If you have been reading about tetrapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-06-30. Numbers and descriptions here follow the published literature rather than marketing material.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. It was designed at the St. Petersburg Institute of Bioregulation and Gerontology as a short, chemically defined analogue of epithalamin, a fraction obtained from bovine pineal tissue. Small peptide bioregulators of this type formed a long-running line of work there from the 1980s onward. Because the molecule is produced by solid-phase synthesis rather than extraction, its composition is exact and its purity can be measured directly.
The most frequently cited proposed action is induction of telomerase, the enzyme that adds repeat sequences to chromosome ends. Cell-culture work from the originating group reported higher telomerase reverse transcriptase expression and measurable telomere elongation in human somatic cells after exposure. How a four-residue peptide would reach nuclear gene regulation is not established, and no cell-surface receptor or uptake route has been identified. Additional reports describe changes in melatonin secretion, antioxidant enzyme activity and lipid peroxidation in aged animals, but these findings remain mechanistically unconnected to the telomerase observation.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Calculated from the four residues with three water losses |
| Molecular mass | About 390.35 g/mol | Monoisotopic mass near 390.14, used for mass-spectrometric identification |
| Peptide sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG; no disulfide bonds or modified residues |
| Appearance | White to off-white solid | Supplied as a dried powder |
| Isoelectric point | Around 4 | Estimated from aspartate and glutamate side-chain pKa values |
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
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.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
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.
A significant proportion of the fatty acids in the body are obtained from the diet, in the form of triglycerides of either animal or plant origin. The fatty acids in the fats obtained from land animals tend to be saturated, whereas the fatty acids in the triglycerides of fish and plants are often polyunsaturated and therefore present as oils. These triglycerides cannot be absorbed by the intestine. They are broken down into mono- and di-glycerides plus free fatty acids (but no free glycerol) by pancreatic lipase, which forms a 1:1 complex with a protein called colipase (also a constituent of pancreatic juice), which is necessary for its activity. The activated complex can work only at a water-fat interface. Therefore, it is essential that fats are first emulsified by bile salts for optimal activity of these enzymes. The digestion products consisting of a mixture of tri-, di- and monoglycerides and free fatty acids, which, together with the other fat soluble contents of the diet (e.g. the fat soluble vitamins and cholesterol) and bile salts form mixed micelles, in the watery duodenal contents (see diagrams on the right). The contents of these micelles (but not the bile salts) enter the enterocytes (epithelial cells lining the small intestine) where they are resynthesized into triglycerides, and packaged into chylomicrons which are released into the lacteals (the capillaries of the lymph system of the intestines).
This engagement is widely regarded in South Africa as the start of the Border War, and according to SWAPO, officially marked the beginning of its revolutionary armed struggle. Operation Blouwildebees triggered accusations of treachery within SWALA's senior ranks. According to SADF accounts, an unidentified informant had accompanied the security forces during the attack. Sam Nujoma asserted that one of the eight guerrillas from the second group who were captured in Kavangoland was a South African mole. Suspicion immediately fell on Leonard "Castro" Shuuya. SWALA suffered a second major reversal on 18 May 1967, when Tobias Hainyeko, its commander, was killed by the South African police. Heinyeko and his men had been attempting to cross the Zambezi River, as part of a general survey aimed at opening new lines of communication between the front lines in South West Africa and SWAPO's political leadership in Tanzania. They were intercepted by a South African patrol, and the ensuing firefight left Heinyeko dead and two policemen seriously wounded. Rumours again abounded that Shuuya was responsible, resulting in his dismissal and subsequent imprisonment. In the weeks following the raid on Omugulugwombashe, South Africa detained thirty-seven SWAPO politicians, namely Andimba Toivo ya Toivo, Johnny Otto, Nathaniel Maxuilili, and Jason Mutumbulua. Together with the captured SWALA guerrillas, they were jailed in Pretoria and held there until July 1967. All were charged retroactively under the Terrorism Act.
== Diver's harness == The diver's harness is an item of strong webbing, and sometimes cloth, which is fastened around a diver over the exposure suit, and allows the diver to be lifted without risk of falling out of the harness. Several types are in use.
Bukele has threatened incarcerated gang members. At the beginning of the crackdown, he tweeted that the government had seized incarcerated gang members' belongings, removed their mattresses, and rationed their food. Bukele also posted a video of prisoners sleeping on floors and complaining about a lack of food and sanitation. He threatened to deprive them of food entirely in April 2022 if the gangs attempted to retaliate against the crackdown, citing rumors about revenge killings. After members of Barrio 18 killed three police officers in Santa Ana in June 2022, Bukele said at a press conference that the gangs were "going to pay dearly" for the "ambush" against the police. The government began destroying gravestones belonging to deceased gang members in November 2022 to prevent them from becoming "shrines" and Bukele compared the gravestone destructions to denazification in post-World War II Germany. He warned Salvadoran parents to keep their children away from gangs, since they would lead to "prison or death". Shortly after the crackdown began, Bukele called for the construction of a new 20,000-inmate prison. He announced the construction in July 2022 of the 40,000-inmate Terrorism Confinement Center (CECOT) in Tecoluca, that would be one of the world's largest prisons. In February 2023, Bukele posted a video on Twitter of him and members of his cabinet touring the prison. It is staffed by 250 police officers and 600 soldiers, and covers 410 acres (170 ha).
Sources: en.wikipedia.org
==== Measures of fractionation ==== The study of HIBGC relies on the fact that various physicochemical processes preferentially enrich or deplete 2H relative to 1H (see kinetic isotope effect [KIE], etc.). Various measures have been developed to describe the fractionation in an isotope between two pools, often the product and reactant of a physiochemical process. α notation describes the difference between two hydrogen pools A and B with the equation:
The following month an attempted coup d'état was staged by a sector of the army that sought to paralyze the democratic process and that only the decisive intervention of King Juan Carlos I managed to stop. After 23-F, the new UCD government presided by Leopoldo Calvo Sotelo managed to rule largely thanks to the support given by the PSOE and its leader Felipe González because the "self-destruction" of the UCD continued until October 1982, when new elections were held and were won overwhelmingly by the PSOE. Thus a party that had been one of the defeated parties in the civil war of 1936–1939 took power. After 1982, the democratic system was consolidated and Spain experienced a long period of political stability in which there was alternation in government between the left and the right in a peaceful manner following the dictates of the elections (the PSOE governed between 1982 and 1996 and between 2004 and 2011; the People's Party, which emerged from the "refounding" in 1989 of the Alianza Popular, between 1996 and 2004 and between 2011 and 2014). It was decisive for the achievement of political stability that the positions of the two major parties on the most important issues were not antagonistic and that there were no major "social fractures", the latter thanks to the development of the Welfare state and "social protection" policies. Also during those years, Spain actively participated in the transformation of the European Community, which it joined in 1986, in the European Union and in the establishment of the common currency, the euro.
A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. The tests are classified by speciality field, conveying in which ward of a hospital or by which specialist doctor these tests are usually performed. The ICD-10-CM is generally the most widely used standard by insurance companies and hospitals who have to communicate with one another, for giving an overview of medical tests and procedures. It has over 70,000 codes. This list is not exhaustive but might be useful as a guide, even though it is not yet categorized consistently and only partly sortable.
Isobutyrylfentanyl is an opioid analgesic that is an analog of fentanyl and has been sold online as a designer drug. It is believed to be around the same potency as butyrfentanyl but has been less widely distributed on illicit markets, though it was one of the earliest of the "new wave" of fentanyl derivatives to appear, and was reported in Europe for the first time in December 2012.
Coordination of international air cargo is an essential component of time- and temperature-sensitive distribution of COVID‑19 vaccines, but, as of September 2020, the air freight network is not prepared for multinational deployment. "Safely delivering COVID‑19 vaccines will be the mission of the century for the global air cargo industry. But it won't happen without careful advance planning. And the time for that is now. We urge governments to take the lead in facilitating cooperation across the logistics chain so that the facilities, security arrangements and border processes are ready for the mammoth and complex task ahead," said IATA's Director General and CEO, Alexandre de Juniac, in September 2020. For the severe reduction in passenger air traffic during 2020, airlines downsized personnel, trimmed destination networks, and put aircraft into long-term storage. As the lead agencies for procurement and supply of the COVID‑19 vaccine within the WHO COVAX facility, GAVI and UNICEF are preparing for the largest and fastest vaccine deployment ever, necessitating international air freight collaboration, customs and border control, and possibly as many as 8,000 cargo planes to deliver just one vaccine dose to multiple countries. Two of the first approved vaccines, Pfizer and BioNTech's Pfizer-BioNTech COVID‑19 vaccine and Moderna's mRNA-1273, must be kept cold during transport.
Sources: en.wikipedia.org
No. Epithalamin is a peptide-containing extract of bovine pineal glands, while epitalon is a single synthetic tetrapeptide. The extract contains many peptides and other tissue components, so its composition varies between batches in ways that a synthesised sequence does not.
It is not recognised as an endogenous peptide hormone. The four-residue sequence can appear inside larger proteins and in digestive fragments of dietary protein, but no dedicated pathway producing it as a signalling molecule has been identified.
Several cell-culture reports describe increased telomerase activity after treatment, measured by enzyme assays or by transcript levels. Results differ between cell types and laboratories, and measured telomere lengthening has been reported in some studies but not in others, which leaves the physiological relevance open.
Epitalon is a synthetic tetrapeptide built from four amino acids: alanine, glutamate, aspartate, and glycine. It is not extracted from a natural source but made in the laboratory by chemical synthesis. Its short length makes it relatively straightforward to produce at high purity.