The short version of Reversed-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-11 and is reviewed periodically as new material appears.
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.
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.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
{\displaystyle {\boldsymbol {B}}=\lambda ^{2}~\mathbf {n} _{1}\otimes \mathbf {n} _{1}+\lambda ^{2}~\mathbf {n} _{2}\otimes \mathbf {n} _{2}+{\cfrac {1}{\lambda ^{4}}}~\mathbf {n} _{3}\otimes \mathbf {n} _{3}~.}
== Publications == Separation of amino acid homopolymers by capillary gel electrophoresis. Retention indices for programmed-temperature capillary-column gas chromatography of polycyclic aromatic hydrocarbons. Ultrasensitive Pheromone Detection by mammalian vomeronasal neurons. Electrophoretic separations of proteins in capillaries with hydrolytically-stable surface structures. Comparison of the methods for profiling glycoprotein glycans—HUPO Human Disease Glycomics/Proteome Initiative multi-institutional study. Structural Investigations of Glycoconjugates at High Sensitivity.
== Side effects and overdose == Side effects from intra-articular administration can include joint pain, swelling, lameness, and, rarely, infection of the joint. Intramuscular injection can cause dose-dependent inflammation and bleeding, since PSGAG is an analogue of the anticoagulant heparin. In dogs, this may manifest as bleeding from the nose or as bloody stools. The increased risk of bleeding has some advising not to give PSGAG to animals with bleeding disorders, though its only absolute contraindication is hypersensitivity to PSAGs when it is being given intra-articularily. Overdose on PSGAG is quite rare, as the LD50 is over 1000 mg/kg when given intravenously to dogs. Signs of overdose include exacerbated side effects such as joint pain, swelling, and lameness. When dogs received three times the normal dose intramuscularly twice a week for 13 weeks, they had increased liver and kidney weight, as well as microscopic lesions on the liver, kidneys, and lymph nodes. At 11 times the normal dose, they also had increased alanine transferase, cholesterol, and prothrombin time (i.e. coagulation via the extrinsic pathway took longer), and fewer platelets.
Half-Life 2: Episode One continues from the events of Half-Life 2. Building on the original, Episode One added cooperative play with friendly non-player characters such as Alyx Vance, whose new abilities complement Freeman's abilities and allow her to comprehend and respond to the player's actions by lending help. It is set immediately after the end of Half-Life 2 in the war-torn City 17 and nearby areas. Episode One follows scientist Gordon Freeman and his companion Alyx Vance as they continue to cope with the events chronicled in Half-Life 2 and humanity's continuing struggle against the Combine. The game was originally released in 2006 for Windows as a standalone game and was generally well received.
To determine this percentage of isotopic exchange, which varies according to local humidity levels, standards of metabolically inert tissue from the species of interest can be constructed and equilibriated to local conditions. This allows measured δD from different regions to be compared against each other.
Sources: en.wikipedia.org
The great beneficiary was the PSOE, which led the campaign in favor of the "YES" vote and from then on became the hegemonic political force in Andalusia. The setback suffered by the UCD in Andalusia was added to the defeat in the municipal and regional elections in Catalonia and the Basque Country. To this was added the worsening of the economic situation as a result of the "second oil crisis" of 1979 (the number of unemployed exceeded one million), the resurgence of ETA's actions which in 1979 and 1980 marked the peak of its activity (174 dead in attacks perpetrated by ETA in those two years, a good part of them military), the growing citizen "disenchantment", etc. All this accentuated the political differences between the groups that made up UCD on various issues which opened a government crisis in mid-April 1980 that resulted in the formation of a new one whose "strong man" was the president's friend, Fernando Abril Martorell. Felipe González then presented a motion of censure against Suárez, which although he did not succeed in getting it through made him the highest-rated political leader in the polls, unseating Adolfo Suárez for the first time, and the PSOE became ahead of UCD in voting intentions. Suárez emerged very weakened from the Socialist motion of censure, which provoked a second crisis in his government in September 1980, which resulted in the departure of the former "strong man" Fernando Abril Martorell. However, the Christian-Democratic sector was not satisfied and started "a full-fledged rebellion".
=== Ischemic fasciitis === Ischemic fasciitis (IF) is a benign tumor in the class of fibroblastic and myofibroblastic tumors that, like pressure ulcers, may develop in elderly, bed-ridden individuals. These tumors commonly form in the subcutaneous tissues (i.e. lower most tissue layer of the skin) that overlie bony protuberances such as those in or around the hip, shoulder, greater trochanter of the femur, iliac crest, lumbar region, or scapular region. IF tumors differ from pressure ulcers in that they typically do not have extensive ulcerations of the skin and on histopathological microscopic analysis lack evidence of acute inflammation as determined by the presence of various types of white blood cells. These tumors are commonly treated by surgical removal.
=== Infections and infestations === Apple scab, an apple tree (genus Malus) fungal disease caused by Venturia inaequalis Black scab, a potato fungal disease caused by Synchytrium endobioticum Common scab, a plant bacterial disease caused by Streptomyces species Fusarium head blight, a fungal disease of plants, e.g., grain crops (especially wheat and oats), golf course grass, caused by the several species of Fusarium Pear scab, a pear fungal disease caused by Venturia pirina or Fusicladium pyrorum Poinsettia scab, a spot anthracnose disease caused by Sphaceloma poinsettiae Powdery scab, a disease of the skin of potatoes caused by the protozoa Spongospora subterranea Sheep scab, a skin disease of sheep caused by the mite Psoroptes ovis
29 January Conservative Party Chairman Nadhim Zahawi is sacked by Rishi Sunak over "a serious breach of the Ministerial Code" relating to the investigation into his tax affairs, conducted on 23 January. The Scottish Prison Service pauses the movement of all transgender prisoners while it carries out an "urgent review" into the transgender cases held in its custody. 30 January William Shawcross, the commissioner for public appointments, steps back from the planned investigation into how Richard Sharp got the job as BBC chairman because of previous contact between them. Another investigator will be appointed to take on the inquiry. Members of the Fire Brigades Union vote to take strike action over pay.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.