Everything below concerns counter-ion. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-12-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
Verification of a sample usually begins with reversed-phase high-performance liquid chromatography, which resolves the peptide from truncated sequences and other impurities and expresses purity as a percentage of total peak area. Mass spectrometry by electrospray ionisation or matrix-assisted laser desorption supplies an independent check, because the measured mass can be compared against the theoretical value for AEDG. Amino acid analysis or tandem mass spectrometry sequencing can confirm residue order. Each of these methods answers a different question: a purity figure does not establish identity, and an identity match does not establish how much of the material is intact peptide.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four-residue sequence |
| Molar mass | About 390.35 g/mol | Free peptide, counter-ion not included |
| Appearance | White to off-white powder | Lyophilised solid from aqueous solution |
| Water solubility | Freely soluble | Short, polar peptide chain |
| Common synonyms | AEDG; epithalone | Catalogues use the names interchangeably |
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.
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.
== Further reading == Timeline of Materials Science Archived 2011-07-27 at the Wayback Machine at The Minerals, Metals & Materials Society (TMS) – accessed March 2007 Burns, G.; Glazer, A.M. (1990). Space Groups for Scientists and Engineers (2nd ed.). Boston: Academic Press, Inc. ISBN 978-0-12-145761-7. Cullity, B.D. (1978). Elements of X-Ray Diffraction (2nd ed.). Reading, Massachusetts: Addison-Wesley Publishing Company. ISBN 978-0-534-55396-8. Giacovazzo, C; Monaco HL; Viterbo D; Scordari F; Gilli G; Zanotti G; Catti M (1992). Fundamentals of Crystallography. Oxford: Oxford University Press. ISBN 978-0-19-855578-0. Green, D.J.; Hannink, R.; Swain, M.V. (1989). Transformation Toughening of Ceramics. Boca Raton: CRC Press. ISBN 978-0-8493-6594-2. Lovesey, S. W. (1984). Theory of Neutron Scattering from Condensed Matter; Volume 1: Neutron Scattering. Oxford: Clarendon Press. ISBN 978-0-19-852015-3. Lovesey, S. W. (1984). Theory of Neutron Scattering from Condensed Matter; Volume 2: Condensed Matter. Oxford: Clarendon Press. ISBN 978-0-19-852017-7. O'Keeffe, M.; Hyde, B.G. (1996). "Crystal Structures; I. Patterns and Symmetry". Zeitschrift für Kristallographie – Crystalline Materials. 212 (12). Washington, DC: Mineralogical Society of America, Monograph Series: 899. Bibcode:1997ZK....212..899K. doi:10.1524/zkri.1997.212.12.899. ISBN 978-0-939950-40-9.{{cite journal}}: CS1 maint: periodical has ISBN (link) Squires, G.L. (1996). Introduction to the Theory of Thermal Neutron Scattering (2nd ed.). Mineola, New York: Dover Publications Inc. ISBN 978-0-486-69447-4.
degree and to have substantial published research. Transfer to general practice or a less favoured specialty could be made at any stage along this pathway: Lord Moran famously referred to general practitioners as those who had "fallen off the ladder". There were also permanent non-training posts at sub-consultant level: previously senior hospital medical officer and medical assistant (both obsolete) and now staff grade, specialty doctor and associate specialist. The regulations did not call for much experience or any higher qualifications, but in practice both were common, and these grades had high proportions of overseas graduates, ethnic minorities and women. Research fellows and PhD candidates were often clinical assistants, but a few were senior or specialist registrars. A large number of "Trust Grade" posts had been created by the new NHS trusts for the sake of the routine work, and many juniors had to spend time in these posts before moving between the new training grades, although no educational or training credit was given for them. Holders of these posts might work at various levels, sharing duties with a junior or middle grade practitioner or with a consultant. In 2005, the structure of medical training was reformed when the Modernising Medical Careers (MMC) reform programme was instituted. House officers and the first year of senior house officer jobs were replaced by a compulsory two-year foundation training programme, followed by competitive entry into a formal specialty-based training programme.
== Early life and education == Phil S. Baran was born in Denville, New Jersey, on August 10, 1977, and grew up in Coral Springs, Florida. He was not a strong academic student in high school, but developed early interests in creative pursuits like role-playing games, computer programming, and Lego building. Encouraged by his chemistry teacher to experiment after school, Baran quickly channeled his creativity into crafting molecules. In 1995 he began a chemistry degree at New York University, and enthusiastically accepted David Schuster's offer to work in his lab, synthesizing compounds that linked C60 with porphyrins to make artificial photosynthetic systems. He received his BS in chemistry from New York University in 1997. He went on to earn his PhD from The Scripps Research Institute in 2001, under the supervision of K. C. Nicolaou, an experience he recalls was 'like hardcore Navy Seal training' and where he co-authored 30 papers in less than four years. He then pursued a postdoctoral fellowship in the laboratory of Nobel Laureate Elias James Corey at Harvard University who reflected on Baran's time in his lab, saying, "He had a phenomenal grasp of synthetic chemistry," and "felt that he could be a leader in his generation." Baran is married to Mariana Baran and has four children.
Sources: en.wikipedia.org
The endocrine glands belong to the body's control system. The hormones which they produce help to regulate the functions of cells and tissues throughout the body. Endocrine organs are activated to release their hormones by humoral, neural, or hormonal stimuli. Negative feedback is important in regulating hormone levels in the blood. The nervous system, acting through hypothalamic controls, can in certain cases override or modulate hormonal effects.
As long as the strategic American nuclear forces could overwhelm their Soviet counterparts, a Soviet pre-emptive strike could be averted. Moreover, the Soviet Union could not afford to build any reasonable counterforce, as the economic output of the United States was far larger than that of the Soviets, and they would be unable to achieve "nuclear parity". Soviet nuclear doctrine, however, did not match American nuclear doctrine. Soviet military planners assumed they could win a nuclear war. Therefore, they expected a large-scale nuclear exchange, followed by a "conventional war" which itself would involve heavy use of tactical nuclear weapons. American doctrine rather assumed that Soviet doctrine was similar, with the mutual in mutually assured destruction necessarily requiring that the other side see things in much the same way, rather than believing—as the Soviets did—that they could fight a large-scale, "combined nuclear and conventional" war. In accordance with their doctrine, the Soviet Union conducted large-scale military exercises to explore the possibility of defensive and offensive warfare during a nuclear war. The exercise, under the code name of "Snowball", involved the detonation of a nuclear bomb about twice as powerful as that which fell on Nagasaki and an army of approximately 45,000 soldiers on maneuvers through the hypocenter immediately after the blast. The exercise was conducted on September 14, 1954, under command of Marshal Georgy Zhukov to the north of Totskoye village in Orenburg Oblast, Russia.
=== Antigen recognition === Garcia's earliest research as a graduate student at Johns Hopkins University focused on understanding how anti-idiotyopic antibodies recognize peptide antigens. As a postdoctoral scholar at The Scripps Research Institute, Garcia conducted a groundbreaking study that revealed how T cells of the immune system survey peptides presented by major histocompatibility complex proteins (MHC), thus allowing them to distinguish between "self" and "non-self". Garcia's research led to the first visualization of a T cell receptor (TCR) bound to a peptide-MHC (pMHC) complex and was published in the journal Science in 1996. Garcia's 1996 article on the TCR-MHC interaction has had broad impact in the fields of immunology and immunotherapy. At Stanford University, the Garcia Laboratory reported the structure of the pre-B cell receptor (pre-BCR) in 2007, which revealed how pre-BCRs oligomerize to signal in the absence of antigen. Garcia's group has also authored several additional landmark articles exploring various aspects of TCR-pMHC interactions, including the first structure of a γδ TCR-pMHC complex, the molecular basis for dual recognition of "self" and "foreign" MHCs by TCRs, insights into the germline basis of TCR/MHC interactions, the extent of cross-reactivity in the TCR repertoire, and elucidation of the structural trigger for TCR signaling. In Garcia's most recent work, his lab developed a peptide-MHC library technology that has enabled the discovery of antigens for orphan T cell receptors, such as those resident in tumors.
Sources: en.wikipedia.org
== History == Dialkylbiaryl phosphine ligands were first described by Stephen L. Buchwald in 1998 for applications in palladium-catalyzed coupling reactions to form carbon-nitrogen and carbon-carbon bonds. Before their development, use of first- or second-generation phosphine ligands for Pd-catalyzed C-N bond-forming cross-coupling (e.g., tris(o-tolyl)phosphine and BINAP, respectively) necessitated harsh conditions, and the scope of the transformation was severely limited. The Suzuki-Miyaura and Negishi cross-coupling reactions were typically performed with Pd(PPh3)4 as catalyst and were mostly limited to aryl bromides and iodides at elevated temperatures, while the widely available aryl chlorides were unreactive. Dialkylbiaryl phosphine ligands are sometimes referred to as the "Buchwald ligands."
The city was procuring only electric buses as of 2021, gradually replacing the diesel bus fleet. Moscow was expected to become the leading European city in its share of electric versus gas fuel in public transit by 2019.
==== Geochemistry ==== Corals are shallow, colonial organisms that integrate oxygen and trace elements into their skeletal aragonite (polymorph of calcite) crystalline structures as they grow. Geochemical anomalies within the crystalline structures of corals represent functions of temperature, salinity and oxygen isotopic composition. Such geochemical analysis can help with climate modeling. The ratio of oxygen-18 to oxygen-16 (δ18O), for example, is a proxy for temperature.
== Bibliography == Michel Demopoulos, directeur de publication, Le Cinéma grec [Greek Cinema], Paris, Centre Georges Pompidou, collection «cinéma/pluriel,» 1995, 263 pages, ISBN 2858508135. (in French) Vrasidas Karalis, A History of Greek Cinema, New York, New York and London, Continuum International Publishing Group, 2012, 344 pages, ISBN 978-1-4411-9447-3. Sylvie Rollet, directeur de publication (préface: Theo Angelopoulos), Théorème 9: Théo Angelopoulos au fil du temps [Theo Angelopoulos over the Course of Time], Paris, Presses Sorbonne Nouvelle, 2007, 189 pages, ISBN 978-2-87854-372-8. (in French) Stéphane Sawas, «Grèce (1967–1974) – Les écrans grecs sous la dictature des colonels: la grande rupture,» [Greece (1967–1974) – Greek Screens Under the Dictatorship of the Colonels: The Great Break] dans Raphaël Muller et Thomas Wieder, directeurs de publication, Cinéma et régimes autoritaires au xxe siècle: Écrans sous influence [Cinema and Authoritarian Regimes in the Twentieth Century: Screens Under Influence], Paris, Éditions École Normale Supérieure rue d'Ulm et Presses Universitaires de France, collection «Les rencontres de Normale Sup',» 2008, 285 pages, ISBN 978-2-13-055749-4.
Sources: en.wikipedia.org
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.
The name derives from epithalamin, a pineal gland extract studied in the former Soviet Union. Researchers proposed that short fragments of that extract carried the biological activity of interest.
No major regulatory agency has approved it as a medicine. It is handled as a research chemical, and products sold under this name are not standardised drugs with defined clinical labelling.
Mass spectrometry provides the identity check, because the observed mass is compared with the theoretical mass of the AEDG sequence. Chromatography separates and quantifies impurities but does not by itself prove which peptide is present. The two techniques are normally used together.