This is a working overview of lyophilised powder, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-04-03. Anything still debated is marked as such rather than presented as settled.
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.
Residue composition is the property that most cleanly separates verified material from mislabelled samples. Alanine, glutamate, aspartate and glycine appear in that order from the N-terminus, and the two acidic residues sit in the middle of the chain. Because the peptide is short, it can be produced by solid-phase synthesis and characterised by mass spectrometry without ambiguity. Any reported sample whose measured mass departs substantially from 390 daltons is a different compound or a degraded mixture rather than epitalon.
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.
Reported biological findings come mainly from cell culture and rodent experiments. Those studies describe changes in telomerase catalytic subunit expression, melatonin rhythm amplitude, and antioxidant enzyme activity after peptide exposure. Human data are sparse and consist of small trials with limited blinding and inconsistent endpoints. The proposed mechanisms remain hypotheses rather than established facts, and there is no consensus on whether effects observed in animals carry over to people. Independent replication outside the original research groups is limited, which is a recognised gap in the published literature.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C14H22N4O9 | Derived from the four constituent residues |
| Molecular mass | About 390.35 Da | Monoisotopic value, confirmed by mass spectrometry |
| Residue sequence | Ala-Glu-Asp-Gly | Read from the N-terminus to the C-terminus |
| Common synonyms | Epithalon; AEDG | Both forms appear in reference catalogues |
| Net charge near neutral pH | Negative | Two acidic side chains give a low isoelectric point |
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Storage recommendations center on limiting moisture, heat, and light. The dry powder is generally kept at minus 20 degrees Celsius, and some suppliers recommend minus 80 degrees for long-term archival. Once dissolved, solutions are usually aliquoted and frozen to avoid repeated freeze-thaw cycles, which can promote aggregation or degradation. Aqueous stability depends on pH and concentration, and buffered saline is often preferred over plain water for biological work. Stability data specific to epitalon remain limited, so general peptide-handling practices are applied by analogy rather than from product-specific validation.
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.
Epitalon is a synthetic tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, commonly abbreviated AEDG. Its design traces to epithalamin, a peptide fraction prepared from bovine pineal gland extracts that researchers in Saint Petersburg began investigating in the 1970s. The compound has a molecular formula of C14H22N4O9 and a nominal molecular mass near 390 daltons. It holds no approved drug status in the United States or the European Union, and material sold under this name is generally offered as a research chemical rather than a finished pharmaceutical product.
Proposed mechanisms centre on cell-culture observations rather than a defined receptor interaction. Several reports describe increased expression of the telomerase catalytic subunit after exposure of cultured human cells, and the authors attributed the effect to short peptide fragments entering the nucleus and influencing gene transcription. No receptor for the tetrapeptide has been identified, and the free peptide is expected to be degraded rapidly by plasma peptidases. Whether any measurable fraction reaches intact tissues after administration remains an unresolved question rather than an established finding.
The published literature is dominated by a small number of research groups, much of it in Russian-language journals, and independent replication outside those groups is limited. Studies are typically small, use cultured cells or rodent models, and report endpoints that differ between papers, which makes comparison difficult. Large randomised human trials have not appeared in the indexed literature. Questions about absorption, distribution and clearance are therefore still treated as open in reviews that mention the compound.
Half-Life: Alyx is a 2020 virtual reality (VR) first-person shooter game developed and published by Valve. It was released for Windows on March 23, 2020, and for Linux on May 15, with support for most PC-compatible VR headsets. Players control Alyx Vance on a mission to seize a superweapon belonging to the alien Combine before the events of Half-Life 2 (2004). Like previous Half-Life games, Alyx incorporates combat, puzzles and exploration. Players use VR to interact with the environment and fight enemies, using "gravity gloves" to snatch objects from a distance, similarly to the gravity gun from Half-Life 2. The previous Half-Life game, Episode Two, was released in 2007 and ended on a cliffhanger. Valve made several attempts to develop further Half-Life games, but could not settle on a direction. In the mid-2010s, Valve began experimenting with VR and identified demand for a major VR game. They experimented with prototypes using their various game series, such as Portal, and found that Half-Life best suited VR. Alyx entered production using Valve's new Source 2 engine in 2016, with the largest team in Valve's history, including members of Campo Santo, a studio acquired by Valve in 2018. VR affected almost every aspect of the design, including level design, combat, movement and pacing. Valve planned to launch Alyx alongside its Index headset in 2019, but delayed it to rewrite the story following internal feedback. Alyx received acclaim for its graphics, voice acting, narrative and atmosphere, and has been described as the first VR killer app.
Affinity towards An(III) over Ln(III) Good An(III) back-extraction to enable solvent recycling Good solubility in a proper diluent CHON compliance to reduce secondary waste Fast complexation kinetics Hydrodynamic stability to prevent third phase and precipitates formation during extraction process Chemical and radiolytic stability to prevent solvent degradation Research on advanced reprocessing of spent nuclear fuel moves on by developing process optimization studies and designing new potential lipophilic and hydrophilic extracting agents that fulfill these industrial requirements.
In early July 2018, then Education Minister, Lisa Thompson, told Queen's Park reporters that starting in September 2018, Ontario schools would no longer be using the sex education curriculum in use since 2015, but would be reverting to the previous curriculum. One of the election campaign promises by the Ford government was to "scrap" the 2015 sex education curriculum. Premier Ford's government said that "it did not order the cancellation." By August 2019, the Ministry of Education, following "widespread consultations," made "only minor tweaks". The "health lesson plan being brought to schools in the fall" of 2019 "is similar to the one Ford crusaded against." On October 11, 2019, Minister Lecce reached a deal with CUPE school support workers, which has to be ratified by CUPE members and averted a pending strike. Premier Ford had said that he would cap "all public sector wage settlements at one per cent per year". The three-year agreement with CUPE was for a "one per cent wage increase annually for the duration of deal." A clause in the agreement clause in the agreement says that if "higher increases are negotiated by other education unions", their union will be able to increase to more than one percent. CUPE also had $58.3 million restored for the "hiring of educational assistants" with an additional $20 million for hiring "more custodians and clerical workers." As well, CUPE's sick leave provisions remained untouched.
The cancerous skin lesions refer to damaged cutaneous tissues with risks of further developing into skin cell carcinoma. Skin carcinoma, or skin cancer, is very common in sun-radiation-abundant areas. The over-exposure to sunlight is the most prevalent cause that leads to Actinic keratosis (AK), a common cancerous cutaneous lesion. Photodynamic therapy (PDT) has proven to be an effective approach for AK at sites of poor healing with few responses to other therapies. In the comparison study between MAL-LEDT and typical cryotherapy, blue-light LEDT with Aminolevulinic acid (ALA) as a photosensitizer reveals significantly higher healing rates. The other clinical trial illustrates the effect of combined therapy of red-light LEDT and nano-emulsion in treating cancerous skin lesions.
For three years, there was an indecisive struggle between the heterogeneous Assembly and the president, who was silently awaiting his opportunity. He chose as his ministers men with little inclination towards republicanism, with a preference for Orléanists, the chief of whom was Odilon Barrot. In order to strengthen his position, he endeavoured to conciliate the reactionary parties, without committing himself to any of them. The chief instance of this was the expedition to Rome voted by the Catholics, to restore the temporal authority of Pope Pius IX, who had fled Rome in fear of the nationalists and republicans. (Garibaldi and Mazzini had been elected to a Constitutional Assembly.) The pope called for international intervention to restore him in his temporal power. The French president moved to establish the power and prestige of France against that of Austria, as beginning the work of European renovation and reconstruction which he already looked upon as his mission. French troops under Oudinot marched into Rome. This provoked an insurrection in Paris in favour of the Roman Republic, that of the Château d'Eau, which was crushed on 13 June 1849. On the other hand, when the pope, though only just restored, began to yield to the general movement of reaction, the president demanded that he should set up a Liberal government. The pope's dilatory reply having been accepted by the French ministry, the president replaced it on 1 November, by the Fould-Rocher cabinet.
Sources: en.wikipedia.org
The first Neanderthal genome sequence was published in 2010, and strongly indicated interbreeding between Neanderthals and early modern humans. Neanderthal-derived genes descend from at least 2 interbreeding episodes outside of Africa: one about 250,000 years ago and another 40,000 to 54,000 years ago. Interbreeding also occurred in other populations which are not ancestral to any living person. An individual whose ancestry lies beyond sub-Saharan Africa may carry about 2% of Neanderthal DNA. Sub-Saharan Africans can carry Neanderthal DNA presumably descending from back migration (the interbreeding population having migrated back to Sub-Saharan Africa). In all, approximately 20% of the Neanderthal genome appears to have survived in the modern human gene pool. This Neanderthal DNA is derived primarily from the children of female modern humans and male Neanderthals. Due to their low population and proliferation of deleterious mutations, many Neanderthal genes were probably selected out of the modern human gene pool (negative selection). Similarly, a large portion of surviving introgression appears to be non-coding ("junk") DNA with few biological functions. Some Neanderthal-derived genes, nonetheless, may have functional implications related to metabolism, brain function, and skeletal and muscular development. Some genes may have helped immigrating modern human populations acclimatise faster, such as genes related to immune response. The genetic evidence suggests that the interbreeding mainly took place between Neanderthal men and modern human women.
It is doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of the genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the Cenozoic: present-day G. biloba (including G. adiantoides) and G. gardneri from the Paleocene of Scotland. At least morphologically, G. gardneri and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have been ecotypes or subspecies. The implications would be that G. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and, though evolving genetically, never showed much speciation. While it may seem improbable that a single species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit: Extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution; and (as far as can be demonstrated from the fossil record) extreme ecological conservatism (restriction to disturbed streamside environments).
Willis, who predicted them using a dynamic homogenization method. Much of the recent interest in Willis couplings has been driven by their local form (the Milton–Briane–Willis equations). By extending Willis's homogenization method, Pernas-Salomón and Shmuel were the first to show that piezoelectric composites exhibit an effective coupling between linear momentum and the electric field, which they termed electro-momentum coupling. Electro-momentum coupling provides a mechanism for wave manipulation similar to Willis coupling, with the added benefit of electrical tunability.
=== Conversion to acyl halides === The hydroxyl group on carboxylic acids may be replaced with a chlorine atom using thionyl chloride to give acyl chlorides. In nature, carboxylic acids are converted to thioesters. Thionyl chloride can be used to convert carboxylic acids to their corresponding acyl chlorides. First, carboxylic acid 1 attacks thionyl chloride, and chloride ion leaves. The resulting oxonium ion 2 is activated towards nucleophilic attack and has a good leaving group, setting it apart from a normal carboxylic acid. In the next step, 2 is attacked by chloride ion to give tetrahedral intermediate 3, a chlorosulfite. The tetrahedral intermediate collapses with the loss of sulfur dioxide and chloride ion, giving protonated acyl chloride 4. Chloride ion can remove the proton on the carbonyl group, giving the acyl chloride 5 with a loss of HCl.
Sources: en.wikipedia.org
It is a four-amino-acid peptide built from alanine, glutamate, aspartate and glycine in that order. Its formula is C14H22N4O9, and it is made by chemical synthesis rather than extracted from tissue. The synthetic peptide is a single defined molecule, unlike the pineal extracts it is often compared with.
No. The two spellings refer to the same tetrapeptide, and the difference reflects transliteration from Russian. Laboratories and catalogues use both forms interchangeably. The material is also indexed as AEDG, taken from the one-letter codes of its residues.
Epithalamin is a mixed preparation derived from animal pineal tissue and contains many peptides. Epitalon is one synthetic sequence chosen for study from that broader mixture. Statements about one do not transfer directly to the other.
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.