A practical reference on tetrapeptide: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-12 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.
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 four residues give epitalon a molecular formula of C14H22N4O9 and a molecular weight near 390.35 daltons. The presence of two acidic residues, glutamate and aspartate, makes the free peptide strongly acidic, while the alanine and glycine ends provide neutral, nonpolar character. This combination produces a molecule with substantial water solubility. Because there are no cysteine, methionine, or tryptophan residues, the peptide lacks the most common oxidation-sensitive side chains, which simplifies handling compared with many longer peptides.
| 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 |
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.
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.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
The initial force of 500 armed Huks which was organized into five squadrons had increased to a fully armed guerrilla force of 20,000 men. By 1944, Huk strength numbers at 76 squadrons. After the Cabiao raid by the Japanese, the PKP adopted a "retreat for defense" policy, which broke up squads to smaller groups of three to five men. In areas controlled by Huk guerrillas, the Huks organized an ad-hoc police force to keep the peace and stop looters and thieves. Huks also formed Sandatahang Tanod ng Bayan (Barrio United Defense Corps), which acted as neighborhood governments in support of the Huk forces in the field. These BUDC's were composed of KPMP and AMT members, which organized popular support for Huks, shielded harvest from the Japanese, and attacked Filipino collaborators; in effect, setting up protected zones and safe havens for the Huks. The Hukbalahap also set-up a government, composed of a President, Vice-President, Secretary, Treasurer, and five policemen. The barrio government also had three departments, with a person-in-charge leading it. One department collected intelligence information about the military, another handled communication between different barrios and Huk members, and the third arranged for supplies. The Hukbalahap government also performed civil tasks, such as officiating in weddings, baptisms, funerals, and issued marriage licenses and birth certificates.
== Applications == HBsAg made through recombinant DNA is used to make the hepatitis B vaccine. It has a very good efficacy of about 95%, with protection lasting for more than 30 years, even after the anti-HbsAg antigen titers have fallen. The RTS,S also makes use of HBsAg. It is a mixture of a version of malaria surface antigen grafted to HBsAg (RTS) and ordinary HBsAg (S), both made through recombinant DNA. Much like ordinary HBsAg, these two are able to assemble into virus-like particles that are soluble in water.
Natriuretic peptide receptor B (NPR2), also known as atrionatriuretic peptide receptor B and formerly as guanylate cyclase B, is an atrial natriuretic peptide receptor which in humans is encoded by the NPR2 gene. A mutation in the NPR2 gene can result in achondroplasia and disproportionate dwarfism with short limbs.
=== Structure === Mesenchyme is characterized morphologically by a prominent ground substance matrix containing a loose aggregate of reticular fibers and unspecialized mesenchymal stem cells. Mesenchymal cells can migrate easily (in contrast to epithelial cells, which lack mobility, are organized into closely adherent sheets, and are polarized in an apical-basal orientation).
==== Low-carbohydrate dietary programs ==== Atkins diet Atkins Nutritionals Robert Atkins (nutritionist) William Banting Richard K. Bernstein Diabetic diet (low-carb) CarbSmart ice cream products from Breyers Ketogenic diet Low-glycemic index diet Meatatarian – (all meat diet, generally not recommended by some nutritionists) Montignac diet No-carbohydrate diet Pritikin diet Shirataki noodles South Beach Living Stillman diet Sugar Busters! Gary Taubes Zone diet
Sources: en.wikipedia.org
=== Possible permanent effects === The adverse effects of isotretinoin may be permanent. This has been proposed to be due to induction of apoptosis (programmed cell death) in sebaceous glands, meibomian glands, neuroblastoma cells, hypothalamic cells, hippocampus cells, Dalton's lymphoma ascites cells, B16F-10 melanoma cells, neuronal crest cells, stem cells and others, that it changes epigenetics and shortens telomeres. Isotretinoin may stop long bone growth in young people who are still growing. Premature epiphyseal closure can occur in people receiving recommended doses of Accutane. Isotretinoin is known to cause meibomian gland dysfunction which causes persistent keratoconjunctivitis sicca (dry eye). Problems with the meibomian and salivary glands are likely due to the non-selective apoptosis of the cells of the exocrine glands. Decreased night vision has been reported to persist in some people after discontinuation of isotretinoin therapy, although most cases of decreased night vision appear to resolve after discontinuing the medication.
Histology image: 09601loa – Histology Learning System at Boston University – "Digestive System: Oral Cavity and Teeth – lip, oral mucosa" Histology image: 95_04 at the University of Oklahoma Health Sciences Center – "Lip" Histology image: 95_07 at the University of Oklahoma Health Sciences Center – "Lip" Common Dental and Oral Mucosal Disorders, Duke University at https://web.archive.org/web/20160303221658/http://pamodules.mc.duke.edu/Oral_Health/Print.asp?CourseNum=1&LessonNum=3
== Society and culture == Depictions of heart attacks in popular media often include collapsing or loss of consciousness which are not common symptoms; these depictions contribute to widespread misunderstanding about the symptoms of myocardial infarctions, which in turn contributes to people not getting care when they should.
A number of people, starting with Gerald Kulcinski in 1986, have proposed to explore the Moon, mine lunar regolith, and use the helium-3 for fusion. Liquid helium-4 can be cooled to about 1 K (−272.15 °C; −457.87 °F) using evaporative cooling in a 1-K pot. Similar cooling of helium-3, which has a lower boiling point, can achieve about 0.2 kelvin in a helium-3 refrigerator. Equal mixtures of liquid 3He and 4He below 0.8 K separate into two immiscible phases due to their dissimilarity (they follow different quantum statistics: helium-4 atoms are bosons while helium-3 atoms are fermions). Dilution refrigerators use this immiscibility to achieve temperatures of a few millikelvins. It is possible to produce exotic helium isotopes, which rapidly decay into other substances. The shortest-lived heavy helium isotope is the unbound helium-10 with a half-life of 2.6(4)×10−22 s. Helium-6 decays by emitting a beta particle and has a half-life of 0.8 seconds. Helium-7 and helium-8 are created in certain nuclear reactions. Helium-6 and helium-8 are known to exhibit a nuclear halo.
=== Primary lymphoid organs === The primary (or central) lymphoid organs, including the thymus, bone marrow, fetal liver, and yolk sac, are responsible for generating lymphocytes from immature progenitor cells in the absence of antigens. The thymus and the bone marrow constitute the primary lymphoid organs involved in the production and early clonal selection of lymphocyte tissues. Bird species' primary lymphoid organs include the bone marrow, thymus, bursa of Fabricius, and yolk sac.
Sources: en.wikipedia.org
==== Premenstrual dysphoric disorder ==== BPD is a psychiatric condition distinguishable from premenstrual dysphoric disorder (PMDD), despite some symptom overlap. BPD affects individuals persistently across all stages of the menstrual cycle, unlike PMDD, which is confined to the luteal phase and ends with menstruation. While PMDD, affecting 3–8% of women, includes mood swings, irritability, and anxiety tied to the menstrual cycle, BPD presents a broader, constant emotional and behavioral challenge irrespective of hormonal changes.
=== Sinking and aftermath === Due to the damage inflicted during the attack, the San Juan Bautista sank in the Bay of Campeche. The Africans left behind with the captain were transported to Veracruz by a frigate, and sold as slaves to work in the New Mexico silver mines. The Africans taken by the Treasurer and White Lion were transported to Point Comfort, and became the First Africans in Virginia.
Acetate CH3COO− (acetic acid) Carbonate CO2−3 (carbonic acid) Chloride Cl− (hydrochloric acid) Citrate HOC(COO−)(CH2COO−)2 (citric acid) Cyanide C≡N− (hydrocyanic acid) Fluoride F− (hydrofluoric acid) Nitrate NO−3 (nitric acid) Nitrite NO−2 (nitrous acid) Oxide O2− (water) Phosphate PO3−4 (phosphoric acid) Sulfate SO2−4 (sulfuric acid) Salts with varying number of hydrogen atoms replaced by cations as compared to their parent acid can be referred to as monobasic, dibasic, or tribasic, identifying that one, two, or three hydrogen atoms have been replaced; polybasic salts refer to those with more than one hydrogen atom replaced. Examples include:
== History == In 1970, new strains of fungi were isolated from soil samples taken from Norway and from Wisconsin in the US by employees of Sandoz (now Novartis) in Basel, Switzerland. Both strains produced a family of natural products called cyclosporins. Two related components that had antifungal activity were isolated from extracts from these fungi. The Norwegian strain, Tolypocladium inflatum Gams, was later used for the large-scale fermentation of ciclosporin. The immunosuppressive effect of the natural product ciclosporin was discovered on 31 January 1972 in a screening test on immune suppression designed and implemented by Hartmann F. Stähelin at Sandoz. The chemical structure of cyclosporin was determined in 1976, also at Sandoz. The success of the drug candidate ciclosporin in preventing organ rejection was shown in kidney transplants by R.Y. Calne and colleagues at the University of Cambridge, and in liver transplants performed by Thomas Starzl at the Children's Hospital of Pittsburgh. The first patient, on 9 March 1980, was a 28-year-old woman. In the United States, the Food and Drug Administration (FDA) approved ciclosporin for clinical use in 1983. Thomas Starzl's 1992 memoir explains through the eyes of a transplant surgeon that ciclosporin was an epoch-making drug for solid organ allotransplantation. It greatly expanded the clinical applicability of such transplantation by substantially advancing the antirejection pharmacotherapy component.
==== Sovereignty ==== During his tenure as prime minister, Mahathir asserted Malaysia's sovereignty over several features in the Spratly Islands, claiming Swallow Reef in 1983, Ardasier Reef and Mariveles Reef in 1986, and Investigator Shoal and Erica Reef in 1999. His administration cited Malaysia's continental shelf limits and the 1982 UNCLOS as the basis for these claims, while also responding to Vietnam's territorial activities in the region. To strengthen Malaysia's position, Mahathir oversaw the transformation of Swallow Reef into an artificial island with military fortifications, establishing it as a permanent naval outpost. Despite this militarisation, he maintained diplomatic engagement with Beijing, balancing relations with ASEAN claimants and employing a hedging strategy involving China and the United States. Mahathir's foreign policy towards China on the Spratlys was notably pragmatic. While Malaysia pursued its territorial claims, he emphasised dialogue over confrontation. In 1993, he stated that Malaysia had "no problem with China" regarding the Spratlys, and in 1994, he welcomed China's proposal for joint exploration, opposing further internationalisation of the dispute.
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.
Epitalon is a synthetic tetrapeptide composed of four amino acids: alanine, glutamate, aspartate, and glycine. It is written as Ala-Glu-Asp-Gly. The free peptide has a molecular weight of about 390 daltons and is normally supplied as a lyophilized powder.