Epitalon raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-03-10. Anything still debated is marked as such rather than presented as settled.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilized solid |
| Solubility | Freely soluble in water | Also dissolves in polar organic solvents |
| Typical storage temperature | −20 °C or below | Sealed, desiccated, protected from light |
| Primary purity assay | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Mass spectrometry | Electrospray ionization commonly used |
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.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Analytical characterization of epitalon relies on standard peptide methods. Reverse-phase high-performance liquid chromatography is used to assess purity, and mass spectrometry confirms identity by checking the observed mass against the expected value near 390 daltons. Amino acid analysis can verify composition. Because the peptide is short and hydrophilic, it elutes early on many reverse-phase columns, so method development often requires ion-pairing reagents to achieve adequate retention and resolution from related impurities.
Storage and handling follow conventional peptide practice. Lyophilized epitalon is typically kept refrigerated or frozen, protected from moisture and light, and allowed to equilibrate to room temperature before opening to avoid condensation. Once dissolved, aqueous solutions are usually stored cold and used within a short period, since dilute peptide solutions can support microbial growth and may slowly degrade. The absence of cysteine and methionine reduces, but does not eliminate, oxidation concerns during long-term storage.
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.
Combined Bisulfite Restriction Analysis (or COBRA) is a molecular biology technique that allows for the sensitive quantification of DNA methylation levels at a specific genomic locus on a DNA sequence in a small sample of genomic DNA. The technique is a variation of bisulfite sequencing, and combines bisulfite conversion based polymerase chain reaction with restriction digestion. Originally developed to reliably handle minute amounts of genomic DNA from microdissected paraffin-embedded tissue samples, the technique has since seen widespread usage in cancer research and epigenetics studies.
== Diagnosis == When an affected individual has fully developed the three clinical elements of uric acid overproduction, neurologic dysfunction, and cognitive and behavioral disturbances, diagnosis of LNS is easily made. Diagnosis is less easy in the early stages, when the three features are not yet obvious. Signs of self-injurious behavior (SIB), results of pedigree analysis and novel molecular biology with genetic testing (called as Diagnostic triad for LNS), often confirms the diagnosis. Suspicion often comes about when the developmental delay of the individual is associated with hyperuricemia. Otherwise, the diagnosis should be alleged when developmental delay is associated with kidney stones (nephrolithiasis) or blood in the urine (hematuria), caused by uric acid stones. For the most part, Lesch–Nyhan syndrome is first suspected when self-inflicted injury behavior develops. However, self-injurious behaviors occur in other conditions, including nonspecific intellectual disability, autism, Rett syndrome, Cornelia de Lange syndrome, Tourette syndrome, familial dysautonomia, choreoacanthocytosis, sensory neuropathy including hereditary sensory neuropathy type 1, and several psychiatric conditions. Of these, only individuals with Lesch–Nyhan syndrome, de Lange syndrome, and familial dysautonomia recurrently display loss of tissue as a consequence.
It included industrial workers and smallholders, broad middle class (including both the agrarian and urban middle classes), as well as entrepreneurs, civil servants and clerics, and lastly a small but influential group of Catholic aristocracy. The uniting element of the factions of the Centre Party was commitment to Political Catholicism. The party also urged union with Austria. The party had a left wing, represented by politicians such as Constantin Fehrenbach, Matthias Erzberger, Joseph Wirth, as well as Catholic workers' associations and trade unions, led by the Centre's laborist politicians such as Adam Stegerwald. Left-wing factions of the Centre Party were committed to republicanism and pressured the Zentrum to officially identify itself as a pro-republican party; however, the party instead adopted a vague label of being a "constitutional party", which was "ready to collaborate with any legal government". The leftists of the Centre Party also promoted cooperation with the SPD and advised Weimar Catholics to join the Reichsbanner; some left-wing Centre factions were also supportive of cooperation with right-wing nationalist trade unions on pragmatic basis. Along with "republican-democratic" wings of the party, the Centre Party also had socialist factions.
=== Defense against pathogens === The exposure to these reactive species in the respiratory burst results in pathology. This is due to oxidative damage to the engulfed bacteria. Notably, peroxynitrite is a very strong oxidising agent that can lead to lipid peroxidation, protein oxidation, protein nitration, which are responsible for its bactericidal effects. It may react directly with proteins that contain transition metal centers, such as FeS, releasing Fe2+ for the Fenton reaction. Peroxynitrite may also react with various amino acids in the peptide chain, thereby altering protein structure and subsequently, protein function. It most commonly oxidises cysteine, and may indirectly induce tyrosine nitration through other generated RNS. Altered protein function includes changes in enzyme catalytic activity, cytoskeletal organisation and cell signal transduction. Hypochlorous acid reacts with a range of biomolecules, including DNA, lipids and proteins. HClO may oxidise cysteines and methionines via their sulfhydryl groups and sulfur groups respectively. The former leads to the formation of disulfide bonds, inducing protein crosslinking. Both oxidations result in protein aggregation, and ultimately, cell death. Sulfhydryl groups can be oxidised up to three times by three HClO molecules, forming sulfenic acids, sulfinic acids and R–SO3H, which are increasingly irreversible and bactericidal. Meanwhile, methionine oxidation is reversible. HOCl can also react with primary or secondary amines, producing chloroamines which are toxic to bacteria.
Sources: en.wikipedia.org
=== Deregulation in cancer === Cyclin D1 overexpression has been shown to correlate with early cancer onset and tumor progression and it can lead to oncogenesis by increasing anchorage-independent growth and angiogenesis via VEGF production. Cyclin D1 overexpression can also down-regulate Fas expression, leading to increased chemotherapeutic resistance and protection from apoptosis. An abundance of cyclin D1 can be caused by various types of deregulation, including:
As with all amino acids, catabolism of lysine is initiated from the uptake of dietary lysine or from the breakdown of intracellular protein. Catabolism is also used as a means to control the intracellular concentration of free lysine and maintain a steady-state to prevent the toxic effects of excessive free lysine. There are several pathways involved in lysine catabolism but the most commonly used is the saccharopine pathway, which primarily takes place in the liver (and equivalent organs) in animals, specifically within the mitochondria. This is the reverse of the previously described AAA pathway. In animals and plants, the first two steps of the saccharopine pathway are catalysed by the bifunctional enzyme, α-aminoadipic semialdehyde synthase (AASS), which possess both lysine-ketoglutarate reductase (LKR) (E.C 1.5.1.8) and SDH activities, whereas in other organisms, such as bacteria and fungi, both of these enzymes are encoded by separate genes. The first step involves the LKR catalysed reduction of L-lysine in the presence of α-ketoglutarate to produce saccharopine, with NAD(P)H acting as a proton donor. Saccharopine then undergoes a dehydration reaction, catalysed by SDH in the presence of NAD+, to produce AAS and glutamate. AAS dehydrogenase (AASD) (E.C 1.2.1.31) then further dehydrates the molecule into AAA. Subsequently, PLP-AT catalyses the reverse reaction to that of the AAA biosynthesis pathway, resulting in AAA being converted to α-ketoadipate.
== Coupling with THG microscopy == Third-Harmonic Generation (THG) microscopy can be complementary to SHG microscopy, as it is sensitive to the transverse interfaces, and to the 3rd order nonlinear susceptibility
Sources: en.wikipedia.org
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.
Reversed-phase HPLC with ultraviolet detection is the usual approach, often paired with mass spectrometry. Together the two methods address both chromatographic purity and molecular identity.
Differences arise from the analytical method, the detection wavelength, and whether the number refers to the peptide or to total powder mass. Counterion and water content can lower the actual peptide fraction considerably.
It is a four-amino-acid peptide with the sequence alanine-glutamate-aspartate-glycine. The chain is unmodified and contains only standard proteinogenic residues, which makes it straightforward to produce by solid-phase synthesis and to characterise by standard peptide methods.