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 2026-02-05. Numbers and descriptions here follow the published literature rather than marketing material.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised and often hygroscopic |
| Solubility class | Freely soluble in water | Poor solubility in non-polar solvents |
| Typical storage temperature | -20 degrees Celsius or colder | Sealed, desiccated, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Establishes purity and confirms mass |
| Common salt form | Trifluoroacetate or acetate | Counterion reported alongside purity values |
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.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
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.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
The most frequently cited laboratory finding is that AEDG increased telomerase activity and extended telomere length in cultured human somatic cells. That work used fetal fibroblast strains and reported changes in enzyme activity alongside altered division counts. Replication by unrelated groups has been limited, and the published record is largely a single-laboratory series rather than a multi-centre programme. The result supports a hypothesis about peptide influence on gene expression in cell culture; it does not by itself establish an effect on telomere length in living animals or in people.
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.
==== Diverse food sourcing ==== Diverse sourcing of food, such as through international trade, is a key strategy for building agrifood systems' resilience because it buffers the food supply against shocks and stresses. The volume of agrifood trade more than doubled between 2000 and 2024. Although international trade buffers against domestic shocks, it increases exposure to external shocks and can itself become a channel of shock transmission, therefore having diverse international trade partners is key. Enhancing diversity in terms of commodities is also essential for ensuring the supply of food necessary for healthy diets. However, evidence on the diversity of food supply in terms of domestic production, imports and stocks reveal that the potential of international trade is not equally well exploited in all countries. Low-income countries, such as in sub-Saharan Africa, are among those with the lowest diversity of imports as the food supply is mostly determined by what is produced for the domestic market.
== Scientific societies == The Society for Cryobiology was founded in 1964 to bring together those from the biological, medical, and physical sciences who have a common interest in the effects of low temperatures on biological systems. As of 2007, the Society for Cryobiology had about 280 members from around the world, and one-half of them are US-based. The purpose of the Society is to promote scientific research in low temperature biology, to improve scientific understanding in this field, and to disseminate and apply this knowledge to the benefit of mankind. The Society requires of all its members the highest ethical and scientific standards in the performance of their professional activities. According to the Society's bylaws, membership may be refused to applicants whose conduct is deemed detrimental to the Society; in 1982, the bylaws were amended explicitly to exclude "any practice or application of freezing deceased persons in the anticipation of their reanimation", over the objections of some members who were cryonicists, such as Jerry Leaf. The Society organizes an annual scientific meeting dedicated to all aspects of low-temperature biology. This international meeting offers opportunities for presentation and discussion of the most up-to-date research in cryobiology, as well as reviewing specific aspects through symposia and workshops. Members are also kept informed of news and forthcoming meetings through the Society newsletter, News Notes. The 2011–2012 president of the Society for Cryobiology was John H. Crowe.
1998 A record for the duration of life among males. The Danish-American Christian Mortensen lived 115 years and 252 days. 1998 Scientists managed to extend, in a laboratory environment, the life of normal human cells beyond the Hayflick limit using telomerase. 1999 Establishment of the Buck Institute for Research on Aging – the first institute originally established primarily to study intervention into the aging process. 1999 Sierra Sciences, a biotechnology company focused on aging research with the goal of curing human aging, was founded by William H. Andrews.
Sources: en.wikipedia.org
== Life == Ogston was educated at Eton College and Balliol College, Oxford. Apart from a period as Freedom Research Fellow at the London Hospital, he spent most of his career at Oxford, being appointed Demonstrator (1938) and Reader (1955) in Biochemistry, and Fellow and Tutor in Physical Chemistry at Balliol (1937). In that capacity he had a major influence on other distinguished scientists, such as the Nobel prizewinner Oliver Smithies, who wrote his first paper with him, and Richard Dawkins, who chose to study zoology on his recommendation. In 1959 he took up an appointment as Professor of Physical Biochemistry at the John Curtin School of Medical Research at the Australian National University (ANU), Canberra, where he remained until 1970, when he returned to Oxford as President of Trinity College. On his retirement in 1978, he held visiting fellowships at the Institute for Cancer Research, Philadelphia and the John Curtin School of Medical Research, ANU. Ogston was elected FRS in 1955, and was awarded Lemberg Medal in 1970 and the Davy Medal in 1986.
== Etymology == The word muscle comes from Latin musculus, diminutive of mus meaning mouse, because the appearance of the flexed biceps resembles the back of a mouse. The same etymology is found in Greek, in which μῦς, mȳs, means both "mouse" and "muscle".
== Veterinary medicine == Tramadol was the most common opioid prescribed by American veterinarians from 2014 to 2019; however, usage has declined in subsequent years due to more recent evidence suggesting that dogs do not metabolise tramadol into O-desmethyltramadol effectively. As metabolisation of tramadol relies on cytochrome P450 enzymes, it is species dependent and even individual genetics can have a profound impact on the efficacy of tramadol. A 2021 meta-analysis of tramadol use in dogs found that although tramadol was more effective than nalbuphine and codeine, it was less effective than methadone, COX inhibitors and multimodal analgesia with poor evidence to support the use of it is an analgesic for dogs. The mean alveolar concentration sparing effect of tramadol is negligible and with a high likelihood of rescue analgesia being required thus tramadol monotherapy is not recommended for the dog. One study looking at tramadol and meloxicam administered preoperatively provided no benefit compared to meloxicam given alone. Another study looking at cimicoxib versus tramadol for long-term post-operative pain following a tibial-plateau-levelling osteotomy found that although the level of analgesia was similar cimicoxib resulted in better mobility and a lower incidence of hock oedema. These studies and other evidence suggest that non-steroidal anti-inflammatory drugs provide superior analgesia to tramadol in dogs. Tramadol is more effective in cats although oral tramadol is poorly tolerated leading to low compliance.
The crests and frills of some dinosaurs, like the marginocephalians, theropods and lambeosaurines, may have been too fragile to be used for active defense, and so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and territorialism. Head wounds from bites suggest that theropods, at least, engaged in active aggressive confrontations.
Sources: en.wikipedia.org
== Overdose == Doses of methenamine much higher than usual have been clinically studied and found to produce significant toxicity. More specifically, doses of 8 g per day (4–8-fold usual doses) for 3 to 4 weeks resulted in bladder irritation, painful and frequent urination, albuminuria (albumin in urine), crystalluria (crystals in urine), and hematuria (blood in urine). Some of these side effects are thought to be due to high levels of formaldehyde in the bladder and consequent irritation. Doses of methenamine of up to 10 to 20 g/day have also been studied and found to be tolerable without major toxicity. When methenamine was first introduced in the late 1800s and early 1900s, doses of 15 to 30 g per day were commonly employed and doses of up to 60 to 180 g per day were tried in some cases. Toxic effects of such high doses included urinary tract and bladder irritation, frequent urination, strangury, and hematuria. Animal studies employing double the modern human dosage of methenamine for 6 to 12 months found no adverse effects.
Since 1978, Lagin's primary life and creativity has been in photography and art. Lagin began photography in 1953, at the age of five, starting with a Baby Brownie camera. With that camera he made his first photographs at the Bronx Zoo of animals sadly in bare cages, photographs which his mother had developed and printed, and he then put together in his first "book". From childhood, and continuing through to the beginning of college, photography, "picture-making", and "picturing" was part of being an amateur naturalist and scientist and grew from his love and fascination with nature, with natural history drawings, maps, and electronic and scientific drawings and schematics. Growing up near New York City in the 1950's and 1960's, Lagin spent a great amount of time looking at dioramas, pictures, exhibits, displays, reconstructions, models, and galleries at the American Museum of Natural History, the Metropolitan Museum of Art, the Museum of Modern Art, and other museums and art galleries. The wide range of photography and art influences and inspirations for Lagin include Ansel Adams, Elliot Porter, Walker Evans, Edward Weston, the natural history books by Rachel Carson, Life magazine and The World We Live In, and National Geographic. as well as by the 20th century artists Juan Miro, Paul Klee and others, and the intent (but not the style) of 19th Century American landscape painters who portrayed nature as "a revelation of spiritual meaning" placing small figures (animals, humans) "in large transcendental landscapes”.
=== Nationalization === After the U.S. entered World War I, due to its German connections, Merck & Co. was the subject of expropriation under the Trading with the Enemy Act of 1917. The government seized 80 percent of the shares owned by the German parent company and sold it. In 1919, George F. Merck (head of the American branch of the Merck family), in partnership with Goldman Sachs and Lehman Brothers, bought the company back at a U.S. government auction for $3.5 million, but Merck & Co. remained a separate company from its former German parent. Merck & Co. holds the trademark rights to the "Merck" name in the United States and Canada, while its former parent company retains the rights in the rest of the world; the right to use the Merck name was the subject of litigation between the two companies in 2016. In 1925, George W. Merck succeeded his father George F. Merck as president. In 1927, the corporation merged with the Powers-Weightman-Rosengarten Company, a Philadelphia quinine manufacturer. George Merck remained president and Frederic Rosengarten became chairman of the board. In 1929, H. K. Mulford Company merged with Sharp and Dohme, Inc. and brought vaccine technology, including immunization of cavalry horses in World War I and delivery of a diphtheria antitoxin to Merck & Co. In 1943, streptomycin was discovered during a Merck-funded research program in Selman Waksman's laboratory at Rutgers University. It became the first effective treatment for tuberculosis.
Sources: en.wikipedia.org
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase HPLC establishes purity and separation from related peptides, and mass spectrometry confirms the molecular mass. Amino acid analysis can verify residue composition. No single method proves identity on its own, so the results are read together.
Yes. Residual trifluoroacetate or acetate from purification adds mass and can shift the value obtained by certain assays. Purity figures are therefore meaningful only when the counterion form is stated. Reporting both peptide content and salt form gives a clearer picture.
It is a synthetic tetrapeptide built from alanine, glutamate, aspartate and glycine. The four residues are joined by standard peptide bonds, giving a linear chain rather than a branched structure.