A practical reference on tetrapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-09 and is reviewed periodically as new material appears.
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.
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.
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
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.
| 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 |
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
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 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.
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.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
Peptides of this size are generally stable as dry solids but degrade in solution over time. The principal routes are hydrolysis of the peptide backbone and oxidation, with hydrolysis favoured by elevated temperature and extreme pH. Aqueous solutions held at room temperature can show measurable loss of purity within days, while frozen aliquots are considerably more durable. Because the sequence contains neither cysteine nor methionine, oxidation is less of a concern than for many other peptides, but pH control during handling still matters.
Typical storage for the lyophilized powder is −20 °C or lower, in a sealed container protected from light and moisture. Hygroscopic material should be allowed to equilibrate to room temperature before the vial is opened, which limits condensation on the contents. Working solutions are commonly divided into single-use aliquots and frozen to avoid repeated freeze-thaw cycles. Dilute solutions are more prone to adsorption onto plastic surfaces and to loss during filtration, so procedures that minimize transfers and use low-binding labware are preferable.
== Arab Spring (2011) == In February 2011, Kermani praised the Arab Spring, noting that the demonstrators had taken to the streets for "freedom, dignity, the rule of law, and equal opportunity". He criticized the policies of Western governments. "Criminality and complicity (with dictatorships)", Kermani wrote, "seem to have become the norm in some European government palaces". He spoke positively of Al Jazeera's role, observing that the network had contributed significantly to a culture of debate. Kermani dismissed the coverage by German media—in which, according to Kermani, people "ramble on about how state and politics are one and the same in Islam"—as a "religiously tinged colonial lens". The protests, Kermani argued, were not about religion. He also spoke out against multiculturalism as a form of culturalism that legitimizes dictatorships, saying that, "Conversely, discussants fall into relativism and claim that people elsewhere do not want democracy at all because they are supposedly simply different and have different traditions." Such a view would work against the original leftist goals of equality for all people and the leveling of living conditions. In general, the "overemphasis on otherness, whether of migrants or Hartz IV [welfare] recipients, ... serves primarily to reinforce differences—especially economic differences".
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==== Monazite identification and mapping ==== Monazite grains are identified by a backscattered electron imaging survey or/and electron microprobe analysis (EMPA) by mapping the concentration of distinctive Ce in monazite. The two images are usually superimposed to reflect sample texture and monazite locations at the same time.
Sources: en.wikipedia.org
Maximinus Thrax, Roman emperor (c. 173, reigned 235–238). Descriptions, as well as depictions, indicate acromegaly, though remains of his body are yet to be found. Lorenzo de' Medici (1449–1492) may have had acromegaly. Historical documents and portraits, as well as a later analysis of his skeleton, support the speculation. Sergei Rachmaninoff (1873–1943), pianist and composer, who was noted for his hands that could comfortably stretch a thirteenth on the piano. He was not diagnosed with acromegaly in his lifetime, but a medical article from 2006 suggests that he might have had it. Adam Rainer (22 February 1899 – 4 March 1950), Austrian man who is the only person in recorded history to have been both a dwarf and a giant. He is believed to have had acromegaly.[51]
The point is sometimes made that, in fact, the adoption by the Liberal Governments of 1905-14 of several major social welfare measures, including old-age pensions and health and unemployment insurance, provoked remarkably little resistance within the party. The measures that did occasion some overt resistance in the party were the Budgets for 1909 and 1914, which provided for the taxes to help finance new measures of reform as well as large increases in naval expenditure. It was, in other words, over the questions of the cost and financing of social reform that the main debate over social reform was waged within the Liberal Party.
In 1916, Grace acquired a controlling interest in the Pacific Mail Steamship Company. In 1921, Pacific received five 535 ft. President class ships from the United States Shipping Board for transpacific operation. In 1923, the US Shipping board decided to place the five ships up for bid and Dollar Shipping Company won the bid. With no large ships for the transpacific operations, Grace sold the Pacific Mail, its registered name, and goodwill to Dollar. Now without a transpacific service, Grace did not need the six intercoastal freighters and sold them to the American Hawaiian Line. At this time, Grace formed the Panama Mail Steamship Company, to operate the smaller ships that were formerly owned and used by the Pacific Mail in the Central American trade. These ships were not involved in the sale to Dollar. On the death of William R. Grace in 1904, he was succeeded by William L. Sauders as company president followed by Joseph Peter Grace Sr. (1872–1950) who became president in 1907. In 1938, the Colombian Line merged with Grace Line bringing an end to the Colombian Line. During World War II, Grace Lines operated transport for the U.S. War Shipping Administration, including the SS Sea Marlin. J. Peter Grace took over management of the company after his father suffered a stroke in 1945. After the war, the Grace line operated 23 ships totaling 188,000 gross tons, and 14 more on bareboat charters.
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.
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.