Everything below concerns GSSG. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Commercial glutathione is available in research-grade, food-grade, and supplement-grade forms, and purity specifications differ accordingly. Certificates of analysis commonly report identity by nuclear magnetic resonance or mass spectrometry, purity by HPLC, residual solvents, and heavy metals. Reference standards with assigned purity support calibration, while isotopically labeled glutathione can serve as an internal standard for mass spectrometry. For supplements, label claims may not be independently verified, and regulatory oversight varies by country. Verification often involves third-party testing for identity, potency, and contaminants.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical assay | Enzymatic recycling assay (Tietze) | Measures total glutathione after reduction of GSSG. |
| Separation method | HPLC or LC-MS/MS | Can quantify GSH and GSSG separately with appropriate standards. |
| Solid storage | -20 °C, desiccated, protect from light | Dry powder is more stable than aqueous solutions. |
| Solution storage | Acidic pH, -80 °C, aliquot | Reduce oxygen exposure and freeze-thaw cycling. |
| Oxidation product | Glutathione disulfide (GSSG) | Formed by thiol oxidation; often measured as a stress marker. |
Measuring glutathione requires attention to sample preparation because the molecule oxidizes readily. Blood, tissue, and cell samples are often treated with acid to precipitate proteins and stabilize the thiol. Without such steps, GSH can convert to GSSG or form mixed disulfides during storage. Analytical methods include spectrophotometric assays, high-performance liquid chromatography, and mass spectrometry. Each approach has different sensitivity, specificity, and susceptibility to interference from related compounds in complex matrices.
For solid glutathione, storage conditions affect shelf life. The reduced form is typically kept cool, dry, and protected from air and light. Moisture can promote oxidation, while elevated temperatures accelerate degradation. Suppliers often specify storage at or below freezing, sometimes under inert gas. Solutions are less stable than powders and may require preparation shortly before use. Buffers and chelating agents can slow oxidation, but they do not eliminate it. Published stability data vary with matrix, pH, and container.
Quality control for glutathione focuses on identity, purity, and oxidation state. Certificates of analysis may report assay value, water content, and the presence of GSSG or other impurities. Chromatographic purity is often expressed as a percentage of peak area. Reference standards help laboratories compare results across instruments and batches. Because glutathione is a small, polar molecule, separation from cysteine, gamma-glutamylcysteine, and related thiols can be challenging. Verification often combines more than one analytical technique.
Measuring glutathione in biological samples requires attention to oxidation, because GSH can convert to GSSG after sample collection. Blood and plasma samples are often treated with acid or alkylating agents to preserve the reduced form. Without stabilization, apparent GSH concentrations can fall while GSSG rises. Differences in sample type, handling delay, and deproteinization method can produce results that are not comparable across studies. Reporting preanalytical details is therefore important for interpreting findings.
Common analytical approaches include enzymatic recycling assays, high-performance liquid chromatography, and mass spectrometry. Enzymatic recycling measures total glutathione after converting GSSG back to GSH, while separation methods can quantify GSH and GSSG separately. Derivatization may be used to improve detection or stability during analysis. LC-MS/MS offers high specificity and can distinguish glutathione from related thiols and adducts. Each method has different sensitivity, throughput, and susceptibility to interference, so method selection depends on the study question and sample matrix.
For solid glutathione reagents, storage at low temperature and protection from moisture and light are typical precautions. Aqueous solutions can oxidize over time, and pH affects stability; alkaline conditions generally promote thiol oxidation. Some protocols prepare fresh solutions, while others use antioxidants or chelators to limit metal-catalyzed oxidation. Purity and counterion content can vary among commercial preparations, affecting concentration calculations. Certificates of analysis and validated assays help verify identity and purity.
== Weitere Anwendung == Die Eigenschaft von hCG, die körpereigene Testosteronproduktion anzuregen, kann ausgenutzt werden, um beim Mann einer Hoden-Atrophie entgegenzuwirken. Athleten aus Kraftsportdisziplinen oder dem Bodybuilding, die ihre Leistung mit anabolen Steroiden wie Dianabol und Sustanon steigern, injizieren hCG, um die durch die Gabe künstlichen Testosterons verursachten Hodenschrumpfungen zu vermeiden. In der Medizin wird hCG bei der Behandlung nicht herabgestiegener Hoden (Kryptorchismus) bei Jungen sowie zur Verbesserung der Fruchtbarkeit bei Frauen verwendet.
== hCG-Antikörper == Da sowohl bei einer Schwangerschaft als auch bei Tumoren das hCG eine Immuntoleranz ausübt, gibt es Studien mit einer hCG-Impfung bestehend aus hCG und Diphtherie-Toxoiden. Hierdurch produziert der Körper Antikörper gegen hCG, was zur Tumorbekämpfung einerseits und zur Kontrazeption andererseits angewandt werden kann (vgl. auch w:en:AVICINE). Ein erster Feldversuch wurde bereits 1993/1994 unternommen, wobei die Frauen, die alle bereits eine Sterilisation hinter sich hatten, vorher über die vermutete Wirkung informiert wurden. Diese Studie wird von Impfgegnern als „Beweis“ für ihre Behauptungen herangezogen, Tetanus-Impfkampagnen würden heimlich Frauen sterilisieren. Diesen Vorwurf erhob nach mehrfach laborbestätigten Untersuchungen im Januar und Februar 2015 auch die Kenianische Konferenz katholischer Bischöfe.
== hCG-Diät == Der britische Endokrinologe Albert T.W. Simeons empfahl hCG erstmals als Ergänzung zu einer ultra-energiearmen Gewichtsverlust-Diät mit weniger als 2000 kJ (500 kcal). Simeons untersuchte in Indien schwangere Frauen, die sich einer energiereduzierten Diät unterzogen. Durch die Behandlung mit kleinen hCG-Dosierungen stellte Simeons fest, dass seine Patienten eher Fettgewebe verloren als Muskelgewebe. Im Jahr 1954 veröffentlichte Simeons sein Buch Pound and Inches zum Thema Gewichtsverlust. Als praktizierender Arzt im Salvator Mundi Krankenhaus in Rom empfahl er Patienten tägliche kleine hCG-Injektionen, kombiniert mit einer individuellen ultra-energiearmen, proteinreichen, kohlenhydrat- und fettarmen Diät. Ziel dieser Diät war der Verlust von Fettgewebe ohne dabei an Muskelgewebe zu verlieren. Simeons Forschungsergebnisse wurden nie von anderen Forschern aufgegriffen oder erweitert. Auf Grund von Beschwerden veranlasste 1976 die amerikanische Behörde für Lebens- und Arzneimittel, dass sämtlichen Werbungen für hCG-Diäten folgender Hinweis beigelegt werden sollte:
Es fand ein wiedererstarkendes Interesse an hCG-Diäten statt, nachdem Kevin Trudeau dafür begann zu werben. Dieser erhielt später ein Verbot von der Bundeshandelskommission, weitere Behauptungen bezüglich hCG-Diäten aufzustellen. Das Verbot resultierte letztlich in einer Haftstrafe für Kevin Trudeau. Als wissenschaftlicher Konsens gilt generell, dass jeglicher Gewichtsverlust, der von Teilnehmern einer hCG-Diät berichtet wird, vollständig an der täglichen Aufnahme von lediglich 2000-4000 kJ (500–1000 kcal) liegt, also deutlich unter der empfohlenen Menge für Erwachsene.
Sources: de.wikipedia.org
The ratio depends on rapid separation or blocking of GSH before oxidation occurs. GSSG can be formed ex vivo if samples are not processed quickly in cold, acidic conditions. Even small delays can shift the apparent ratio, making standardized protocols essential.
Enzymatic recycling assays measure total glutathione, while HPLC and LC-MS/MS can resolve GSH and GSSG separately. Derivatization or thiol-blocking reagents are sometimes used to stabilize and detect the compounds. Method choice depends on the sample type and required specificity.
Dry glutathione powder is typically stored at -20 °C in a desiccated container protected from light. Solutions should be prepared fresh, kept acidic or frozen, and avoid repeated freeze-thaw cycles. Stability should be confirmed for each specific laboratory condition.
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.