This is a working overview of tetrapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-12-25. Anything still debated is marked as such rather than presented as settled.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
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 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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised and often hygroscopic |
| Solubility class | Freely soluble in water | Poor solubility in non-polar solvents |
| Typical storage temperature | -20 degrees Celsius or colder | Sealed, desiccated, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Establishes purity and confirms mass |
| Common salt form | Trifluoroacetate or acetate | Counterion reported alongside purity values |
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 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.
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 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.
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.
1995 membership 1,789. Grants scholarships and donations to St. Tikhon's Seminary and Monastery, St. Vladimir's Orthodox Theological Seminary; and the Monastery of the Transfiguration, Orthodox Press Fund, Alaskan Fund and the UPMC Children's Hospital of Pittsburgh.
== Further reading == Goldman, Lee (15 April 2001). "Key challenges confronting internal medicine in the early twenty-first century". The American Journal of Medicine. 110 (6): 463–470. doi:10.1016/S0002-9343(01)00649-0. PMID 11331058. Meltzer, David; Manning, WG; Morrison, J; Shah, MN; Jin, L; Guth, T; Levinson, W (Dec 3, 2002). "Effects of Physician Experience on Costs and Outcomes on an Academic General Medicine Service: Results of a Trial of Hospitalists". Annals of Internal Medicine. 137 (11): 866–74. doi:10.7326/0003-4819-137-11-200212030-00007. PMID 12458986. S2CID 31987327. Salerno, Stephen M; Landry, Francis J; Kaboli, Peter J (Feb 1, 2001). "Patient perceptions of the capabilities of internists: a multi-center survey". The American Journal of Medicine. 110 (2): 111–117. doi:10.1016/S0002-9343(00)00666-5. PMID 11165552. Sox, Harold C (Jun 15, 2001). "Supply, demand, and the workforce of internal medicine". The American Journal of Medicine. 110 (9): 745–749. doi:10.1016/S0002-9343(01)00756-2. PMID 11403763. Wetterneck, Tosha B.; Linzer, M; McMurray, JE; Douglas, J; Schwartz, MD; Bigby, J; Gerrity, MS; Pathman, DE; et al. (Mar 25, 2002). "Worklife and Satisfaction of General Internists". Archives of Internal Medicine. 162 (6): 649–56. doi:10.1001/archinte.162.6.649. PMID 11911718.
In contrast, the concentration of the activator is primarily determined by its solubility in acetonitrile and is irrespective of the scale of the synthesis. Upon the completion of the coupling, any unbound reagents and by-products are removed by washing.
Sources: en.wikipedia.org
== Occurrence == After its discovery in elastic tendons in dragon flies and wing hinges in locusts, resilin has been found in many structures and organs in arthropods. Resilin is often found as a composite with chitin in insect cuticle, where chitin serves as the structural component. Resilin provides elasticity and possibly other properties. It has been discovered in the salivary pump of assassin bugs (Rhodnius prolixus), tsetse flies, and honey bees, and in the resistance providing mechanism for the venom-dispensing pump of honey bee stingers. Resilin has also been found in the sound production organs of arthropods, such as cicadas and the moth family Pyralidae, where both high elasticity and high resilience of resilin play important roles due to the rapid stress-release cycles of sound-producing tymbals. Besides these structures, resilin exists most widely in the locomotion systems of arthropods. It was discovered in wing hinges to enable recovery from deformation of wing elements, and to dampen the aerodynamic forces felt by the wing; in ambulatory systems of cockroaches and flies to facilitate rapid joint deformation; in jumping mechanisms, resilin stores kinetic energy with great efficiency and releases it upon unloading. It is also abundant in the cuticle surrounding the abdomens of termites, ants, and bees, which expand and swell to a great extent during feeding and reproduction process.
Many children who experience abuse go on to develop an addiction in adolescence or adult life. This pathway towards addiction that is opened through stressful experiences during childhood can be avoided by a change in environmental factors throughout an individual's life and opportunities of professional help. Social and environmental influences include family dynamics, early and adverse experiences, socioeconomic status, peer networks, and cultural norms. Adverse childhood exposures and maladaptive developmental trajectories are robust environmental influences on the development of alcohol use disorder, and adverse childhood experiences are recognized more generally as a social determinant of vulnerability to substance use disorders. Social networks exert a bidirectional influence, while wider sociocultural factors (including public-health control policies and the social determinants of health) shape both exposure and outcome. Because social risk factors are modifiable, prevention that targets them in childhood and adolescence can reduce the risk of later disorder. Together, these levels of analysis present addiction as a dynamic condition emerging from the interaction of neurobiological processes, individual psychological traits and broader social environments. Social factors act largely through chronic stress, peer modeling, socioeconomic constraint and the availability of substances, influencing both the likelihood of exposure and the risk of escalation or relapse.
=== Additional toxic effects === Apart from its mutagenic nature, thiotepa can exert skin toxicity, such as redness and hyperpigmentation. Other less frequent symptoms are peeling skin and mucositis. These effects can be unified under the term of "toxic erythema of chemotherapy". Due to thiotepa's excretion via sweat, skin exposure is especially high in regions with a high density of sweat glands. Namely, symptoms are more abundant at skin folds, the groin, armpits, and generally obstructed skin where accumulation of sweat can take place. The symptoms can be minimized by washing the skin with water and preventing the use of soap and moisturizers, together with preventing obstructions of the skin, 36 hours after thiotepa administration. Thiotepa's ability to cross the blood-brain barrier can lead to diseases related to the white brain matter and neurotoxic symptoms such as memory deficits, dizziness, blurred vision, and others. Additionally, neurotoxicity and mucositis are the main dose-limiting factors in high-dose treatment (whereas the main dose-limiting factor, myelosuppression, is remedied by applying transplantation of bone marrow). Other general adverse effects of chemotherapy with thiotepa are infections, diarrhea, nausea, vomiting, oedema and hair loss. In-vivo experiments in animals displayed additional and potentially important toxicities. Thiotepa has been found to negatively affect fertility in male and female mice by interfering with spermatogenesis and impairing ovarian function, respectively.
=== Pathogenic susceptibility === Some pathogenic bacteria cause disease under certain conditions, such as entry through the skin via a cut, through sexual activity or through compromised immune function.
Sources: en.wikipedia.org
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase HPLC establishes purity and separation from related peptides, and mass spectrometry confirms the molecular mass. Amino acid analysis can verify residue composition. No single method proves identity on its own, so the results are read together.
Yes. Residual trifluoroacetate or acetate from purification adds mass and can shift the value obtained by certain assays. Purity figures are therefore meaningful only when the counterion form is stated. Reporting both peptide content and salt form gives a clearer picture.
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.