The short version of epitalon fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-17 and is reviewed periodically as new material appears.
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.
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.
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.
=== Designed proteins === Numerous protein structures are the result of rational design and do not exist in nature. Proteins can be designed from scratch (de novo design) or by making calculated variations on a known protein structure and its sequence (known as protein redesign). Rational protein design approaches make protein-sequence predictions that will fold to specific structures. These predicted sequences can then be validated experimentally through methods such as peptide synthesis, site-directed mutagenesis, or Artificial gene synthesis.
== Elastosis == Elastosis is the buildup of elastic fibers in tissues, and is a form of degenerative disease. There are a multitude of causes, but the most commons cause is actinic elastosis of the skin, also known as solar elastosis, which is caused by prolonged and excessive sun exposure, a process known as photoaging. Uncommon causes of skin elastosis include elastosis perforans serpiginosa, perforating calcific elastosis and linear focal elastosis.
=== Reproduction === The same specimen of S. prima which had preserved a lizard in its stomach contents (NIGP 127587) also had several small eggs in its abdomen. Two eggs were preserved just in front of and above the pubic boot, and several more may lie underneath them on the slab. It is unlikely that they were eaten by the animal, as they are in the wrong part of the body cavity for the egg shells to have remained intact. It is more likely that they are unlaid eggs produced by the animal itself, proving the specimen to be a female. Each egg measured 36 mm (1.4 in) long by 26 mm (1.0 in) wide. The presence of two developed eggs suggests that Sinosauropteryx had dual oviducts and laid eggs in pairs, like other theropods.
Sources: en.wikipedia.org
Darglitazone (previously known as CP 86325-2) is a member of the thiazolidinedione class of drugs and an agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ), an orphan member of the nuclear receptor superfamily of transcription factors. It has a variety of insulin-sensitizing effects, such as improving glycemic and lipidemic control, and was studied by Pfizer as a potential treatment of metabolic disorders such as type 2 diabetes mellitus. Its development was terminated in 1999.
=== Cellular mechanisms === DNA polymerases, used in DNA replication, have a high specificity of 104 to 106-fold in base pairing. They have proofreading abilities to correct incorrect matches, allowing 90-99.9% of mismatches to be excised and repaired. The base mismatches that go unnoticed are repaired by the DNA mismatch repair pathway, also inherent in cells. The DNA mismatch repair pathway uses exonucleases that move along the DNA strand and remove the incorrectly incorporated base in order for DNA polymerase to fill in the correct base.Exonuclease1 is involved in many DNA repair systems and moves 5' to 3' on the DNA strand.
== Genetic methods == Experimental analysis of proteins typically requires expression and purification of proteins. Expression is achieved by manipulating DNA that encodes the protein(s) of interest. Hence, protein analysis usually requires DNA methods, especially cloning. Some examples of genetic methods include conceptual translation, Site-directed mutagenesis, using a fusion protein, and matching allele with disease states. Some proteins have never been directly sequenced, however by translating codons from known mRNA sequences into amino acids by a method known as conceptual translation. (See genetic code.) Site-directed mutagenesis selectively introduces mutations that change the structure of a protein. The function of parts of proteins can be better understood by studying the change in phenotype as a result of this change. Fusion proteins are made by inserting protein tags, such as the His-tag, to produce a modified protein that is easier to track. An example of this would be GFP-Snf2H which consists of a protein bound to a green fluorescent protein to form a hybrid protein. By analyzing DNA alleles can be identified as being associated with disease states, such as in calculation of LOD scores.
Former Richmond player Kevin Sheedy started as head coach in 1981. Essendon reached the Grand Final in 1983, the first time since 1968. Hawthorn won by a then-record 83 points. In 1984, Essendon won the pre-season competition and completed the regular season on top of the ladder. The club played, and beat, Hawthorn in the 1984 VFL Grand Final to win their 13th premiership — their first since 1965. The teams met again in the 1985 Grand Final, which Essendon also won. At the start of 1986, Essendon were considered unbackable for three successive flags, but a succession of injuries to key players Paul Van der Haar (only fifteen games from 1986 to 1988), Tim Watson, Darren Williams, Roger Merrett and Simon Madden led the club to win only eight of its last eighteen games in 1986 and only nine games (plus a draw with Geelong) in 1987. In July 1987, the Bombers suffered a humiliation at the hands of Sydney, who fell two points short of scoring the then highest score in VFL history. In 1988, Essendon made a rebound to sixth place with twelve wins, including a 140-point thrashing of Brisbane in which they had a record sixteen individual goalkickers. In 1989, they rebounded further to second on the ladder with only five losses and thrashed Geelong in the Qualifying Final. However, after a fiery encounter with Hawthorn ended in a convincing defeat, the Bombers were eliminated by Geelong the following week. In 1990, Essendon finished top of the ladder.
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== Radiometric age and geological age == Radiometric age represents the time when the decay process starts. Geological age represents the time when a geological event occurs. Manipulating the isotopic ratios can only give us radiometric age. To obtain the geological age, we need to know the relationship between the two. In other words, how do geological events affect the radioactive system in monazite? Actually, the radioactive system is like a digital 'clock', while the geological processes can be like replacing a battery. When a new battery is inserted, this 'clock' starts counting from 00:00. This process is what we call the age resetting mechanism. In monazite, the age resetting is caused by the loss of Pb. Pb is produced continuously by the decays of U and Th since the radioactive system (clock) starts running. The more Pb (or less U and Th) the system contains means the longer period has been passed. If all Pb are suddenly removed from monazite by a geological event (replacing battery), the age become zero (00:00) again. Before thinking what exact geological events trigger Pb loss (see section: Interpretation and application), it is important to know the two mechanisms causing Pb loss in monazite.
Thebacon is an opioid agonist narcotic analgesic of the middle range and a strong antitussive, primarily used in Europe, although it is no longer in common use. Currently, dihydrocodeine and nicocodeine are used as second-line codeine replacements. The other dihydromorphinone used as an antitussive is hydromorphone (Dilaudid cough syrup); the other narcotic antitussives are either more directly related to codeine or not related at all (open chain methadone relatives and thiambutenes). Thebacon is indicated for moderate to moderately severe pain and dry painful coughing, like hydrocodone. It has a duration of action in the range of 5 to 9 hours and doses typically start at 5 mg q6h. For both pain and coughing, thebacon can be made more effective along with NSAIDs, muscle relaxants, and/or antihistamines like tripelennamine, hydroxyzine, promethazine, phenyltoloxamine and chlorpheniramine.
Calculations in 2007 expected that copernicium may be a semiconductor with a band gap of around 0.2 eV, crystallizing in the hexagonal close-packed crystal structure. However, calculations in 2017 and 2018 suggested that copernicium should be a noble metal at standard conditions with a body-centered cubic crystal structure: it should hence have no band gap, like mercury, although the density of states at the Fermi level is expected to be lower for copernicium than for mercury. 2019 calculations then suggested that in fact copernicium has a large band gap of 6.4 ± 0.2 eV, which should be similar to that of the noble gas radon (predicted as 7.1 eV) and would make it an insulator; bulk copernicium is predicted by these calculations to be bound mostly by dispersion forces, like the noble gases. Like mercury, radon, and flerovium, but not oganesson (eka-radon), copernicium is calculated to have no electron affinity.
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.