Everything below concerns reversed-phase HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Updated 2025-09-05. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
Literature searches for this compound must account for several spelling variants. Indexing databases contain epitalon, epithalon, epithalone, and AEDG, and relevant records are scattered across Russian-language and English-language journals that do not consistently cross-cite. Early publications describe the parent extract as a mixture of many peptides, whereas later work addresses the single synthetic tetrapeptide. That shift in nomenclature complicates comparison between studies, because extract data and tetrapeptide data are sometimes cited interchangeably. A search strategy omitting the alternate spellings will return an incomplete set of references.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised and often hygroscopic |
| Solubility class | Freely soluble in water | Poor solubility in non-polar solvents |
| Typical storage temperature | -20 degrees Celsius or colder | Sealed, desiccated, protected from light |
| Typical analytical method | Reversed-phase HPLC with mass spectrometry | Establishes purity and confirms mass |
| Common salt form | Trifluoroacetate or acetate | Counterion reported alongside purity values |
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.
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.
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.
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.
Identity and purity of epitalon samples are normally established by reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, combined with mass spectrometry. The mass spectrum confirms the expected molecular ion and can reveal truncated or oxidised by-products. Amino acid analysis after acid hydrolysis verifies that the four residues are present in the expected ratio. Certificates typically report a purity figure taken from chromatographic peak area, expressed as a percentage of total integrated signal.
Lyophilised epitalon is generally held at minus twenty degrees Celsius in a sealed container kept dry and dark. Cooler conditions are sometimes recommended for long-term archives. The solid takes up moisture readily enough that repeated opening of a vial introduces water, so dividing a batch into smaller portions before storage lowers degradation risk. Aqueous solutions are less durable than the dry powder and are usually prepared shortly before use, then kept cold and shielded from light to slow hydrolysis and oxidation.
Verification of research-grade material involves comparing a supplier chromatogram against an in-house reference, checking the observed mass against the calculated value, and where possible confirming residue order by tandem mass spectrometry or enzymatic peptide mapping. Purity claims should be read alongside the method used to obtain them, because detection wavelength and integration settings alter the result. Batch-specific data, rather than a generic grade statement, is the informative part of a certificate.
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.
They also extend into, but are not destined to supplant, systems biology models of metabolic pathways. They are also parallel to physiome models, but do not aim at modelling physiological functions beyond fluid circulation in detail. In fact the above four types of models can reinforce each other when integrated.
== History, geography and ethnography == In West Africa, the bark, roots, leaves, flowers, fruits, and seeds are commonly used in traditional medicine to treat a wide diversity of complaints, both internally and externally, sometimes in combination with other medicinal plants. The bark is most important for medicinal uses, followed by the leaves. Medicinal applications include the treatment of parasitic infections, circulatory system disorders, such as arterial hypertension, and disorders of the respiratory system, digestive system and skin. In veterinary medicine, a root decoction is used to treat coccidiosis in poultry. Green pods are crushed and added to rivers to kill fish. The tree locust bean is also known as "arbre à farine, fern leaf, irú, monkey cutlass tree, two ball nitta-tree, nété and néré"). The use of fermented locust beans in West Africa was documented as early as the 14th century, and described by Michel Adanson in his Histoire naturelle du Sénégal, published in 1757. Geographically, Parkia biglobosa can be found in a belt stretching from the Atlantic coast in Senegal to southern Sudan and northern Uganda. The tree currently exists within a wide range of natural communities but is most abundant in anthropic communities – places where cultivation is semi-permanent. Annual production of seeds in northern Nigeria is estimated at around 200,000 t. While the products of the tree are not common in international trade, they form an important part of local and regional trade in West Africa.
== Benefits of laser gum disease surgery == According to the Academy of General Dentistry (AGD), there are benefits to dental lasers including: reduce symptoms and healing times associated with traditional therapies; reduce the amount of bacteria in both diseased gum tissue and in tooth cavities; and control bleeding during surgery. The 1064 Nd:YAG laser kills at least three different periodontal pathogens without harming normal tissues: (Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi), and Candida albicans (Ca); a pathogenic fungus. This unique aspect of laser irradiation to affect some tissue and not others is termed Selective Photoantisepsis, and is due to differential absorption between host tissue and pathogens. Nd:YAG laser light treatment has shown a long-lasting effect on the shift of bacterial subgingival flora, decreasing pathogenic bacteria and creating an environment where normal flora survives.
Sources: en.wikipedia.org
=== Engineering strain === Engineering strain, also known as Cauchy strain, is expressed as the ratio of total deformation to the initial dimension of the material body on which forces are applied. In the case of a material line element or fiber axially loaded, its elongation gives rise to an engineering normal strain or engineering extensional strain e, which equals the relative elongation or the change in length ΔL per unit of the original length L of the line element or fibers (in meters per meter). The normal strain is positive if the material fibers are stretched and negative if they are compressed. Thus, we have
By total area (including its waters), Canada is the second-largest country. By land area alone, Canada ranks fourth, due to having the world's largest area of fresh water lakes. Stretching from the Atlantic Ocean in the east, along the Arctic Ocean to the north, and to the Pacific Ocean in the west, the country encompasses 9,984,670 square kilometres (3,855,100 sq mi) of territory. Canada also has vast maritime terrain, with the world's longest coastline of 243,042 kilometres (151,019 mi) In addition to sharing the world's largest land border with the United States—spanning 8,891 kilometres (5,525 mi)—Canada shares a short (1,280 metres (4,200 ft)) land border with Greenland (and hence the Kingdom of Denmark) to the northeast, on Hans Island, and a maritime boundary with France's overseas collectivity of Saint Pierre and Miquelon to the southeast. Canada is also home to the world's northernmost settlement, Canadian Forces Station Alert, on the northern tip of Ellesmere Island—latitude 82.5°N—which lies 817 kilometres (508 mi) from the North Pole. In latitude, Canada's most northerly point of land is Cape Columbia in Nunavut at 83°6′41″N, with its southern extreme at Middle Island in Lake Erie at 41°40′53″N. In longitude, Canada's land extends from Cape Spear, Newfoundland, at 52°37′W, to Mount St. Elias, Yukon Territory, at 141°W. Canada can be divided into seven physiographic regions: the Canadian Shield, the Interior Plains, the Great Lakes–St. Lawrence Lowlands, the Appalachian region, the Western Cordillera, Hudson Bay Lowlands, and the Arctic Archipelago.
From the mid-19th century to the 1930s, American physicians prescribed Cannabis sativa as a prescription drug for various medical conditions. In the 1960s, the counterculture movement introduced the use of psychoactive drugs, including cannabis. Young adults and college students reported the recreational prevalence of cannabis, among other drugs, at 20-25% while the cultural mindset of using was open and curious. In 1969, the FBI reported that between the years 1966 and 1968, the number of arrests for marijuana possession, which had been outlawed throughout the United States under Marijuana Tax Act of 1937, had increased by 98%. Despite acknowledgement that drug use was greatly growing among America's youth during the late 1960s, surveys have suggested that only as much as 4% of the American population had ever smoked marijuana by 1969. By 1972, however, that number would increase to 12%. That number would then double by 1977. The Controlled Substances Act of 1970 classified marijuana along with heroin and LSD as a Schedule I drug, i.e., having the relatively highest abuse potential and no accepted medical use. Most marijuana at that time came from Mexico, but in 1975 the Mexican government agreed to eradicate the crop by spraying it with the herbicide paraquat, raising fears of toxic side effects. Colombia then became the main supplier. The "zero tolerance" climate of the Reagan and Bush administrations (1981–1993) resulted in passage of strict laws and mandatory sentences for possession of marijuana.
== External links == "Carol Robinson's Interview with Denis Noble". YouTube. voicesfromoxfordUK. 18 December 2013. (See Denis Noble.) "A New Phase for Structural Biology – with Carol Robinson". YouTube. The Royal Institution. 6 July 2016. "Mass spectrometry: From ribosomes to receptors | Prof Dame Carol Robinson DBE FRS FMedSci". YouTube. Cambridge SciSoc. 26 March 2021. "Carol Vivien, DBE, FRS, FMedSci ~ 10/14/2020 – Physiology Bashour Speaker". YouTube. UTSW Department of Physiology. 29 March 2021. "JACS in Conversation with Professor Dame V. Robinson". YouTube. ACS Productions. 7 September 2021. (interview conducted by Erick M. Carreira)
Sources: en.wikipedia.org
Sealed lyophilised powder is normally kept at minus twenty degrees Celsius or below, away from light and moisture. Vials are allowed to reach room temperature before opening to limit condensation. Repeated warming and cooling of the same vial is discouraged.
Reversed-phase HPLC establishes purity and separation from related peptides, and mass spectrometry confirms the molecular mass. Amino acid analysis can verify residue composition. No single method proves identity on its own, so the results are read together.
Yes. Residual trifluoroacetate or acetate from purification adds mass and can shift the value obtained by certain assays. Purity figures are therefore meaningful only when the counterion form is stated. Reporting both peptide content and salt form gives a clearer picture.
It is based on epithalamin, a peptide-rich preparation obtained from pineal gland tissue and studied in the former Soviet Union. Researchers later identified the tetrapeptide AEDG as a constituent fragment of that material. Modern supplies are produced by chemical synthesis rather than tissue extraction.