This is a working overview of certificate of analysis, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-16. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four-residue sequence |
| Molar mass | About 390.35 g/mol | Free peptide, counter-ion not included |
| Appearance | White to off-white powder | Lyophilised solid from aqueous solution |
| Water solubility | Freely soluble | Short, polar peptide chain |
| Common synonyms | AEDG; epithalone | Catalogues use the names interchangeably |
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
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.
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.
Stability of the tetrapeptide follows ordinary peptide chemistry rather than any unusual structural feature. The aspartate-glycine pair is prone to aspartimide formation under mildly basic or neutral conditions, and deamidation can follow, altering both mass and chromatographic retention. Dry lyophilised powder kept at or below minus twenty degrees Celsius is the usual handling recommendation, with repeated freeze-thaw cycles avoided. Once dissolved in neutral aqueous buffer, degradation proceeds over days to weeks depending on pH and temperature, while acidic conditions generally slow the aspartimide route. A formal stability-indicating study has not been published in the indexed literature.
Because epitalon has no pharmacopoeial monograph, quality assessment depends on supplier documentation and independent testing. Certificates of analysis typically report a purity figure from a single chromatographic run, a measured mass and sometimes an appearance description, but methods and acceptance criteria are not harmonised across vendors. Third-party laboratories can repeat identity and purity measurements, and mismatches between labelled and measured peptide content have been described for research peptides generally. What constitutes adequate identity confirmation for a molecule of this size stays an open question, since mass agreement alone does not separate closely related sequences.
Identity testing for epitalon relies on reversed-phase high-performance liquid chromatography for purity and mass spectrometry for mass confirmation. Because the sequence contains no tryptophan or tyrosine, ultraviolet detection at 280 nanometres is insensitive, so chromatographic methods usually monitor absorbance near 214 nanometres, where the peptide backbone absorbs. Electrospray ionisation or matrix-assisted laser desorption/ionisation then checks the intact mass against the expected value near 390 daltons. Peptide mapping or amino acid analysis after acid hydrolysis can supplement these measurements, although such confirmatory work is seldom reported on commercial certificates of analysis.
The diagnosis of MADD needs to be considered in patients who have exercise induced myalgia, cramps and sometimes weakness. A mildly elevated creatine kinase may also occur. Exclusion of other muscular diseases such as McArdle's Disease and carnitine cycle abnormalities should occur. MADD may be identified if there is a lack of ammonia rise after forearm exercise testing. The diagnosis may then be confirmed with genetic testing.
Thorium also forms the corresponding sulfates (for example Na2SO4·Th(SO4)2·5H2O), nitrates and thiocyanates. Salts with the general formula An2Th(NO3)6·nH2O are of coordination nature, with the coordination number of thorium equal to 12. Even easier is to produce complex salts of pentavalent and hexavalent actinides. The most stable coordination compounds of actinides – tetravalent thorium and uranium – are obtained in reactions with diketones, e.g. acetylacetone.
=== Perception === Machine perception is the ability to use input from sensors (such as cameras, microphones, wireless signals, active lidar, sonar, radar, and tactile sensors) to deduce aspects of the world. Computer vision is the ability to analyse visual input. The field includes speech recognition, image classification, facial recognition, object recognition, object tracking, and robotic perception.
Sources: en.wikipedia.org
==== Combination drugs ==== Carbidopa/entacapone/levodopa (LECIGel; LECIGon; Lecigon; Trigel) – combination of carbidopa (aromatic L-amino acid decarboxylase (AAAD) inhibitor), entacapone (catechol O-methyltransferase (COMT) inhibitor), and levodopa (dopamine precursor) [345] Levodopa/carbidopa/entacapone (ELC-200; Stalevo; Stavelo) – combination of levodopa (dopamine precursor), carbidopa (aromatic L-amino acid decarboxylase (AAAD) inhibitor), and entacapone (catechol O-methyltransferase (COMT) inhibitor) [346]
The enteric nervous system consists of some one hundred million neurons that are embedded in the peritoneum, the lining of the gastrointestinal tract extending from the esophagus to the anus. These neurons are collected into two plexuses – the myenteric (or Auerbach's) plexus that lies between the longitudinal and the smooth muscle layers, and the submucosal (or Meissner's) plexus that lies between the circular smooth muscle layer and the mucosa. Parasympathetic innervation to the ascending colon is supplied by the vagus nerve. Sympathetic innervation is supplied by the splanchnic nerves that join the celiac ganglia. Most of the digestive tract is innervated by the two large celiac ganglia, with the upper part of each ganglion joined by the greater splanchnic nerve and the lower parts joined by the lesser splanchnic nerve. It is from these ganglia that many of the gastric plexuses arise.
Another submarine, USS Cavalla, was able to maneuver to an attack position on the 25,675-ton carrier Shōkaku by about noon. The submarine fired a spread of six torpedoes, three of which struck Shōkaku on her starboard side. Badly damaged, the carrier came to a halt. One torpedo had hit the forward aviation fuel tanks near the main hangar, and aircraft that had just landed and were being refueled exploded into flames. Ammunition and exploding bombs added to the conflagration, as did burning fuel spewing from shattered fuel pipes. With her bows subsiding into the sea and fires out of control, the captain gave orders to abandon ship. Within minutes, there was a catastrophic explosion of aviation fuel vapor which had built up between decks, which blew the ship apart. The carrier rolled over and sank about 140 miles (230 km) north of the island of Yap. 887 crew and 376 men of the 601st Naval Air Group, 1,263 men in all, were killed. There were 570 survivors, including the carrier's commanding officer, Captain Hiroshi Matsubara. Destroyer Urakaze attacked the submarine, but Cavalla escaped with relatively minor damage despite near misses from depth charges. Meanwhile, Taihō was falling victim to poor damage control. Hoping to clear the explosive fumes, an inexperienced damage-control officer ordered her ventilation system to operate at full blast. This action instead spread the vapors throughout Taihō, putting the entire vessel at risk.
Sources: en.wikipedia.org
== Properties and applications == Cyclic peptides tend to be extremely resistant to the process of digestion, making them of interest to scientists working on novel oral medications. Examples include:
== History == In traditional oil painting as practiced by the Renaissance painter, skin glue was used to seal the canvas. This is necessary because the linseed oil that forms the base of most oil paint contains linolenic acid that will destroy the canvas fibers over time. Renaissance artists also knew that pure size (hide glue) became brittle once dry, and would mix it with oil and chalk to make a "half-ground" for canvases. Pure hide glue was usually applied only to rigid supports like panels. Though this does help to seal the canvas or panel, artists still applied a layer of "oil ground", which was often lead-based paint, in order to provide a binding layer for the final oil paint to adhere to.
== Etiology == The etiology of anxiety disorder remains unknown. There are several contributing factors that are yet to be proved to cause anxiety disorders. These factors include childhood anxiety, drug induction by central stimulant drugs, metabolic diseases or having depressive disorder.
== Adverse effects == Injection site reactions such as redness and pain are common, occurring in approximately 15.5% of cases. The FDA prescribing information includes a warning for potential increased risk of serious infections due to IL-1 blockade. Macrophage activation syndrome (MAS) is a known, life-threatening disorder that may develop in people with rheumatic conditions, in particular Still's disease, and should be aggressively treated. Treatment with immunosuppressants may increase the risk of malignancies. People are advised not to receive live vaccinations during treatment.
Sources: en.wikipedia.org
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.
The name derives from epithalamin, a pineal gland extract studied in the former Soviet Union. Researchers proposed that short fragments of that extract carried the biological activity of interest.
No major regulatory agency has approved it as a medicine. It is handled as a research chemical, and products sold under this name are not standardised drugs with defined clinical labelling.
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.