This is a working overview of Deamidation, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-03-01 and is reviewed periodically as new material appears.
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.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
Epitalon is a synthetic tetrapeptide whose four residues are alanine, glutamate, aspartate and glycine, commonly abbreviated AEDG. Its molecular formula is C14H22N4O9 and its monoisotopic mass is near 390.35 daltons. The peptide carries two acidic side chains, so it is neutral to negatively charged in most aqueous buffers. Published reference summaries usually list it under both spellings, epitalon and epithalon, and treat the two names as the same material.
| Property | Value | Notes |
|---|---|---|
| Analytical method | Reversed-phase HPLC | Purity determination, typically 214 nm |
| Mass confirmation | ESI or MALDI mass spectrometry | Compared with mass near 390 Da |
| Common synonyms | Epitalon, epithalon, AEDG | Naming differs between suppliers |
| Storage temperature | −20 °C or lower | Lyophilised powder, kept desiccated |
| Solution stability | Limited in neutral aqueous buffer | Aspartimide and hydrolysis pathways |
Regulatory treatment differs by country. No formulation of epitalon holds a marketing authorisation as a medicine in the United States or the European Union, where material sold for laboratory use is handled as a research chemical and is not intended for human consumption. In Russia, several short peptide preparations from the same institute's peptide series are registered medicinal products, and epitalon appears in that national context. Elsewhere it is frequently offered as a cosmetic ingredient, a category with lighter requirements. Advertising claims about longevity or disease prevention are restricted in most jurisdictions, which limits how sellers describe the compound.
Freeze-dried epitalon is normally kept at minus twenty degrees Celsius in a sealed, desiccated container, protected from light. Short excursions at ambient temperature during shipping are generally tolerated, but repeated warming and cooling cycles encourage moisture uptake, which shortens shelf life. Once dissolved, the peptide is far less stable than the solid: aqueous solutions are subject to hydrolysis and to deamidation at the aspartate and glutamate residues. Working solutions are therefore held refrigerated and used within days, and repeated freezing and thawing of the same vial is best avoided.
Identity and purity are checked by reversed-phase high-performance liquid chromatography, usually with ultraviolet detection near 214 nanometres, where the peptide bond absorbs. Mass spectrometry confirms the expected mass and reveals whether truncation products or adducts are present. Acid hydrolysis followed by amino acid analysis gives the residue ratio, which should approximate one alanine, one glutamate, one aspartate and one glycine. Counter-ions such as acetate or trifluoroacetate remain in the dried product and lower net peptide content, so a stated purity figure on a label does not by itself describe how much peptide a vial holds.
In its supplied form epitalon is a white to off-white powder, usually lyophilized and often hygroscopic. It dissolves readily in water and in aqueous buffers, and it is commonly handled as the acetate or trifluoroacetate salt to improve stability during purification and drying. The amide backbone is labile in aqueous media, so solutions are less durable than the dry solid. Handling notes in the chemical literature therefore emphasize keeping the powder dry, cool and shielded from light until it is dissolved.
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.
Storage practice centres on limiting moisture, oxygen, and repeated temperature cycling. Freeze-dried powder is generally held desiccated at minus twenty degrees Celsius or colder and protected from light. Reconstituted solutions are markedly less stable, and the aspartate-glycine junction is prone to succinimide formation at neutral to mildly alkaline pH. Portioning material into single-use aliquots reduces degradation compared with repeated freeze-thaw cycles. Stability data specific to this tetrapeptide remain scarce, so most handling guidance is extrapolated from general peptide chemistry rather than measured directly.
Documentation accompanying research peptides usually includes a certificate of analysis listing the batch number, purity figure, and test methods applied. Buyers comparing suppliers should check whether the reported purity refers to chromatographic area or to a mass-balance calculation, because the two are not equivalent. Counter-ion content, residual solvents, and water content are sometimes omitted from such certificates even though they affect the actual peptide mass present. Independent verification through a second laboratory is the most direct way to confirm that a supplied material matches its label.
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.
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.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
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Colonel Sanders was a key component of KFC advertising until his death in 1980. Despite his death, Sanders remains a key icon of the company as an "international symbol of hospitality". Early official slogans for the company included "North America's Hospitality Dish" (from 1956) and "We fix Sunday dinner seven nights a week". The "finger lickin' good" slogan was used from 1956 and went on to become one of the best-known slogans of the 20th century. The trademark expired in the US in 2006. The first KFC logo was introduced in 1952 and featured a "Kentucky Fried Chicken" typeface and a logo of the Colonel. In 1962, Dave Thomas took Colonel Sanders' bucket and turned it into a sign that revolved in a circular motion in front of almost every American KFC outlet. Advertising played a key role at KFC after it was sold by Sanders and the company began to advertise on US television with a budget of US$4 million in 1966. In order to fund nationwide advertising campaigns, the Kentucky Fried Chicken Advertising Co-Op was established, giving franchisees 10 votes and the company three when deciding on budgets and campaigns. In 1969, KFC hired its first national advertising agency, Leo Burnett. A notable Burnett campaign in 1972 was the "Get a bucket of chicken, have a barrel of fun" jingle, performed by Barry Manilow. By 1976, KFC was one of the largest advertisers in the US.
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Sources: en.wikipedia.org
=== Prussian Blue === Prussian Blue, also known as Berlin Blue, Paris Blue, or Turnbull's Blue, is an inorganic pigment, produced in large quantities for both artistic purposes and textiles. It has the chemical formula FeIII4[FeII(CN)6]3. With a history dating back to the early 18th century, Prussian blue remains a popular artistic pigment. Studies of Prussian Blue lead to discoveries about hydrogen cyanide. It is an antidote for heavy metal poisoning, and is famed for being used to color the uniforms of the Prussian army in the 18th century.
HATU (Hexafluorophosphate Azabenzotriazole Tetramethyl Uronium) is a reagent used in peptide coupling chemistry to generate an active ester from a carboxylic acid. HATU is used along with Hünig's base (N,N-diisopropylethylamine), or triethylamine to form amide bonds. Typically dimethylformamide is used as solvent, although other polar aprotic solvents can also be used.
== Mechanism of action == Brincidofovir is a prodrug that is composed of cidofovir conjugated with a lipid molecule. The lipid aspect of the molecule takes on the action of endogenous lysophosphatidyl choline, which then is able to enter cells in the body which are infected with smallpox. Once the infected cell takes in the drug, the drug cleaves to generate cidofovir. Cidofovir is then consequently phosphorylated to yield cidofovir diphosphate, which is the active drug. Cidofovir diphosphate inhibits the variola virus' DNA polymerase-mediated DNA synthesis. The drug acts as an acyclic nucleotide and incorporates itself into the viral DNA chain, which then stops viral DNA synthesis.
=== March === 1 March – 2024 Rochdale by-election: Sir Keir Starmer apologises to the voters of Rochdale for disowning the Labour Party's candidate, but says it was "the right decision". In a statement outside 10 Downing Street, Sunak warns that Islamists and far-right extremists, which he describes as "two sides of the same extremist coin", are trying to "deliberately" undermine the UK's "multi-faith democracy", and says the UK must face them down. Figures from the National Audit Office show the UK government will pay Rwanda a total of £350m for the agreement to take asylum seekers, with £150,000 also being paid to Rwanda for each person sent there. Conservative peer Lord Bamford, chairman of JCB, retires from the House of Lords. 2–3 March – The London Labour conference is held at the Leonardo Royal Hotel in Tower Bridge. 4 March – Sunak says the UK economy is "getting on the right track" ahead of what is expected to be the last budget before the next election. George Galloway is sworn in as an MP at Westminster. Paul Scully, MP for Sutton and Cheam, announces he is standing down from Parliament at the next general election. Lee Waters announces he is stepping down as Wales's Transport Minister when the new First Minister of Wales is elected. 5 March – A bid by the Welsh Conservatives and Welsh Liberal Democrats to change planned reforms to the way Senedd members are elected from the 2026 election is rejected by the parliament. 6 March – Chancellor Jeremy Hunt delivers the 2024 United Kingdom budget.
Potent and selective MMP-3 inhibitors have been developed by using a hydroxypyrone as the zinc binding group. By attaching an aryl backbone to the 2-position of the pyrone ring, more selectivity was gained. On the hydroxypyrone ring, three positions are available to attach backbones, position 2-, 5- and 6-. Hydroxypyrone-based MMP inhibitors are structurally corresponding to the pyrimidinetriones. A recent inhibitor is the compound 3-hydroxypyran-4-one nominated 868368-30-3. It is MMP-3 selective and its 0,0-bidentate chelation of zinc is the structural part proposed to be responsible for the MMP recognition.
Sources: en.wikipedia.org
The molecule lacks aromatic residues, so it absorbs weakly near 280 nanometres, the wavelength applied to many other peptides. The peptide bond absorbs strongly below 220 nanometres, making 214 nanometres a practical compromise. Gradient methods must therefore use mobile phases with low ultraviolet absorbance to keep the baseline clean.
Neutral and slightly basic aqueous conditions promote aspartimide formation at the aspartate-glycine step, often followed by deamidation. Elevated temperature and repeated freeze-thaw cycles accelerate the loss. Acidic solutions and dry lyophilised powder are comparatively stable over short periods.
No monograph exists in the United States Pharmacopeia or the European Pharmacopoeia, and no widely distributed certified reference standard is available. Purity and identity therefore rest on supplier methods that are not harmonised. This absence is the main reason reported purities are difficult to compare between sources.
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.