The short version of Khavinson fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-10. Anything still debated is marked as such rather than presented as settled.
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.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
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.
Purity assessment of peptide reagents normally relies on reversed-phase high-performance liquid chromatography. A gradient of acetonitrile in water with trifluoroacetic acid, paired with a C18 stationary phase, separates the target tetrapeptide from truncated sequences and deletion analogues. Detection at 214 nanometres exploits absorbance of the peptide backbone, since the molecule contains no aromatic residue. Results are expressed as a percentage of total peak area. Values above ninety-five percent are typical for research-grade material, although reporting conventions vary between suppliers.
Identity confirmation uses mass spectrometry, usually electrospray ionisation in positive mode or matrix-assisted laser desorption. The protonated free peptide produces a signal near three hundred and ninety-one daltons, while salt adducts shift that value slightly. Tandem mass spectrometry or amino acid analysis supplies sequence-level confirmation, which a single mass measurement cannot. Peptides containing aspartate can cyclise into succinimide intermediates that hydrolyse to isoaspartate isomers of identical mass. Because those isomers are difficult to separate chromatographically, identity and purity results carry more weight when interpreted together.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Computed for the free acid of Ala-Glu-Asp-Gly |
| Molecular mass | About 390.35 g/mol | Free peptide; salt forms shift the value |
| Appearance | White to off-white solid | Typical of short peptides after freeze-drying |
| Solubility class | Freely soluble in water | Aqueous buffers are also commonly used |
| Common synonyms | Epitalon, epithalone, AEDG | AEDG is the single-letter sequence |
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
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 report also noted that between 1960 and 1980, China's state propaganda chose to publish "gray-cover books" (Chinese: 灰皮书, romanized: huī pí shū), a large range of socialist and anti-socialist foreign literature criticizing the Soviet system. These included Leon Trotsky's The Revolution Betrayed and Stalin, works of Eduard Bernstein and Karl Kautsky, Milovan Djilas' The New Class, and Friedrich Hayek's The Road to Serfdom. The report suggested these publications influenced interest in the Soviet failures among Chinese leaders Xi, Jiang, and Deng Xiaoping.
== See also == Hyperbaric chamber – in contrast to hypobaric chambers, a hyperbaric chamber places subjects under increased atmospheric pressure or increased oxygen saturation, or both, for purposes including improved wound healing.
In June 1997, Zhang Hongchao was studying at Henan University of Economics and Law when he opened a shaved‑ice stall in Zhengzhou using a CN¥3,000 loan from his grandmother. The stall's early success convinced him to expand, and in 1999 he opened a second stand called Mixue Bingcheng. Due to a lack of experience, Hongchao had closed three stores in a little more than a year. Following the closure of his third store, he went to Hefei to sell tanghulu, which also failed. In spring 1999, Hongchao returned to Zhengzhou to start a new cold drink shop, though this would also be demolished; the failures of these street stalls were attributed to poor locations and ongoing urbanization.
=== PGSS === In the PGSS method (Particles from Gas Saturated Solutions) the solid material is melted and the supercritical fluid is dissolved in it. However, in this case the solution is forced to expand through a nozzle, and in this way nanoparticles are formed. The PGSS method has the advantage that because of the supercritical fluid, the melting point of the solid material is reduced. Therefore, the solid melts at a lower temperature than the normal melting temperature at ambient pressure.
Sources: en.wikipedia.org
trinucleotide repeat Any sequence in which an individual nucleotide triplet is repeated many times in tandem, whether in a gene or non-coding sequence. At most loci some degree of repetition is normal and harmless, but mutations which cause specific triplets (especially those of the form CnG) to increase in copy number above the normal range are highly unstable and responsible for a variety of genetic disorders.
== Hemodynamic stress == Hemodynamic stress overrides fatty acid inhibition of glucose metabolism. During this time there is a decrease in substrate supply and an increase in the substrate demand. This leads to an activation of AMP-activated protein kinase (AMPK) as the AMP concentration rises in intracellular fluids and the ATP concentration decreases. The stress-induced activation of AMPK provides an immediate metabolic adaption and protects the heart from ischemic stress.
=== Razin and Pugachev Rebellions === As a largely independent nation, the Cossacks had to defend their liberties and democratic traditions against the ever-expanding Muscovy, succeeded by the Russian Empire. Their tendency to act independently of the Tsardom of Russia increased friction. The Tsardom's power began to grow in 1613, with the ascension of Mikhail Romanov to the throne following the Time of Troubles. The government began attempting to integrate the Cossacks into the Russian Tsardom by granting elite status and enforcing military service, thus creating divisions among the Cossacks themselves as they fought to retain their traditions. The government's efforts to alter their traditional nomadic lifestyle resulted in the Cossacks being involved in nearly all the major disturbances in Russia over 200 years, including the rebellions led by Stepan Razin and Yemelyan Pugachev.
=== Peroxide stress response === In response to an increased flux of hydrogen peroxide and other organic peroxides such as tert-butyl hydroperoxide and cumene hydroperoxide, peroxide stimulon gets activated. Studies of E. coli response to H2O2 have shown that exposure to H2O2 elevated mRNA levels of 140 genes, of which 30 genes are members of the OxyR regulon. The genes include many genes coding for metabolic enzymes and antioxidant enzymes demonstrating the role of these enzymes in reorganization of metabolism under stress conditions.
== Protein folding == Proline is unique among the natural amino acids in having a relatively small difference in free energy between the cis configuration of its peptide bond and the more common trans form. The activation energy required to catalyse the isomerisation between cis and trans is relatively high: ~20kcal/mol (cf. ~0kcal/mol for regular peptide bonds). Unlike regular peptide bonds, the X-prolyl peptide bond will not adopt the intended conformation spontaneously, thus, the process of cis-trans isomerization can be the rate-limiting step in the process of protein folding. Prolyl isomerases therefore function as protein folding chaperones. Cis peptide bonds N-terminal to proline residues are often located at the first residue of certain types of tight turns in the protein backbone. Proteins that contain structural cis-prolines in the native state include ribonuclease A, ribonuclease T1, beta lactamase, cyclophilin, and some interleukins. Prolyl isomerase folding can be autocatalytic and therefore the speed of folding depends on reactant concentration. Parvulin and human cytosolic FKBP are thought to catalyze their own folding processes.
Sources: en.wikipedia.org
The body fluid contains phagocytic cells called coelomocytes, which are also found within the hemal and water vascular systems. These cells engulf waste material, and eventually migrate to the tips of the papulae, where a portion of body wall is nipped off and ejected into the surrounding water. Starfish keep their body fluids at the same salt concentration as the surrounding water; the lack of an osmoregulation system probably explains why starfish are not found in fresh water and rarely in estuarine environments.
== Preparation == Imidazole was first reported in 1858 by the German chemist Heinrich Debus, although various imidazole derivatives had been discovered as early as the 1840s. It was shown that glyoxal, formaldehyde, and ammonia condense to form imidazole (glyoxaline, as it was originally named). This synthesis, while producing relatively low yields, is still used for generating C-substituted imidazoles.
=== Electromagnetic radiation === Acoustic photonic intellectual neurostimulation (APIN) Light therapy (phototherapy) Ultraviolet light therapy PUVA therapy Photodynamic therapy Photothermal therapy Pulsed electromagnetic field therapy Cytoluminescent therapy Blood irradiation therapy Laser therapy Low-level laser therapy Transcranial pulsed electromagnetic fields (tPEMF)
Opportunistic bands of Normans successfully established a foothold in southern Italy. Probably as the result of returning pilgrims' stories, the Normans entered southern Italy as warriors in 1017 at the latest. In 999, according to Amatus of Montecassino, Norman pilgrims returning from Jerusalem called in at the port of Salerno when a Muslim attack occurred. The Normans fought so valiantly that Prince Guaimar III begged them to stay, but they refused and instead offered to tell others back home of the Prince's request. William of Apulia tells that, in 1016, Norman pilgrims to the shrine of the Archangel Michael at Monte Gargano were met by Melus of Bari, a Lombard nobleman and rebel, who persuaded them to return with more warriors to help throw off the Byzantine rule, which they did. The two most prominent Norman families to arrive in the Mediterranean were descendants of Tancred of Hauteville and the Drengot family. A group of Normans with at least five brothers from the Drengot family fought the Byzantines in Apulia under the command of Melus of Bari. Between 1016 and 1024, in a fragmented political context, the County of Ariano was founded by another group of Norman knights headed by Gilbert Buatère and hired by Melus of Bari. Defeated at Cannae, Melus of Bari escaped to Bamberg, Germany, where he died in 1022. The county, which replaced the pre-existing chamberlainship, is considered to be the first political body established by the Normans in the south of Italy.
Sources: en.wikipedia.org
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.
Epitalon and epithalon both circulate, and the difference reflects transliteration of a name coined in Russian-language publications. Reference to the extract it derives from, epithalamin, explains the shared stem. Databases and suppliers are inconsistent, so a search for one spelling alone may miss relevant entries.
No. Epithalamin is a multi-component preparation obtained from pineal tissue, and its exact composition is not fully characterised. Epitalon is a single defined tetrapeptide described as a short synthetic counterpart of that extract, so the two are related in origin but not interchangeable in identity.
Reversed-phase high-performance liquid chromatography with ultraviolet detection at 214 nanometres is the usual approach. Peak area percentage provides a purity figure relative to other components in the sample. Mass spectrometry is then applied to confirm identity.