Everything below concerns LC-MS/MS. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-03-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 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.
Biosynthesis occurs in two ATP-dependent steps. The enzyme glutamate-cysteine ligase joins glutamate and cysteine, forming gamma-glutamylcysteine; glutathione synthetase then adds glycine to produce the complete tripeptide. Because the peptide bond from glutamate uses the gamma-carboxyl group, glutathione resists digestion by many ordinary peptidases. Tissues vary in synthesis capacity, and the liver generally contains high concentrations relative to many other organs. This uneven distribution contributes to organ-specific differences in redox buffering and affects how experimental results are interpreted across tissue types.
Glutathione participates in detoxification reactions, amino acid transport, and the maintenance of protein thiols. It serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. In research literature, altered glutathione status appears in studies of aging, infection, metabolic stress, and environmental exposure. Whether low glutathione is a cause, consequence, or marker of such conditions often remains unresolved. Direct measurement in blood or tissue provides a snapshot, but results depend on sample handling, timing, and the method used.
| Property | Value | Notes |
|---|---|---|
| Typical assay | HPLC-UV or LC-MS/MS | Derivatization may improve detection |
| Storage temperature | -20 °C or below | Keep desiccated and protected from light |
| Appearance | White to off-white crystalline powder | Reduced form |
| Solubility | Freely soluble in water | Insoluble in lipids and nonpolar solvents |
| Common synonyms | L-Glutathione; GSH | GSH denotes reduced form |
Measuring glutathione in biological samples requires attention to oxidation and matrix effects. High-performance liquid chromatography with ultraviolet or fluorescence detection can separate reduced and oxidized forms after derivatization. Liquid chromatography with tandem mass spectrometry offers higher specificity and can quantify glutathione alongside related thiols. Because glutathione can oxidize during sample handling, many protocols use rapid acidification with metaphosphoric acid or sulfosalicylic acid. Internal standards help correct for losses during extraction and analysis.
Enzymatic recycling assays provide a complementary approach for total glutathione. In these methods, glutathione reductase reduces oxidized glutathione while a thiol-reactive reagent, such as 5,5'-dithiobis(2-nitrobenzoic acid), produces a colored product. The reaction cycles between reduced and oxidized forms, amplifying the signal. Spectrophotometric or fluorometric detection can then estimate concentration. Distinguishing reduced glutathione from glutathione disulfide often requires separate aliquots, masking agents, or chromatographic separation, and the choice affects reported values.
Accurate measurement of glutathione begins with careful sample handling. Because GSH oxidizes rapidly to GSSG, samples must be processed quickly or frozen immediately. Acid precipitation with metaphosphoric acid or perchloric acid is common; it lowers pH, precipitates proteins, and helps preserve the reduced form. Chelating agents such as EDTA can limit metal-catalyzed oxidation. For whole blood, hemolysis releases glutathione from erythrocytes, so plasma and serum values differ substantially from whole blood values.
Several analytical methods can quantify glutathione, including high-performance liquid chromatography (HPLC) with UV or fluorescence detection for separating GSH and GSSG. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) offers higher specificity and sensitivity, often detecting nanomolar concentrations. The enzymatic recycling assay, often called the Tietze method, measures total glutathione by coupling reduction of GSSG to a colorimetric or fluorometric readout. Capillary electrophoresis and electrochemical detection are also used in specialized laboratories. Each method has distinct advantages and limitations regarding throughput, cost, and susceptibility to interference.
Interpreting glutathione measurements requires attention to pre-analytical variables. The GSSG concentration in a sample can rise artificially during storage or processing, making the GSH/GSSG ratio unreliable if not controlled. Reference ranges vary by specimen type, assay, and population, so comparisons across studies are difficult. Plasma glutathione is low and sensitive to hemolysis, while whole blood reflects primarily erythrocyte content. Many studies measure total glutathione rather than the reduced and oxidized forms separately, which limits conclusions about redox status.
=== ADHD === Selegiline has been limitedly studied in the treatment of attention deficit hyperactivity disorder (ADHD) in children, adolescents, and adults. In a small randomized trial of selegiline for treatment of ADHD in children, there were improvements in attention, hyperactivity, and learning/memory performance but not in impulsivity. A small clinical randomized trial compared selegiline to methylphenidate, a first line treatment for ADHD, and reported equivalent efficacy as assessed by parent and teacher ratings. In another small randomized controlled trial of selegiline for the treatment of adult ADHD, a high dose of the medication for 6 weeks was not significantly more effective than placebo in improving symptoms. Selegiline in its transdermal patch form (brand name Emsam) has also been assessed in the treatment of ADHD in children and adolescents in a small open-label pilot study sponsored by the manufacturer in 2003. However, there was a high rate of discontinuation and development was not further pursued.
Hazard research is published: several dietary habits and products including teabags are linked to PFAS intake (4 Feb), an additional three billion people may face water scarcity by 2050 when river pollution is considered, an aspect neglected by prior assessments (6 Feb), HPV infection linked to higher cardiovascular mortality (7 Feb), researchers use simulations to develop an early-warning signal for a potential collapse of the atlantic meridional overturning circulation (AMOC) and suggest it indicates the AMOC is "on route to tipping" (9 Feb), researchers report the H5N1 bird flu virus may be changing and adapting to infect more mammals (12 Feb), researchers report how compounding disturbances could trigger unexpected ecosystem transitions in the Amazon rainforest (14 Feb), harmful chlormequat is found in ~80% of U.S. adult urine samples, rising during 2023, and in oat-based foods widely thought to be healthy (15 Feb), excess amounts of widely-supplemented niacin (B3) are linked to cardiovascular risk (19 Feb), a review concludes available evidence on the use of puberty blockers and cross-sex hormones in minors with gender dysphoria is very limited and based on only a few studies with small numbers which have problematic methodology and quality, warning about their use outside of clinical studies or research projects after careful risk-benefit evaluation (27 Feb).
Huáng bǎi (黃栢 or 黃柏, literally "yellow cypress"), huáng bó (黃柏) or huáng bò (黃檗) is one of the fifty fundamental herbs of traditional Chinese medicine. Known also as Cortex Phellodendri, it is the bark of one of two species of Phellodendron tree: Phellodendron amurense or Phellodendron chinense.
According to Pino Arlacchi, the former head of the UN Office on Drugs and Crime, the portrayal of Venezuela as a "drug state" is a "geopolitically motivated smear campaign" by the US government; he refers to the World Drug Report 2025 and his own experience, according to which the Venezuelan government's cooperation in the fight against drug trafficking is among the best in South America. According to Arlacchi, the US has taken an interest in Venezuelan oil reserves, which are among the largest in the world. The International Federation for Human Rights (FIDH) in the Americas demands an immediate cessation of aggression against Venezuela. The U.S. government's instrumentalisation of the "fight against drugs" conveys a disproportionate use of force and sets a dangerous precedent. Russia and China reiterated their condemnation of US actions against Venezuela at an emergency UN Security Council meeting on 23 December. Russia's Foreign Ministry called the deployment "excessive military force" and spokesperson Maria Zakharova stated that Russia "confirms our firm support for the Venezuelan leadership in defending its national sovereignty". On 19 November 2025, Chinese foreign ministry spokesperson Mao Ning said that China opposes "any interference in Venezuela's internal affairs under any pretext" and called on the United States to "choose a course of action conducive to peace and stability".
Sources: en.wikipedia.org
== References == Hodgson, Barbara (2001), In the Arms of Morpheus: The Tragic History of Morphine, Laudanum and Patent Medicines, Firefly Books, ISBN 1-55297-540-1. Majno, Guido (1991), The Healing Hand: Man and Wound in the Ancient World, Harvard University Press, pp. 413–417, ISBN 0-674-38331-1. Schafer, Edward H. (1985), The Golden Peaches of Samarkand: A Study of T'Ang Exotics, University of California Press, ISBN 0-520-05462-8. Di Gennaro Splendore, Barbara (2025), The State Drug: Theriac, Pharmacy, and Politics in Early Modern Italy, Harvard University Press ISBN 9780674299788.
== Function == Produced mainly in the liver, plasminogen is the inactive zymogen form of plasmin, and circulates in plasma in a closed conformation that cannot be activated. Binding clots or cell surfaces cause their conformation to change, allowing them to be activated by plasminogen activators. Plasminogen activators do so by cleaving the R561/V562 peptide bond, producing the active protein plasmin, which catalyzes the degradation of fibrin polymers that make up the structure of blood clots.
== Mechanism of action == Thiamazole inhibits the enzyme thyroperoxidase, which normally acts in thyroid hormone synthesis by oxidizing the anion iodide (I−) to iodine (I2), hypoiodous acid (HOI), and enzyme linked hypoiodate (EOI), facilitating iodine's addition to tyrosine residues on the hormone precursor thyroglobulin, a necessary step in the synthesis of triiodothyronine (T3) and thyroxine (T4). It does not inhibit the action of the sodium-dependent iodide transporter located on follicular cells' basolateral membranes. Inhibition of this step requires competitive inhibitors such as perchlorate and thiocyanate. A study has shown that it modulates secretion of CXCL10.
Sources: en.wikipedia.org
According to Stéphane Quideau, the term "polyphenol" refers to compounds derived from the shikimate/phenylpropanoid and/or the polyketide pathway, featuring more than one phenolic unit and deprived of nitrogen-based functions. Ellagic acid, a molecule at the core of naturally occurring phenolic compounds of varying sizes, is itself not a polyphenol by the WBSSH definition, but is by the Quideau definition. The raspberry ellagitannin, on the other hand, with its 14 gallic acid moieties (most in ellagic acid-type components), and more than 40 phenolic hydroxyl groups, meets the criteria of both definitions of a polyphenol. Other examples of compounds that fall under both the WBSSH and Quideau definitions include the black tea theaflavin-3-gallate shown below, and the hydrolyzable tannin, tannic acid.
In molecular biology, the leguminous lectin family is a family of lectin proteins. It is one of the largest lectin families with more than 70 lectins reported in a review in 1990. Leguminous lectins consist of two or four subunits, each containing one carbohydrate-binding site. The interaction with sugars requires tightly bound calcium and manganese ions. The structural similarities of these lectins are reported by the primary structural analyses and X-ray crystallographic studies. X-ray studies have shown that the folding of the polypeptide chains in the region of the carbohydrate-binding sites is also similar, despite differences in the primary sequences. The carbohydrate-binding sites of these lectins consist of two conserved amino acids on beta pleated sheets. One of these loops contains transition metals, calcium and manganese, which keep the amino acid residues of the sugar-binding site at the required positions. Amino acid sequences of this loop play an important role in the carbohydrate-binding specificities of these lectins. These lectins bind either glucose, mannose or galactose. The exact function of legume lectins is not known but they may be involved in the attachment of nitrogen-fixing bacteria to legumes and in the protection against pathogens. Some legume lectins are proteolytically processed to produce two chains, beta (which corresponds to the N-terminal) and alpha (C-terminal). The lectin concanavalin A (conA) from jack bean is exceptional in that the two chains are transposed and ligated (by formation of a new peptide bond).
In the same month, The United Kingdom published its 10-year National AI Strategy, which states the British government "takes the long-term risk of non-aligned Artificial General Intelligence, and the unforeseeable changes that it would mean for ... the world, seriously". The strategy describes actions to assess long-term AI risks, including catastrophic risks. The British government held first major global summit on AI safety. This took place on the 1st and 2 November 2023 and was described as "an opportunity for policymakers and world leaders to consider the immediate and future risks of AI and how these risks can be mitigated via a globally coordinated approach". China Media Project stated "key aspects of its approach remain fundamentally unsafe by the standards of democratic societies worldwide", arguing that part of China's AI safety approach is focused on strengthening the Chinese Communist Party (CCP)'s information control. Government organizations, particularly in the United States, have also encouraged the development of technical AI safety research. The Intelligence Advanced Research Projects Activity initiated the TrojAI project to identify and protect against Trojan attacks on AI systems. The DARPA engages in research on explainable artificial intelligence and improving robustness against adversarial attacks. And the National Science Foundation supports the Center for Trustworthy Machine Learning, and is providing millions of dollars in funding for empirical AI safety research.
Sources: en.wikipedia.org
Common methods include spectrophotometric enzyme cycling assays, HPLC with UV or fluorescence detection, and LC-MS/MS. Detection often requires derivatization because glutathione lacks a strong chromophore. Method choice depends on the sample type and the required sensitivity.
Yes, especially in solution or when exposed to oxygen, light, and heat. The reduced form can oxidize to GSSG or form disulfides with other thiols. Powdered material stored cool and dry is generally more stable than aqueous preparations.
Purity refers to the proportion of the intended compound in a sample, often determined by chromatography. A high purity value does not necessarily indicate a specific oxidation state. Buyers may also need information about GSSG content, water, and residual solvents.
GSH is the reduced form of glutathione, with a free thiol group on cysteine. GSSG is the oxidized disulfide form, created when two GSH molecules become linked. The two forms exist together, and their balance is often reported as the GSH/GSSG ratio in laboratory studies.