If you have been reading about tetrapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2025-11-19. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 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.
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.
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.
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.
== Use and effects == According to Albert Hofmann and colleagues, iso-LSD is inactive as a psychedelic in humans at doses of up to 500 μg, which is up to 25 times the minimum given doses of LSD (i.e., 20–50 μg). In other sources, iso-LSD was also stated as being inactive at doses of up to 50 μg/kg (3.5 mg for a 70-kg person), whereas LSD is active at a dose of 1 μg/kg (70 μg for a 70-kg person). Hence, iso-LSD is inactive in humans at doses of up to 50 times those of a common psychedelic dose of LSD and at doses of up to 175 times the minimum dose of LSD. Alexander Shulgin has additionally reported that iso-LSD was inactive at a dose of 4 mg orally. The related drug isoergine is known to be active in terms of psychoactive and hallucinogenic effects at doses of 2 to 5 mg orally.
=== Animal use === Nitrofurazone is indicated for topical use in dogs, cats, and horses, for the treatment or prophylactic treatment of superficial bacterial infections, burns, and cutaneous ulcers. Preparations for treating infections, such as fin rot, in ornamental fish are also still commercially available. The use of nitrofurazone, or related compounds, in animals raised for human consumption has been strictly banned.
5-Hydroxyeicosanoid dehydrogenase (5-HEDH) or more formally, nicotinamide adenine dinucleotide phosphate (NADP+)-dependent dehydrogenase, is an enzyme that metabolizes between two eicosanoid metabolites of arachidonate 5-lipoxygenase (5-LOX): 5-hydroxyeicosatetraenoic acid (5-(S)-HETE), and its 5-keto analog 5-oxo-eicosatetraenoic acid (5-oxo-ETE). It also acts in the reverse direction, metabolizing 5-oxo-ETE to 5(S)-HETE. Since 5-oxo-ETE is 30–100-fold more potent than 5(S)-HETE in stimulating various cell types, 5-HEDH is regarded as a regulator and promoter of the influence that 5-LOX and its metabolites have on cell function. Although 5-HEDH has been evaluated in a wide range of intact cells and in crude microsome preparations, it has not yet been evaluated for its structure or gene, and most studies on it have been limited to human tissues.
Sources: en.wikipedia.org
What is the strength of the component as a function of crack size? What crack size can be tolerated under service loading, i.e. what is the maximum permissible crack size? How long does it take for a crack to grow from a certain initial size, for example the minimum detectable crack size, to the maximum permissible crack size? What is the service life of a structure when a certain pre-existing flaw size (e.g. a manufacturing defect) is assumed to exist? During the period available for crack detection how often should the structure be inspected for cracks?
Limited maceration, early pressing, and early racking to limit contact time of the LAB with potential nutrient sources Maintain sulfur dioxide levels to at least 25 ppm of "free" (unbound) SO2, depending on the pH of the wine, this may mean an addition of 50–100 mg/L of SO2 Maintain pH levels below 3.3 Keep the wine cool at temperatures between 10 and 14 °C (50. 0 to 57.2 °F) Filter the wine at bottling with at least a 0.45-micron membrane filter to prevent any bacteria from making it into the bottle In addition, winemakers can use chemical and biological inhibitors such as lysozyme, nisin, dimethyl dicarbonate (Velcorin), and fumaric acid, though some (like Verlcorin) are restricted in winemaking countries outside the United States. Fining agents, such as bentonite, and putting the wine through cold stabilization will also remove potential nutrients for LAB, thus inhibiting malolactic fermentation. Some experimentation with the use of bacteriophages (viruses that infect bacteria) has been conducted to limit malolactic fermentations, but disappointing results in the cheesemaking industry have led to skepticism about the practical use of bacteriophages in winemaking.
=== Other === In 2009, LifeVantage was sued by Utah-based Zrii LLC, a marketer of nutritional fruit drinks endorsed by Deepak Chopra, based on allegations that LifeVantage had conspired with former Zrii executives to "ruin the company" and take it over “on the cheap” following a "mass exodus". The case was closed in December 2009 following LifeVantage's settlement payment of $400,000 to Zrii. On October 14, 2011, Burke Hedges, a former LifeVantage distributor (hired for his background as a speaker and trainer) filed a lawsuit with the Utah District Court against LifeVantage and its executives, seeking $3 million in punitive damages over allegations of wrongful termination and tortious interference. In September 2016, a class action lawsuit was filed against LifeVantage in Utah alleging that the company and its executive Darren Jensen and Mark Jaggi made false and/or misleading statements, as well as failed to disclose material adverse facts about the Company's business, operations, and prospects. Specifically, the case alleged that the defendants made false and/or misleading statements and/or failed to disclose that: (i) LifeVantage lacked effective internal financial controls; (ii) as a result, the Company had improperly accounted for sales in certain international markets, along with associated revenue and income tax accruals; and (iii) as a result of the foregoing, LifeVantage's public statements were materially false and misleading at all relevant times. The case was dismissed in June 2017.
Physicians trained in the relatively new specialty of pediatric endocrinology provided most of this care, but in the late 1960s there were only a hundred of these physicians in a few dozen of the largest university medical centers around the world. In 1977, the NPA GH extraction and purification procedure was refined and improved. A shortage of available cadaver GH worsened in the late 1970s as the autopsy rate in the U.S. declined, while the number of pediatric endocrinologists able to diagnose and treat GH deficiency increased. GH was "rationed." Often, treatment would be stopped when a child reached an arbitrary minimal height, such as 5 ft 0 in (1.52 m). Children who were short for reasons other than severe GH deficiency were lied to and told that they would not benefit from treatment. Only those pediatric endocrinologists that remained at university medical centers with departments able to support a research program had access to NPA growth hormone. In the late 1970s, a Swedish pharmaceutical company, Kabi, contracted with a number of hospitals in Europe to buy pituitary glands for the first commercial GH product, Crescormon. Although an additional source of GH was welcomed, Crescormon was greeted with ambivalence by pediatric endocrinologists in the United States. The first concern was that Kabi would begin to purchase pituitaries in the U.S., which would quickly undermine the NPA, which relied on a donation system like blood transfusion.
Sources: en.wikipedia.org
Experiments manipulating the oxygen content, carbon dioxide content, and pH of bowfin extradural fluid did not affect breathing rate, heart rate, or blood pressure, pointing to a lack of central chemoreceptor regulation. Instead, bowfin respiratory patterns respond to water oxygen content and water temperature, as water temperatures play a role in oxygen content. In the laboratory, bowfin showed an increase in breathing rate when the temperatures were raised above 10 °C. Bowfin also showed an increase in breathing rate when exposed to lower oxygen levels in the water. Herpetologist W. T. Neill reported in 1950 that he unearthed a bowfin aestivating (in a dormant state) in a chamber 4 inches (10 cm) below the ground surface, 8 inches (20 cm) in diameter, 0.25 miles (0.4 km) from a river. Flood levels, of note, had previously reached the area and receded. Not unusually, riverine species like bowfin move into backwaters with flood currents and become trapped when water levels recede. While aestivation is anecdotally documented by multiple researchers, laboratory experiments have suggested, instead, that bowfin are physiologically incapable of surviving more than 3 to 5 days of air exposure, but no field manipulation has been performed. Regardless of the lack of evidence confirming the bowfin's ability to aestivate, bowfin can survive prolonged conditions of exposure to air because they have the ability to breathe air. Their gill filaments and lamellae are rigid in structure, which helps prevent the lamellae from collapsing and aids gas exchange even during air exposure.
== Effects of lack of CCAP == There have been no mutant individuals of any species found to possess CCAP who have a genetic defect meaning they are not able to produce the peptide. It is likely any such mutation would be lethal. In Drosophila the destruction of CCAP-containing neurons during development causes major changes in and disruptions to timing and behaviour of moulting.
== Medical uses == Nandrolone esters are used clinically, although increasingly rarely, for people in catabolic states with major burns, cancer, and AIDS, and an ophthalmological formulation was available to support cornea healing. The positive effects of nandrolone esters include muscle growth, appetite stimulation and increased red blood cell production, and bone density. Clinical studies have shown them to be effective in treating anemia, osteoporosis, and breast cancer. Nandrolone sulfate has been used in an eye drop formulation as an ophthalmic medication.
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.