The short version of freeze-drying fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-02-25 and is reviewed periodically as new material appears.
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.
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.
| 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 |
Identity is normally established by reversed-phase high-performance liquid chromatography combined with mass spectrometry, a pairing that separates components and confirms molecular mass at once. Purity is quoted as a percentage from the chromatogram, and figures above ninety-five percent are a frequent commercial specification. Amino acid analysis or sequencing supplies further confirmation when required. Because many short peptides behave similarly under chromatography, retention time alone does not establish sequence; the mass measurement is what separates one tetrapeptide from another, and certificates should report both.
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.
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.
The compound is generally described as a synthetic analogue of a fragment isolated from a pineal gland extract. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology introduced it during the 1980s and 1990s while studying short peptides from animal tissue. The original extract, called epithalamin, is a heterogeneous mixture, whereas epitalon is a single defined sequence. That distinction matters because findings reported for the extract are not automatically findings about the pure tetrapeptide, and claims about broader biological effects remain a separate question from the chemical identity described here.
== Bibliography (selection) == Langer, Ellen J. (1989). Mindfulness. Reading, MA: Addison Wesley. ISBN 978-0-201-52341-6. Langer, Ellen J. (1997). The Power of Mindful Learning. Reading, MA: Addison-Wesley. ISBN 978-0-201-33991-8. Langer, Ellen J. (2005). On Becoming an Artist. New York: Ballantine Books. ISBN 978-0-345-45629-8. Langer, Ellen J. (2009). Counter clockwise: mindful health and the power of possibility. New York: Ballantine Books. ISBN 978-0-345-50204-9. Langer, Ellen J. (2023). The Mindful Body: Thinking Our Way to Chronic Health. New York: Ballantine Books. ISBN 978-0-593-49794-4.
=== Aortic stenosis === Aortic stenosis is typically the result of aging, occurring in 12.4% of the population over 75 years of age, and represents the most common cause of outflow obstruction in the left ventricle. Bicuspid aortic valves are found in up to 1% of the population, making it one of the most common cardiac abnormalities.
=== Recreational === Benzydamine has been used recreationally. If taken in excess amounts, it acts as an atypical deliriant and CNS stimulant. Such use, particularly among teenagers, has been reported in Brazil, Poland, Romania, and Turkey.
== Selected publications == Zubarev, R. A.; Kelleher, N. L.; McLafferty, F. W. (1998). "Electron Capture Dissociation of Multiply Charged Protein Cations. A Non-ergodic Process". Journal of the American Chemical Society. 120 (13): 3265–3266. Bibcode:1998JAChS.120.3265Z. doi:10.1021/ja973478k. Xie, X.; Zubarev, R. A. (2015). "Isotopic resonance hypothesis: experimental verification by Escherichia coli growth measurements". Scientific Reports. 5 9215: 9210. arXiv:1407.4847. Bibcode:2015NatSR...5.9215X. doi:10.1038/srep09215. PMID 25782666. Yang, H.; Lyutvinskiy, Y.; Herukka, S.-K.; Soininen, H.; Rutishauser, D.; Zubarev, R. A. (2014). "Prognostic polypeptide blood plasma biomarkers of Alzheimer's disease progression". Journal of Alzheimer's Disease. 40 (3): 659–666. doi:10.3233/JAD-132102. PMID 24503613. Xie, X.; Backman, D.; Lebedev, A. T.; Artaev, V. B.; Jiang, L.; Ilag, L. L.; Zubarev, R. A. (2015). "Primordial soup was edible: abiotically produced Miller–Urey mixture supports bacterial growth". Scientific Reports. 5 14338. Bibcode:2015NatSR...514338X. doi:10.1038/srep14338. PMC 4585927. PMID 26412575.
=== LGR4 === LGR4 binds R-spondins to activate the Wnt signaling pathway. Wnt signaling regulates bone mass and osteoblast differentiation and is important for the development of bone, heart, and muscle. An LGR4 nonsense mutation in a healthy population has been linked to low bone mass density and symptoms of osteoporosis. LGR4 mutant mice showed the observed low bone mass is not due to age-related bone loss. Mutations in LGR4 have been associated with family lineages with medical histories of rare bone disorders. Wild-type mice lacking LGR4 also displayed delayed osteoblast differentiation during development, showcasing the important role of LGR4 in bone mass regulation and development.
Sources: en.wikipedia.org
== Gameplay == Bloodlines is an action role-playing video game optionally presented from the first- or third-person perspective. Before the game begins, players create a male or female vampire character by selecting a vampire clan and configuring available points in three areas—Attributes, Abilities, and Disciplines (vampiric powers)—or by answering questions, which create a character for the player. The player can select one of seven vampire clans: the powerful Brujah, the decadent Toreador, the insane Malkavian, the aristocratic Ventrue, the monstrously deformed Nosferatu, the blood-magic-wielding Tremere, or the animalistic Gangrel. The player builds their character by spending acquired points to increase their ratings in the three areas. The points spent on Attributes and Abilities combine to determine a player's success or effectiveness in performing tasks such as using firearms, brawling, and lock-picking; for example, determining how accurate or how far the player can shoot or if they can hack a computer. Attributes are represented by physical (strength, dexterity, and stamina), social (charisma, manipulation, and appearance), and mental (perception, intelligence, and wits). Abilities are talents (such as brawling and dodging), skills (such as firearms and melee), and knowledge (such as computers and investigation). The player is initially assigned points to spend in the three areas, with the amount they can spend determined by clan; for example, the Brujah can spend the most points on physical and skill attributes.
== Research == Trimebutine is investigated for the treatment of functional dyspepsia-IBS overlap syndrome, post-operative nausea and vomiting. A clinical trial evaluating trimebutine as an adjunctive treatment to rabeprazole-resistant reflux oesophageitis was withdrawn due to lack of funds.
Besides their role in photogrammetry, aerial and satellite imagery can be used to identify and delineate terrain features and more general land-cover features. Certainly they have become more and more a part of geovisualization, whether maps or GIS systems. False-color and non-visible spectra imaging can also help determine the lie of the land by delineating vegetation and other land-use information more clearly. Images can be in visible colours and in other spectra.
== Redox reactions in industry == Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects protected metal to a more easily corroded "sacrificial anode" to act as the anode. The sacrificial metal, instead of the protected metal, then corrodes. Oxidation is used in many industries, such as in the production of cleaning products and oxidizing ammonia to produce nitric acid, whose principal industrial route is the catalytic oxidation of ammonia in the Ostwald process. Redox reactions are the foundation of electrochemical cells, which can generate electrical energy or support electrosynthesis. Metal ores often contain metals in oxidized states, such as oxides or sulfides, from which the pure metals are extracted by smelting at high temperatures in the presence of a reducing agent. The process of electroplating uses redox reactions to coat objects with a thin layer of a material, as in chrome-plated automotive parts, silver plating cutlery, galvanization and gold-plated jewelry.
=== Venezuela === Despite Castillo having recognized the Venezuelan government as democratic during the electoral campaign, Castillo's Vice Foreign Minister has claimed that Peru has declared that there is no legitimate authority within Venezuela since 5 January 2021. The Vice Foreign Minister has claimed that Peru supports "intra-Venezuelan dialogue" and a negotiated solution to the crisis. While not a recognition of the Maduro government, this represents a shift away from Peru's previous stance of backing the National Assembly, which opposes Maduro. The next day, then Prime Minister Guido Bellido rejected the Vice Foreign Minister's claims that Peru did not recognize a legitimate authority in Venezuela. Bellido claimed that the Vice Foreign Minister's claim was against the Peruvian government's position, and that President Castillo had a meeting with Venezuelan President Maduro to solve the Venezuelan migrant crisis. Bellido also implied that he was willing to replace the Foreign Ministry if they didn't like the government's stance on Venezuela. However, later that day, the Interior Minister Juan Carrasco claimed that although he respected Bellido's views, he backed the Foreign Ministry's stance regarding Peru's position on Venezuela. Castillo's meeting with President Maduro wasn't recorded on his official agenda. As such, Foreign Minister Óscar Maúrtua was summoned before Congress to explain on the matter. Maúrtua said that Castillo did not plan to meet with Nicolas Maduro, and that the meeting was brief.
Sources: en.wikipedia.org
Palmitoyl tetrapeptide-7 (Pal-GQPR) is a tetrapeptide that is derived from an amino acid sequence Gly-Gln-Pro-Arg found in the immune system modulator immunoglobulin G, conjugated with a lipophilic palmitoyl chain to enhance skin absorption. Even though it is not derived from connective tissue proteins, it is commonly grouped with the matrikine peptides as it has similar effects in the body in promoting synthesis of collagen, and is claimed to produce anti-aging and anti-wrinkle effects. It also has an additional antiinflammatory action due to inhibition of interleukin 6 production and is used in skin creams.
=== Respiratory depression === Respiratory depression is the most serious adverse reaction associated with opioid use, but it usually is seen with the use of a single, intravenous dose in an opioid-naïve patient. In patients taking opioids regularly for pain relief, tolerance to respiratory depression occurs rapidly, so that it is not a clinical problem. Several drugs have been developed which can partially block respiratory depression, although the only respiratory stimulant currently approved for this purpose is doxapram, which has only limited efficacy in this application. Newer drugs such as BIMU-8 and CX-546 may be much more effective.
== Flavouring properties == Glycyrrhizin is obtained as an extract from licorice root after maceration and boiling in water. Licorice extract (glycyrrhizin) is sold in the United States as a liquid, paste, or spray-dried powder. When in specified amounts, it is approved for use as a flavor and aroma in manufactured foods, beverages, candies, dietary supplements, and seasonings. It is 30 to 50 times as sweet as sucrose (table sugar).
=== Manufacturing === In 2017, the total output (gross value added) in the manufacturing industry amounted to 14.4% of total output in Denmark. 325,000 people or a little less than 12% of all employed persons worked in manufacturing (including utilities, mining and quarrying) in 2016. Main sub-industries are manufacture of pharmaceuticals, machinery, and food products.
=== Dual-flow === Dual-flow, also known as dual, countercurrent chromatography occurs when both phases are flowing in opposite directions inside the column. Instruments are available for dual-flow operation for both Hydrodynamic and hydrostatic CCC. Dual-flow countercurrent chromatography was first described by Yoichiro Ito in 1985 for foam CCC where gas-liquid separations were performed. Liquid–liquid separations soon followed. The countercurrent chromatography instrument must be modified so that both ends of the column have both inlet and outlet capabilities. This mode may accommodate continuous or sequential separations with the sample being introduced in the middle of the column or between two bobbins in a hydrodynamic instrument. A technique called intermittent countercurrent extraction (ICcE) is a quasi-continuous method where the flow of the phases is alternated "intermittently" between normal and reversed-phase elution so that the stationary phase also alternates.
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.
The peptide contains four residues in the order alanine, glutamate, aspartate and glycine, abbreviated AEDG. The chain is linear and held together by three peptide bonds. Its calculated mass for the uncharged free form is about 390.3 daltons.