mass spectrometry raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four residues, linear chain |
| Residue sequence | Ala-Glu-Asp-Gly | Single-letter form AEDG |
| Calculated mass | 390.3 daltons | Value for the free, uncharged form |
| Appearance | White to off-white powder | Usually supplied lyophilized |
| Solubility | Freely soluble in water | Often handled as a salt form |
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
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.
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.
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.
In a letter to Crick on 11 December 1954, discussing how RNA could be produced from DNA since they contain fundamentally similar nucleotide compositions, he wrote: "I suspect the answer is staring us in the face." To solve the riddle of protein synthesis, Gamow (as the Synthesiser) created an informal team of scientists which he called the RNA Tide Club in 1954. As his prediction to denote 20 amino acids, the club could have only 20 members, with the designated officers: Crick (as the Pessimist), Rich (the Lord Privy Seal) and Watson (the Optimist) among them. It was meant partly to be humorous.
p is the pressure ρ is the density and ρ(p) indicates that it is a function of pressure v is the flow speed Ψ is the potential associated with the conservative force field, often the gravitational potential In engineering situations, elevations are generally small compared to the size of the Earth, and the time scales of fluid flow are small enough to consider the equation of state as adiabatic. In this case, the above equation for an ideal gas becomes:
== Early life == Louis Szathmary was born on June 2, 1919, on a train heading from Transylvania to Budapest as his parents fled the post World War I Hungarian–Romanian War. He earned his master's degree in journalism and doctorate in psychology from the University of Budapest before being drafted into the Hungarian army to serve in World War II. Szathmary originally served as a psychologist to Hungarian Army men, before transferring positions to Army private, where he wrote manuals, including one for cooking. Subsequently, he enrolled in a Hungarian chef's school and took an advanced course.
=== IRAP allosteric site inhibitors === Spiro-oxindole dihydroquinazolines During a screening process in 2016, a spiro-oxindole dihydroquinazoline compound was identified as one of the most potent hits towards IRAP. This kind of compounds shows a high specificity for IRAP against APN (Compound 8 IC50 = 5.8 μM) and according to docking studies, the inhibitor acts in a binding pocket close to the GAMEN loop without interacting with the zing atom, leading to uncompetitive inhibition, confirmed later on by kinetic studies.
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The reduction of the permissible exposure limit (PEL) for respirable crystalline silica from 250 to 50 micrograms per cubic meter of air, averaged over an 8-hour shift. Shifts the focus of controlling silica exposure from the use of PPE (respirators) to the use of engineering controls (such as using water-integrated tools or vacuum systems) and administrative controls (limiting exposure time per shift). Employers are still required to provide respirators when engineering and administrative controls cannot adequately limit exposure. Additional provisions include limiting worker access to high exposure areas, signage requirements in high exposure areas, the development of a written exposure control plan, and training for workers on silica risks and how to limit exposures. Special equipment may be needed to prevent machine water from evaporating and leaving behind dust, and the standard also provides requirements for cleaning up the slurry left behind when water-integrated tools are used as an engineering control. Requires medical exams for highly exposed workers which include a discussion with a physician or licensed health care provider (PLHCP) of prior respiratory health, chest X-ray, pulmonary function test, latent tuberculosis infection, and any other tests deemed necessary by the PLHCP, which are to occur within 30 days of initial silica exposure and must be made available for renewal at least every three years unless the PLHCP deems otherwise.
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=== Pharmacokinetics === PSGAG reaches peak blood concentration in 20–40 minutes when injected intramuscularly; 30–40% of it binds to blood proteins. It enters all tissues, reaching cartilage within two hours. When PSGAG reaches the synovial fluid, it is then taken up by the cartilage matrices, with osteoarthritic cartilage showing a stronger preference for taking it up. It reaches its peak levels in the joints at 48 hours, and lasts up to 96 hours, before leaving and being excreted by the kidneys.
The Source 2006 branch was the term used for Valve's games using technology that culminated with the release of Half-Life 2: Episode One. HDR rendering and color correction were first implemented in 2005 using Day of Defeat: Source, which required the engine's shaders to be rewritten. The former, along with developer commentary tracks, were showcased in Half-Life 2: Lost Coast. Episode One introduced Phong shading and other smaller features. Image-based rendering technology had been in development for Half-Life 2, but was cut from the engine before its release and mentioned again by Gabe Newell in 2006 as a piece of technology he would like to add to Source to implement support for much larger scenes that are impossible with strictly polygonal objects.
Sources: en.wikipedia.org
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.
Epithalamin refers to a crude preparation derived from bovine pineal tissue, which contains many components. Epitalon is a single synthetic tetrapeptide identified from that material and produced by chemical synthesis. The two names are sometimes confused because early reports treated the synthetic peptide as an active fragment of the extract.
It has been registered for clinical use in Russia, where it is associated with a small family of short peptides. In most other jurisdictions it is not an approved medicine and is traded as a research chemical. Regulatory status varies by country and changes over time.
Small studies with human participants have been reported, chiefly in Russian-language journals, but they are limited in size and design. No large randomised controlled trial with published results is available.