tetrapeptide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-03-30 and is reviewed periodically as new material appears.
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.
Laboratory handling begins with dissolution of the lyophilized powder in water or a suitable aqueous buffer. The dry solid is the more stable form, so stock solutions are generally prepared only when required and kept cold afterwards. Repeated freezing and thawing of a solution is avoided because it encourages aggregation and gradual loss of the intact chain. Diluents and containers are selected to limit adsorption of a short peptide onto plastic surfaces and to reduce microbial growth in aqueous preparations.
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.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, dry powder | -20 degrees Celsius or lower | Sealed, dark, low humidity |
| Storage temperature, solution | 2 to 8 degrees Celsius | Short-term use expected |
| Primary purity method | Reversed-phase HPLC | Ultraviolet detection near 214 nm |
| Identity confirmation | Electrospray mass spectrometry | Compared with calculated mass |
| Typical purity specification | Area percent of 95 or higher | Depends on column and gradient |
Solubility is high in water, phosphate-buffered saline and normal saline, a pattern that follows from the two acidic residues in the chain. The peptide dissolves poorly in non-polar solvents such as hexane or chloroform. Stock solutions are often prepared in water first and then diluted into the buffer of interest. Because the molecule is small and hydrophilic, filtration through a low-protein-binding membrane is usually straightforward, and visible particulates are uncommon in freshly made solutions.
Identity and purity are established with reversed-phase high-performance liquid chromatography and mass spectrometry. The chromatogram shows the main peak and any truncated or oxidised by-products, while the mass spectrum confirms the expected 390 dalton mass. Amino acid analysis can corroborate composition when a sample's origin is uncertain. Counterion content, particularly residual trifluoroacetate from purification, is frequently reported alongside purity because it shifts the net mass of the solid.
Reference material is normally supplied as a lyophilised powder in a sealed vial. Product literature typically recommends storage at minus twenty degrees Celsius or colder, protected from light and moisture. Freeze-thaw cycling is usually avoided because repeated condensation can introduce water into the vial. Working solutions are commonly prepared fresh, aliquoted, and kept cold for short periods rather than stored at ambient temperature. Labelling the date of opening helps track how long a vial has been in use.
The proposed relationship between epitalon and pineal function is a central part of its background. Khavinson's group reported that short peptides corresponding to regions of larger pineal proteins could influence gene expression in cells. Epitalon was framed as a synthetic analogue of an active fragment rather than a direct isolation product. Whether the tetrapeptide reproduces the effects of the parent extract is an open question, because comparative studies are limited and the parent extract itself is not a single defined substance.
Interest in epitalon is usually discussed within the broader field of short peptide bioregulators, a category that includes other synthetic di-, tri-, and tetrapeptides studied by the same research group. These compounds share a common rationale: that small fragments of tissue-derived proteins can retain biological activity and can be produced reproducibly. The category as a whole remains outside mainstream pharmacological consensus, and epitalon specifically has a limited presence in independent, non-Russian research literature, which shapes how its evidence base is described.
Epitalon is a synthetic tetrapeptide with the amino acid sequence alanine-glutamate-aspartate-glycine, abbreviated Ala-Glu-Asp-Gly or AEDG. It was developed by the Russian researcher Vladimir Khavinson and colleagues during work on peptide bioregulators derived from the pineal gland. The compound is short enough to be produced by standard solid-phase peptide synthesis and is typically handled as a lyophilized white powder. Its small size distinguishes it from larger pineal peptides such as epithalamin, a complex extract from which the tetrapeptide was conceptually derived.
The molecule is a short, linear, hydrophilic peptide that dissolves readily in water or aqueous buffer. Its principal chemical liabilities are hydrolytic rather than oxidative, since it contains no cysteine, methionine, or tryptophan residues. The aspartate–glycine step is a recognised site for aspartimide formation under mildly acidic or basic conditions, generating isoaspartate and succinimide-related products over time. Desiccated lyophilised powder held at −20 °C is comparatively stable, whereas dilute solutions degrade faster and are best frozen as single-use aliquots rather than thawed repeatedly.
No pharmacopoeial monograph exists for this peptide, so quality rests on the supplier's internal specifications and on whatever independent testing a purchaser arranges. Certificates of analysis differ widely in which tests they report and in the limits applied. The counter-ion introduced during purification, commonly acetate or trifluoroacetate, changes the net peptide content of a given mass of powder, so two samples of equal weight may not contain equal amounts of the active sequence. Third-party laboratories can verify purity, identity, residual solvents, and counter-ion content for a fee, which makes documentation more informative than labelling.
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.
=== Processing issues and solutions === Nanocapsules tend to aggregate and become unstable. Thus, substances within capsules can leak. To control the instability, nanocapsules can be dried either through spray drying or freeze-drying (lyophilization). Spray drying – Solutions are sprayed into a drying medium. This method is more widely used in the food industry and used for encapsulation of many food products as flavors, minerals, colors, and vitamins. This method makes nanocapsules more stable, and increases shelf-life of foods. Freeze-drying – This process involves dehydration of materials that are heat-sensitive. Unlike spray drying, water is removed through the sublimation process without changing the structure or shape of the nanoparticles. Freeze-drying involves four states: freezing, primary drying, secondary drying, and storage. Because of the multiple stages involved, this method is considered to demand more energy and time.
{\displaystyle {\begin{array}{lll}M({\ce {H2}})&=2\times 1.00794(7)\times M_{\mathrm {u} }&=2.01588(14){\text{ g/mol}}\\M({\ce {N2}})&=2\times 14.0067(2)\times M_{\mathrm {u} }&=28.0134(4){\text{ g/mol}}\\M({\ce {O2}})&=2\times 15.9994(3)\times M_{\mathrm {u} }&=31.9988(6){\text{ g/mol}}\\M({\ce {S8}})&=8\times 32.065(5)\times M_{\mathrm {u} }&=256.52(4){\text{ g/mol}}\\M({\ce {Cl2}})&=2\times 35.453(2)\times M_{\mathrm {u} }&=70.906(4){\text{ g/mol}}\end{array}}}
Moore and another Liverpool biochemist, Edward Whitney, founded the Biochemical Journal in 1906, one year after the creation of the US-based Journal of Biological Chemistry in 1905. Both journals still exist. Moore served as the first Biochemical Journal editor with the journal initially being published by the Liverpool University Press, the 3rd oldest University Press in England. Moore was concerned with the high mortality for the United Kingdom of pulmonary tuberculosis (TB), which he called the ‘Great White Plague', concluding that with 'the foundation of a new National Health Service and the provision of segregation for infectious cases in sanatoria, the disease could be eradicated'. Other holders of the Johnston Chair include RA Morton, FRS HH Rees, the late Trevour Goodwin FRS and the current Head of Department PA Eyers The Liverpool-originated Biochemical Journal was acquired by the London-based Biochemical Club (later renamed the Biochemical Society in 1911.
Sources: en.wikipedia.org
Significant efforts in the mid-20th century helped clarify its nomenclature, stabilising its current name. Although there were challenges to this name in the 1980s, it was confirmed as valid in 2004. More recently, DNA studies suggest that there may be hidden diversity within the species, indicating the need for further taxonomic evaluation. The lichen is used as a spice in Indian cuisine. For this purpose, it is commonly known as black stone flower or kalpasi (among other names). Although nearly tasteless on its own, it releases an earthy fragrance and taste when cooked in with oil or butter.
Methyl p-(hydroxymethyl)benzoate undergoes reaction with ethylene oxide with boron trifluoride etherate and dichloromethane to yield 2-hydroxyethyl ether. Then, the hydroxy group is substituted with tert-butyldimethylsilyl chloride (TMS-Cl) in dimethylformamide (DMF). Next, the ester is reduced into an according alcohol using lithium aluminium hydride (LAH) in tetrahydrofuran. The newly created hydroxy moiety undergoes addition with 2-tert-butyl-4-chloro-5-hydroxy-pyridazin-3-one. The TBSO group is then substituted with a tosyl group with a two-step reaction using (1) tetra-n-butylammonium fluoride (TBAF) in THF and (2) tosyl chloride in 4-dimethylaminopyridine (DMAP), triethylamine (TEA) and dichloromethane. To create the final radiolabelled radiopharmaceutical, potassium fluoride-18 is used. This step is performed using kryptofix, a phase-transfer catalyst, and acetonitrile. Kryptofix (5-decyl-4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane), a cryptand, increases the solubility of the fluoride ion in organic solvents (here, acetonitrile), by chelating it.
In a related change, Twitter introduced additional gold and gray checkmarks, used by Verified Organizations and government-affiliated accounts, respectively. Twitter claims that the changes to verification are required to "reduce fraudulent accounts and bots". Twitter users who had been verified through the previous system were known as "legacy verified" accounts; legacy verification was deprecated in April 2023, and stripped from accounts who do not meet the new payment requirements. Musk later implied that he had been personally paying for the X Premium subscriptions of several notable celebrities.
=== Pharmacogenomics === Two percent of Caucasians and 18% of people from African descent are desloratadine poor metabolizers. In these people, the drug reaches threefold higher plasma concentrations at seven hours after intake, and it has a half-life of 89 hours (compared to a 27-hour half-life in normal metabolizers). Adverse effects were reported at similar rates in poor metabolizers, suggesting that it is not clinically relevant.
Sources: en.wikipedia.org
Amino acid-based formula is a type of infant milk formula made from individual amino acids. It is hypoallergenic and intended for infants suffering from severe allergy to milk and various gastrointestinal conditions, such as food protein-induced enterocolitis syndrome and malabsorption syndromes. It is sometimes referred to as elemental formula but this is considered a misleading name. Issues with the use of amino acid-based formula include its high cost and its unpalatable taste. Intake of amino-acid formula for healthy infants shows no advantage in growth.
Vampire: The Masquerade – Bloodlines is a 2004 action role-playing video game developed by Troika Games and published by Activision for Microsoft Windows. Set in White Wolf Publishing's World of Darkness, the game is based on White Wolf's role-playing game Vampire: The Masquerade and follows a human who is killed and revived as a fledgling vampire. The game depicts the fledgling's journey through early 21st-century Los Angeles to uncover the truth behind a recently discovered relic that heralds the end of all vampires. Bloodlines is presented from first-person and third-person perspectives. The player assigns their character to one of several vampire clans—each with unique powers—customizes their combat and dialog abilities, and progresses through Bloodlines using violent and nonviolent methods. The selection of clan affects how the player is perceived in the game world and which powers and abilities they possess; this opens up different avenues of exploration and methods of interacting with or manipulating other characters. The player can complete side missions away from the primary storyline by moving freely between the available hubs: Santa Monica, Hollywood, downtown Los Angeles, and Chinatown. Troika's 32-member team began developing Bloodlines in November 2001 as an indirect sequel to the previous year's Vampire: The Masquerade – Redemption. Troika used Valve's Source game engine, then in development, which was used for Valve's own Half-Life 2.
== Medical uses == Pioglitazone is used to lower blood glucose levels in type 2 diabetes either alone or in combination with sulfonylurea, metformin, or insulin. The effects of pioglitazone have been compared in a Cochrane systematic review to that of other blood sugar lowering-medicine, including metformin, acarbose, and repaglinide, as well as with appropriate diet and exercise, not showing any benefit in reducing the chance of developing type 2 diabetes in people at risk. It did, however, show reduction of risk of developing type 2 diabetes when compared to a placebo or to no treatment. These results should be interpreted considering that most of the data of the studies included in this review were of low or very-low certainty. While pioglitazone does decrease blood sugar levels, the main study that looked at the medication found no difference in the main cardiovascular outcomes that were looked at. The secondary outcome of death from all causes, myocardial infarction, and stroke were lower. Pioglitazone has been found to reduce all-cause mortality in type 2 diabetic patients compared to other therapies, with a 60% reduction in mortality in those exposed to pioglitazone, compared to those never exposed. Another study found an all-cause mortality hazard ratio of 0.33 for pioglitazone after adjusting for >40 covariates, compared to insulin. Due to insufficient data on all-cause mortality, cardiovascular mortality, myocardial infarction and stroke, this was not possible to compare in a more recent review.
== Overview == A sequence begins with a greater-than character (">") followed by a description of the sequence (all in a single line). The lines immediately following the description line are the sequence representation, with one letter per amino acid or nucleic acid, and are typically no more than 80 characters in length. For example:
==== United Arab Emirates ==== The United Arab Emirates has launched several cyber-attacks in the past targeting dissidents. Ahmed Mansoor, an Emirati citizen, was jailed for sharing his thoughts on Facebook and Twitter. He was given the code name Egret under the state-led covert project called Raven, which spied on top political opponents, dissidents, and journalists. Project Raven deployed a secret hacking tool called Karma, to spy without requiring the target to engage with any web links. In September 2021, three of the former American intelligence officers, Marc Baier, Ryan Adams, and Daniel Gericke, admitted to assisting the UAE in hacking crimes by providing them with advanced technology and violating US laws. Under a three-year deferred prosecution agreement with the Justice Department, the three defendants also agreed to pay nearly $1.7 million in fines to evade prison sentences. The court documents revealed that the Emirates hacked into the computers and mobile phones of dissidents, activists, and journalists. They also attempted to break into the systems of the US and rest of the world.
Sources: en.wikipedia.org
The dry powder is typically held at -20 degrees Celsius or lower, protected from light and moisture. Allowing a sealed vial to reach room temperature before opening reduces condensation on its contents. Conditions stated on a supplier certificate of analysis take precedence over general guidance.
Mass spectrometry supplies an observed molecular mass that is compared with the calculated value for the tetrapeptide. Reversed-phase chromatography then separates the main peak from related impurities. Neither technique alone establishes residue order, so sequence-level confirmation may call for tandem mass spectrometry or amino acid analysis.
No single published figure applies, because stability depends on pH, concentration, temperature and sterility. Cold storage slows hydrolysis without halting it, and microbial growth is a separate concern in non-sterile solutions. Most laboratories rely on their own analytical checks rather than a fixed expiry period.
Epitalon is a synthetic tetrapeptide built from four amino acids: alanine, glutamate, aspartate, and glycine. It is not extracted from a natural source but made in the laboratory by chemical synthesis. Its short length makes it relatively straightforward to produce at high purity.