If you have been reading about tetrapeptide 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 2025-12-05. Numbers and descriptions here follow the published literature rather than marketing material.
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 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.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Tetrapeptide, often abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free peptide, unmodified termini |
| Molecular weight | ~390.35 Da | Calculated for the free acid form |
| Appearance | White to off-white powder | Typical lyophilized product form |
| Solubility class | Freely soluble in water | Two acidic residues dominate ionic character |
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.
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.
The most frequently cited proposed action is induction of telomerase, the enzyme that adds repeat sequences to chromosome ends. Cell-culture work from the originating group reported higher telomerase reverse transcriptase expression and measurable telomere elongation in human somatic cells after exposure. How a four-residue peptide would reach nuclear gene regulation is not established, and no cell-surface receptor or uptake route has been identified. Additional reports describe changes in melatonin secretion, antioxidant enzyme activity and lipid peroxidation in aged animals, but these findings remain mechanistically unconnected to the telomerase observation.
Published evidence comes mainly from Russian-language journals and from a single research group, with small sample sizes and limited independent replication. A few laboratories outside that group have examined related peptides and reported weaker or absent telomerase effects, so the central claim is best described as contested rather than settled. Rodent studies report modest changes in some ageing markers and in survival, but designs vary and control conditions are often sparse. No large randomised trial in humans has been published, and long-term safety data in healthy populations are correspondingly thin.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
==== Buprenorphine ==== Buprenorphine can be administered either as a standalone product or in combination with the opioid antagonist naloxone. This inclusion is strategic: it deters misuse by preventing the crushing and injecting of the medication, encouraging instead the prescribed sublingual (under the tongue) route. Buprenorphine/naloxone formulations are available as tablets and films; these formulations operate efficiently when taken sublingually. In this form, buprenorphine's bioavailability remains robust (35–55%), while naloxone's is significantly reduced (~10%). Buprenorphine's role as a partial opioid receptor agonist sets it apart from full agonists like methadone. Its unique pharmacological profile makes it less likely to cause respiratory depression, thanks to its "ceiling effect". While the risk of misuse or overdose is higher with buprenorphine alone compared to the buprenorphine/naloxone combination or methadone, its usage is linked to a decrease in mortality. Approved in the U.S. for opioid dependence treatment in 2002, buprenorphine has since expanded in form, with the FDA approving a month-long injectable version in 2017. When initiating buprenorphine/naloxone therapy, several critical factors must be considered. These include the severity of withdrawal symptoms, the time elapsed since the last opioid use, and the type of opioid involved (long-acting vs. short-acting). A standard induction method involves waiting until the patient exhibits moderate withdrawal symptoms, as measured by a Clinical Opiate Withdrawal Scale, achieving a score of around 12.
== Structure–activity relationship == Even though μ-opioid receptor (MOR) targeting drugs have been used for a long time, not much is known about the structure-activity relationship and the ligand-receptor interactions on the basis of well-defined biological effects on receptor activation or inhibition. Also, the distinction in the receptor-ligand interaction patterns of agonists and antagonists is not known for sure. One theory states that the morphinans biological activity could be determined by the size of the N-substituents. For example, antagonists usually have larger substituents, such as allyl- or cyclopropyl methyl at the morphinan nitrogen, while agonists generally contain a methyl group. On the other hand, agonist activity is also shown in ligands with larger groups at the morphinan nitrogen, and therefore this hypothesis is challenged.
=== Typical views === Required projections can vary by country and hospital, although an erect posteroanterior (PA) projection is typically the first preference. If this is not possible, then an anteroposterior view will be taken. Further imaging depends on local protocols which is dependent on the hospital protocols, the availability of other imaging modalities and the preference of the image interpreter. In the UK, the standard chest radiography protocol is to take an erect posteroanterior view only and a lateral one only on request by a radiologist. In the US, chest radiography includes a PA and Lateral with the patient standing or sitting up. Special projections include an AP in cases where the image needs to be obtained stat (immediately) and with a portable device, particularly when a patient cannot be safely positioned upright. Lateral decubitus may be used for visualization of air-fluid levels if an upright image cannot be obtained. Anteroposterior (AP) Axial Lordotic projects the clavicles above the lung fields, allowing better visualization of the apices (which is extremely useful when looking for evidence of primary tuberculosis).
Sources: en.wikipedia.org
== 1960 attempted coup and disbandment == "It remained the elite force of the empire," notes historian Bahru Zewde, "until discredited in the wake of the attempted coup of 1960." That unsuccessful coup had been planned by its commander Brigadier-General Mengistu Neway, and his brother Germame Neway. In 1961, it numbered nine battalions; in 1969 some 7,000 men. In 1974, the Commander was Major-General Tafessa Lemma. The Kebur Zabagna was disbanded after the Derg consolidated their hold on Ethiopia. After the Imperial Bodyguard attempted to overthrow the Emperor in 1962 its most lethal element, the Berari Neber whose paratroopers had just completed training and received their wings from the Emperor a bare 2 months earlier were separated and attached to the regular army. The men selected out of the Berari-Nebir were responsible for the anti-hijack program. The Anti-Hijack program interdicted about 4 hijack attempts. In the most famous one of these was in 1972 when Wallelign Mekonnen with ELF (Eritrean Liberation Front) trained operatives led a 3 man 2 women cell in an abortive attempt to hijack an Ethiopian airlines Boeing 707. They reportedly smuggled 1 grenade and 1 handgun on the plane in the women's underpants. Ethiopian anti-Hijack commandos shot and killed two hijackers and the rest were killed by a bomb they set off.
== Sources == Douglas, James Sholto (1975). Hydroponics: The Bengal System: with Notes on Other Methods of Soilless Cultivation. Oxford University Press. ISBN 978-0-19-560530-3. Douglas, James Sholto (1985). Advanced Guide to Hydroponics. Pelham. ISBN 978-0-7207-1571-2. OCLC 1341823405. Jones Jr., J. Benton (2016). Hydroponics. doi:10.1201/9780849331671. ISBN 978-1-4200-3770-8.
5-oxoprolyl-peptide + H2O Hence, this enzyme has one substrate, L-glutaminyl-peptide or L-glutamyl-peptide, and two products, 5-oxoprolyl-peptide and NH3 or H2O. The N-terminal 5-oxoproline residue on the peptide is also commonly known as pyroglutamic acid. This enzyme belongs to the family of transferases, specifically the aminoacyltransferases. The systematic name of this enzyme class is L-glutaminyl-peptide gamma-glutamyltransferase (cyclizing). Other names in common use include glutaminyl-tRNA cyclotransferase, glutaminyl cyclase, and glutaminyl-transfer ribonucleate cyclotransferase.
Sources: en.wikipedia.org
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.
No. Epitalon is chemically synthesized, not extracted. It was designed as a short synthetic fragment conceptually related to larger pineal peptides studied in the same research tradition, particularly the extract known as epithalamin. The two are distinct materials with different compositions.
The term bioregulator is used in this research tradition for short peptides proposed to influence gene expression or cell function. Epitalon is grouped with other synthetic short peptides under this label. The term reflects a proposed mechanism rather than an established drug classification.
The usual approach is reversed-phase HPLC with ultraviolet detection, reported as a percentage of total peak area. Mass spectrometry is used alongside chromatography to confirm identity rather than purity alone.