AEDG raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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.
Published work on this compound consists mainly of in vitro experiments, animal studies, and small clinical investigations, a substantial share of which appeared in Russian-language journals. Sample sizes are generally small, control conditions differ between studies, and several endpoints rely on markers whose clinical meaning is itself debated. Reviews of the longevity field treat the peptide as an early example of telomerase-directed research rather than an established intervention. Regulatory treatment varies by country: some jurisdictions place it under prescription controls, others treat it as a laboratory material, and importation may be restricted regardless of local status.
Epitalon is a synthetic tetrapeptide whose sequence is alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. It was developed in Russia during the 1980s and 1990s by investigators associated with the St. Petersburg Institute of Bioregulation and Gerontology, who studied short peptides as regulators of gene expression and tissue function. The alternative spelling epithalon appears interchangeably in the literature, and the two names refer to the same molecule. Outside Russia it is encountered chiefly as a research chemical rather than a licensed medicine, and it holds no approval from the United States Food and Drug Administration or the European Medicines Agency.
The peptide is a synthetic analogue of epithalamin, a preparation extracted from bovine pineal glands. Investigators sought a short, chemically defined molecule that would reproduce some of the endocrine and gerontological observations attributed to the glandular extract. Proposed mechanisms centre on induction of telomerase activity, an effect reported in cultured human somatic cells in the early 2000s, together with influences on melatonin secretion and neuroendocrine regulation. Those mechanisms remain incompletely characterised, and the reported telomerase response has not been consistently reproduced by independent groups working in comparable systems.
== Medical uses == In the United States, it is indicated for the treatment of adults with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with an aromatase inhibitor as initial endocrine-based therapy; or fulvestrant as initial endocrine-based therapy or following disease progression on endocrine therapy in postmenopausal women or in men. In the European Union, it is indicated for the treatment of women with hormone receptor (HR)‑positive, human epidermal growth factor receptor 2 (HER2)‑negative locally advanced or metastatic breast cancer in combination with an aromatase inhibitor or fulvestrant as initial endocrine-based therapy, or in women who have received prior endocrine therapy. In pre‑ or perimenopausal women, the endocrine therapy should be combined with a luteinising hormone‑releasing hormone (LHRH) agonist. In September 2024, the US Food and Drug Administration (FDA) expanded the indication for ribociclib, in combination with an aromatase inhibitor, for the adjuvant treatment of adults with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative stage II and III early breast cancer at high risk of recurrence. Additionally, the FDA approved the ribociclib and letrozole co-pack for the same indication.
Along the western coast of South America, water near the ocean surface is pushed westward due to the combination of the trade winds and the Coriolis effect. This process is known as Ekman transport. Colder water from deeper in the ocean rises along the continental margin to replace the near-surface water. This process cools the East Pacific because the thermocline is closer to the ocean surface, leaving relatively little separation between the deeper cold water and the ocean surface. The northward-flowing Humboldt Current carries colder water from the Southern Ocean to the tropics in the East Pacific. The combination of the Humboldt Current and upwelling maintains an area of cooler ocean waters off the coast of Peru. The West Pacific lacks a cold ocean current and has less upwelling as the trade winds are usually weaker than in the East Pacific, allowing the West Pacific to reach higher temperatures. These warmer waters provide energy for the upward movement of air. As a result, the warm West Pacific has, on average, more cloud and rain than the cool East Pacific. ENSO describes a quasi-periodic change of both oceanic and atmospheric conditions over the tropical Pacific Ocean. These changes affect weather patterns across much of the Earth. The tropical Pacific is said to be in one of three states of ENSO (also called "phases") depending on the atmospheric and oceanic conditions. When the tropical Pacific roughly reflects the average conditions, the state of ENSO is said to be in the neutral phase.
Afucosylated antibodies are intensely used in the field of advanced medicine, also due to their high ADCC (antibody-dependent cellular cytotoxicity). This makes them effective in binding to specific targets while minimizing damage to surrounding tissue. Some of the fields in which afucosylated antibodies are used or considered for application are: cancer immunotherapy autoimmune diseases Infectious diseases Furthermore, afucosylated antibodies are used as diagnostic tools and play a role in the development of personalized medications.
Twin helical strands form the DNA backbone. Another double helix may be found tracing the spaces, or grooves, between the strands. These voids are adjacent to the base pairs and may provide a binding site. As the strands are not symmetrically located with respect to each other, the grooves are unequally sized. The major groove is 22 ångströms (2.2 nm) wide, while the minor groove is 12 Å (1.2 nm) in width. Due to the larger width of the major groove, the edges of the bases are more accessible in the major groove than in the minor groove. As a result, proteins such as transcription factors that can bind to specific sequences in double-stranded DNA usually make contact with the sides of the bases exposed in the major groove. This situation varies in unusual conformations of DNA within the cell (see below), but the major and minor grooves are always named to reflect the differences in width that would be seen if the DNA was twisted back into the ordinary B form.
Color markers are sometimes added to loading dyes for gel electrophoresis in the separation of DNA fragments. Loading dyes keep DNA samples below the surface of the agarose gel, and the color markers within help keep track of the migration front of the DNA as it moves along the gel. For PAGE, some commercially available molecular weight markers (also called "ladders" because they look like the rungs of a ladder after separation) contain pre-stained proteins of different colours, so it is possible to determine more accurately where the proteins of interest in the samples might be.
Sources: en.wikipedia.org
The tree was created by maximum likelihood analysis without bootstrap: consequently accuracy is traded off for size and many phylum level clades are not correctly resolved (such as the Firmicutes). (Eukaryotes not present in analysis). This phylogeny is a summary of the 16S rRNA based LTP_07_2026 and contains all type species with validly published names up to July 2026. Branching order of bacterial phyla (Woese, 1987) Branching order of bacterial phyla (Gupta, 2001) Branching order of bacterial phyla (Cavalier-Smith, 2002) Branching order of bacterial phyla (Rappe and Giovanoni, 2003) Branching order of bacterial phyla (Battistuzzi et al., 2004) Branching order of bacterial phyla (Ciccarelli et al., 2006) Branching order of bacterial phyla (Genome Taxonomy Database, 2018) Bacterial phyla List of Archaea genera List of bacteria genera List of bacterial orders LPSN, list of accepted bacterial and archaeal names http://www.arb-silva.de/projects/living-tree/
33. Eksp Klin Farmakol. 2006 Nov-Dec;69(6):13-6. [Comparative study of the effects of melatonin and epitalon on the protracted memory under the shuttle labyrinth test conditions in rats in the course of aging]. [Article in Russian] Vinogradova IA. The influence of the chronic administration of melatonin (epiphyseal hormone) and epitalon (a synthetic tetrapeptide increasing melatonin production) on the learning process and the protracted memory has been studied in LIO rats in the course of aging for 2 years under standard illumination regime (12L :12D). The daily administration of melatonin (Sigma, USA) with drinking water (in 10 mg/liter dose at night) in rats beginning with the age of 4 months did not influence the learning processes in young and adult animals but it was found to contribute to optimization of the brain cognitive function in rats in the course of aging, by improving the protracted memory process. Epitalon administered in a daily dose of 0.1 microg per animal beginning with the age of 4 months showed mnemotropic properties (decreasing the extent of memory disorders) in old rats under conditions of the shuttle labyrinth test.
Because glycine is the smallest amino acid with no side chain, it plays a unique role in fibrous structural proteins. In collagen, Gly is required at every third position because the assembly of the triple helix puts this residue at the interior (axis) of the helix, where there is no space for a larger side group than glycine's single hydrogen atom. For the same reason, the rings of the Pro and Hyp must point outward. These two amino acids help stabilize the triple helix – Hyp even more so than Pro because of a stereoelectronic effect; a lower concentration of them is required in animals such as fish, whose body temperatures are lower than most warm-blooded animals. Lower proline and hydroxyproline contents are characteristic of cold-water, but not warm-water fish; the latter tend to have similar proline and hydroxyproline contents to mammals. The lower proline and hydroxyproline contents of cold-water fish and other poikilotherm animals lead to their collagen having a lower thermal stability than mammalian collagen. This lower thermal stability means that gelatin derived from fish collagen is not suitable for many food and industrial applications. The tropocollagen subunits spontaneously self-assemble, with regularly staggered ends, into even larger arrays in the extracellular spaces of tissues. Additional assembly of fibrils is guided by fibroblasts, which deposit fully formed fibrils from fibripositors.
=== Coating === Gelatin was first used as an external surface sizing for paper in 1337 and continued as a dominant sizing agent of all European papers through the mid-nineteenth century. In modern times, it is mostly found in watercolor paper, and occasionally in glossy printing papers, artistic papers, and playing cards. It maintains the wrinkles in crêpe paper.
Tendinosis: non-inflammatory injury to the tendon at the cellular level. The degradation is caused by damage to collagen, cells, and the vascular components of the tendon, and is known to lead to rupture. Observations of tendons that have undergone spontaneous rupture have shown the presence of collagen fibrils that are not in the correct parallel orientation or are not uniform in length or diameter, along with rounded tenocytes, other cell abnormalities, and the ingrowth of blood vessels. Other forms of tendinosis that have not led to rupture have also shown the degeneration, disorientation, and thinning of the collagen fibrils, along with an increase in the amount of glycosaminoglycans between the fibrils. Tendinitis: degeneration with inflammation of the tendon as well as vascular disruption. Paratenonitis: inflammation of the paratenon, or paratendinous sheet located between the tendon and its sheath. Tendinopathies may be caused by several intrinsic factors including age, body weight, and nutrition. The extrinsic factors are often related to sports and include excessive forces or loading, poor training techniques, and environmental conditions.
Sources: en.wikipedia.org
==== Ultrastructure and collagen synthesis ==== Collagen fibres coalesce into macroaggregates. After secretion from the cell, cleaved by procollagen N- and C-proteases, the tropocollagen molecules spontaneously assemble into insoluble fibrils. A collagen molecule is about 300 nm long and 1–2 nm wide, and the diameter of the fibrils that are formed can range from 50–500 nm. In tendons, the fibrils then assemble further to form fascicles, which are about 10 mm in length with a diameter of 50–300 μm, and finally into a tendon fibre with a diameter of 100–500 μm. The collagen in tendons are held together with proteoglycan (a compound consisting of a protein bonded to glycosaminoglycan groups, present especially in connective tissue) components including decorin and, in compressed regions of tendon, aggrecan, which are capable of binding to the collagen fibrils at specific locations. The proteoglycans are interwoven with the collagen fibrils – their glycosaminoglycan (GAG) side chains have multiple interactions with the surface of the fibrils – showing that the proteoglycans are important structurally in the interconnection of the fibrils. The major GAG components of the tendon are dermatan sulfate and chondroitin sulfate, which associate with collagen and are involved in the fibril assembly process during tendon development. Dermatan sulfate is thought to be responsible for forming associations between fibrils, while chondroitin sulfate is thought to be more involved with occupying volume between the fibrils to keep them separated and help withstand deformation.
=== Germany === In November 2005, a German translation was launched by the publishing house Computec Media AG. The German edition was thinner than the English original, the covers were slightly changed and the ratings raised. In January 2007 it was changed to a bi-monthly schedule and in July 2007 it was finally shut down.
Psychiatry is the medical specialty devoted to the diagnosis, treatment, and prevention of deleterious mental conditions. These include matters related to cognition, perceptions, mood, emotion, and behavior. Initial psychiatric assessment begins with taking a case history and conducting a mental status examination. Laboratory tests, physical examinations, and psychological assessments may also be used. On occasion, neuroimaging or neurophysiological studies are performed.
== Overview == The election produced an unusual result—Labor did not gain any net seats in the Legislative Assembly of Queensland, maintaining 44 of 89, or one short of a governing majority, but the National-Liberal coalition which had governed with the support of Independent Liz Cunningham was reduced from 44 to 32 due mainly to the rise of Pauline Hanson's One Nation Party in their rural heartland. After negotiations between the Labor Party, Cunningham and a new independent, Peter Wellington, the latter announced on 25 June 1998 that he would support a minority Labor government on votes of confidence in return for specific commitments on accountability. The following day, Labor leader Peter Beattie and his deputy, Jim Elder, were sworn in by the Governor of Queensland as a two-man cabinet. Three days later, on 29 June 1998, they resigned so that a full ministry chosen by Caucus could be sworn in.
CaSO4 · 1/2 H2O + 1+1/2 H2O → CaSO4 · 2 H2O This reaction is exothermic and is responsible for the ease with which gypsum can be cast into various shapes including sheets (for drywall), sticks (for blackboard chalk), and molds (to immobilize broken bones, or for metal casting). Mixed with polymers, it has been used as a bone repair cement. Small amounts of calcined gypsum are added to earth to create strong structures directly from cast earth, an alternative to adobe (which loses its strength when wet). The conditions of dehydration can be changed to adjust the porosity of the hemihydrate, resulting in the so-called α- and β-hemihydrates (which are more or less chemically identical). On heating to 180 °C (356 °F), the nearly water-free form, called γ-anhydrite (CaSO4·nH2O where n = 0 to 0.05) is produced. γ-Anhydrite slowly reabsorbs water to return to the dihydrate state, a property exploited in some commercial desiccants. On heating above 250 °C, the completely anhydrous form called β-anhydrite or "natural" anhydrite is formed. Natural anhydrite does not absorb water, even over geological timescales, unless very finely ground. The variable composition of the hemihydrate and γ-anhydrite, and their easy inter-conversion, is due to their nearly identical crystal structures containing "channels" that can accommodate variable amounts of water, or other small molecules such as methanol.
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 synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.