Thiol comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-07-31. Numbers and descriptions here follow the published literature rather than marketing material.
Cells synthesize glutathione through two ATP-dependent enzymatic steps. The first step combines glutamate and cysteine to form gamma-glutamylcysteine, catalyzed by glutamate-cysteine ligase. The second step adds glycine, producing the complete tripeptide, catalyzed by glutathione synthetase. Glutathione itself can inhibit the first enzyme, providing negative feedback when levels are high. Because cysteine is often limiting, its availability influences how quickly the pathway proceeds. These reactions occur in the cytosol, and the resulting glutathione can be distributed to other compartments.
Glutathione functions in redox balance, detoxification, and sulfur amino acid storage. It participates in reactions that help maintain ascorbate and protein thiol status. The molecule serves as a cofactor for several enzymes, including glutathione peroxidases and glutathione S-transferases. These enzymes reduce peroxides and conjugate electrophiles, respectively. Glutathione also contributes to the metabolism of xenobiotics and to the transport of cysteine between tissues. How interorgan transport and tissue-specific regulation shape whole-body pools remains an active area of study.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. Its cysteine residue carries a thiol group, which allows the molecule to participate in reduction and oxidation reactions. The compound exists in most living cells, where the reduced form, often abbreviated GSH, is usually more abundant than the oxidized disulfide form, GSSG. Intracellular concentrations are commonly in the millimolar range, while extracellular concentrations are much lower. This uneven distribution supports its role as a major cellular redox buffer.
Glutathione is a tripeptide composed of glutamate, cysteine, and glycine. It occurs in nearly all living cells, with highest concentrations in liver, kidney, and red blood cells, and exists in reduced (GSH) and oxidized disulfide (GSSG) forms. The cysteine thiol group enables reversible oxidation and reduction reactions. This property makes glutathione a central participant in cellular redox balance. The balance between these forms is often used as an indicator of oxidative stress.
Glutathione synthesis proceeds in two ATP-dependent steps catalyzed by glutamate-cysteine ligase and glutathione synthetase. The first step joins glutamate and cysteine to form gamma-glutamylcysteine and is generally rate-limiting. The second step adds glycine to complete the tripeptide. Cysteine availability, feedback inhibition by glutathione, and oxidative conditions influence flux through this pathway. The pathway is conserved across many organisms, and degradation by gamma-glutamyl transpeptidase and related peptidases recycles amino acids for new synthesis.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C10H17N3O6S | Reduced glutathione (GSH) |
| Molar mass | 307.32 g/mol | Calculated for C10H17N3O6S |
| Appearance | White to off-white powder | Typical solid form |
| Solubility | Water-soluble | Polar tripeptide |
| Common synonyms | GSH; L-glutathione | Gamma-glutamylcysteinylglycine |
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.
Glutathione supports several cellular processes beyond direct antioxidant action. It serves as a cofactor for glutathione peroxidase and glutathione S-transferase enzymes, which reduce peroxides and conjugate electrophiles, respectively. The molecule also acts as a reservoir of cysteine, an amino acid that can limit protein synthesis and redox signaling. In human nutrition, oral glutathione is sold as a supplement, but how much intact glutathione reaches tissues after ingestion remains an active research question. Clinical claims about supplementation are not uniformly supported by controlled trials.
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.
Glutathione is a small tripeptide built from glutamate, cysteine, and glycine. The peptide bond between glutamate and cysteine uses the gamma-carboxyl group, a linkage that resists ordinary peptidases. Cells make it in two ATP-dependent steps: gamma-glutamylcysteine synthetase joins glutamate and cysteine, then glutathione synthetase adds glycine. The pathway is feedback-inhibited by glutathione itself, so intracellular levels tend to stay within a narrow range. Because cysteine is often limiting, sulfur amino acid supply influences how much glutathione a cell can produce.
In its reduced form, glutathione carries a sulfhydryl group that can donate electrons. This property lets it act as a major cellular antioxidant and redox buffer. Glutathione peroxidase uses it to reduce hydrogen peroxide and lipid peroxides, while glutathione reductase regenerates the reduced form using NADPH. The ratio of reduced glutathione to glutathione disulfide is widely used as an indicator of oxidative stress, though the ratio changes with compartment, cell type, and sample handling. Oxidized glutathione can also form mixed disulfides with proteins, affecting their activity.
Glutathione supports detoxification by conjugating reactive electrophiles through glutathione S-transferases. The resulting conjugates are processed and exported, often after further metabolism. It also stores cysteine, transports amino acids across membranes through the gamma-glutamyl cycle, and assists in the maturation of iron-sulfur clusters and some prostaglandins. In plants, animals, and many microbes, the molecule appears in similar roles, but concentrations vary enormously between tissues. Liver, kidney, and red blood cells tend to contain high amounts, while blood plasma contains much less.
=== Nitriles in medicine === Nitriles occur in numerous classes of drugs. Between 2010 and 2020, at least one drug containing a nitrile function was approved annually by the US Food and Drug Administration. The nitrile group exhibits characteristic physicochemical properties that are important in drug design. Structurally, it has a linear geometry and occupies very little space—approximately one eighth of the volume of a methyl group. As a ligand substituent, it is therefore well suited to occupying narrow and deep cavities within the binding site of a target protein that are otherwise difficult to access. Incorporation of a nitrile group into a molecule generally reduces its octanol-water partition coefficient or increases its aqueous solubility. This often favorably influences bioavailability, plasma half-life, and thus the duration of action of lipophilic compounds. In medicinal products, the nitrile group is typically metabolically stable. The nitrile group is isosteric with the carbonyl group, the hydroxy group, and the chlorine atom. It therefore exhibits similar electronic and steric properties and can be exchanged with these groups to fine-tune molecular characteristics. The hydrogen bond represents the principal pharmacodynamic interaction of the nitrile group, which acts as a proton acceptor due to the electronegativity of its nitrogen atom, in contrast to the ethynyl group.
Experiments on its genotoxicity at high doses are inconsistent. Its oxidized form TBBQ may be responsible for some toxic effects. There exists a wide margin of safety between food-additive doses and doses used in studies. There have been reports of vision disturbances in individuals exposed to this chemical.
The minimum bactericidal concentration (MBC) is the lowest concentration of an antibacterial agent required to kill a particular bacterium. It can be determined from broth dilution minimum inhibitory concentration (MIC) tests by subculturing to agar plates that do not contain the test agent. The MBC is identified by determining the lowest concentration of antibacterial agent that reduces the viability of the initial bacterial inoculum by ≥99.9%. The MBC is complementary to the MIC; whereas the MIC test demonstrates the lowest level of antimicrobial agent that inhibits growth, the MBC demonstrates the lowest level of antimicrobial agent that results in microbial death. This means that even if a particular MIC shows inhibition, plating the bacteria onto agar might still result in organism proliferation because the antimicrobial did not cause death. Antibacterial agents are usually regarded as bactericidal if the MBC is no more than four times the MIC. Because the MBC test uses colony-forming units as a proxy measure of bacterial viability, it can be confounded by antibacterial agents which cause aggregation of bacterial cells. Examples of antibacterial agents which do this include flavonoids and peptides.
Sources: en.wikipedia.org
=== Pharmacokinetics === The oral bioavailability of aticaprant is 25%. The drug is rapidly absorbed, with maximal concentrations occurring 1 to 2 hours after administration. It has an elimination half-life of 30 to 40 hours in healthy subjects. The circulating levels of aticaprant increase proportionally with increasing doses. Steady-state concentrations are reached after 6 to 8 days of once-daily dosing. Aticaprant has been shown to reproducibly penetrate the blood–brain barrier.
2021 meta-analyses of trials over periods of 1 to 28 months found limited evidence to indicate that lifestyle modifications and nutritional supplementation affect mortality, liver cirrhosis, liver decompensation, liver transplantation, and hepatocellular carcinoma in people with non-alcohol-related fatty liver disease; authors said that it was unlikely that differences in clinical outcomes would become apparent in trials with less than 5 years to 10 years of follow‐up, and that sample sizes needed to be much larger than had been used.
In contrast to these serotonin releasing agents however, mCPP does not appear to cause long-term serotonin depletion (a property thought to be related to serotonergic neurotoxicity). Trazodone's 5-HT2A receptor antagonism and weak serotonin reuptake inhibition form the basis of its common label as an antidepressant of the serotonin antagonist and reuptake inhibitor (SARI) type.
Sources: en.wikipedia.org
== External links == Cooking For Engineers: Smoke Point of Various Fats - another list of smoke points along with some discussion on the subject Good Eats: Cooking Oil Smoke Points Archived 2016-03-03 at the Wayback Machine The Culinary Institute of America (1996). The New Professional Chef (6th ed.). John Wiley & Sons.
Known in antiquity to such medical doctors as Hippocrates and Galen, noma was once reported around the world, including in Europe and the United States. The disease was well-known in the Netherlands in the 1500s and 1600s. The first clinical description of noma was in 1595 by a Dutch man, Carolus Battus. Dutch surgeon Cornelis van de Voorde first used the term "noma" to describe the disease in 1680. A European scientist, Gabriel Lund, attributed noma to poverty, cramped living conditions, and malnutrition in 1765. English medical doctor John Addington Symmonds linked the disease to previous infection with measles. The first surgical treatment for noma sequelae was performed in 1781. Surgical treatments for sequelae developed throughout the 1800s. In the late 1800s, scientists suspected that noma was caused by bacteria. With improvements in hygiene and nutrition, noma has disappeared from industrialized countries since the 20th century, except during World War II when it was endemic to the Auschwitz and Belsen concentration camps. The disease and treatments were studied by Berthold Epstein, a Czech medical doctor and forced-labor prisoner who had recommended the study under Josef Mengele's direction. Since 1970, there has been little research done on noma, with few exceptions. One such exception is Cyril Enwonwu, a Nigerian scientist focusing on noma.
In Vietnam, iced coffee (Vietnamese: cà phê đá, lit. 'iced coffee') is a traditional Vietnamese coffee recipe. It is created using coffee roasted between medium and dark. The drink is made by passing hot water through the grounds into a cup that already contains condensed milk. To serve the drink cold, ice is added to the cup. Variations involve additions of ice, sugar or condensed milk. A popular variation is cà phê sữa đá (or nâu đá in the North), which is iced coffee served with sweetened condensed milk. This is done by putting two to three teaspoons or more of condensed milk into the cup prior to the drip filter process.
=== Nutritional fortification === Breakfast cereals may be fortified with dietary minerals and vitamins. For example, breakfast cereal in Canada may be fortified with specific micronutrient amounts per 100 grams of cereal, including thiamin, (2.0 mg), niacin (4.8 mg), and vitamin B6 (0.6 mg), among others.
Sources: en.wikipedia.org
Glutathione is built from three amino acids: glutamate, cysteine, and glycine. The linkage involves the gamma-carboxyl group of glutamate rather than the alpha-carboxyl group, which is unusual for peptides. This structure protects the bond from some common peptidases.
It is present in nearly all cells, with notable amounts in the liver, kidneys, and red blood cells. The highest intracellular concentrations are usually in the millimolar range. Levels differ by tissue, age, and physiological state.
It is not classified as an essential nutrient because cells can synthesize it from amino acids. Dietary sources exist, but their contribution to tissue pools is not fully established. The body's production depends on enzyme activity and precursor availability.
GSH is the reduced thiol form, while GSSG is the disulfide-linked oxidized dimer. The GSH:GSSG ratio is used as a redox indicator, though the ratio can vary with sample handling and cell type.