reversed-phase HPLC is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-02-09. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Reversed-phase high-performance liquid chromatography is the standard approach for assessing purity, usually with ultraviolet detection near 214 nm, where the peptide bond absorbs. Mass spectrometry, most often with electrospray ionization, confirms the molecular mass and helps reveal truncation or deletion byproducts. Amino acid analysis can verify composition, and counterion content is sometimes measured because peptides purified with trifluoroacetic acid retain variable amounts of that salt. Purity figures reported without a stated method and detection wavelength are difficult to interpret.
Material sold for research use varies widely in documented quality. A useful verification package includes a certificate of analysis that states peptide content rather than only net weight, the chromatographic method and column used, and a mass spectrum consistent with the expected mass. Independent testing by a third-party laboratory is occasionally reported. Statements of identity resting only on a supplier label provide little assurance, and the gap between nominal mass and actual peptide content can be substantial once counterions and residual water are counted.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic tetrapeptide | Four amino acid residues |
| Residue sequence | Ala-Glu-Asp-Gly | Abbreviated AEDG |
| Approximate mass | 390.35 Da | Monoisotopic, free base form |
| Parent preparation | Epithalamin extract | Derived from pineal tissue |
| Common spelling variants | Epithalon, epithalone, AEDG | Affects literature retrieval |
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
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.
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.
In 1965, when Stein was 18, his father, a retired managing director of The Distillers Company, who suffered from bipolar disorder, killed himself by jumping from a cliff near the family's holiday home at Trevose Head. Stein met his first wife Jill Newstead in Padstow. They married in 1975, both aged 28, and set up their restaurant and hotel business. Stein has three sons with Jill: Edward, Jack, and Charles, who are involved in the family business. Stein met Sarah Burns, 20 years his junior, in Australia in 1997, when he was 50. She was also married, and working as a publicity manager for Australia Gourmet Traveller magazine. Stein and Burns had a secret five-year affair before Jill found out in 2002. She and Stein separated in 2002 and divorced in 2007, but agreed to continue to run the business together. Burns divorced in 2003, and she and Stein married on 7 October 2011. Stein has a brother, John, and a sister, Henrietta. He also has a half-brother, Jeremy, his mother's son from her first marriage. He is the uncle of DJ and music producer Judge Jules, and the artist Lucy Stein. In 2022, Stein underwent open heart surgery at the Royal Brompton Hospital to repair a defective heart valve. Appearing live on BBC's The One Show in October 2023, promoting his book, Simple Suppers, he shared that his heart surgery experience had inspired his back to basics recipes but he inadvertently used a swear word and the show's host and Stein had to apologise for the error.
Banting stated that the reporter had betrayed his confidence, but did not retract his statement and reaffirmed that HBC was responsible for the death of indigenous residents by supplying the wrong kind of food and introducing diseases into the Arctic. As A. Y. Jackson notes in his memoir, since neither the governor nor the general manager had been to the Arctic, the meeting ended with them asking Banting's advice on what HBC ought to do: "He gave them some good advice and later he received a card at Christmas with the Governor's best wishes."
==== Surface roughness ==== The physical topology of a surface will determine the viable environment for bacteria. It may affect a microbe's ability to adhere to its surface. Textile surfaces tend to be very easy for microbes to adhere to due to the abundance of interstitial spacing between fibers.
=== ColdFusion and Java === The standard ColdFusion installation allows the deployment of ColdFusion as a WAR file or EAR file for deployment to standalone application servers, such as Macromedia JRun, and IBM WebSphere. ColdFusion can also be deployed to servlet containers such as Apache Tomcat and Mortbay Jetty, but because these platforms do not officially support ColdFusion, they leave many of its features inaccessible. As of ColdFusion 10 Macromedia JRun was replaced by Apache Tomcat. Because ColdFusion is a Java EE application, ColdFusion code can be mixed with Java classes to create a variety of applications and use existing Java libraries. ColdFusion has access to all underlying Java classes, supports JSP custom tag libraries, and can access JSP functions after retrieving the JSP page context (GetPageContext()). Prior to ColdFusion 7.0.1, ColdFusion components could only be used by Java or .NET by declaring them as web services. However, beginning in ColdFusion MX 7.0.1, ColdFusion components can now be used directly within Java classes using the CFCProxy class. Recently, there has been much interest in Java development using alternate languages such as Jython, Groovy and JRuby. ColdFusion was one of the first scripting platforms to allow this style of Java development.
Sources: en.wikipedia.org
=== Photosynthesis === Submerged aquatic plants have more restricted access to carbon as carbon dioxide compared to terrestrial plants. They may also experience reduced light levels. In aquatic plants diffuse boundary layers (DBLs) around submerged leaves and photosynthetic stems vary based on the leaves' thickness, shape and density and are the main factor responsible for the greatly reduced rate of gaseous transport across the leaf/water boundary and therefore greatly inhibit transport of carbon dioxide. To overcome this limitation, many aquatic plants have evolved to metabolise bicarbonate ions as a source of carbon. Environmental variables affect the instantaneous photosynthetic rates of aquatic plants and the photosynthetic enzymes pigments. In water, light intensity rapidly decreases with depth. Respiration is also higher in the dark per the unit volume of the medium they live in.
Aprataxin is 342 amino acids long and consists of FHA domain and HIT-ZnF catalyc core. It works by binding to adenylated DNA and removing AMP by catalytic side. Aprataxin is localised in the nucleus and mitochondria, which means aprataxin participates in mitochondrial DNA repair. This protein participates in base excision repair (BER) by returning abortive DNA ligation into scheduled repair by DNA polymerase beta, which would remove 5'-deoxyribosephosphate residue (dRP) and fill the gap; consequently, DNA ligase III-XRCC1 complex would seal the gap; consequently this mechanism is hampered in AOA1. Also, it might participate in microhomology-mediated end joining (MMEJ) by associating with XRCC1 and DNA ligase III and safeguarding DNA from abortive ligations by DNA ligase I, which might, again, be hampered in AOA1. iPSC with AOA1-associated mutation showed hindered differentiation into neurons which could be responsinble for early onset. Additionally, these neurons showed increased levels of cleaved PARP1 and decreased levels of APEX1. Due to the unique structure of chromatin in Purkinje cells, DNA damage (caused by aprataxin dysfunction) would hamper RNA polymerase II function, which would lead to improper splicing of some genes (such as: ITPR1, GRID2, CA8) and consequeent formation of R-loops; R-loops can exacerbate DNA damage. Because of dysregulation of genes, this would lead to ataxia. Decreased levels of albumin and elevated alpha-fetoprotein in AOA1 might be caused by transcriptional dysregulation in the liver.
Fimbrian legions: 86 BC – 66 BC, Lucius Valerius Flaccus. These two legions fought in the Mithridatic Wars. Legio I Germanica (Germanic): 48 BC – AD 70 (Revolt of the Batavi), Julius Caesar (emblem: bull) Legio II Sabina (Sabine): 43 BC – 4th century AD, early name of the Legio II Augusta, Octavian Legio III Cyrenaica (from Cyrene): probably c. 36 BC to (at least) the 5th century, Mark Antony Legio III Gallica (Gallic): around 49 BC to at least early 4th century, Julius Caesar (emblem: bull) Legio IV Macedonica (Macedonian): 48 BC – AD 70 (renamed by Vespasian), Julius Caesar (emblem: bull, capricorn) Legio IV Scythica (from Scythia): c.
== External links == Quantum Dots: Technical Status and Market Prospects Quantum dots that produce white light could be the light bulb's successor Single quantum dots optical properties Quantum dot on arxiv.org Quantum Dots Research and Technical Data Simulation and interactive visualization of Quantum Dots wave function
=== Europe === Marketing authorisation for 177Lu-DOTATATE was granted by the European Medicines Agency on 26 September 2017. 90Y-DOTATOC (international nonproprietary name: yttrium (90Y) edotreotide) and 177Lu-DOTATOC are designated as orphan drugs, but have not yet received marketing authorisation.
Sources: en.wikipedia.org
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.
No. Epithalamin is a heterogeneous extract containing many peptides, while epitalon is a single synthesised tetrapeptide. Publications sometimes treat findings from the two as equivalent, which is a common source of confusion. Their compositions differ and they are not interchangeable in analytical terms.
Most published work uses cell cultures or rodents because those models are faster and less costly to run. The few human trials that have been reported are small, and several lack control groups or blinding. This restricts what can reasonably be concluded about effects in people.
The powder is normally kept at −20 °C or below in a sealed, moisture-protected container. Letting the vial reach room temperature before opening helps prevent condensation on the contents.