two months in prison for spreading "fake news" about the actions of the Russian military in Ukraine. The US State Department condemned the arrest of a local embassy employee in Russia for alleged spying.
Hydrogen peroxide (H2O2) is a nonplanar molecule with (twisted) C2 symmetry; this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy. Although the O−O bond is a single bond, the molecule has a relatively high energy barrier of 386 cm−1 (4.62 kJ/mol) for rotation between enantiomers via the anti configuration, and 2460 cm−1 (29.4 kJ/mol) via the eclipsed configuration. These barriers are proposed to be due to repulsion between the lone pairs of the adjacent oxygen atoms and dipolar effects between the two O–H bonds. For comparison, the rotational barrier for ethane is 1040 cm−1 (12.4 kJ/mol). The approximately 100° dihedral angle between the two O–H bonds makes the molecule chiral. It is the smallest and simplest molecule to exhibit enantiomerism. It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of ribonucleic acids and therefore an origin of homochirality in an RNA world. The molecular structures of gaseous and crystalline H2O2 are significantly different. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state. Crystals of H2O2 are tetragonal with the space group D44 or P41212.
Sources: en.wikipedia.org
GSH is the reduced form with a free thiol group, while GSSG is the oxidized disulfide-linked dimer. Most assays distinguish the two because their balance reflects redox conditions. The names are not interchangeable.
It is synthesized in the body from amino acids, so it is not classified as an essential dietary nutrient for most people. Dietary and supplemental forms are studied for their effects on tissue levels and health markers. Evidence varies by population and outcome.
The phrase highlights its high intracellular concentration and its role in several antioxidant and detoxification reactions. It is not the only antioxidant, and the term can oversimplify its functions. Scientific descriptions usually specify the pathway or enzyme involved.
It is a tripeptide rather than a full protein. Proteins generally contain many amino acids joined by alpha-peptide bonds, while glutathione has three residues and an unusual gamma-glutamyl linkage. That structure affects how enzymes recognize and break it down.