A practical reference on thiol: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-07. Anything still debated is marked as such rather than presented as settled.
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.
Glutathione is a small tripeptide composed of glutamate, cysteine, and glycine, with the unusual gamma-glutamyl linkage between glutamate and cysteine. Its cysteine thiol group makes it a major non-enzymatic antioxidant in cells. The reduced form, GSH, predominates in most intracellular compartments, while the oxidized disulfide form, GSSG, is produced when GSH reduces reactive oxygen species. Intracellular concentrations often reach millimolar levels, whereas plasma concentrations are much lower, typically in the low micromolar range. This gradient reflects active synthesis, transport, and consumption rather than passive distribution.
Synthesis occurs in two ATP-dependent steps: glutamate-cysteine ligase joins glutamate and cysteine to form gamma-glutamylcysteine, and glutathione synthetase adds glycine to complete the tripeptide. The pathway is feedback-inhibited by GSH and limited by cysteine availability, so cysteine supply often constrains production. Once formed, GSH participates in redox buffering, xenobiotic conjugation, and protein glutathionylation. Glutathione peroxidase uses GSH to reduce hydrogen peroxide and lipid peroxides, yielding GSSG, while glutathione reductase regenerates GSH using NADPH. Glutathione S-transferases conjugate electrophiles to GSH, supporting detoxification and excretion.
Because GSH is central to redox balance, its status is studied in aging, liver disease, neurodegenerative conditions, and metabolic disorders. Observational studies often report lower GSH or higher GSSG in affected tissues, but such associations do not establish that raising glutathione changes disease outcomes. Oral glutathione is digested into amino acids, and whether intact absorption occurs remains debated; precursors such as N-acetylcysteine and cysteine donors are also investigated. Regulatory agencies generally treat glutathione as a dietary supplement, not an approved drug, and clinical claims require evidence from controlled trials.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C10H17N3O6S | Reduced form; oxidized dimer is C20H32N6O12S2 |
| Molar mass | 307.32 g/mol | For reduced glutathione (GSH) |
| Appearance | White crystalline powder | Typical laboratory and supplement-grade material |
| Solubility | Soluble in water | Poorly soluble in ethanol and other nonpolar solvents |
| Typical storage | -20 C, desiccated, protected from light | Reduced form can oxidize in solution |
== Epidemiology == The National Eye Institute reports keratoconus is the most common corneal dystrophy in the United States, affecting about one in 2,000 Americans, but some reports place the figure as high as one in 500. In the pediatric populations, ages three to 18, the prevalence of keratoconus was found to be as high as one in 334 children. The inconsistency may be due to variations in diagnostic criteria, with some cases of severe astigmatism interpreted as those of keratoconus, and vice versa. A long-term study found a mean incidence rate of 2.0 new cases per 100,000 population per year. Some studies have suggested a higher prevalence amongst females, or that people of South Asian ethnicity are 4.4 times as likely to develop keratoconus as Caucasians, and are also more likely to be affected with the condition earlier. Keratoconus is normally bilateral (affecting both eyes) although the distortion is usually asymmetric and is rarely completely identical in both corneas. Unilateral cases tend to be uncommon, and may in fact be very rare if a very mild condition in the better eye is simply below the limit of clinical detection. It is common for keratoconus to be diagnosed first in one eye and not until later in the other. As the condition then progresses in both eyes, the vision in the earlier-diagnosed eye will often remain poorer than that in its fellow.
== Function == The function of beta cells is primarily centered around the synthesis and secretion of hormones, particularly insulin and amylin. Both hormones work to keep blood glucose levels within a narrow, healthy range by different mechanisms. Insulin facilitates the uptake of glucose by cells, allowing them to use it for energy or store it for future use. Amylin helps regulate the rate at which glucose enters the bloodstream after a meal, slowing down the absorption of nutrients by inhibiting gastric emptying. Recent single-cell transcriptomic profiling during pancreatic beta-cell regeneration in zebrafish models has identified distinct molecular markers associated with the regenerative response. Following beta-cell ablation, single-cell RNA-seq datasets have characterized the robust activation and enrichment of keratin 4 (krt4) expression within specific pancreatic cell populations. These transcriptomic dynamics indicate that krt4 serves as a prominent marker capturing the cellular transitions and ductal responses crucial for in vivo beta-cell neogenesis.
=== Levels === Total levels of testosterone in the body have been reported as 264 to 916 ng/dL (nanograms per deciliter) in non-obese European and American men age 19 to 39 years, while mean testosterone levels in adult men have been reported as 630 ng/dL. Although commonly used as a reference range, some physicians have disputed the use of this range to determine hypogonadism. Several professional medical groups have recommended that 350 ng/dL generally be considered the minimum normal level, which is consistent with previous findings. Levels of testosterone in men decline with age. In women, mean levels of total testosterone have been reported to be 32.6 ng/dL. In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.
Sources: en.wikipedia.org
Common adverse effects which have an incidence rate of 20% are fatigue, asthenia, diarrhea, nausea, dyspepsia, abdominal pain, constipation, hypertension, skin discoloration, altered taste, stomatitis and mild bleeding. Sorafenib is a small molecule inhibitor of many tyrosine kinase receptors such as VEGFR-2. Side effects are in most cases mild to moderate such as rash, hand-foot skin reaction, diarrhea and dermatitis, and occur in about 33-38% patients using sorafenib. Other side effects are mild hypertension, leukopenia and bleeding. Uncommon side effects are cardiac ischaemia or infarction, gastrointestinal perforation, life-threatening haemorrhage and reversible posterior leukoencephalopathy syndrome. Hypertension is one of the most common side effects regarding inhibition of VEGF signalling. VEGF increases synthesis of NO through upregulation of endothelial NO synthase and therefore inhibition of VEGF diminishes NO synthesis. Decrease in NO causes vasoconstriction, increased peripheral resistance and increased blood pressure. Hypertension caused by VEGF inhibition can usually be treated with oral antihypertensive agents. Proteinuria is common when VEGF signalling is inhibited which shows how important VEGF is for normal renal function. VEGFR-2 can be found on the glomerular capillary endothelial cells and is activated by VEGF. Proteinuria is in most cases asymptomatic and usually decreases when treatment ends. Impaired wound healing can be an adverse effect of VEGF inhibition as angiogenesis is an important step in wound healing.
Nihonium at The Periodic Table of Videos (University of Nottingham) Uut and Uup Add Their Atomic Mass to Periodic Table Archived 7 September 2006 at the Wayback Machine Discovery of Elements 113 and 115 Superheavy elements WebElements.com: Nihonium
==== Inflammatory and systemic autoimmune disorders ==== Conditions that may closely resemble polymyositis include dermatomyositis, inclusion body myositis, immune-mediated necrotizing myopathy, systemic lupus erythematous, systemic sclerosis, and Sjögren syndrome. Overlapping skin features, such as facial redness/flushing in lupus, is an example of how these conditions can cause clinical confusion when diagnosing.
Sources: en.wikipedia.org
=== Cells === In the lymphatic system a lymph node is a secondary lymphoid organ. Lymph nodes contain lymphocytes, a type of white blood cell, and are primarily made up of B cells and T cells. B cells are mainly found in the outer cortex where they are clustered together as follicular B cells in lymphoid follicles, and T cells and dendritic cells are mainly found in the paracortex. There are fewer cells in the medulla than the cortex. The medulla contains plasma cells, as well as macrophages which are present within the medullary sinuses. In case of diseases like cancer, macrophages within the lymph nodes may play pro-cancerous role by deleting anticancer T cells e.g., PD-L1+ macrophages in lymph nodes, facilitated by anticancer vaccines, can directly delete CD8+ T cells via extrinsinc apoptotic signalling. As part of the reticular network, there are follicular dendritic cells in the B cell follicle and fibroblastic reticular cells in the T cell cortex. The reticular network provides structural support and a surface for adhesion of the dendritic cells, macrophages and lymphocytes. It also allows exchange of material with blood through the high endothelial venules and provides the growth and regulatory factors necessary for activation and maturation of immune cells.
The gateway hypothesis is the idea that using less harmful drugs can lead to more harmful ones. Some users who begin by vaping will go on to also smoke traditional cigarettes. People with mental illnesses, who as a group are more susceptible to nicotine addiction, are at particularly high risk of dual use. The correlation between vaping and subsequent smoking does not necessarily imply a causal effect. Users may have underlying characteristics that predispose them to nicotine use. There is a genetic association between smoking, vaping, gambling, promiscuity, and risk-taking behaviors. Young people with poor executive function vape, smoke, and drink alcohol more than their peers. E-cigarette users are also more likely to use both cannabis and unprescribed Adderall or Ritalin. Longitudinal studies of e-cigarettes and smoking have been criticized for failing to adequately control for these and other confounding factors. Smoking rates have declined as e-cigarette use has grown, especially among young people. This may be because there is little gateway effect at the population level, or because of anti-smoking interventions.
In situ is a Latin phrase meaning 'in the place' or 'on site', derived from in ('in') and situ (ablative of situs, lit. 'place'). The term refers to studying or working with something in its natural or original location rather than moving it elsewhere. This approach preserves environmental factors and relationships that might be lost when materials or specimens are relocated to controlled settings. In comparison, ex situ ('out of the place') methods involve removing materials or specimens for study, preservation, or modification under controlled conditions, often at the expense of their original context. The earliest recorded use of in situ in English dates back to the mid-17th century. Its use in scientific literature expanded from the late 19th century onward, beginning in medicine and engineering, and later spreading to a wide range of disciplines. The natural sciences typically use in situ methods to study phenomena in their original context. In geology, field studies of soil composition and rock formations may provide direct insights into Earth's processes. Biologists observe organisms in their natural habitats to understand behaviors and ecological interactions that cannot be reproduced in a laboratory. In chemistry and experimental physics, in situ techniques make it possible to watch substances and reactions as they occur, capturing transient phenomena in real time. The scope of in situ methods extends into applied sciences and the humanities. In aerospace engineering, in situ inspections and monitoring systems evaluate performance without interrupting operations.
Starting in the United Kingdom in the 18th century, the discovery of steam power set off the Industrial Revolution, which saw wide-ranging technological discoveries, particularly in the areas of agriculture, manufacturing, mining, metallurgy, and transport, and the widespread application of the factory system. This was followed a century later by the Second Industrial Revolution, which led to rapid scientific discovery, standardization, and mass production. New technologies were developed, including sewage systems, electricity, light bulbs, electric motors, railroads, automobiles, and airplanes. These technological advances led to significant developments in medicine, chemistry, physics, and engineering. They were accompanied by consequential social change, with the introduction of skyscrapers accompanied by rapid urbanization. Communication improved with the invention of the telegraph, the telephone, the radio, and television. The 20th century brought a host of innovations. In physics, the discovery of nuclear fission in the Atomic Age led to both nuclear weapons and nuclear power. Analog computers were invented and asserted dominance in processing complex data. While the invention of vacuum tubes allowed for digital computing with computers like the ENIAC, their sheer size precluded widespread use until innovations in quantum physics allowed for the invention of the transistor in 1947, which significantly compacted computers and led the digital transition.
Sources: en.wikipedia.org
It is a tripeptide of glutamic acid, cysteine, and glycine. The linkage between glutamate and cysteine uses the gamma-carboxyl group, which is unusual for peptides.
GSH is the reduced form with a free thiol group. GSSG is the oxidized dimer formed when two GSH molecules join by a disulfide bond.
It is synthesized inside cells and is not classified as an essential dietary nutrient for most people. Dietary and supplemental sources are studied, but direct requirements are not established in the same way as for vitamins.
GSH is the reduced, thiol-containing form of glutathione, while GSSG is the oxidized disulfide dimer formed when two GSH molecules react. Cells maintain a high GSH-to-GSSG ratio under normal conditions. A shift toward GSSG is often interpreted as oxidative stress, though sample handling can affect the measured ratio.