The short version of RP-HPLC fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-05-17 and is reviewed periodically as new material appears.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
Material supplied for laboratory use is normally a lyophilised white to off-white powder that dissolves readily in water and in isotonic saline. Lyophilised cakes are hygroscopic and should be equilibrated to room temperature before opening to limit condensation on the solid. Solutions are typically prepared at milligram-per-millilitre concentrations and divided into single-use aliquots, because repeated freeze–thaw cycles degrade short peptides. Aqueous solutions are far less stable than the dry powder, and identity is usually verified by mass spectrometry alongside purity estimation from reversed-phase high-performance liquid chromatography.
Human data are limited to small studies, often without the randomization, blinding, or control groups expected in contemporary clinical research. Reported outcomes have included changes in melatonin levels, immune markers, and subjective measures, but sample sizes were generally too small to support firm conclusions. Some reviews treat the peptide as promising while noting methodological weaknesses; others question whether the observed effects are specific. The compound is frequently discussed in longevity-focused communities, where enthusiasm often outpaces the published evidence. Separating established findings from speculation is therefore important when reading summaries of this research.
Epitalon emerged from research conducted in Saint Petersburg by Vladimir Khavinson and colleagues, who studied short peptides as potential regulators of aging. The work built on epithalamin, a pineal gland extract reported to influence neuroendocrine function. Epitalon was designed as a synthetic counterpart with a defined sequence, allowing reproducible experiments that extracts could not support. Early publications described effects on melatonin rhythms and lifespan in animal models. These findings circulated mainly in Russian-language journals during the 1990s, which limited their visibility among English-speaking researchers.
| Property | Value | Notes |
|---|---|---|
| Amino acid sequence | Ala-Glu-Asp-Gly | Linear tetrapeptide, also written AEDG |
| Molecular mass | About 390.35 g/mol | Value calculated from the sequence |
| Appearance | White to off-white powder | Lyophilised material forms a loose cake |
| Solubility | Freely soluble in water | Also dissolves in isotonic saline |
| Storage | -20 °C, desiccated | Aliquot solutions to avoid freeze–thaw cycling |
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
（TG:@pojiaai）Epitalon is a synthetic linear tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. It emerged from work on epithalamin, a peptide fraction prepared from bovine pineal tissue, and was designed as a short, chemically defined analogue of that extract. Early publications came mainly from Russian laboratories studying pineal peptides and aging-related endpoints. The compound appears in the literature under several spellings, including epithalon and epithalone, which complicates systematic searching. Its small size makes solid-phase assembly and routine analytical characterization straightforward.
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.
Dissolution is usually performed in water or a suitable aqueous buffer, and the resulting liquid is divided into single-use portions before freezing. Freeze-thaw cycling is a recognised source of loss for short peptides, since each cycle can encourage aggregation or adsorption onto container walls. Working solutions are generally kept cold and used within a short window, although published stability data specific to epitalon are thin. Containers should be marked with concentration and date, and solutions examined for cloudiness before use.
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.
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.
=== Industrial sources === PFOA is released directly from industrial sites. For example, the estimate for the DuPont Washington Works facility is a total PFOA emissions of 80,000 pounds (lbs) in 2000 and 1,700 pounds in 2004. A 2006 study, with two of four authors being DuPont employees, estimated about 80% of historical perfluorocarboxylate emissions were released to the environment from fluoropolymer manufacture and use. PFOA can be measured in water from industrial sites other than fluorochemical plants. PFOA has also been detected in emissions from the carpet industry, paper and electronics industries. The most important emission sources are carpet and textile protection products, as well as fire-fighting foams.
Legendary sniper Thomas Beckett and his son, Special Ops sniper Brandon Beckett, are on the run from the CIA, Russian mercenaries, and a Yakuza-trained assassin with sniper skills that rival both legendary sharp shooters.
=== Food and Drug Administration (FDA) === In vitro diagnostic (IVD) products use the same categorization as medical devices (Class I, II, and III) to assure safety and effectiveness. Regulatory controls and premarket approval process are determined by this classification, with Class I being the lowest risk (least regulated) and Class III being the highest risk (most regulated). Under the CLIA, it is the role of the FDA to assess the complexity of the in vitro laboratory diagnostic tests. Tests are only scored after the FDA has cleared or approved a premarketing request, or upon request. Manufacturers can apply for CLIA waivers during this premarket approval/clearance process. Tests that are already cleared or approved for home use or are waived by 42 CRF 293.15(c), are classified as waived. Otherwise, the tests are either classified as moderate or high complexity based on seven categorization criteria listed in 42 CFR 493.17. If the test is classified as moderate, the manufacturer may request the test be waived through the CLIA Waiver by Application. The application must show that the test meets the criteria in 42 U.S.C. § 263a(d)(3), that the test is simple and will not cause harm to the patient if performed incorrectly. These test classifications determine the certifications needed for laboratories to perform said tests. Waived tests require the least regulation, while moderate to high complexity tests require higher regulation and standards within the laboratory.
Aside from individual reported experiences, there has been a limited amount of published work summarizing salvia divinorum's effects. A survey of salvia users found that 38% described the effects as unique in comparison to other methods of altering consciousness. 23% said the effects were like yoga, meditation, or trance. Users have written prose about their experiences; some describing their visions pictorially, and there exist examples of 'salvia-inspired' visionary art. Others claim musical inspiration from the plant.
== Tissue culture == In many cases, creation of functional tissues and biological structures in vitro requires extensive culturing to promote survival, growth and inducement of functionality. In general, the basic requirements of cells must be maintained in culture, which include oxygen, pH, humidity, temperature, nutrients and osmotic pressure maintenance. Tissue engineered cultures also present additional problems in maintaining culture conditions. In standard cell culture, diffusion is often the sole means of nutrient and metabolite transport. However, as a culture becomes larger and more complex, such as the case with engineered organs and whole tissues, other mechanisms must be employed to maintain the culture, such as the creation of capillary networks within the tissue.
Sources: en.wikipedia.org
== Structure and properties == Oligonucleotide phosphorothioates (OPS) are modified oligonucleotides where one of the oxygen atoms in the phosphate moiety is replaced by sulfur. Only the phosphorothioates having sulfur at a non-bridging position as shown in figure are widely used and are available commercially. Nucleoside organothiophosphate (PS) analogs of nucleotides give oligonucleotides some beneficial properties. Key beneficial properties that PS backbones give nucleotides are diastereomer identification of each nucleotide and the ability to easily follow reactions involving the phosphorothioate nucleotides, which is useful in oligonucleotide synthesis. PS backbone modifications to oligonucleotides protects them against unwanted degradation by enzymes. Modifying the nucleotide backbone is widely used because it can be achieved with relative ease and accuracy on most nucleotides. Fluorescent modifications on 5' and 3' end of oligonucleotides was reported to evaluate the oligonucleotides structures, dynamics and interactions with respect to environment. The replacement of the non-bridging oxygen with sulfur creates a new center of chirality at phosphorus. In a simple case of a dinucleotide, this results in the formation of a diastereomeric pair of Sp- and Rp-dinucleoside monophosphorothioates whose structures are shown in Figure. In an n-mer oligonucleotide where all (n – 1) internucleosidic linkages are phosphorothioate linkages, the number of diastereomers m is calculated as m = 2(n – 1).
=== Australia === Australia has documented 10 cases of healthcare-acquired CJD (iatrogenic or ICJD). Five of the deaths resulted after the patients, who were in treatment either for infertility or short stature, were treated using contaminated pituitary extract hormone but no new cases have been noted since 1991. The other five deaths occurred due to dura mater grafting procedures that were performed during brain surgery, in which the covering of the brain is repaired. There have been no other ICJD deaths documented in Australia due to transmission during healthcare procedures.
==== Sigma bond cleavage / σ-cleavage ==== Sigma bond cleavage is most commonly observed in molecules that can produce stable cations, such as saturated alkanes or secondary and tertiary carbocations. This occurs when an alpha electron is removed. The C-C bond elongates and weakens causing fragmentation. Fragmentation at this site produces a charged and a radical fragment.
== History == Levodopa was first synthesized in 1911 by Torquato Torquati from the Vicia faba bean. It was first isolated in 1913 by Marcus Guggenheim from the V. faba bean. Guggenheim tried levodopa at a dose of 2.5 g and thought that it was inactive aside from nausea and vomiting. In work that earned him a Nobel Prize in 2000, Swedish scientist Arvid Carlsson first showed in the 1950s that administering levodopa to animals with drug-induced (reserpine) Parkinsonian symptoms caused a reduction in the intensity of the animals' symptoms. In 1960 or 1961 Oleh Hornykiewicz, after discovering greatly reduced levels of dopamine in autopsied brains of patients with Parkinson's disease, published together with the neurologist Walther Birkmayer dramatic therapeutic antiparkinson effects of intravenously administered levodopa in patients. This treatment was later extended to manganese poisoning and later parkinsonism by George Cotzias and his coworkers, who used greatly increased oral doses, for which they won the 1969 Lasker Prize. The first study reporting improvements in patients with Parkinson's disease resulting from treatment with levodopa was published in 1968. Levodopa was first marketed in 1970 by Roche under the brand name Larodopa. The neurologist Oliver Sacks describes this treatment in human patients with encephalitis lethargica in his 1973 book Awakenings, upon which the 1990 movie of the same name is based. Carbidopa was added to levodopa in 1974 and this improved its tolerability.
Sources: en.wikipedia.org
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.
AEDG is the one-letter code for the four amino acids alanine, glutamate, aspartate and glycine in that order. The same molecule is written in three-letter form as Ala-Glu-Asp-Gly.
Identity is normally confirmed by mass spectrometry against the calculated mass of roughly 390.35 g/mol. Purity is then estimated by reversed-phase high-performance liquid chromatography with ultraviolet detection.
Vladimir Khavinson and colleagues at research institutes in Saint Petersburg developed and studied the peptide. Their program examined short peptides as regulators of aging and neuroendocrine function. Epitalon was one of several compounds produced by that group.