This is a working overview of tetrapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-28. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Typical purity specification | 95 percent or higher by HPLC area | Higher grades are also offered |
| Primary analytical method | Reversed-phase HPLC, UV detection | Frequently paired with mass spectrometry |
| Confirmatory technique | Electrospray mass spectrometry | Observed mass compared with theory |
| Storage temperature | Minus 20 degrees Celsius, dry powder | Sealed, desiccated, protected from light |
| Solution handling | Prepare fresh before use | Hydrolysis proceeds in aqueous media |
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
Stability depends strongly on pH, temperature and the presence of oxygen and trace metals. Cleavage of the backbone proceeds faster under neutral to alkaline conditions, whereas acidic solutions tend to slow that reaction. The aspartate and glutamate side chains can undergo deamidation or imide formation over time, generating closely related impurities. Published stability data specific to epitalon are sparse, so the usable life of a given solution is best regarded as an open question that depends on buffer composition, concentration and storage temperature.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography with ultraviolet detection, frequently near 214 nanometers where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the observed molecular mass and helps separate the intact peptide from truncated or modified forms. Amino acid analysis or tandem mass spectrometry can establish residue order. Purity is commonly quoted as an area percentage, yet such values are method-dependent, and comparisons between laboratories require matching column, gradient and detection wavelength.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
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.
==== Physiology ==== Techniques in genetics have advanced in the Culture to the point where bodies can be freed from built-in limitations. Citizens of the Culture refer to a normal human as "human-basic" and the vast majority opt for significant enhancements: severed limbs grow back, sexual physiology can be voluntarily changed from male to female and back (though the process takes time), sexual stimulation and endurance are strongly heightened in both sexes (something that is often the subject of envious debate among other species), pain can be switched off, toxins can be bypassed away from the digestive system, autonomic functions such as heart rate can be switched to conscious control, reflexes like blinking can be switched off, and bones and muscles adapt quickly to changes in gravity without the need to exercise. The degree of enhancement found in Culture individuals varies to taste, with certain of the more exotic enhancements limited to Special Circumstances personnel (for example, weapons systems embedded in various parts of the body). Most Culture individuals opt to have drug glands that allow for hormonal levels and other chemical secretions to be consciously monitored, released and controlled. These allow owners to secrete on command any of a wide selection of synthetic drugs, from the merely relaxing to the mind-altering: "Snap" is described in Use of Weapons and The Player of Games as "The Culture's favourite breakfast drug". "Sharp Blue" is described as a utility drug, as opposed to a sensory enhancer or a sexual stimulant, that helps in problem solving.
=== Contraindications === Labia reduction surgery is relatively contraindicated for the woman who have active gynecological disease, such as an infection or a malignancy; the woman who is a tobacco smoker and is unwilling to quit, either temporarily or permanently, in order to optimize her wound-healing capability; and the woman who is unrealistic in her aesthetic goals. The latter should either be counselled or excluded from labioplastic surgery. Davison et al write that it should not be performed when the patient is menstruating to reduce potential hormonal effects and the increased risk of infection.
=== Media coverage === During the first few months of the COVID-19 pandemic in 2020, Chinese food markets were heavily criticized in media outlets as a potential source for the virus. Media reports urging for permanent blanket bans on all such markets, as opposed to solely live animal markets or wildlife markets, have been criticized for undermining infection control needs to be specific about wildlife markets and distracting public attention from local public health threats. Some Western media portrayed food markets without distinguishing between general food markets, live animal markets, and wildlife markets, using montages of explicit images from different markets across Asia without identifying locations. These depictions have been criticized by other journalists and anthropologists as sensationalist, exaggerated, Orientalist, and fueling Sinophobia and "Chinese otherness". Before 2020, most English speakers had never heard the term "wet market". Some coverage presented it as the local name for the Huanan market; NPR described the market as "known in the region as a 'wet market'". The market's Chinese name, 华南海鲜批发市场, identifies it as a seafood wholesale market; with more than 1,000 stalls across roughly 50,000 square metres, it was the largest seafood wholesale market in central China. Its main goods were crab, shrimp and striped bass, with wildlife sold in a separate section. Critics also argued that the word "wet" itself evokes unhygienic conditions.
===== SeV stimulation of dendritic cells ===== UV-inactivated SeV can cause dendritic cells (DCs) to maturate and to infiltrate a tumor. Ex vivo infection of DCs with recombinant non-transmissible SeV induces maturation and activation of DCs within 60 minutes. When activated DCs that carry non-transmissible variants of SeV are administered, survival of animals injected with melanoma, colorectal cancer, squamous cell carcinoma, hepatic cancer, neuroblastoma, and prostate cancer is significantly improved. It has been shown that the administration of such DCs prior to tumor cell injection prevents metastasis of neuroblastoma and prostate adenocarcinoma to the lungs. The enzymatic removal of sialic acids from the surface of dendritic cells by sialidase significantly promote the antigen-induced activation of naive T cells, while concurrently enhancing the resurgence of effector T cells. It is plausible that sialidase from Sendai virus (SeV) could execute this function. The removal not only improves antigen cross-presentation but boosts anti-tumor immune responses as well. Dendritic cells with reduced sialylation form higher avidity interactions with CD8+ T cells.
Sources: en.wikipedia.org
=== Primary or secondary === The distinction between primary and secondary immunodeficiencies is based on whether the cause originates in the immune system itself or insufficiency of a supporting component or an external factor.
Sodium azide is an inorganic compound with the formula NaN3. This colorless salt is the gas-forming component in some car airbag systems. It is used for the preparation of other azide compounds. It is highly soluble in water and is acutely poisonous.
==== Baldness can be caused by emotional stress and/or sleep deprivation ==== Emotional stress has been shown to accelerate baldness in genetically susceptible individuals. Stress due to sleep deprivation in military recruits lowered testosterone levels, but it is not noted to have affected SHBG. Thus, stress due to sleep deprivation in fit males is unlikely to elevate DHT, which is one cause of male pattern baldness. Whether sleep deprivation can cause hair loss by some other mechanism is not clear.
Sources: en.wikipedia.org
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.
The dry powder is commonly kept at minus twenty degrees Celsius, desiccated and away from light. Solutions are generally prepared fresh because they break down faster than the solid form.
Tandem mass spectrometry or enzymatic peptide mapping can establish residue order. A single intact mass value indicates composition and molecular weight but not always the precise arrangement of residues.
Epitalon is a synthetic four-amino-acid peptide with the sequence alanine–glutamate–aspartate–glycine, also written AEDG. It was developed in Russian gerontology research and is studied for proposed effects on telomerase, melatonin regulation, and neuroendocrine function. It is not an approved pharmaceutical in the United States or the European Union.