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.
Updated 2025-12-17. Numbers and descriptions here follow the published literature rather than marketing material.
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.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
| 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 |
Published studies on epitalon are dominated by a small number of research groups, and independent replication in other laboratories remains limited. Proposed mechanisms include activation of telomerase and modulation of melatonin rhythms, but the evidence for either rests mainly on cell cultures and animal models. Whether the peptide produces comparable effects in humans is an open question, and the absence of large controlled trials means the literature is best read as exploratory rather than settled.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9, and its calculated molar mass is approximately 390.35 grams per mole. The compound is a short fragment related to a peptide fraction isolated from bovine pineal gland extracts, and it is normally supplied as a lyophilised powder intended for laboratory research. It is not a registered pharmaceutical product in most countries.
The peptide emerged from research carried out in Saint Petersburg from the late 1980s onward, where investigators searched for shorter active fragments of a pineal preparation known as epithalamin. The name epitalon was chosen to reflect that parent extract. Early reports described effects on neuroendocrine markers and on the lifespan of laboratory animals. Much of that work appeared in Russian-language journals, with English translations following later, which affects how readily the original protocols can be assessed by outside groups.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
==== Emulsions ==== Water-in-oil emulsions of steroids were studied in the late 1940s and in the 1950s. Long-acting emulsions of progesterone were introduced for use by intramuscular injection alone under the brand name Progestin and with estradiol benzoate under the brand name Di-Pro-Emulsion by the 1950s. Steroid emulsions by intramuscular injection are reported to have similar properties, such as duration, as aqueous suspensions.
=== 21 March === The SAF retook the Republican Palace in Khartoum from the RSF. An RSF drone strike on the palace that same day killed six journalists including two military reporters and four members of a Sudan TV crew.
== External links == Official website Centers for Medicare and Medicaid Services in the Federal Register Centers for Medicare & Medicaid Services in the Code of Federal Regulations Centers for Medicare & Medicaid Services reports and recommendations from the Government Accountability Office Grants to States for Medicaid account on USAspending.gov Centers for Medicare and Medicaid Innovation account on USAspending.gov State Grants and Demonstration account on USAspending.gov Centers for Medicare and Medicaid Services apportionments on OpenOMB GitHub Repositories GitHub Repositories for Digital Service at CMS
== Cis/trans isomers of the peptide group == Significant delocalisation of the lone pair of electrons on the nitrogen atom gives the group a partial double-bond character. The partial double bond renders the amide group planar, occurring in either the cis or trans isomers. In the unfolded state of proteins, the peptide groups are free to isomerize and adopt both isomers; however, in the folded state, only a single isomer is adopted at each position (with rare exceptions). The trans form is preferred overwhelmingly in most peptide bonds (roughly 1000:1 ratio in trans:cis populations). However, X-Pro peptide groups tend to have a roughly 30:1 ratio, presumably because the symmetry between the Cα and Cδ atoms of proline makes the cis and trans isomers nearly equal in energy, as shown in the figure below.
Sources: en.wikipedia.org
Žarković, N.; Zarković, K.; Schaur, R. J. R.; Stolc, S.; Schlag, G. N.; Redl, H.; Waeg, G.; Borović, S.; Loncarić, I.; Jurić, G.; Hlavka, V. (1999). "4-Hydroxynonenal as a second messenger of free radicals and growth modifying factor". Life Sciences. 65 (18–19): 1901–1904. doi:10.1016/S0024-3205(99)00444-0. PMID 10576434. Sharma, R.; Brown, D.; Awasthi, S.; Yang, Y.; Sharma, A.; Patrick, B.; Saini, M. K.; Singh, S. P.; Zimniak, P.; Singh, S. V.; Awasthi, Y. C. (2004). "Transfection with 4-hydroxynonenal-metabolizing glutathione S-transferase isozymes leads to phenotypic transformation and immortalization of adherent cells". European Journal of Biochemistry. 271 (9): 1690–1701. doi:10.1111/j.1432-1033.2004.04067.x. PMID 15096208.
==== List of P-CABs in the markets (First year of approval for clinical use) ==== Revaprazan (2006) Vonoprazan (2014) Tegoprazan (2018) Fexuprazan (2021) Keverprazan (2023/China) Zastaprazan (2024/South Korea)
The pharmaceutical sciences are a group of interdisciplinary areas of study concerned with the design, manufacturing, action, delivery, and classification of drugs. They apply knowledge from chemistry (inorganic, physical, biochemical and analytical), biology (anatomy, physiology, biochemistry, cell biology, and molecular biology), epidemiology, statistics, chemometrics, mathematics, physics, and chemical engineering. The pharmaceutical sciences are further subdivided into several specific specialties, with four main branches:
===== Morphology change ===== As shown by flow cytometry and electron microscopy, the most sensitive sign of activation, when exposed to platelets using ADP, are morphological changes. Mitochondrial hyperpolarization is a key event in initiating morphology changes. Intraplatelet calcium concentration increases, stimulating the interplay between the microtubule/actin filament complex. The continuous changes in shape from the unactivated to the fully activated platelet are best seen via scanning electron microscopy. The three steps along this path are named early dendritic, early spread, and spread. The surface of the unactivated platelet looks similar to the surface of the brain–a wrinkled appearance from numerous shallow folds that increase the surface area; early dendritic, an octopus with multiple arms and legs; early spread, an uncooked frying egg in a pan, the "yolk" is the central body; and the spread, a cooked fried egg with a denser central body. These changes are all brought about by the interaction of the microtubule/actin complex with the platelet cell membrane and open canalicular system (OCS), which is an extension and invagination of that membrane. This complex runs just beneath these membranes and is the chemical motor that pulls the invaginated OCS out of the interior of the platelet, like turning pants pockets inside out, creating the dendrites. This process is similar to the mechanism of contraction in a muscle cell. The entire OCS thus becomes indistinguishable from the initial platelet membrane as it forms the "fried egg".
Late historian Tony Judt likewise traced the trigger to Milošević's nationalist rise in Serbia from 1987 and to the failed hope for a "democratic and unified Yugoslavia" back to communism's collapse and the Cold War's end. Once Slovenia and Croatia seceded and the federal army moved on Slovenia's border, what followed were five distinct tragic wars that included a brief campaign against Slovenia ending in withdrawal, a bloodier Croatian-Serb war, the siege of Bosnia after its 1992 independence referendum, a separate Croat-Muslim conflict within Bosnia from 1993, and finally Kosovo, where Milošević—having lost everywhere else—turned back to the province he had first exploited in 1989, until NATO's 1999 military intervention stopped him.
Sources: en.wikipedia.org
==== Nuclear power ==== The Trump administration has sought to drastically expand the US's nuclear power generation, setting a goal to quadruple it by 2050. The administration seeks to revive production at decommissioned plants, such as the plant at Three Mile Island in Pennsylvania. It also seeks to promote the construction of new small modular reactors. The administration considers nuclear power generation a strategic priority because of its potential use in powering data centers needed to compete in the international AI development race. Experts are divided on the feasibility of Trump's nuclear power goals, with many expressing skepticism that they can be reached because of the high cost of nuclear power generation, while others say the conditions for financing nuclear power are relatively favorable. Despite efforts to increase nuclear power generation, data centers have led to steep increases in the cost of power in some communities, prompting local backlash.
Vernix caseosa, or simply vernix, is the waxy white substance found coating the skin of newborn human babies. It is produced by dedicated cells and is thought to have some protective roles during fetal development and for a few hours after birth.
== Reception == The film holds a score of 86% on Rotten Tomatoes based on 14 reviews, with an average grade of 7.7 out of 10. Bosley Crowther of The New York Times wrote, "After all the spy and mystery movies of a romantic and implausible nature that we have seen, it is great to see one as realistic, and believable too, as The Spy Who Came In from the Cold." Variety called the film "an excellent contemporary espionage drama of the Cold War which achieves solid impact via emphasis on human values, total absence of mechanical spy gimmickry, and perfectly controlled underplaying." Philip K. Scheuer of the Los Angeles Times wrote: "It is not an easy, certainly not a pleasant, picture to sit through; too impersonal, too objective, to move us to weep, so that its ending can only leave us tremendously depressed." Richard L. Coe of The Washington Post declared: "Not having shared the evidently widespread admiration for The Spy Who Came In from the Cold in its original form as a novel, I nonetheless find it a wholly absorbing picture." Brendan Gill of The New Yorker called it "in every respect an admirable translation [to] the screen of the fantastically popular thriller by Jean [sic] le Carré." The Monthly Film Bulletin wrote, "Concentration is demanded; and earned by the tension and accuracy of the dialogue and the high level of performance ... [the cast] all give performances of a kind which instantly engage attention, even if the characters scarcely develop beyond the point at which we first meet them."
With his assistant Daniel Picard, Adrià has made almonds into cheese and asparagus into bread with the help of natural ingredients. In autumn 2010, Adrià and José Andrés taught a culinary physics course, "Science and Cooking" at Harvard University. In October 2010, Adrià announced an alliance with Telefónica. In March 2012 he announced a new project, LaBullipedia. In a later interview he described the project as "A Western haute cuisine Wikipedia at the service of information but also creativity". As of 2025, this project has not materialized. An art exhibition about Adrià and his restaurant, 'elBulli: Ferran Adrià and The Art of Food', was hosted at Somerset House in London in 2013. The exhibition will be included in a new permanent museum Adrià was set to open at the El Bulli Foundation in 2021. The El Bulli museum opened in 2023 under the name elBulli1846. He received the 1995 Lucky Strike Designer Award.
=== Diabetics === The prevention of hypoglycemia depends on the cause. In those with diabetes treated by insulin, glinides, or sulfonylurea, the prevention of hypoglycemia has a large focus on patient education and medication adjustments. The foundation of diabetes education is learning how to recognize the signs and symptoms of hypoglycemia, as well as learning how to act quickly to prevent worsening of an episode. Another cornerstone of prevention is strong self-monitoring of blood glucose, with consistent and frequent measurements. Research has shown that patients with type 1 diabetes who use continuous glucose monitoring systems with insulin pumps significantly improve blood glucose control. Insulin pumps help to prevent high glucose spikes, and help prevent inappropriate insulin dosing. Continuous glucose monitors can sound alarms when blood glucose is too low or too high, especially helping those with nocturnal hypoglycemia or hypoglycemic unawareness. In terms of medication adjustments, medication doses and timing can be adjusted to prevent hypoglycemia, or a medication can be stopped altogether.
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.
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.