Tetrapeptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-06-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
Animal and clinical reports appear mainly in Russian-language journals from the 1990s and 2000s, covering endpoints such as melatonin rhythm, lifespan in aged rodents, and retinal function. Many of these papers involve small groups, lack blinding or placebo comparison, and are difficult to retrieve through indexed databases. Review articles published in English generally summarise the claims without reanalysing the underlying data. Because no large randomised trial exists, the clinical importance of these reported effects stays unresolved and is properly described as an open question.
No national medicines regulator has approved epitalon as a therapeutic product. It is generally distributed as a research chemical, and in some jurisdictions selling peptides for human consumption without approval is restricted or prohibited. Certificates of analysis accompanying commercial material vary in which tests are performed, and independent verification of identity and purity is uncommon. Statements about anti-ageing or disease-prevention benefits on vendor pages are marketing claims rather than regulatory findings, a distinction that shapes how the compound is discussed in scientific and popular sources alike.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four amino acid residues |
| Residue sequence | Ala-Glu-Asp-Gly | Abbreviated AEDG |
| Approximate mass | 390.35 Da | Monoisotopic, free base form |
| Parent preparation | Epithalamin extract | Derived from pineal tissue |
| Common spelling variants | Epithalon, epithalone, AEDG | Affects literature retrieval |
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
== Mechanism == Most of the information on mechanism comes from work on the pea cytosolic and soybean cytosolic enzymes. The mechanism of oxidation of ascorbate is achieved by means of an oxidized Compound I intermediate, which is subsequently reduced by substrate in two, sequential single electron transfer steps (equations [1]–[3], where HS = substrate and S• = one electron oxidized form of substrate). APX follows the typical heme-peroxidase mechanism with high-valent iron intermediates:
== Applications == The nanoDSF technology was used to confirm on-target binding of BI-3231 to HSD17B13 and to elucidate its uncompetitive mode of inhibition with regards to NAD+. NanoDSF was used to compare the thermal stability of a matched set of anti-CD20 antibodies representing a range of variants. The results revealed a spectrum of activities. NanoDSF has also been applied in drug repurposing and anticancer research. In a large-scale screen of FDA-approved molecules, the method was used to identify several dozen novel microtubule-targeting agents (MTAs), including clinically used drugs such as aprepitant, disulfiram, and toremifene, by directly demonstrating their interaction with tubulin and their effects on microtubule polymerization.
=== Lawsuit === Fenn's work with electrospray ionization was at the center of a lawsuit pitting him against his alma mater and former employer, Yale University. His initial dispute with the university began in 1987, when he turned 70 – Yale's mandatory retirement age. Per university policy, Fenn was made an emeritus professor, which resulted in a reduction to his lab space. Emeritus professors at Yale are still provided with an office, but cannot conduct their own research, nor manage their own labs. In 1989, when Yale University inquired about the progress and potential about his electrospray work, he downplayed its potential scientific and commercial value. Fenn believed he had the rights to the invention under the Bayh–Dole Act. Fenn patented the technology on his own, and sold licensing rights to a company he partly owned – Analytica of Branford. In 1993, a private company seeking to license the use of electrospray technology traced its invention to Yale, when the university discovered that Fenn held the patent. Yale's policy regarding patents generated by faculty or students requires that a percentage of any royalties generated from the patent are used by the university to fund future research. They do not claim the rights to patents that are produced away from university facilities or not related to the researcher's "designated activities." Fenn claimed that he owned the technology because the work was completed after he had been forced to downsize at the university's mandatory retirement age.
Alice in Chains was plagued by extended inactivity from 1996 onward, largely due to Staley's substance abuse, which resulted in his death in 2002 and caused the band to go on hiatus. Alice in Chains reunited in 2005, with DuVall joining in 2006 as rhythm guitarist and sharing lead vocal duties; the band has since released three more albums: Black Gives Way to Blue (2009), The Devil Put Dinosaurs Here (2013), and Rainier Fog (2018). In the US, Alice in Chains has sold over 30 million RIAA-certified records. They have had 18 Top 10 songs on Billboard's Mainstream Rock Tracks chart and five No. 1 hits, and have received 11 Grammy Award nominations. The band has been included in numerous greatest of all time lists, including a position of No. 34 on VH1's "100 Greatest Artists of Hard Rock" special and No. 15 in Hit Parader's "Greatest Live Bands" list.
Sources: en.wikipedia.org
Barrett developed her current theory of constructed emotion originally during her graduate training. According to Barrett, emotions are "not universal, but vary from culture to culture" (see Emotions and culture). She says that emotions "are not triggered; you create them. They emerge as a combination of the physical properties of your body, a flexible brain that wires itself to whatever environment it develops in, and your culture and upbringing, which provide that environment.". Barrett also claims that "Smiling was an invention of the Middle Ages" and that smiling "became popular only in the eighteenth century as dentistry became more accessible and affordable".
=== Primary ion source === Three types of ion guns are employed. In one, ions of gaseous elements are usually generated with duoplasmatrons or by electron ionization, for instance noble gases (40Ar+, Xe+), oxygen (16O−, 16O2+, 16O2−), or even ionized molecules such as SF5+ (generated from SF6) or C60+ (fullerene). This type of ion gun is easy to operate and generates roughly focused but high-current ion beams. A second source type, the surface ionization source, generates 133Cs+ primary ions. Caesium atoms vaporize through a porous tungsten plug and are ionized during evaporation. Depending on the gun design, fine focus or high current can be obtained. A third source type, the liquid metal ion gun (LMIG), operates with metals or metallic alloys, which are liquid at room temperature or slightly above. The liquid metal covers a tungsten tip and emits ions under influence of an intense electric field. While a gallium source is able to operate with elemental gallium, recently developed sources for gold, indium, and bismuth use alloys which lower their melting points. The LMIG provides a tightly focused ion beam (<50 nm) with moderate intensity and is additionally able to generate short pulsed ion beams. It is therefore commonly used in static SIMS devices. The choice of the ion species and ion gun respectively depends on the required current (pulsed or continuous), the required beam dimensions of the primary ion beam, and on the sample which is to be analyzed.
The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments (larger than necessary just for ice cubes) were introduced in 1940. Frozen foods, previously a luxury item, became commonplace. Freezer units are used in households as well as in industry and commerce. Commercial refrigerator and freezer units were in use for almost 40 years prior to the common home models. The freezer-over-refrigerator style had been the basic style since the 1940s, until modern, side-by-side refrigerators broke the trend. A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. Newer refrigerators may include automatic defrosting, chilled water, and ice from a dispenser in the door. Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest are Peltier-type refrigerators designed to chill beverages. A large domestic refrigerator stands as tall as a person and may be about one metre (3 ft 3 in) wide with a capacity of 0.6 m3 (21 cu ft). Refrigerators and freezers may be free standing, or built into a kitchen. The refrigerator allows the modern household to keep food fresh for longer than before. Freezers allow people to buy perishable food in bulk and eat it at leisure, and make bulk purchases.
==== W ==== Winter salami – a type of Hungarian salami based on a centuries-old producing tradition. Made from mangalitsa pork and spices: white pepper, allspice and others. Winter salami is cured in cold air and smoked slowly.
=== India === According to statistics from the Crisis Intervention Team of LGBT Collective in Telangana, India, in 2024 there had been 15 reported instances of corrective rape in the previous five years. Corrective rape in India typically happens in order to protect the family name, and to prevent abnormal perception by the surrounding community. In India, there is a generally negative attitude towards homosexuality and the fact is that individuals in India who identify as homosexual are victimized at a higher rate. There is also a high level of negativity towards the trans community in India.
Sources: en.wikipedia.org
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.
No. Epithalamin is a heterogeneous extract containing many peptides, while epitalon is a single synthesised tetrapeptide. Publications sometimes treat findings from the two as equivalent, which is a common source of confusion. Their compositions differ and they are not interchangeable in analytical terms.
Most published work uses cell cultures or rodents because those models are faster and less costly to run. The few human trials that have been reported are small, and several lack control groups or blinding. This restricts what can reasonably be concluded about effects in people.
Small studies with human participants have been reported, chiefly in Russian-language journals, but they are limited in size and design. No large randomised controlled trial with published results is available.