tetrapeptide 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.
Last reviewed on 2026-01-13. Where a claim depends on a specific study, the study is described rather than over-claimed.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
The most widely cited claim is that epitalon activates telomerase and thereby extends telomere length. Supporting evidence comes largely from cultured human cells, where treatment was associated with increased telomerase activity and delayed replicative senescence. Telomerase activation is a biologically consequential effect, since the enzyme is largely silenced in most somatic cells. However, the route by which a short peptide would reach and act on the enzyme's regulatory machinery has not been established. Independent replication in human trials is scarce, so the link between cell-culture observations and whole-body aging remains an open question.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Linear tetrapeptide | Four residues joined by three peptide bonds |
| Sequence | Ala-Glu-Asp-Gly | Commonly abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free acid form |
| Monoisotopic mass | Approximately 390 Da | Matches values reported from mass spectrometry |
| Net charge near neutral pH | Negative | Contributed by glutamate and aspartate side chains |
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.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
On 31 December 2021, in a speech, al-Burhan said he was committed to "building all the institutions of transitional government and holding free, fair, and transparent elections at their scheduled time", in July 2023. Both al-Burhan and Hemedti had ties to Vladimir Putin's government in Russia. According to Business Insider, "The two generals helped Russian President Vladimir Putin exploit Sudan's gold resources to help buttress Russian finances against Western sanctions and fund his war in Ukraine." On 9 February 2023, al-Burhan met with Russian Foreign Minister Sergey Lavrov. On 2 January 2022, Abdalla Hamdok resigned from his post of prime minister and Osman Hussein was sworn in as acting prime minister. On 4 July 2022, it was reported that al-Burhan mentioned the army will withdraw from the ongoing political talks and will allow political and revolutionary groups to form a transitional civilian government. This statement followed recent pro-democracy protests where 117 people were killed. On 10 November 2023, al-Burhan condemned Israel's actions in the Gaza Strip during the Gaza war, saying that "We declare our full solidarity with the Palestinian people and their right to establish their legitimate state on the 1967 borders." On 16 January 2025, the U.S. Treasury Department imposed sanctions on al-Burhan. According to sources the reasons were: "targeting of civilians and civilian infrastructure and denial of aid access, as well as refusal to participate in peace talks".
Southern Kuriles / Northern Territories: A Stumbling-block in Russia-Japan Relationship, history and analysis by Andrew Andersen, Department of Political Science, University of Victoria, May 2001 http://depts.washington.edu/ikip/index.shtml (Kuril Island Biocomplexity Project) Kuril Islands at Ocean Dots.com at the Wayback Machine (archived 23 December 2010) (includes space imagery) Kuril Islands at Natural Heritage Protection Fund The International Kuril Island Project http://www.mofa.go.jp/region/europe/russia/territory/index.html Chishima: Frontiers of San Francisco Treaty in Hokkaido Short film on the disputed islands from a Japanese perspective USGS Map showing location of Magnitude 8.3 Earthquake 46.616°N, 153.224°E Kuril Islands region, November 15, 2006 11:14:16 UTC Pictures of Cats – Kurilian Bobtail Pictures of Kuril Islands Kuril Islands at Encyclopædia Britannica
Founded in 1984, Bio-Synthesis, Inc. was known as OCS Laboratories and was one of the first companies providing commercially available synthetic oligonucleotides to the biomedical research community worldwide. It was the first producer of commercially available synthetic DNA and became a producer of synthetic peptides in 1985, and became the only company to provide both synthetic DNA and peptide under one roof. Also in 1985 the process, now known as PCR, was discovered by Mullis et al. A key activity for Bio-Synthesis was to synthesize large number of PCR primer thus assisting and solidifying the early adoption of this now common and crucial process in biology.
Sources: en.wikipedia.org
== Contraindications == Under the US approval, ertugliflozin is contraindicated for people with severe kidney failure, end-stage renal disease, and dialysis. The European Union approval does not list any contraindications apart from hypersensitivity to the drug, which is standard for all drug approvals.
James Sherr, head of Russia and Eurasia Programme at Chatham House, wrote in The Telegraph: "The current crisis demonstrates that the Cold War has not been replaced by common values between East and West, but by the revival of hard Realpolitik. [...] Mikhail Saakashvili, Georgia's President, might have been profoundly unwise to employ massive force against the pro-Russian separatists in South Ossetia last Thursday, but his lapses of judgement are not the point. The commanders of Russian forces and their political masters in the Kremlin hoped he would behave exactly as he did. [...] Ukraine has no territorial conflicts, but it has a potential territorial dispute, Crimea." On 10 August 2008, Quentin Peel wrote in the Financial Times, "Saakashvili boosted military spending and refused to rule out the use of force. But he did not intend to use it. By all accounts he was unprepared for the latest confrontation: he was booked to be on a flight to Beijing." On 11 August 2008, The New York Times noted Putin's strong personal enmity towards Georgian president Saakashvili. On 11 August 2008, Robert Kagan wrote that the war was not a result of a "miscalculation" by Georgia, but "revanchist" Russia's attempt to respond to revolutions in Georgia and Ukraine.
=== Clinical examination === Nipple pain is a symptom with many possible causes. A thorough maternal breast and infant mouth inspection can help identify the specific cause and thus assign the appropriate treatment. A maternal nipple examination can be used to diagnose traumatic factors including nipple fissure, nipple blisters and infections with prominent symptoms. A breast biopsy detecting breast mass can diagnose for breast engorgement. If a breast mass is present, a core needle biopsy and diagnostic imaging are required for further assessment of underlying causes, including mastitis, blocked milk ducts, cancers and benign breast tumours called lactating adenoma. By checking the infant mouth, causes like tongue-tie, candidiasis and abnormal tongue motion can be diagnosed.
Sources: en.wikipedia.org
This algorithm is used to identify the specific type of CAD events based on the surface pressure ridge, its associated cold dome, and ageostrophic northeasterly flow which flows at a significant angle to the isobaric pattern. These values are calculated using hourly data from surface weather observations. The Laplacian of sea level pressure or potential temperature in the mountain-normal—perpendicular to the mountain chain—direction provides a quantitative measure of the intensity of a pressure ridge or associated cold dome. The detection algorithm is based upon Laplacians (
Opicapone, sold under the brand name Ongentys, is a medication which is administered together with levodopa in people with Parkinson's disease. Opicapone is a catechol-O-methyltransferase (COMT) inhibitor. The most common side effects are dyskinesia (difficulty controlling movement), constipation, increased blood creatine kinase, hypotension/syncope, and decreased weight. Opicapone, works to restore the levels of dopamine in the parts of the brain that control movement and coordination. It enhances the effects of levodopa, a precursor of the neurotransmitter dopamine that can be taken by mouth. Opicapone blocks an enzyme that breaks down levodopa in the body called catechol-O-methyltransferase (COMT). It is peripherally selective and does not inhibit COMT in the brain. As a result of its COMT inhibition, levodopa remains active for longer. This helps to improve the symptoms of Parkinson's disease, such as stiffness and slowness of movement. In June 2016, it was authorised for use in the European Union. It was authorised for use in the United States in April 2020.
In addition to reworking Xen from scratch, as the team members got closer to release, they recognized they saw the game more as an entry for new players into the Half-Life series, and worked to introduce designs and features that would be more appropriate a decade since Half-Life's release. They made combat more interesting by improving the enemy's artificial intelligence while creating combat areas with more cover and options for the player. Because of their expansion of Xen, they also wanted to make sure players were not slowed down in the earlier parts of the game, and made redesigns in some of these levels. The release of Xen in the early access version of Black Mesa had been pushed off a few times; initially planned for a December 2017 release, a beta version of a segment of the remade Xen was released in June 2019 for stress-testing by players The full beta was released on December 6, 2019. Additional Xen levels were added over time, and by December 24, 2019, the full Xen chapter was released as part of the game's early access. The finished Black Mesa was released for Windows on March 6, 2020. By chance, this release was about two weeks before Valve's official return to the Half-Life universe after 13 years with the virtual reality game Half-Life: Alyx. Black Mesa project lead Adam Engels said this was not intentional as they had planned to have Black Mesa out earlier, but the attention to Alyx had helped to boost interest in Black Mesa.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, often abbreviated AEDG. The molecule is linear and contains no modified residues, so it is fully described by its sequence.
The compound came out of work on epithalamin, a peptide preparation derived from pineal tissue, conducted largely in Russian laboratories. Later studies in other countries examined it mainly in cell cultures and animal models.
The tetrapeptide sequence is a synthetic construct rather than a described circulating peptide. It was derived by analogy to peptide fractions obtained from tissue extracts, not isolated from blood or tissue as such.
Vladimir Khavinson and colleagues at research institutes in Saint Petersburg developed and studied the peptide. Their program examined short peptides as regulators of aging and neuroendocrine function. Epitalon was one of several compounds produced by that group.