If you have been reading about Replicative senescence 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 2026-08-01. Numbers and descriptions here follow the published literature rather than marketing material.
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
Short peptides such as AEDG are normally supplied as a freeze-dried solid and are kept dry, cold, and shielded from light. Holding at minus twenty degrees Celsius is common for the long term, while a refrigerator suffices for brief periods before use. The material takes up moisture to some degree, so containers should stay sealed and be allowed to reach room temperature before opening, which limits condensation on the contents. Repeated warming and cooling of a single container is discouraged because it admits water and can lower the amount of intact peptide.
The four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
Interest in epitalon is usually discussed within the broader field of short peptide bioregulators, a category that includes other synthetic di-, tri-, and tetrapeptides studied by the same research group. These compounds share a common rationale: that small fragments of tissue-derived proteins can retain biological activity and can be produced reproducibly. The category as a whole remains outside mainstream pharmacological consensus, and epitalon specifically has a limited presence in independent, non-Russian research literature, which shapes how its evidence base is described.
| Property | Value | Notes |
|---|---|---|
| Sequence | Ala-Glu-Asp-Gly | Written in three-letter amino acid code |
| Single-letter code | AEDG | Form used in most catalogue entries |
| Typical purity specification | 95 percent or higher | Value read from the HPLC chromatogram |
| Storage, dry solid | Minus 20 degrees Celsius, desiccated | Sealed container, protected from light |
| Handling, solution | Divide into single-use portions | Limits losses from freeze-thaw cycling |
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
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.
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.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
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.
The climate of mainland Portugal and Madeira, together with their surrounding waters, is Mediterranean, whereas the Azores and its adjacent waters mainly have a temperate oceanic climate. Portugal's terrain has a diverse variety of regional climates for its size. The average temperature in Portugal varies from 4–20 °C (39.2–68.0 °F) in the mainland, around 18 °C (64.4 °F) in the Azores, and 9–19 °C (48.2–66.2 °F) in Madeira. The Iberian Peninsula is located at the southern margin of the temperate zone and at the northern margin of the subtropical high-pressure zone. Additionally, Portugal's climate is influenced by the seasonal latitudinal shift of the jet stream, which directly impacts the trajectory of the polar front. Typically in the winter, the jet stream moves southwards and Portugal comes under the influence of the polar front, producing colder temperatures. When the polar front moves northward, Portugal comes under the influence of the Azores High bringing atmospheric stability during the summer. Upwelling occurs at the coast creating the Nortada, a summer wind along the coast. Wildfires are a serious challenge in Portugal, with nearly 30% of those recorded in 2024 having an undetermined origin and arson accounting for almost five-sixths of the total burned area. Between 2014 and 2024, Portugal recorded an annual average of 12,496 fires and 112,455 ha (434 sq mi) burned, making it the European Union country with both the highest average number of wildfires and the greatest average burned area over that period.
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Half Bad is a 2014 young adult fantasy novel written by English author Sally Green. It won the 2015 Waterstones Teen Book Prize and was shortlisted for the 2015 Branford Boase Award. On 3 March 2014, the book set the Guinness World Record as the 'Most Translated Book by a Debut Author, Pre-publication', having sold in 45 languages prior to its UK publication by Penguin books.
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Both the new Law of Political Parties and the process of illegalization of Batasuna were strongly contested by the Basque nationalist parties and, as an alternative, the lehendakari Juan José Ibarretxe proposed a "pacification plan" based on the holding of a referendum regulating "the free association of Euskadi to the plurinational Spanish State". By the end of 2003, the tension between the central government and the "peripheral" nationalisms moved to Catalonia as a result of the formation of a left-wing "tri-party" government after the Catalan elections of November 2003 consisting of the Socialists' Party of Catalonia (PSC), Republican Left of Catalonia (ERC, a pro-independence party that had experienced a meteoric rise), and Initiative for Catalonia Greens (a party associated with United Left) and presided by the socialist Pasqual Maragall. The "Tinell Pact" of the PSC-PSOE, IC and ERC (in which the "tri-party" program was agreed, expressly excluding any agreement with the PP) was harshly criticized by the Aznar government and by the new PP leader Mariano Rajoy ─ who at the end of August 2003 had been proposed by Aznar to replace him as candidate in the following year's elections. By the end of January 2004, a scandal broke out that shook the "tri-party" government. In its 24th edition, the newspaper "ABC" published that the leader of ERC, Josep Lluís Carod Rovira, conseller en cap of the Generalitat, had met in Perpignan with the top leadership of ETA to negotiate an exclusive truce for Catalonia.
Sources: en.wikipedia.org
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Euphorbia caducifolia is a subtropical succulent species of flowering plant in the spurge family Euphorbiaceae. It is found in the arid regions of northwestern Indian subcontinent. In India it is known as the leafless milk hedge.
Labour Party leader Sir Keir Starmer publishes details of his tax returns, a day after the prime minister. The Westminster Parliament announces that the TikTok app will be banned on "all parliamentary devices and the wider parliamentary network". The British Medical Association announces that junior doctors in England will stage a four-day strike from 11 to 15 April in their continued quest for a 35% pay rise. England footballer Harry Kane becomes the England national football team all-time leading goalscorer with 54 goals in a 2–1 win vs Italy national football team, surpassing the previous record of 53 goals held by Wayne Rooney, who broke the record back in September 2015. 24 March Charles III's state visit to France, his first official overseas visit as King, is postponed following a request by French president Emmanuel Macron after unions threatened to stage a day of protests over pension reforms during his visit. MPs vote to back the Protection from Sex-based Harassment in Public Bill, which will make catcalling, following someone or blocking their path an offence in England and Wales with a punishment of up to two years in prison. COVID-19 in the UK: The final Coronavirus Infections Survey is published by the Office for National Statistics, with data for the week up to 13 March. It shows an increase in COVID-19 cases for England, but an uncertain picture for the rest of the UK.
This is a timeline of women in science, spanning from ancient history up to the 21st century. While the timeline primarily focuses on women involved with natural sciences such as astronomy, biology, chemistry, and physics, it also includes women from the social sciences (e.g. sociology, psychology), and the formal sciences (e.g. mathematics, computer science), as well as notable science educators and medical scientists. The chronological events listed in the timeline relate to both scientific achievements and gender equality within the sciences.
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Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography is run alongside mass spectrometry. The chromatogram separates components and gives a purity figure, while the mass spectrum confirms that the measured molecular mass matches the expected sequence. Neither measurement on its own is treated as sufficient.
Long-term holding is usually at minus twenty degrees Celsius in a sealed, desiccated container. A refrigerator is adequate for short intervals before use. Light exposure is normally avoided as well. Allowing a cold container to warm before opening reduces moisture condensation on the contents.
Repeated cycles are generally avoided. Each freeze and thaw can promote aggregation or loss of peptide to container surfaces, which reduces the amount available for later work. Dividing a solution into single-use portions at the outset is the usual way to limit this problem.
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.